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Why has the A340 not been fitted with only three engines? The A340 was created because the airlines wanted an aircraft they could cross the atlantic ocean with (They couldn't with their twins because of ETOPS so far). So Airbus upgraded the A330 and added two engines. Because of the four engines, the plane was now allowed to cross the ocean. However, four engines instead of two increase fuel cost dramatically (I assume). And the A340 is the same size as the A330. The A330 could fly with 2 engines. So why hasn't Airbus built the A340 with three engines instead of four. The fuel cost could have been reduced significantly without loosing the permission to cross the atlantic ocean. For example the MD-11 had three engines and also had permission to cross the ocean. <Q> Because the third engine would need to be near on centerline. <S> That means in the tail. <S> Putting the engine in the tail significantly changes its design requirements. <S> Supporting an engine requires a lot of structural support. <S> Then you need to run fuel to it. <S> The effective height of the rudder is decreased. <S> You probably need to switch over to a T-tail. <S> The center of mass is also shifted which influences where the wings need to go. <S> In short, adding a single engine requires a redesign of the entire tail. <S> While adding an engine to the wings is much simpler. <A> That would affect the airplane's handling characteristics so much that many calculations have to be redone. <S> In fact, the A330 and A340 are so similar that pilots are allowed to operate both of them with very little additional training. <S> For example, Cathay Pacific pilots who are trained on the Airbus can operate both A330 and A340 in their fleet. <S> This adds flexibility to an airline's schedule and reduce their training cost. <S> If the A340 were a tri-jet, that would not be possible. <A> Project decisions like this based on are return on investment for the manufacturer. <S> In other words, what will sales revenue be compared costs to engineer, certify, manufacture, and support be compared to sales revenue for the life of the project? <S> A center engine would require redesign of the empennage and all related systems. <S> The certification requirements and cost to add an engine to the fuselage would be astronomically higher than hanging additional engines on the wing. <S> Additional engine nacelles would have many parts and assemblies in common and would not impact as many other systems, flight controls, and aerodynamics to name a few. <A> It only needs 2 engines. <S> Twin engine jets have had ETOPS ratings for decades, 757, 767, 737, etc. <S> The engines on modern planes are gigantic, 8 ft dia fans and provide 50,000 to 60,000 lbs thrust, so they are plenty powerful. <S> Tri jet designs such as L1011 (beautiful design) and the DC10 had the issue of difficult maintenance of the high tail mounted engine and as technology improved, that configuration was phased out, although many tri's are still in service. <S> Quad engine designs are disappearing, too, except for heavy lifters and low wing designs that would cause clearance issues if larger twin engines were used. <S> No reason to use more engines than needed for the purpose.
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Adding a third engine would require re-designing the tail section, and shifting the CG considerably at the same time. Adding engines to the wings allows the minimum amount of changes to be made to the aircraft.
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Can two captains fly an airliner? If the First Officer cannot take his role for some reason, and the company only has another Captain available, can two captains fly the airliner, assuming they routinely fly as captains for that company in the aircraft of that type? Can one of them simply take a FO role for that flight? In other words, is the First Officer a separate certification that must be current? <Q> Yes. <S> What allows you as a pilot to fly large aircraft (legally under the FAA) is a type rating . <S> However one of the two of them will be performing the duties of the first officer and that should be decided prior to the flight. <S> First Officer and Captain are rankings given by the airline not any governing body. <S> Both the FO and Captain cary the type cert required to fly the aircraft (as far as I know). <S> The limited (and quickly dwindling) exception to this is aircraft that require a crew of 3 where the third is a flight engineer. <S> The Flight Engineer position does hold its own certification. <A> Two-captain pairings are possible, and not particularly exceptional even -- obviously, both captains are fully type rated in the aircraft, so together they make a full crew for the aircraft (barring a F/E as Dave points out). <S> There are two scenarios where this is common : <S> A pilot is being upgraded to Captain of a specific type or is otherwise undergoing training "on the line", such as differences training. <S> He will occupy the left seat, while the instructor Captain will occupy the right seat during his line upgrade flying. <S> A line check is being performed. <S> In this case, the line captain occupies the left seat, while the check captain occupies the right seat. <S> There is also the case where while you have a captain and a first officer, the first officer has more seniority/experience than the captain. <S> This is common with a junior captain -- <S> "green on green" rules prohibit pairing a junior captain with a junior first officer, so many times, a junior captain will fly with senior first officers until they get some seasoning of their own under their belt. <A> Yes if the captain is right seat checked - in my oufit anyway. <S> At my previous employer all capatain were approved, in my current one just management and trainers. <S> Makes for easier scheduling perhaps but requires a bit more sim time for the right seat V1 cut check.
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As long as the two Captains hold proper type ratings for the aircraft they suffice for the required two crew members needed to fly the plane.
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Which fixed-wing aircraft has the highest number of required flight crew members? Most modern airliners require two pilots to operate. Older airliners require a flight crew of three: two pilots plus one flight engineer. Has there ever been an aircraft where the number of required flight crew members is extraordinarily high, for example five or six? To clarify the question: "required flight crew member" is the number required by relevant regulations, not the number needed to physically operate the plane. If that number is not met, the plane could not legally have taken off gunners / weapon operators of military aircraft who are not necessary for a safe flight are not included flight attendants are not included <Q> The Antonov An-225 Mriya requires a crew of six- <S> you have the pilot, copilot, 2 flight engineers, navigator and a communications specialist/radio operator. <S> An-225 cockpit; image from sas1946.com <A> In addition to the An-225, a few historic examples at five, a couple at six, and one (possibly) at seven. <S> I don't know how firmly worded regulations were at the time <S> so I can't speak as to whether all of them were absolutely required to be in place for takeoff. <S> As neither of the six-crew airliners entered service, the question might be moot for them anyway. <S> Two prototype airliners with six - The Bristol Brabazon had a crew of six - two pilots, navigator, radio operator, two flight engineers. <S> The Saunders-Roe Princess also had six; again, two pilots, two flight engineers, radio operator and navigator. <S> (I can't find a clear statement, but see this cockpit diagram ) <S> At least one operational airliner had a minimum of five - The Boeing 314 had a flight crew of five - two pilots, a navigator, a radio operator, and a mechanic. <S> However, for the intended long-duration flights, it apparently carried two full crews plus two additional people - a chief engineer and a clerk. <S> Relief crew are probably outside the scope of your question, but it's not clear to me if the two additional crew would have been "required" even for a shorter flight (the engineer maybe, the clerk probably not) <S> - so the answer might be six. <S> - I say apparently because that list doesn't seem to mention gunners. <S> There may have been some duplication of roles. <S> The Linke-Hofmann R.I (did not enter service) appears to have had a flight crew of six, but the details are sketchy. <S> I think the basic "flying" crew of <S> the B-36 was five, after taking out everyone with a combat duty - two pilots, one engineers, radio operator & navigator; see this list - but it's hard to break out the exact roles and determine who was there for relief purposes. <S> The XC-99 cargo variant also had a crew of five, which seems consistent with this. <S> The Me 323 transport had a crew of five not counting gunners (two pilots, two flight engineers, radio operator) <A> While only one was built, plus two copies which were built in Italy, the Dornier DO-X with twelve engines, is listed as having a flight crew of 10 to 14 during normal operation. <S> Twelve of the relatively high maintenance engines of that era must have been a handful to keep operational during flights. <S> Dornier DO-X
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And some military aircraft with five or more - The Zeppelin-Staaken R.VI apparently had a flight crew of seven (commander, pilot, copilot, radio operator, fuel engineer, and two engine mechanics)
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Can a MEI CFI give a valid flight review in a plane for which he is not endorsed? A friend of mine is working towards his initial CFI. I'm helping him work through regulatory, weather, and other knowledge stuff when time permits. During our most recent ground session he asked me a question that I had never been asked. Here's the setup... A CFI with a freshly minted MEI (airplane, land) is asked to conduct a flight review for a customer in the customer's own Cessna 421C, a pressurized piston twin certified to >30,000'. This CFI has only flown one type of twin (pick a common training twin, doesn't really matter). He has no time at all in a 421 of any sort or any other twin aside from the trainer in which he trained for his commercial-multi and MEI. Our MEI is otherwise current in all categories and classes for which he is certified, holds a complex endorsement gained during his commercial training, and holds a First Class with no limitations. The customer is current in all categories and classes for which he is certified, is within the 24mo flight review window, and has a First Class. In short, the customer is fully qualified to be PIC for the flight portion of the flight review. What's obvious: The five hour rule does not apply since a flight review is notinstruction given for a certificate or rating. Our MEI cannot act as PIC of the customer's 421C because the MEI is missing a high altitude endorsement and a high performance endorsement even though he is category and class certified for airplane multi land. A CFI does not need to be PIC, or even hold a medical, in cases where the student/customer is able to act as PIC. Edit: it's a really bad idea to do fly an aircraft type with which you are not familiar. The question is this: Can our fresh MEI give the customer a valid flight review in the customer's 421C? <Q> The flight instructor is limited to give training in the category and class ratings of their pilot and instructor certificates, not by make and model. <S> Per §61.193 and §61.195 <S> the flight instructor is authorized to train and issue endorsements for a flight review <S> so long she or he holds a pilot certificate and flight instructor certificate with the applicable category and class rating. <S> Furthermore, per §61.51(e)(3) , the flight instructor may log pilot in command flight time for all flight time while serving as the authorized instructor in an operation if the instructor is rated to act as pilot in command of that aircraft. <S> The instructor is advised according to Advisory Circular: <S> AC 61-98C , Section 4-2 Paragraph e. Instructor Qualifications: <S> Instructors should also consider their own experience and qualifications in a given make and model aircraft prior to giving a review in that model... ... <S> To conduct a flight review in a multiengine airplane, the instructor must hold an airplane multiengine rating on their pilot and flight instructor certificates. <S> For aircraft in which the CFI is not current or with which he or she is not familiar, he or she must obtain recent flight experience or sufficient knowledge of aircraft limitations, characteristics, and performance before conducting the review. <S> In any case, the CFI must observe the rating limitations of § 61.195. <S> So, yes. <S> An appropriately rated flight instructor (whether or not <S> they should ) is authorized to conduct the flight review. <S> What's more, even if the instructor is not qualified to act as PIC (e.g. does not have a high-performance training endorsement), that instructor will still log pilot-in-command time as instructor because he or she is appropriately rated to do so. <A> I may be oversimplifying, but it looks to me like the main question here is just "can an instructor give a flight review without acting as PIC?". <S> You've given one specific example of why the instructor can't act as PIC, but there could be others. <S> The short answer is that as long as the pilot can legally act as PIC, the instructor doesn't have to. <S> AOPA has a nice guide that gives this advice for instructors: 35. <S> Who acts as pilot in command during a flight review? <S> This question should be resolved before the flight so that both you and the pilot have a clear understanding of PIC responsibilities. <S> You should inspect the pilot’s logbook, pilot certificate, and medical certificate to ensure that he or she is qualified to act as pilot in command. <S> If the pilot does not meet the pilot-in-command requirements, you must assume that role. <S> While you are in the process of inspecting paperwork, don’t forget to check the status of the aircraft. <S> Is it airworthy? <S> There's also a secondary question of whether it's a good idea for an instructor to give a flight review in an aircraft that he isn't familiar with. <S> STWilson's answer covers that nicely. <A> Your "What's obvious" list pretty much sums up the issue. <S> As a CFI, I would insist that a written note attesting to the fact that the customer is accepting his/her role as PIC be signed and remain behind on the ground. <S> This ensures that should a potential violation, incident, etc. <S> occur during the flight, the customer is on record acknowledging PIC responsibility.
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As long as it is clearly decided before the flight begins that the CFI is NOT going to act as PIC, there is nothing in the FARs that would preclude giving the customer the Flight Review.
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How should I deal with a cable break at low level during a glider winch launch? What should I do when rope breaks at 220-360 ft [75-120m] when there is not sufficient runway to land ahead and not sufficient altitude to make a return manuover and land with the wind direction? <Q> Depends on the wind and the surrounding area. <S> If there is enough headwind, you will be surprised how short your approach will be in a proper sideslip. <S> Practise sideslipping at altitude, so you know what to do in an emergency! <S> Otherwise, look around for an open field where to land; gliders are easily disassembled and carried back to the airport. <S> When the cable breaks, push the stick forward. <S> Be prepared for dirt flying up and into your eyes if you push hard enough! <S> Then stabilise at the minimum sink speed, release the remaining cable and look around for your options. <S> There should be some: <S> Fly straight a bit, then turn around 180° and land opposite to your direction at take-off. <S> Do this only when there is no or almost no wind! <S> 100m of altitude is plenty enough for this trick. <S> Keep flying straight and land on an open field near the airport. <S> If the airport is surrounded by forest or houses on all sides, try to land on the glider port - normally, the altitude bands required for the landing straight on, the 180° return landing and a landing from a proper pattern overlap enough so that there is never an altitude that would not allow to land on the airfield. <A> It depends very much on your field which is why (in the UK at least <S> ) you list Eventualities (usually cable breaks) as part of the CBSIFTCBE pre-flight checks. <S> Usually you have Low level - land ahead, higher level - part turn and cross field landing, higher again-turn and reciprocal landing and higher <S> still-run a truncated circuit and land as normal. <S> My main field has crops or turf fields ahead depending on wind direction <S> so I have a lot of scope for a forward landing <S> , it is a wide field with two main strips and a short diagonal strip so a cross field landing is possible and it is a long field so a reciprocal landing is straightforward. <S> Your best bet is to ask advice on your specific field from the CFI. <A> when there is not sufficient runway to land ahead and not sufficient altitude to make a return manuover and land with the wind direction <S> If this is really case, I would not launch in such site. <S> But since you have winch there I assume its fine - maybe its just your feeling? <S> ~90 <S> m alt when cable was broken, with return option, with 10 m/s wind - downwind landing, <S> and I ended up 25cm before a fence on the end of an airfield <S> 10 m/s is a lot ( 20knts, 36 km/h), if you manage to do tailwind landing, it means you probably could land ahead as well... <S> Anyway, BGA has great sources about safe winch launch: https://members.gliding.co.uk/bga-safety-management/safe-winching/
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Fly a triangular, shortened pattern and land in the regular direction. Land straight away if headwind plus sideslip allow for a steep descent.
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Is induced drag caused because of the tilt of the wing backwards? In this question: Why is induced drag less on a high span wing? In the answer it was stated that wing tip vortices do not cause induced drag. If this is the case then what causes the induced drag. Thinks about this for 10 minutes What if the Induced drag occurs because of the tilt backwards of the wing. Do the vortices just make the induced drag worse but, not cause it. So basically I am asking if the backwards tilt of the wing causes induced drag and how do the wingtip vortices affect the induced drag This may sound like a duplicate of: Is induced drag not caused by tip vortices? but, It is not because I am asking if the induced drag is causes by the tilt of the wing. I am not asking if induced drag is caused by wing-tip vortices or not. <Q> I look at it from two different perspectives. <S> The airfoil is designed to accelerate air thus creating the pressure differentials that make the plane fly. <S> The higher pressure areas will try to push the wing toward the lower pressure areas. <S> The overall sum of these forces is called the resultant force. <S> That resultant force will have an amplitude and a direction or vector associated with it. <S> The goal of designing an airfoil is to orient those forces upward to counteract gravity. <S> So the designer will make the low pressure areas on top of the wing and the high pressure areas on the bottom to make the vector point upward. <S> A perfect airfoil would create a vector pointing directly upward, 180° from the ground and 90° from the direction of travel. <S> In reality, nothing is perfect, so that vector is always pointed backward to some degree. <S> So we break that resultant force into two components. <S> The part we're trying to accomplish, which is 90° from the direction of travel is called lift and the remaining part which is 180° from the direction of travel is called the induced drag since it is induced by the creation of lift. <S> Even a wing producing lift at a 0° angle of attack will still produce a certain amount of induced drag. <S> Now we come back to your explanation. <S> Although any time a wing is producing lift it will also produce some induced drag, as you increase the angle of attack the vector of the resultant force tilts back with it. <S> Not necessarily at exactly the same rate, but usually not far off. <S> Since we are still defining lift as 90° from the direction of travel and drag as 180° from it, the ratio between the two changes. <S> For every bit of lift produced there is a lot more drag the further you tilt the wing back. <S> The second way of looking at it is from the inertia point of view. <S> The intent of the wing is to accelerate air downward. <S> Once again, a perfect airfoil would accelerate the air straight down, but in reality it will always accelerate it slightly forward also. <S> And as you tilt the wing backwards you will produce more forward movement and less downward. <A> You're on the right track. <S> Induced drag is caused by a rearward component of aerodynamic force. <S> And to be certain, whenever there is lift, there is drag. <S> The more a wing "plows" at slow speed, vs "planes" as higher speed, it will create more induced drag. <A> You can say, as above, that the drag is the horizontal component of the tilt to the overall lift vector. <S> You can just as easily say the tilt of the overall lift vector is due to the drag. <S> So what causes the drag? <S> Lift is ultimately created by deflecting the airstream downwards (Newton's action/reaction law). <S> As such, the wing is adding energy to the ambient air by deflecting it. <S> Adding energy to the air requires energy from the aircraft. <S> Energy is force times distance. <S> That force is the drag. <S> You can get a given amount of lift by deflecting a small amount of air at a high velocity or a large amount of air at a small velocity - the change of momentum is the same (m*v is the same). <S> But the change of energy (.5*m v v) is not - the high velocity option costs more energy so has higher drag. <S> So? <S> A short wing deflects less air <S> so does so at a higher deflection compared to a long wing. <S> In other words, high aspect ratio wings (sailplanes) have a higher lift to drag ratio than low aspect ratio (stubby) wings, all else being equal. <S> All of which is why the vector points back a bit - <S> and there's a drag component.
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Although your explanation isn't entirely wrong, It isn't necessarily the backward tilt of the wing , but the backward tilt of the aerodynamic force .
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How do wing tip vortices interact with the airflow on an wing with winglets? If winglets are added to an aircraft, do the vortices still interact with the airflow and create up wash and down wash. If the vortices do interact with the rest of the flow I am wondering how they do it. So basically I am asking if wingtip vortices can affect airflow when there are winglets on an aircraft. <Q> Winglets do not change the laws of physics. <S> In particular, they do not change the flow around a wing such that there is no up- or downwash. <S> All they do is to involve a little more air into the creation of lift such that the vortex strength is slightly reduced. <S> With winglets, wingtip vortices now form at the tip of the winglet instead of at the wingtip. <S> The wake behind the wing still rolls up and creates the usual wake vortices into which the wingtip vortices are absorbed. <S> In order to create the same lift with a slightly less powerful vortex, the distance between both vortices is increased slightly. <S> Actually, in order to support the winglet's weight, the aircraft needs to create slightly more lift with winglets than without, which reduces their benefit. <A> It depends what you mean by Wingtip Vortices. <S> If you mean the ones from this answer, no amount of winglet will prevent them. <S> These are the consequence of lift creation, and mainly influenced by weight and airspeed. <S> A very long winglet would prevent that, but a Cessna would still flop around mightily when it falls into the hole that the A380 wing left behind at approach speed. <S> The wing tip is where lift creation ends, and there is a discontinuity there, winglet or not. <A> Without winglets the wingtip vortices (or wake turbulence) stabilize at about two thirds of the wingspan. <S> The closer the wake turbulence is to the planes body the more drag is induced. <S> Winglets virtually extend the wingspan (by a multiple of their own length) so that the wake turbulence stabilizes more distant from the body and thus the winglets reduce the induced drag.
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Strictly speaking, wingtip vortices are only the bit of air that flips around the tip of the wing.
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Will air traffic control ever ask a plane to not brake hard on a landing? In another question , somebody asked why an airplane might not deploy thrust reversers on a landing. One of the answers suggested a few options, including: Depending where the gate was, they may simply have wanted use more of the runway to speed up the taxi It occurred to me that it's not just a matter of a pilot wanting to get to the gate sooner; it could be that ground control wants them to take that last exit (for whatever reason), but air traffic control wants them off the runway quickly so that they can use it for another airplane. I assume the final decision of how to conduct the landing is the pilot's. But will air traffic control ever ask nicely, "you're going to be taking the last exit, but please don't do the final bit of braking until the end, because we'd like to get another flight taking off right after you land"? <Q> Yes, we can ask you to plan your landing roll in a certain way. <S> We won't technically instruct you to brake the aircraft in a specific way, but simply to aim for a specific taxiway after landing. <S> There can be different reasons for this, but generally it is an attempt to expedite traffic flow on the ground at the airport. <S> For example, if you are landing on a long runway and your parking position is near the far end of the runway, I might ask you to keep the plane rolling down the runway and vacate at the end, in order for you to have a shorter taxi time. <S> However, extending the landing roll does extend the runway occupancy time as well, so if there is another aircraft behind you on short final I will not offer you to perform a long landing roll. <S> This is also why you should always ask ATC if you are planning to perform a long landing for one reason or the other – if we have someone else just a couple miles behind you, we might have to instruct them to go around if you do not vacate the runway like we expect you to. <S> With regards to reverse thrust specifically, there are airports where the use of reverse thrust is only permitted in special situations. <S> This is to reduce the noise level at and around the airport. <S> However, this is purely a regulatory thing, and is not actually related to ATC. <S> ICAO offers the following guidance on the subject (DOC 4444): <S> 7.10.3.1 <S> When necessary or desirable in order to expedite traffic, a landing aircraft may be requested to: a) hold short of an intersecting runway after landing; b) land beyond the touchdown zone of the runway; c) vacate the runway at a specified exit taxiway; <S> d) expedite vacating the runway. <S> 7.10.3.2 <S> In requesting a landing aircraft to perform a specific landing and/or roll-out manoeuvre, the type of aircraft, runway length, location of exit taxiways, reported braking action on runway and taxiway, and prevailing meteorological conditions shall be considered. <S> A HEAVY aircraft shall not be requested to land beyond the touchdown zone of a runway. <A> Situations vary, but more than once I have been asked to: "Extend rollout to the end of the runway" "Land long on the runway" <S> "Will you accept a landing after the half-way point on Runway 4, 6,000 feet remaining?" <S> Addendum <S> #1Heard yesterday, the tower telling a bizjet, while on 2 mi final, "123MA, cleared to land 27, taxi to end of the runway for left turn at Alpha." <A> There are times that ATC can and does ask for the aircraft to turn off of the runway at a specific point. <S> From the FAA Order 7110.65W, para. <S> 3-10-9, the phraseology would be something like: Example: <S> "IF ABLE, TURN LEFT/RIGHT at . . . <S> " <S> Taxiway Bravo; Or, "Land and Hold Short Operations" (LAHSO), ref: para. <S> 3-10-4 b. in the 7110.65W, the phraseology would be something like: Cleared to Land "Hold Short of Runway" One Two. <S> A couple of points: <S> Controllers should not/do not normally issue runway exiting or taxiing instructions prior to or immediately after touchdown (ref: 7110.65 para. <S> 3-10-9 NOTE). <S> Also, if ATC issues (using IF ABLE phraseology) taxiway or runway exiting instructions it is for expediting traffic and not to ensure legal separation will exist between airplanes. <S> The legal separation (assuming normal operations) should exist in anticipation that the pilot might not be able to make an early turnoff. <S> Normally LAHSO operations are advertised on the ATIS and are used during simultaneous/intersecting runway operations. <S> There are various limits as to what type of aircraft can use the LAHSO and the pilot can always refuse to accept the clearance. <S> If refused or the aircraft type is not authorized for LAHSO, ATC will ensure that no intersecting runway traffic will pose a confliction. <S> Lastly, there are some times that the pilot will request to roll-out to the end of the runway, for example, to get to the aircraft's parking spot quicker. <S> This would normally be a light aircraft and not an air carrier. <S> You can read about these procedures: <S> FAA Order 7110.65W can be found here
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It could also be that the taxiway you would normally use to leave the runway is blocked by another aircraft or vehicle, and I want you to leave the runway via a taxiway that is further down the runway.
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Is there a maximum or minimum temperature for take-off and landing? Is there a maximum or minimum temperature that a plane can take off or land at? <Q> There is a maximum temp but that varies by airport altitude, runway length, aircraft and payload. <S> You can find an answer to that question here . <S> There is not really a minimum temperature but it needs to be warm enough out to run the engines. <S> Again this varies by aircraft and a preheat can usually solve this problem but there are places on earth where it be comes practically to cold to operate some aircraft. <S> On a similar note if icing conditions prevail you are not really going anywhere but those can occur at lots of altitudes and temperatures. <S> If the given airplane is stored outside and the airport lacks proper de-ice equipment you may be grounded. <A> Maximum and minimum temperatures are governed by two factors. <S> First, there is the limitations imposed by the manufacturer. <S> For example, recently the media has been reporting that some regional jets have max temps for operations, and they have been unable to operate in the southwest US. <S> Some manufacturers also limit low temperature operations, and may require different lubricants, fuel, etc. <S> Second, aside from manufacturer (or company) limitations, there are practical limitations. <S> Engines can be hard to start at -40. <S> Fuel can gel. <S> Batteries can render insufficient power to perform normal starts. <S> These limitations are normally determined by practicality, experience or other sources of information by the crew. <S> In my experience, dealing with hot soaked planes is normally easier than dealing with cold soaked planes. <S> Other issues like density altitude (DENALT) are operational issues, that while normally are considerations, are usually not hard limitations. <S> For example, departing a 1200 foot strip in South American mountains on 35C days has been a limitation with a turboprop aircraft, for me, but the number of times I have had those operational considerations limit flight can probably be counted on my fingers and toes. <S> So in general, there are two limitations: <S> Those imposed by the manufacturer and the aircraft certification, and those imposed by practicality (which includes best practices). <A> Yes, there are some temperature limitations, but these are typically aircraft specific. <S> For example, the Beechcraft King Air B200 has the following limitation: <S> Max Outside Air Temperature Limitations Sea Level to 25,000 FT pressure altitude: ISA + 37 <S> ° C <S> These limitations are given in the AFM, and compliance is required. <S> Practically speaking, this limits aircraft operation of any kind—including takeoff and landing. <S> Takeoff would not be authorized at sea level above 52°C, or at 5000 ft pressure altitude above 42°C. <A> The aircraft's Pilot Operating Handbook will include a set of performance charts. <S> To determine whether you can safely takeoff or land, you would plot the values (including temperature) into the chart. <S> This related question discusses some of the precautionary steps one should take when operating in very cold or hot weather. <S> In general, aircraft performance will be the limiting factor in hot weather, and in cold weather the challenge is to get things started and stop things from freezing. <S> There is no absolute temperature regulation-wise. <S> Practically you can argue that the minimum temperature is when the fuel freezes and the maximum temperature is when the tire melts, but you will likely run into other troubles before this extreme is reached.
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It depends on the model of the plane, particularly its engines, the length of runway available, and surface wind conditions. For a minimum temperature, the engines have a starting limitation of at or above -40°C.
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Can a GA magneto-spark plug ignition survive an EMP? Can the coil and capacitor (condenser) magneto/spark plug ignition system as exists on most general aviation aircraft survive an EMP? Let's talk about a standard Lycoming or Continental engine. How about most turbine engines? I'll use a PT-6 as an example. I assume the FADEC would be toast? How about other parts of the electrical system such as the battery? Is there any data or research on this? <Q> Can the coil and capacitor (condenser) magneto/spark plug ignition system as exists on most general aviation aircraft survive an EMP? <S> Like anything it depends on the EMP's strength, the angle of incident to the device and the device in question. <S> The various things in an aircraft will break down for different reasons. <S> But for the rest of this lets assume an EMP that is sufficient to fry stuff. <S> A magneto will suffer toasted coils as the induced current could potentially generate enough heat to degrade the resin coating on the wire they use on coils. <S> It should however be noted that the magneto is more than likely shielded to prevent interference with avionics which will play out in your favor here. <S> How about most turbine engines? <S> I'll use a PT-6 as an example. <S> I assume the FADEC would be toast? <S> Most likely yes. <S> Again the unit is generally housed at least in some capacity in a shielded case but modern PCB components don't play nice with large induced currents. <S> Turbines do have an Igniter system that may see some damage depending on the severity. <S> How about other parts of the electrical system such as the battery? <S> Things like interior lights will most likely blow out, batteries (depending on type and casing) could go. <S> Overheating is a concern if enough current is forced over the line. <S> Is there any data or research on this? <S> There is some Mil-Specs (MIL-STD-1541 (USAF)) out there that cover it for the military. <S> This question covers it for airliners . <S> You can find at least one book on the topic here . <S> There was a lot of research on this that pertains to missile systems as one anti-missile defense was to detonate a nuke in front of the oncoming unit. <S> If the blast did not take it out the resulting EM field would fry what ever guidance and control systems were on board (assuming it was not ballistic). <S> As such, work went into making the units EMP hardened. <S> I'm not sure that work is very public though. <S> The soviets were big users of vacuum tubes as they believed them to be far less susceptible to EMP's. <S> It looks like this company does testing and research on EM hardened aircraft. <A> Concerning ignition, and if no semiconductors are used (some capacitor-discharge systems use SCRs) there is little possibility of any damage, since coils, capacitors or mechanical switches can withstand very high transient currents. <A> All electrical devices are susceptible to EMP to varying degrees. <S> EMP causes a disruption in the electrical and magnetic field (see Wikipedia ). <S> The magneto uses magnets and coils to generate AC pulses. <S> When a strong magnetic or electric field passes through such a system excess current and voltage would likely be introduced and so a device who's operation depends on magnetic fields would likely falter (though maybe not fail) during a magnetic event. <S> The wires in a coil have a thin insulation on them to keep from shorting to other coils or the component body. <S> A high voltage spike could cause that material to fail and create a short. <S> Another concern is that large currents amplified via transformers could cause other components (and even the transformers themselves) to fail like during the 1989 geomagnetic storm . <S> In your aircraft a few critical items could cause a similar failure. <S> The ignition coil could amplify current flow on the battery side of the system. <S> While a fuse would likely blow in this scenario it's conceivable that a string of smaller pulses wouldn't trip the breaker and could damage the battery or other components on that system. <S> If a high voltage/high current system like a power station can be effected it seems likely that a close pulse to an aircraft would cause similar failure, or at least degradation, to discrete electrical components.
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One concern is that all discrete electric components have sub-components (usually insulation) that have a maximum breakdown voltage .
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Is it possible to upgrade a Boeing 747-8 and Airbus A380's engines for greater speed? Is it possible to upgrade the Boeing 747-8 and Airbus A380's engines (upgrading to a newer engines) for greater speed, if the engines were more efficient and used less fuel at higher speeds relative to distance? If so, what are the maximum speeds that the airframes or entire aircraft could handle or are designed to handle? <Q> I just wanted to comment on this question since some of my code is on the A380's GE engine. <S> Those engines are optimized for fuel efficiency at their cruising altitude and speed. <S> The tradeoff that you fight against when designing the engine for cruising altitude is that it makes the engine hard to start, and the stall margin (the pressure and fuel combo <S> you need to keep the engine from stalling) is razor thin when they are on the ground. <S> Just to echo what Kevin said, any improvements to allowing the engine to start without stalling would surely go to the fuel efficiency, not to speed. <A> The limitation is the airframe. <S> If you try to push it faster, you will run into aerodynamic problems, for example part of the flow is supersonic around certain areas of the wing. <S> It is undesirable and cannot be changed without redesigning the airframe. <S> However, other things are relatively easy. <S> Even if you do nothing to strengthen the structural elements, an improved engine would allow better climb performance, shorter runway length under the same conditions etc. <S> It will give airlines more flexibility. <S> Better efficiency means lower fuel consumption, which translates to either more payload or more flight distance, again giving more flexibility to airlines. <A> Since there is inevitably a big change in the aerodynamic behaviour of any plane at Mach 1.0, there is a relatively limited speed gain to be had from pushing beyond Mach 0.85 before some parts of the airflow become transonic and the whole design would need to be changed. <S> The same applies to the air flow within the engine itself. <S> Supersonic aircraft don't have large diameter, high bypass ratio, wing-mounted engines with (at least conceptually) <S> simple intake designs. <S> From the customer's (i.e. the airline's) point of view, the simplest way to operate a plane is to be able to cruise at the same speed as everyone else when flying busy routes (e.g. transatlantic from Europe - USA), not by trying to jump the queue and save a few minutes. <S> It would certainly be technically possible to do what the OP proposes, but it's not economically sensible if either the customer or the manufacturer wants to run a profitable business. <A> Airfoils and frame are optimized for a certain speed. <S> The newer aircraft are optimized to operate closer to the trans-sonic regime, if not in it. <S> The 747 is a great workhorse, and was designed to actually fly quite fast. <S> Pan Am wanted the 747 to fly at 0.9 mach, but Boeing made a compromise of 0.87. <S> Realize that all of this was before the oil crisis of the 1970s and the current stringent regulations on engine emissions. <S> The thing is the 747 was designed back in the 1960s and <S> I am sure its drag profile is a lot bigger than current aircraft that can fly 0.87. <S> Now the issue one will have to take into account <S> is cycle time for a 747. <S> Fatigue will be setting in for older aircraft as opposed to one that is in mint condition... <S> right off the factory floor. <S> The wings will be a little less stiffer and aero-elastic effects can become more prominent for the 747 at 0.87 compared to several decades ago.
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If the engines are upgraded to "better" ones, the manufacturer would make it result in increased carrying capacity or increased range (or both), but not increased speed.
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Can a human be blown away by jet engines of an A380? Can a human be blown away by jet engines of an A380 at full throttle? If so what is the largest object that it can blow away and cause significant damage? Can it blow away another parked Airbus A380 and cause damage? Can it perhaps blow away the A320 and cause damage? If so what is the safest parking distance between aircraft, with regards to jet air at full throttle. What are the safest recommendations? <Q> Absolutely. <S> Other (large) airliners, not so much. <S> It depends on the aircraft's size, weight and distance from the engine actually. <S> There are records of a F-16 being tipped over by a B-1B Lancer ; as the thrust of an A380 engine is quite higher than that of the Lancer, the damage would be worse. <S> The minimum safe distance between the aircraft varies depending on the aircraft and engine type. <S> For example, according to the Australian Civil Aviation Order 20.9 - Air service operations - Precautions in refuelling, engine and ground radar operations : An aircraft engine shall not be started or operated: ... (b) within 8 metres (25 ft) of other aircraft; ... turbine engines, in addition, shall not be operated within the appropriate distance specified below of any other aircraft, fuelling equipment or exposed public areas which lie to the rear of and within a 15 degree arc either side of the exhaust outlet axis of that engine: Minimum distance between aircraft for operation of engines; image from Civil Aviation Order 20.9 - Air service operations - Precautions in refuelling, engine and ground radar operations <A> Here is a youtube clip from the Top Gear television show, where they show what the blast from a 747 engine can do to cars. <S> Top Gear jet engine blast demonstration <S> The answer is: yes, exhaust blast from a jumbo jet engine can do considerable damage, to a person or to a vehicle. <A> Manufacturers publish this kind of information in aircraft characteristics documents, as it is useful for airport planning and operational safety. <S> You can find the A380 document here . <S> The document lists the exhaust danger area at max takeoff power. <S> For the Trent 900, this extends 1800 ft aft of the nozzles, and the GP 7200 extends 1553 ft aft. <S> Anything not bolted down should probably be removed from this area. <S> The document also lists exhaust velocities. <S> At max takeoff power, for GP 7200 engines, the exhaust velocity exceeds 105 mph out to 724 feet, and 65 mph out to 1090 feet. <S> Higher velocities are not labeled. <S> On Physics. <S> SE , it's been calculated that 45 mph is enough to move a person, and 70 mph could start to overcome gravity (depending on orientation). <S> So if you don't want to be blown over, it's probably best to stay out of the exhaust danger zone. <S> This paper suggests 95 mph is enough to tip some high profile trucks, trailers, and buses. <S> 200 mph is enough to tip most cars, vans, and pickups. <S> If the vehicles are light, much less than this could be sufficient. <S> Based on this info we know that at full power, large profile vehicles could be tipped over even at almost 750 feet behind the aircraft. <S> Aircraft designed to fly at slower speeds or lighter aircraft could easily be picked up by these high wind speeds. <S> Tornadoes have been known to move aircraft as large as a C-130. <S> Jet aircraft generally do not go to max takeoff power unless they are starting their takeoff. <S> Engine speed is usually limited in ramp areas for safety. <S> For engine run ups, the aircraft go to dedicated areas with jet blast deflectors. <S> Even at ground idle, the exhaust danger area extends 230-280 feet aft of the nozzles. <S> You may also want to consider temperatures, which can exceed 212 F up to 100 feet aft of the nozzles at takeoff power. <A> Here's a person being blown away by an A320. <S> You can test it out yourself at St Maarten, a lovely tropical island in the Caribbean! <S> Park your car in the jet blast and see what it does. <A> Can a human be blown away by jet engines of an A380 at full throttle? <S> yes Human will blown away without any doubt. <S> If so what is the largest object that it can blow away and cause significant damage? <S> Jet-Engines will have high thrust,it will easily blow away car in close proximity. <S> Can it perhaps blow away the A320 and cause damage? <S> If it blown form front then It will not blow away the another Flight bus <S> it will give significant lift so that another aircraft will tilt little bit. <S> If so what is the safest parking distance between aircraft, with regards to jet air at full throttle. <S> What are the safest recommendations? <S> As per the aviation rules no aircraft will be in full throttle in parking. <S> Full throttle will be applied Only while take off on runway.
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The jet engines used in airliners are quite powerful and can easily blow away human beings, vehicles and small aircraft .
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Why do aircraft have two brake pedals instead of one? Why do aircraft have two brake pedals instead of one? If each pedal controls different sets of wheels e.g. the left wheels and the right wheels of the main gear, is that not a safety flaw given that at any point in time, it is impossible for the pilot to apply an equal amount of pressure to the brakes? Isn't ABS enough to the point that only one pedal is enough? Finally do both captain and pilot step on the brakes at landing? If not then why have two pedals? <Q> In an aircraft the brake pedals control the respective side brakes. <S> This allows for the pilot to turn the aircraft not only with the pivoting nose wheel (if it has one) but also with the brakes. <S> This allows for a very tight turning radius. <S> ( source ) <S> If each pedals controls different sets of wheels eg the left wheels and the right wheels of the main gear, is that not a safety flaw rather than measure given that at any point in time, It is by design to allow for the tight turning. <S> Some smaller aircraft also do not have a steerable nose wheel so differential braking is the only option. <S> it is impossible for the pilot to apply an equal amount of pressure to the brakes? <S> Pushing equally on each toe pedal will result in equal brake operation. <S> Isn't ABS enough to the point that only one pedal is enough. <S> The pedals allow for brake steering which a single pedal would prevent. <S> Airplanes also do have ABS but that simply prevents the tires from skidding. <S> Finally do both captain and pilot step on the brakes at landing. <S> IF not then why have two pedals? <S> Im not sure, when I fly with an instructor or co-pilot in smaller planes only one person operates the brakes. <A> The left pedal is for brake(s) on the left side of the aircraft only, and likewise the right pedal for the right side. <S> We use two pedals because it is common where differential braking are applied, in other words different amount of braking on the two sides of the aircraft. <S> This is handy for maneuvering the aircraft around corners. <S> For example if the plane needs to be turned to the left 90 degrees to enter a taxiway, and the length of the fuselage is long, applying left brake during the turn can reduce the turn radius, making it possible to turn without the outer set of wheels running onto the grass. <S> During a normal landing rollout, equal amount of pressure is applied to both pedals. <S> The difference between both pedals caused by human application is minimal and does not have an observable effect. <S> Usually, only the pilot flying would be operating the controls, therefore only the pilot flying would apply the brake pedals. <S> Except in an emergency where stopping distance is critical, the pilot monitoring may apply pressure to his own pedals to ensure maximum braking is achieved. <A> Note also, the pedals are used to swing the rudder to the right and left, to yaw the aircraft, so two pedals are already there. <S> It then makes perfect sense to split the brakes for all the above reasons. <A> In light planes, differential braking eliminates the need for a steerable nose wheel. <S> Instead, the nose gear simply casters, rotates as differential braking alters the path of the aircraft while in taxi. <S> This makes for a much simpler and lighter nose wheel, plus no linkage to a wheel in the cockpit. <S> With aircraft, simple is good. <S> Simple doesn't go wrong as often as complex. <S> In heavy aircraft that usually have a steerable nose wheel, differential braking takes a lot of stress off of the nose wheel. <S> Steering a heavy aircraft with the nose wheel alone puts a lot of angular stress on it. <S> If all steering was done with the nose wheel, it would need to be beefed up to handle that, on top of being retractable. <S> Differential braking on a heavy aircraft makes for a lighter nose gear arrangement.
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To add to the correct answer: two brake pedals allow for differential braking to steer the aircraft when it is on the ground Heavy aircraft are, well, heavy.
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What is this radar-like thing? A friend of mine sent me this picture, which Is somewhere in Miami. But I don't seem to recognize it <Q> It is a wind tee; it serves the same function as a wind sock. <S> It is designed to resemble an airplane from the air so that pilots overflying the field can more easily determine in which direction they should land. <S> The top of the "T" is the front of the airplane and represents the direction in which an airplane should land. <S> When the wind hits the vertical tail surface it weathervanes. <S> The tail points in the direction that the wind is blowing. <S> Unlike the wind sock, the wind tee does not provide wind speed information, only wind and landing direction. <A> this website shows various wind direction indicators <A> It's a weathervaning landing T , one of the standard landing direction indicators defined by ICAO , complete with lights for use at night. <S> That sign, together with others, is often placed in the airfield's signal square , such as this one: (source: Touchdown Point ) <S> The tail of the pivoting T, thank to its vertical fin, always points downwind, showing to overflying pilots the landing direction as the one that would make you read the symbol as a 'T'. <S> Other, simpler installations have a T lying on the ground that is rearranged manually to switch between the two landing directions of the runway, if present. <S> It is unclear what the symbol itself is supposed to represent, if anything. <S> The original Annex 14 of ICAO's Convention on International Civil Aviation (p. 42) - first published in 1951 - only specifies shape, size and color of the landing T; no rationale is given.
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It's a lighted 'wind tee'.
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What is the shed bus in the Phenom 100? I recently came across a part of the electrical system of aircraft named SHED BUS . I am specifically asking for the Embraer Phenom 100. Source (Page 122) , Added red square What is the SHED BUS for and what is it doing? <Q> The shed bus powers non-essential aircraft systems. <S> In the case of the phenom 100 this is things like the air conditioning, passenger power sockets and entertainment systems, the toilet and some lighting. <S> The shed bus is the first thing to lose power (be shed) should the aircraft not be generating enough electricity through, for example, a generator dropping offline. <A> By powering off the shed bus, all non-essential loads can be removed in the case, for example, of a generator or engine failure with a single action rather than having to switch systems off one by one. <S> This might happen either automatically or via a cockpit switch or both. <A> Embraer aircraft have automated Electrical Distribution Logic (EDL). <S> The intent to to minimize crew workload. <S> Part of the EDL protects the generators from being overloaded. <S> It does that by disconnecting the Bus Tie Connector (BTC) for the Shed bus. <S> This typically occurs when one generator (or more) goes off line. <S> The Shed bus itself provides power to non-essential systems, such as the galley and reading lights.
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A SHED BUS is used to provide power to non-essential systems.
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Is there any disadvantage to slipping as a way to lose altitude? I learned how to slip during my powered training as a way to lose altitude when too high and, of course, a way to track the runway center-line during a crosswind landing. Quite a bit more emphasis was put on slipping during my glider training. I guess the reason for this is pretty much common sense. There is no concept of a "go-around" when landing a glider...you only get one shot. That said, I don't practice slips often enough when soaring because purposefully losing altitude in a glider is counter-productive, except when too high in the pattern. For this reason, I've now gotten into the habit of using a slip to descend when flying powered. This allows me to practice slipping with the knowledge that I am guaranteed by virtue of having an engine to have the option of regaining that altitude. Note: I usually only do this while flying solo since slipping can be a comfort issue for passengers. This got me to wondering... Questions: Putting aside the comfort of passengers, Is there any disadvantage to always using a slip to descend when flying powered? If not, why does it seem that this method of losing altitude is not used/taught more frequently? Update after reviewing answers I wanted to give this some time to stew before I checked an answer. I came into this fairly (but not absolutely) certain that the short answer was no. I think the responses confirm this. I understand the need some have to "warn" against stalling, but I don't really see how this warning couldn't be applied to any maneuver and really has nothing to do with the fact that you are slipping, short of making a mistake...like skidding instead. The conclusion I'm taking from the answers is: Slipping can be uncomfortable to passengers, pretty much for the same reason that healing in a sailboat can be perceived as uncomfortable. Slipping is aerodynamically inefficient. Since the objective is to lose altitude, this would appear to be a benefit, rather than a detractor. That some planes, in some configurations, have restrictions on when slipping is allowed/recommended/optimal. That slipping will get you down faster, thus making it preferred if getting down faster is the objective. <Q> To address your questions: First, slips are perfectly reasonable for controlling descents. <S> In some aircraft, for example, many Cessna 172s, are placarded warning against extended slips with full flaps. <S> In the 172 case, there may be some buffeting. <S> Years ago, slips were emphasized more than they are today. <S> Of course there were more primary aircraft without flaps then. <S> So today the vast majority of primary trainers have flaps, and with time instructors have simply avoided emphasizing slips as much. <S> Consequently, the forward slip becomes more of a saving maneuver than a routine maneuver. <S> Your mileage will vary. <S> Most instructors will emphasize them for more "urgent" maneuvers like making a field with a simulated engine out. <S> Addendum <S> #1Being the best pilot you can means constantly developing skill and adding new tools to your bag. <S> Slips are normally covered when doing simulated engine outs. <S> I also cover them first with pre-solo students when we cover other emergencies such as flap failure (asymmetric flap extension) or electrical failures with electric flaps. <S> Slips are also helpful when there is a cabin fire, and help clear smoke faster (it's never really fast enough) in planes with bilateral windows. <S> Addendum <S> #2Slips have an advantage over flaps, in a temporal sense. <S> You can slip, and then take it out, then put it back in. <S> As much or as little as you want. <S> Since flap changes normally mean trim changes, and in the case of the 172 there is a flap motor limiting application and removal rates, the same cannot be said for using flaps. <S> As an example, landing during very turbulent and gusty conditions, I might only use partial flaps, and use slips for glide path management, particularly if going to some mountain top strip with all kinds of up and down drafts influencing the path. <S> Just another thought, for someone as they consider enhancing their proficiency with slips. <A> Putting aside the comfort of passengers, Is there any disadvantage to always using a slip to descend when flying powered? <S> No not really. <S> Practically speaking it's well within the maneuvering limits of the aircraft so you are not really going to cause any problems. <S> Apparently some aircraft can not be slipped with flaps extended One additional thought! <S> Some manufacturers specifically placard their aircraft that slips are not allowed with flaps extended. <S> Not sure if that's their lawyers or their safety folks speaking, but it is a reality we must acknowledge. <S> If not, why does it seem that this method of losing altitude is not used/ <S> taught more frequently? <S> My instructor was big on it when we practiced emergency engine outs and I received plenty of training in slipping. <S> I'll use it on occasion if I'm really high on final but most powered planes don't have nearly the glide ratio of gliders so cutting the power is more than enough to get the plane to really come down. <S> I would say its not used as much in powered aircraft because you have plenty of control already and you don't need to over-complicate the situation. <A> I wouldn't use it as a "normal" means of descent, simply because it isn't aerodynamically efficient. <S> You are purposefully creating more drag and lowering the glide ratio of the airplane without a good reason. <S> You end up using more fuel when you could have just pulled the power back (using less fuel) and started a descent or glide earlier. <S> That being said, good job practicing it in a safe, learning environment when you don't actually need it. <S> This should pay off down the road when you do want to lower your glide ratio by slipping when high on final, etc. <S> It's a good tool to have and should be used when appropriate. <S> As far as those who discuss spinning from a slip, you should always maintain sufficient airspeed (just like when you aren't slipping), but please take a look at this question about what happens when you stall during a slip: <S> What happens in a stall during a slip? . <A> Another disadvantage of slipping in order to lose altitude rapidly is that, at any section of the wing, the AoA is considerably increased, because the horizontal speed is reduced slightly, while the sink speed (and thus, the vertical airspeed component) becomes much higher. <S> The combination of both factors result in an increase of the AoA, even if the attitude of the plane is kept the same, and increasing the AoA may lead to a partial or total wing stall...
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The only disadvantage might be a slightly higher risk of a low altitude stall due to the uncoordinated flight and presumably low speed. There are some instructors who put more emphasis on slips for energy management.
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What is the slowest fixed-wing airplane? It's easy to find information about the fastest airplanes, in different categories (e.g. X-15 , SR-71 , the Concorde etc), but what is the slowest one? Which powered, manned airplane is capable of sustained level flight at lowest velocity? <Q> The Gossamer Albatross is a human-powered plane with a top speed of 29 km/h (18mph). <S> It was used to cross the English Channel and seems to meet the criteria of the question. <A> The Antonov AN-2 has no stall speed quoted in the operating manual and can fly under full control at about 30 mph. <S> Thus if the headwind is sufficiently large the aircraft will move backwards with respect to the ground. <A> The Harrier , Yak-38 , Yak-141 , XV-15 , and V-22 are all fixed wing aircraft. <S> All can hover in mid air, controlled. <S> So they are in controlled flight at 0 velocity. <S> At least the Harrier can even be in controlled flight flying backwards, so with negative velocity. <S> The others may as well, I don't know. <A> now, if you're looking at modern, more commonly used transportation, powered paragliding would probably take the cake. <S> CC <S> BY 3.0, <S> https://en.wikipedia.org/w/index.php?curid=13110495 <S> Powered paragliders usually fly between 15 and 50 mph (25 and 72 km/h) at altitudes from 'foot-dragging on the water' up to 24,000+ ft (5400 m) <S> https://en.wikipedia.org/wiki/Powered_paragliding <S> The beginners equipment are often the slowest, and with proper skill, and the right weather, can have a stall speed of zero . <S> Whilst being lifted by a thermal, the only thing that will push the glider forward is the natural tilt. <S> naturally, on a still day, the slowest of equipment will stall at below 10mph . <S> Disclaimer: this is not an airplane, but it is a fixed wing vehicle, made to primarily move forward to generate lift, akin to most airplanes. <A> If you are including historical aircraft, the Wright Flyer averaged 10 fps (approx 6.8 mph or 11 kph) <S> over it's first 120 foot flight in 1903. <S> Reference: https://airandspace.si.edu/exhibitions/wright-brothers/online/fly/1903/triumph.cfm <A> Building it just for very slow speed does not look practical (if you really need this, use helicopter). <S> Some old planes may be slower, but they do not use the newest technologies and may not be built for slow flight anyway. <S> Some patrol, agricultural planes may benefit from slow flying, but we need something more extreme. <S> I expect such aircraft to be some specific machine that has a huge wing and low weight for other reasons, and should be recently built to benefit from latest technologies. <S> Solar impulse looks like a good candidate. <S> It has take-off speed of 35 km/h (22 mph) only. <S> Looks like <S> its minimal speed is about 20.67 mph only. <S> Its large wing holds the solar batteries. <S> It has a wingspan larger than Boeing 747 and the weight close to Cessna 172 ! <S> (picture from Wikimedia Commons ). <A> The Ruppert Archaeoptrix Electro <S> ( Wikipedia , official website ) apparently has a stall speed of 30 km/h (19 mph / 16 kn) , and I think that makes it a candidate for the current "slowest" fixed wing aircraft. <S> It is a relatively new glider that can be foot launched, but there are also wheeled and motorless configurations, and it can also be launched by towing. <S> For the motorized version: <A> When it finally won the Kremer prize for a 1 mile figure 8 course <S> it did that course in 7 minutes and 22 seconds. <S> The later Gossamer Albatross that crossed the English Channel had to be faster. <S> This assumes that the question criteria was AIRSPEED (not groundspeed) for a fixed-wing, man-carrying aircraft that could take off and land under its own power and maneuver both into and out of the wind (figure 8 maneuver). <A> You should check out planes with custer wings. <S> https://en.wikipedia.org/wiki/Custer_CCW-5 <S> It was claimed that the aircraft could fly under control at 11 mph (18 km/h) and that it could take off with a 1,500 lb (680 kg) load at 70% power in 90 ft (28 m). <A> Slepcev Storch <S> (A 3/4-size replica of the Fieseler Fi 156 Storch , a German WW2 reconnaissance aircraft well known for its slow-speed performance) <S> 36 km/h or 40 km <S> /h (19kn/22kn) <S> Picture Source Performance <S> according to Wikipedia : <S> Maximum speed: 150 km/h (93 mph; 81 kn) <S> Cruise speed: 133 km/h (83 mph; 72 kn) <S> Stall speed: 40 km/h (25 mph; 22 kn) <S> Rate of climb: 6 m/s (1,200 ft/min) <S> Performance according to <S> ulm.it : <S> Maximum speed: 150 km/h <S> VNE: <S> 182 km <S> /h <S> Stall speed: (flaps out) 36 <S> Km/h Climb rate: 9,1 m/s (1800 ft/min) <A> I was at the Biggen Hill <S> airshow <S> many years ago where not one but two different aircraft flew backwards. <S> One was the AN-2 which was able to nose up into the headwind so far that it actually flew backwards for a short distance down the runway. <S> The other was a Russian super jet, (possibly a Sukhoi 27 or Sukhoi 35 ?) <S> that did a vertical climb on afterburners that shock the ground then slowed to a stop before falling on its tail while still vertical. <S> It flew tail first towards the ground before lowering the nose. <A> Alaskan Bush Planes are modified to fly very slowly for short landings: Features include:"Short <S> runway requirements, typically gained through high aspect ratio wings and high-lift devices such as flaps, slots and slats to improve low speed flight characteristics, allowing shorter ground rolls on landing or takeoff." <S> https://en.wikipedia.org/wiki/Bush_plane <S> This might be helpful too: https://en.wikipedia.org/wiki/List_of_STOL_aircraft <A> Here is a video showing that the Gossamer Albatross flew at lowest speed, 7mph (11.2kmph). <S> Very slow. <S> But the save speed will be 10mph (16.1kmph), as mentioned in that video. <S> It lasted 2 hours to cross England strait from England to France.
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Gossamer Condor , the first human powered airplane capable of basic maneuvered flight.
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Is the MTOW determined by the wheel maximum supported weight? I was on a LATAM flight a couple days ago, and decided to have a read through their VAMOS magazine. As a lot of airlines do, they had a couple of pages on their fleet, and also a double spread on one specific plane. This plane was the 777, which was a little bit surprising as they are about to get rid of those I think. Anyway, it had all the usual facts and figures, and also a couple of highlights about the plane. I managed to find a web copy of the magazine, and the picture is below: https://issuu.com/spafax/docs/vamos_latam_junio_2017_web One of these highlights is the wheels, and it says (roughly translated): Each of the wheels is capable of supporting a maximum of 29,294 kg. My first reaction was "That's pretty impressive!", then "I wonder how much above the MTOW that is?" The MTOW is specified at the side there: 351,530 kg, which correspondes to the 777-300ER. So 29,294 x 6 x 2 = 351,528 Oh. That's under the MTOW. I wonder if there's some rounding off here: So 351,530 / 2 / 6 = 29,294.166 - yes there is. I was surprised that the maximum each tyre/wheel could take summed up to the MTOW, as I thought that they would experience larger forces on landing. Also, what would happen if a tyre blew? So, does the maximum load for a tyre/wheel have anything to do with the MTOW? Or is this just marketing guys jumping the gun? I have seen this question How is Maximum Take Off Weight determined? and that says that the manufacturers determine it, and it is based on the required payload of the aircraft and the design configuration, which doesn't really answer this question. Edit with extra info mentioned in comments : When stationary, the wheels will have a total force on them of 351,530 kgs, which according to this magazine is their max. When landing, the wheel like have to bear a weight of 251,290 kgs, plus the force of the landing . In my mind, the extra force of the landing would push the total above the MTOW, but this is just in my mind so I'm probably wrong :P <Q> Boeing 1 [pdf] specs for 777-300ER: <S> Max taxi weight: 777,000 lbs (352,442 kg) <S> Max take off weight: 775,000 lbs (351,535 kg) <S> Max landing weight: 554,000 lbs (251,290 kg) <S> Bridgestone 2 specs for approved tires: <S> Main: 66,500 lbs (30,264 kg) <S> x 12 = <S> 798,000 lbs (361,967 kg) <S> Nose: 44,500 lbs (20,185 kg) <S> x 2 = <S> 89,000 lbs (40,370 kg) <S> Total tire rated load = <S> 887,000 lbs (402,337 kg) <S> So at taxi weight on all 3 gear there's roughly a 110,000 lbs / 50,000 kg margin (about 14%). <S> At max landing weight, main gear only, there's a 244,000 lbs / 110,677 kg margin (44%). <S> At MTOW there's about a 112,000 lbs / 51,000 kg margin (14%) on all gear, but only a 23,000 lbs / 10,400 kg (3%) margin after nose gear lift off. <S> But, when the nose gear lifts off the ground the wings are supporting nearly all of the weight. <S> Their numbers are pretty close to what the manufacturers list. <S> I think you're just not accounting for the nose gear at takeoff and the weight difference at landing. <S> As far as Is the MTOW determined by the wheel maximum supported weight? <S> It's the other way around. <S> A more important tire consideration is speed. <S> The tires are rated at 204 kt. <S> This paper gives an example of a 747 at 825,000 lb there is a weight margin of 30,000 lb. <S> But liftoff speed is 199 kt, so there's only a 5 kt speed margin. <A> Another factor in MTOW is the ability to maintain control after takeoff. <S> Just getting airborne isn't enough. <S> Northwest 255 managed to lift off with flaps improperly set, but couldn't maintain control and crashed. <S> Air Florida 90 also lifted off, but crashed almost immediately due to icing and less than full power from the engines. <S> An aircraft too heavy for the design can suffer the same fate. <S> Ernest Gann described an incident where a C87 (B24 derivative) with an accidental overload of fuel he was flying out of India during WW2 almost hit the Taj Mahal, because it would barely stay airborne with no ability to climb or change direction without stalling. <S> Only a last minute application of flaps got it over the towers. <A> An aircraft will have a certified MTOW which it can't exceed, but keep in mind the actual MTOW for a specific flight can be lower (and often is). <S> MTOW will always be the lowest of the following limits: Field Length (runway length, condition) Climb Obstacle Clearance <S> Tire speed & brake energy <S> Landing Limit weight (i.e. can't plan to arrive at something greater than MLWD)
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The MTOW determines how many tires of what weight rating are needed.
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Why does the U-2 Dragon Lady not have swept wings? Swept wings increase the critical mach number for aircraft with otherwise identical wings ( Source 1 ). The U-2 Dragon Lady is limited in altitude by its critical mach number, as it needs more speed in order to go higher ( Source 2 ), but going faster would put it into its "coffin corner" ( Source 3 ). However, looking at the following photo of a modern U-2 from Lockheed's website, the wings seem to have little to no significant sweep. The top speed (presumably what is used during the highest-altitude cruising) is only Mach 0.67 ( Source 4 ), while modern aircraft like the Boeing 737 (which do have swept wings) often cruise at speeds between Mach 0.75 and 0.8 ( Source 5 ). Why does the U-2 not have swept wings? I know that wing sweep was first developed in Germany during WWII; had the technology not taken hold in the USA by the time the U2 was developed in the 1950s? Or is there a deeper technical reason I'm missing? <Q> Sweeping a wing costs weight, for several reasons. <S> Therefore, if the goal is to fly high and achieve long range , an unswept wing is the better choice. <S> Only when transport performance needs to be maximized will a moderately swept wing look better. <S> Why is a swept wing heavier? <S> Sweep reduces aerodynamic efficiency, so a larger wing is needed to create the same amount of lift. <S> Sweep introduces torsion when a straight wing will mostly see bending only. <S> Adding torsion strength needs more structure. <S> In the end, Kelly Johnson decided to cut weight and drag as much as possible but not to pursue maximum speed to achieve the greatest flight altitude. <S> Another reason was that the U-2 begun as a modification of the XF-104 with extremely stretched wings. <S> Adding sweep would had resulted in too many modifications to the U-2 fuselage, which was initially built in the same tooling than that of the XF-104. <A> Basically, because of its mission requirements. <S> It wasn't intended to fly fast, and because it didn't need to go particularly fast, there was no need to sweep the wing. <S> Instead, it was supposed to provide a massive amount of data (by 20th century standards) along its flight path, which necessitated long flight times: thus the long, straight wings providing a lot of lift at low airspeeds were ideal for its mission. <A> A swept wing would most likely adversely affect the handling of a U2 during a typical mission profile, and would adversely affect the structure required (weight) of the aircraft. <S> A swept wing adversely impacts the stall characteristics and stability when flying near a stall. <S> It should be noted that while a swept wing helps manage effects due to the compressibility of air near mach speed. <S> The primary effect is a swept wing delays the near mach shock wave development. <S> This results in reduced drag near transonic speeds. <S> The U-2 is designed to operate just below transonic speeds, so in theory, there could be a benefit of a swept wing on the U-2. <S> The benefits of a swept wing comes at a price. <S> In addition to requiring a beefier structure to handle the torsional load stresses of a swept wing, the stall characteristics of the wing are different. <S> The resultant stall characteristics can become more pronounced and more difficult to recover from. <S> In the case of the U-2, which at higher altitudes can fly with as little as a 2.5 to 7.5 knot gap between stall and MMO, the pilot must be sensitive to the pre-stall buffet. <S> A swept wing would make the sensing of that buffet potentially a little more difficult, but more importantly, it would make stall recovery much more difficult . <S> In many aircraft that would be manageable, however, in the case of the U-2 stalls are not docile, and have been known to cause tail structural failures and separation. <S> The risks of a swept wing on the U-2 outweigh any benefit of reduced aerodynamic drag from a swept wing, given that there was a decision to have the U-2 be a subsonic aircraft. <S> The additional weight of the structure needed for the swept wing could also be construed as to further close the stall to MMO gap. <S> Therefore, not implementing a swept wing on the U-2 helps control the stall characteristics, and should the onset of a stall occur, it is easier and with less risk, to recover from a stall. <A> The limiting factor for U2's speed is not the wing, but the engine. <S> According to Unlimited Horizons (also U2 Developments ), engine performance is only 6% of sea level at 70000 ft due to oxygen starvation. <S> Before engine is improved to the point that the same airframe can reach M0.8, there's no need to sweep the wing.
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The stall characteristics of a swept, high aspect ratio wing are extremely unpleasant and require a healthy margin from the stall angle of attack, when flying high requires to fly just at the edge of stall .
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Do small civilian aircraft have autopilots? If not, why? Doesn't it make flying safer? It seems to me that automating a small plane should be easier than automating a car (excluding dealing with Air Traffic Control). Is it too expensive? <Q> Many small, light aircraft are equipped with an autopilot today. <S> They can range from very simple autopilots, without altitude selector and so on, Source , ST SYS 30, <S> $ 12,000 to advanced systems with altitude selector, automatic trim and so on. <S> Source , Bendix/King KFC 225, <S> $ 15,000 - 42,000 And with this GPS, feeding the autopilot with data, it has the abilities of an airliner. <S> Source , Garmin® GTN™ 750, $ 17,000 <S> You have to know, the systems in the general aviation industry are getting better and better. <S> Of course they are way below the complexity of the avionics of airliners, but the features are the same if not more. <S> For example: A captain of an airliner has to review or change the flight plan with the FMC, respectively MCDU on Airbus, a not very straight-forward device to control the plane. <S> Of course, the FMS has a lot more capabilities than a GA GPS, but one of it's primary features is the input of the flight plan. <S> And in that, from the usability-view, the Garmin <S> ® GPS has the better solution: <S> An all-in-one navigation device with touchscreen input. <A> Yes. <S> They are very expensive (~$20,000) but are occasionally added to planes as aftermarket modifications or as updates to existing systems. <S> Autopilots in small planes range from simple wing levelers to fully coupled systems that can use GPS systems fly instrument procedures all the way to published minimums (200' above the ground in some cases). <S> I owned a small four seat plane with an autopilot that could hold altitude and a heading -or- <S> a VOR/LOC course -or- a GPS track. <S> It was considered a relatively basic system. <A> Does it make flying safer? <S> That is a very interesting question that is open to debate. <S> The great thing about an autopilot is that when turned on, it frees up the part of your mind you are using to control the aircraft to actually think about other things such as where you are going. <S> The bad thing about autopilots is that they are complex and need to be set correctly (and can fail). <S> So you need to be more familiar (or current in pilot speak) with the make and model of autopilot, GPS, whatever, in your aircraft. <S> Years ago when I learned to fly the CAA here in the UK didn't encourage the use of Autopilots or GPS. <S> Should they? <S> Like I said it cuts both ways. <S> Before I get loads of comments saying what a dinosaur I am etc etc. <S> I would like to refer to one example I read about in a light aircraft where the autopilot was set to altitude hold in cloud and the engine failed. <S> The autopilot held the altitude and the aircraft stalled, spun, and crashed. <S> For sure they have their place <S> but I just don't get the button I can press <S> and then I don't need to do anything mentality. <S> Maybe thats just me. <A> To answer the why part of your question, turn it around. <S> Most of us who fly small airplanes do so at least in part because we enjoy doing the flying. <S> Why on Earth would we want an expensive device to keep us from doing what we are paying good money to do? <S> We might as well just fly commercial :-( <S> Indeed, I honestly don't see why Tesla is wasting all that money trying to develop self-driving cars. <S> It just ensures that I'll never buy one.
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Small airplanes can have autopilots.
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Was the miracle on the Hudson saved exclusively by the APU? In the film Sully , (staring Tom Hanks) the APU is switched on straight after both engines rollback, why was this step necessary; Airbus said this was the "15th thing" to do on the checklist. How or why did this step in particular prevent the loss of lives of over 100 people? <Q> Yes, the solution to start APU was important. <S> The ditching procedure directs the use of maximum available slats and flaps for the final approach and touchdown ( source , chapter 10.3). <S> This is not possible without APU, as Airbus A320-214 cannot move flaps if only powered by RAT (only blue hydraulic line, same source, chapter 9.3). <S> The running APU adds the green hydraulic line that can also move flaps. <S> Hence, without running APU, the optimal ditching procedure is not possible; that gives less chances for success. <A> The engines provide electrical and hydraulic power to the systems that control the flight path of the aircraft: elevator, aileron etc. <S> If all power is lost, a Ram Air Turbine (RAT) is deployed which spins up and powers the systems from the airspeed. <S> However, this creates extra drag. <S> The RAT deploys automatically upon loss of AC bus 1 and AC bus 2. <S> This takes a while after engine fail since the engines spool down - if APU is switched on before the buses are detected down, the APU then powers the AC buses and the AC pumps that drive the Blue and Yellow hydraulic systems. <S> Below 125 knots the RAT stalls. <S> The RAT was found deployed in the accident report . <S> It has an automatic blade pitch adjust system that retains constant speed under load - if the RAT is deployed and needs to provide the backup power for Blue hydraulic and AC electrical, it extracts energy from the air stream and provides extra drag. <S> If the APU provides power for electrical and hydraulic systems, the RAT windmills and there is less drag. <S> The A320 had just taken off and did not have much altitude yet. <S> Aircraft without engine power can glide - the distance they can cover while gliding depends on the starting altitude of course, but also on Lift over Drag: the lower the drag, the further the aircraft can glide. <S> Switching on the APU provided them with extra gliding distance due to less drag - although that may not have been the captain's main objective, it may have been an attempt at engine start. <S> They needed all the distance they could get, and all the clearheadedness that could be provided. <S> And that is what the pilots delivered. <S> Switching on the APU bought them time, and more choice in landing the plane at a suitable spot. <A> No, the "Miracle on the Hudson" flight was NOT saved exclusively by the APU. <S> Airline flights are routinely dispatched with a non-operable APU. <S> It is not needed or required to complete a safe flight. <S> On the Boeing B777 starting the APU(if avaialable) is number 5 in the checklist for dual engine failure. <S> In my opinion the starting of the APU had very little to do with the success of the water landing and survival of all the passengers and crew. <S> Sully is on record as saying he started the APU to provide an addition electrical source: <S> Sully Speaks Out <S> I had taken by memory the first two remedial actions that would help us the most, that we would later get to on the checklist over a minute later <S> , over a third of the way through the remaining flight time, and that was to turn on the engine ignition so the engines would recover if they could (it turned out they were irreparably damaged), <S> and I started the airplane’s auxiliary power unit, the APU, to provide a backup source of electrical power. <S> Since this is a fly-by-wire airplane and there’s no longer a direct mechanical connection with the flight controls, instead you have electrical impulses that are fed through computers that then move actuators. <S> In this particular case the APU may have allowed a slightly longer glide, but that would just have meant touching down on the water slightly upstream from where they did touch down. <S> Map Source: CNN Map <A> Jep, I think it was very beneficial to the outcome of this event. <S> However I think that in addition to the reasons stated here, the APU also prevented Sully from stalling the airplane. <S> If I remember correctly, if all electrical power is lost/provided by the RAT, the airplane goes to "direct law" mode. <S> This means, that all inputs by the pilots are translated directly into proportional movements of the flight control surfaces. <S> The systems that usually keep the pilot from getting the plane into a unrecoverable situation are deactivated. <S> As Sully pulled the plane up just before touchdown in order to execute a flare, he would have stalled the airplane, had the fly-by-wire system not prevented him from doing so. <S> As this system would not have been active if he had not switched on the APU, he would have dropped into the water like a stone. <S> So yes, the APU saved the day, by reducing drag, burning a tiny bit of weight of, moving the flaps, and keeping Sully from stalling.
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The situation was not exclusively saved by switching on the APU, it was a factor in a chain of events where everything needed to be right - and it was.
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Is it okay to divert to another airport in IFR lost comms situations? In the event of lost communications, FAR 91.185 allows pilots to divert to a nearby airport if they encounter VMC conditions en route to their destination. But what if IMC conditions persist? Are they legally allowed to divert to another airport, which is not designated as the alternate airport in the flight plan, and shoot an approach to land? Doesn't that conflict with the regulation requiring pilots to follow "last assigned, last vectored, EFC route, route in the flight plan" in order? I ask this question because I came across this phrase in my study material called Everything Explained (p.82) : "Do not continue on to your destination if there is a suitable airport for you to land at, unless you're just minutes from your original destination." <Q> AIM 6−4−1. <S> Two-way Radio Communications Failure <S> a. <S> It is virtually impossible to provide regulations and procedures applicable to all possible situations associated with two-way radio communications failure. <S> During two-way radio communications failure, when confronted by a situation not covered in the regulation, pilots are expected to exercise good judgment in whatever action they elect to take. <S> Should the situation so dictate they should not be reluctant to use the emergency action contained in 14 CFR Section 91.3(b). <A> Short answer: you're expected to follow the rules you mentioned unless it's an emergency. <S> The regulations are in 91.185 and they say (among other things): <S> Unless otherwise authorized by ATC, each pilot who has two-way radio communications failure when operating under IFR shall comply with the rules of this section. <S> [...] If the failure occurs in IFR conditions, or if paragraph (b) of this section cannot be complied with [i.e. the aircraft doesn't enter VMC], each pilot shall continue the flight according to the following: [route, altitude, clearance limit rules] <S> As written, that seems clear: if you aren't in VMC and don't enter VMC, you "shall" continue your flight according to the usual rules. <S> The AIM 6-4-1(c) says the same thing: <S> In the event of two-way radio communications failure, ATC service will be provided on the basis that the pilot is operating in accordance with 14 CFR Section 91.185. <S> A pilot experiencing two-way communications failure should (unless emergency authority is exercised) comply with 14 CFR Section 91.185 <S> The whole point of 91.185 is that you don't want to fly around literally blind in IMC with no way to know what other aircraft are out there. <S> And especially in busy airspace, ATC and other pilots certainly don't want an aircraft they can't see behaving unpredictably. <S> If the comms failure also took out your transponder, for example, then ATC could only track you on primary radar, which is quite limited. <S> Having said that, the AIM is clear that if the PIC decides that the situation is an emergency, then he can do whatever seems best. <S> There are just too many possible scenarios to have a strict yes/no rule. <A> I agree with all answers given, but will add this: If IMC and deviating from Asssigned, Vectored, Expected or Filed, don't just squawk 7600, roll it to 7700 to get their attention and let them know you maybe aren't going to be as predictable as they might think... <S> Also, I was always taught to broadcast intentions in the blind <S> just in case they can hear you, but you can't hear them. <S> You may not fully understand the exact failure mode causing you to be lost comm. <S> I once experienced an ICS/ headset failure where I couldn't hear a thing, but the controllers and my crew could hear me transmitting just fine.
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Comms failure by itself isn't an emergency (see the AIM 6-4-1(b)), but every situation is different and if other equipment fails or you have other safety issues to deal with then diverting might be the best decision.
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When did airlines start using seat belts for passengers? When did airlines start using seat belts on passenger flights? <Q> The world's first airline used Zeppelins, and there was no need for seatbelts. <S> In WW <S> I seatbelts were standard issue for pilots, at least in Germany. <S> After the war, the airlines used seatbelts irregularly. <S> Below are two pictures of the cabin of the Junkers F-13 , the first all-metal passenger aircraft, which was first operated in 1919. <S> Junkers F-13 <S> cabin, front view (picture source ) <S> Junkers F-13 cabin <S> , rear view (picture source ) <S> While the belts on the front seats are clearly visible, the rear seats seem not to have them. <S> If the picture date (Oct. 10, 1919) is to be trusted, they were used right from the start in 1919. <S> The way they are fixed to the wicker seats, however, looks rather flimsy and will not give much protection in a crash. <A> I've found photos of Fokker F.IXs from the late 1920s with seatbelts for the passenger seats. . <S> The earlier F.VII from 1924 does not appear to have had seat belts. <S> This more or less frames the introduction of seat belts in airliners in the late 1920s, as Fokker was a leading and innovative airliner manufacturer in those days. <S> Of course it is always possible that some aircraft were retrofitted even earlier, but this seems to set the start of including them as standard. <A> [He] equipped <S> the S.C. No. <S> 1 with the first seat belt, using a four-foot leather cinch obtained from the cavalry saddlery ( Wikipedia ). <S> By 1940, seat belts on "transport liners" were common ( Flying Magazine , Aug 1940).
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Benjamin Foulois (a United States Army general) is credited with inventing the first seat belt on an aircraft in 1910 ( Wilbur and Orville: A Biography of the Wright Brothers ).
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For the elliptical wing, which property is actually elliptically distributed? A well-known "elliptical" wing: One of the 50 Spitfire still flying in the World. Source My questions What is elliptical in the elliptical wing? What is regularly distributed: lift? drag? something else? <Q> It is both the planform and the circulation distribution. <S> Note that circulation is not lift coefficient but bound vortex intensity. <S> You can interpret it as local lift coefficient times local chord. <S> This, when combined with the elliptical chord distribution over span, means that the circulation distribution will stay elliptical over the linear angle of attack range. <S> This is the special characteristic of an elliptical wing: While any wing can have an elliptical circulation distribution at one angle of attack (given the right twist distribution), the elliptical wing will keep that elliptical circulation distribution over the whole operating range. <S> With an elliptic circulation distribution comes also a constant induced angle of attack and downwash angle over span. <S> I guess this is expressed by some authors with the term "regular". <S> However, only the aerodynamicists will see that as an advantage. <S> Both weight and stall characteristics of elliptical wings are less than optimum; the low induced drag coefficient is bought with higher structural mass and, consequently, lift. <S> A more triangular circulation distribution will yield the lowest wing weight and overall drag for a given non-lifting mass (that is, all mass that is not involved in lift generation, especially the payload). <S> Note that for such a triangular distribution drag will be highest near the center. <S> When people talk about elliptical lift distribution, they mean lift per span . <S> I prefer to use the more correct term circulation, since lift is a force as in pressure times area and can only be produced by a whole wing or at least wing section, not one spanwise station. <A> (Edited after comments by mods. <S> Thanks for guiding me through the process!) <S> The only thing that is elliptical is the planform shape of an elliptical wing. <S> Many people unfortunately confuse an elliptical pressure distribution with the pressure distribution over an elliptical wing. <S> They are not equivalent. <S> On an untwisted elliptical wing the local lift coefficient is not constant over span, as some here and in many other places on the internet maintain. <S> Arguments from lifting line theory are not appropriate for discussing the behaviour of the flow near wing tips. <S> It is unreasonable to expect lifting line theory to be valid near the wing tips because is not a consistent large aspect ratio asymptotic expansion. <S> See: <S> Van Dyke, "Perturbation methods in fluid mechanics", 1964. <S> The span loading includes a logarithmic term, hence it is not elliptical. <S> Furthermore, it cannot induce a constant downwash, and so at the trailing edge the vortex wake does not start as a flat sheet. <S> The process whereby the vortex sheet rolls up is far more vigorous than if it started out as a flat sheet because the relatively weak effect of viscosity would be the main mechanism driving that rolling-up process. <S> There is a strong upwash in the flow-field near to and around the wing tips which initiates the rolling-up process far more vigorously. <S> See, for example, among many other papers: Peter F. Jordan, "Exact Solutions for Lifting Surfaces", AIAA Journal, Vol. 11, No. 8, 1973. <S> , pp. 1123-1129. <S> Peter F. Jordan, "On Lifting Wings with Parabolic Tips", ZAMM 54, pp. <S> 463-477, 1974. <A> The beautiful shape of the Spitfire planform also made it difficult and expensive to produce. <S> The target was an elliptical lift distribution, at the time of design regarded as resulting in the highest lift/drag ratio. <S> This lift distribution is obtained by shaping the wing geometry, in the case of the Spitfire by making the chord an elliptical function of wing span. <S> The other way of achieving this is to use a combination of wing taper and wing twist: the chord reduces linearly with span, plus the wing is twisted with the wing tip having a lower angle of attack than the wing root. <S> This shape creates elliptical lift distribution as well, but at only one AoA of the aircraft. <S> The elliptical wing has an elliptical planform and elliptical lift distribution throughout all aircraft AoA. <S> The eliptical planform wing has a constant AoA, and drag changes as a function of wing chord only. <S> The twisted wing has a wing root with a higher AoA, and a wing tip with lower AoA than aircraft AoA: the fat bit of the wing has the higher drag, since wing drag is a function of chord and AoA. <S> So total wing drag of the tapered wing is higher than that of the elliptical wing. <S> The tapered twisted wing rules though, because: It is cheaper and faster to produce. <S> The wing tip stalls last, and that is where the ailerons are.
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On the untwisted elliptical wing the local lift coefficient is constant over span, and changes in angle of attack over the linear range will change the lift coefficient equally everywhere.
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What is the relationship between your tail number and air traffic control? Obviously a tail number is used to distinguish yourself from other aircraft, but after the first call, a callsign does the same thing. It is also used for investigation purposes I would imagine, by listening to radio recordings, but are controllers typically even able to read tail numbers from the tower or do they just see a plane around where you say you are calling from and assume that it's you? <Q> Sometimes your callsign is your tail number, particularly on General Aviation flights. <S> For example, if you are flying the Cessna 152 with tail number "N123AB", you would call ATC with " November-One-Two-Three-Alpha-Bravo ". <S> Commercial flights, on the other hand, tend to use their flight number as the callsign. <S> E.g. if an aircraft is operating for Delta Air Lines flight 123, the callsign would be "Delta-One-Two-Three". <S> This is not applicable to GA as GA do not usually fly a particular route or for a particular company. <S> Assigning a flight number to every GA flight would be troublesome, it is simpler to just use your tail number as it is guaranteed to be unique. <S> If this is your initial call to the controller, you would describe your location, which allows the controller to identify you on the radar screen. <S> If the controller is unsure, you may be assigned a squawk code and even asked to push the IDENT button. <S> You may also describe your type to the controller, like: "Tower, N123AB is Cessna 152, 5 miles South of XYZ, (...) <S> " You are correct that if you do lie about your callsign, ATC as no way of knowing it unless somebody sees you, as described in the "Inside Air Force One" documentary by National Geographic when they tried to pretend to be a GulfStream aircraft to secretly transport the president. <A> Check out the image on the bottom of this page: http://www.oocities.org/rjt02/behind.htm . <S> For a general aviation aircraft (as the above poster described), when you contact a controller from the air, you'll tell him what you are (Cessna Skyhawk), who you are (N123AB), where you are (5 miles south east of XYZ airport at 6,000 feet), and what you want (inbound to land at XYZ (or) requesting flight following to JKL airport (or) transitional <S> your airspace (or) requesting Bravo clearance etc). <S> The controller will look on his radar, which shows not only the position of aircraft, but also the altitude and squawk code. <S> When you tell him the tail number and type, he can edit that blip to add that information. <S> Callsigns are useful for a few situations. <S> First of all, the controller will know instantly that Delta 1234 is heavy and fast. <S> Similarly, they can identify some special operations by name (SAR missions, military aircraft, police helicopters, skydive ops). <S> It's not plausible to give every aircraft its own callsign, but for aircraft that a controller interacts with frequently, and operate differently from the norm, it's another tool <S> allow ATC to manage mental workload. <A> Mostly, it's used for billing and resolving disputes. <S> We also use it for incident reporting, as you mentioned.
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Controllers may identify a plane by tail number when you are on the ground, but once in the air it is almost impossible to sight a plane this way.
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What does the area around the fan blades in the engine nacelle contain? I was intrigued to find this picture below. There was so much space around the engine. So what is inside of that extra space? Or is it just a hollow casing? Image Source Details about the picture as provided in the image source: [Last Year] A Southwest Airlines Co. flight landed safely Saturday morning following a major malfunction of one of its two engines during a flight across the Southeastern U.S. The Boeing Co. 737-700 was flying from New Orleans to Orlando early Saturday operating as flight 3472 when it suffered the failure, causing the jet to quickly divert to Pensacola International Airport in northern Florida at 9:40 a.m. CDT, according to a statement from the airline. A Southwest spokesman said its initial reports indicated no injuries were reported among the 99 passengers and five crew aboard. <Q> Yes a bit of the engine called the nacelle is missing. <S> In the drawing underneath it states Inlet Cowl. <S> It has some thickness, because it requires a certain nose shape for its function. <S> Mainly a hollow casing indeed, but with a high tech shape. <A> In the image the front part of the engine nacelle (the inlet region) is missing. <S> The main purpose of the missing region is aerodynamic. <S> In the image below, you can see the equipment and various other items covered by the cowlings (which are open). <S> The separator wall can be seen in the far end of the engine, near the fan blades. <S> Though this is not the 737-700's engine, the design is similar. <S> Engine with cowlings open; image from kativ.eu <A> What is missing from your photo is the engine inlet. <S> As someone stated, the inlet does contain some anti icing components, likely a swirl nozzle for a commercial application. <S> The engine inlet structure is composed of an inner composite barrel, and outer composite barrel, a forward bulkhead, an aft bulkhead, and the inlet lipskin. <S> The inlet attaches to the forward mounting flange on the fan case (the forward most flange). <S> Anti-ice ducting from the core interfaces with the inlet, which has another tube (most commonly with some sort of flexible component for thermal expansion) that spans the distance between the forward and aft bulkhead (which appears to be hanging back from about the 11 o'clock position on the engine from what is left of the aft inlet bulkhead). <S> This then interfaces on the forward side with the anti-ice distribution system in the area inside the lipskin, known as the "D-Duct". <S> The area between the bulkhead of the inlet is indeed empty. <S> The inlet is specially designed for acoustic attenuation. <S> The components you are expecting to see are contained in two places: the engine core and the engine fan compartment. <S> Depending on the engine, these two locations house the electrical, fuel, hydraulic, pneumatic, and oil components of the engine. <S> These systems are commonly referred to as the "EBU" or engine build unit or engine build up. <S> Source: I am an EBU Systems Design Engineer <A> The area immediately at the end of the fan blades is filled with a fairing compound. <S> It is smoothed to within a few thousandths of an inch (slightly) bigger than the diameter of the fan. <S> This compound sits in a depressed are built into the support ring for the cowl. <S> It keeps the air flowing smoothly through the fan blades. <S> Between the support ring and the cowl there are some control actuators and support structure. <S> Also the bleed air ducts for engine anti ice may be routed there. <S> It will all depend on the model and manufacturer design considerations. <S> Modern cowls are actually designed to provide forward lift and airflow acceleration. <S> First used on WW2 radial engine aircraft.
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This region is usually hollow, with the equipment (like control unit) and tubing coming after the separator wall visible in the photo. This is an aerodynamic structure that slows the air down before it enters the compressor, the pointy bit in your photo.
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Why would a pilot want to land with less than full flaps? So for example if I am flying the Boeing 737-800, the FMC gives me three flap settings and approach speeds. Why would a pilot want to fly with anything less than full flaps where possible? <Q> In some scenarios, a faster approach speed is better than a slow one, for example: <S> Strong crosswind Possible wind shear One-engine failure <S> A higher approach speed provides a better stall margin and higher control authority in challenging situations. <S> For example, the Boeing 737 QRH calls for a flaps 15 landing in "One Engine Inoperative" and "Stabilizer Trim Inoperative" scenarios. <S> In the crosswind scenario, let's assume your approach speed is 100 knots, and the crosswind is 20 knots. <S> The crosswind is therefore 1/5 of the approach speed, and you need a larger crab angle to keep the airplane aligned with the runway. <S> If you increase your approach speed to 120 knots, then the crosswind is only 1/6 of the approach speed, and the crab angle is smaller, making landing easier. <A> In strong crosswind-conditions you want to consider not using full flaps to give the wind less attack area. <S> So you have a slightly higher approach and landing speed, but you aren't blown as much to the side as you would be with full flaps. <S> In a Cessna 172, for example, this is normal practice. <A> In a Cessna 150 for example, you want to be on the downwind going 70-75 knots, 65-70 on base, and 55-65 on final, depending on wind gusts. <S> A pilot in a small plane might tend to put in 10° of flaps on the downwind, 10° on base, and adjustments or anything extra on final to allow them to get their speed to where they need it. <S> It is nice to be in the middle where you can add or remove some if necessary (assuming you're not too close to the ground).
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Less flaps gives a faster approach speed.
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Should I land a Cessna 172 with or without a little power? Cessna 172 landings with full flaps. I have been taught to land with and without power. Give me feedback please. Which way should I continue my training? <Q> This is really a question for your instructor: if you've been taught both methods then he should be able to explain when to use a little power and when not to. <S> Having said that, it all depends: there are good reasons to land with and without power, depending on the situation. <S> A normal landing with full flaps in a 172 is typically done without power. <S> The Cessna 172S POH <S> I have doesn't even mention power in the normal landing procedures; it gives a target airspeed instead. <S> A short -field landing is also usually without power, to minimize the runway distance needed. <S> The same POH says: Power -- REDUCE to idle after clearing obstacle <S> The FAA's Airplane Flying Handbook says in Chapter 8 : <S> Power is used throughout the [soft-field] level-off and touchdown to ensure touchdown at the slowest possible airspeed, <S> Finally, you might also use a little power if you bounce on landing, to stabilize the aircraft and re-flare (runway length permitting). <S> But that's a bit more challenging and most low-time pilots should just apply full power and go around instead. <A> As a 172 pilot I cannot think of any normal cases where landing with power would be a good idea as any power will extend the landing distance significantly and extend the float and hold-off. <S> In a normal landing I might add burst of power if the sink rate gets too high, but I would always cut it off as soon as I reach ground effect. <S> Throttle is used in short/soft field landings which are at the edge of the performance envelope. <S> These are done at low speed and high drag, the throttle is needed to keep the airplane above stall speed and force air over the tail's control surfaces so you maintain control. <S> You keep the throttle on in the flare until you reach your touchdown point <S> and then you gently close it, and the airplane stalls onto the strip. <S> So as you continue your training you should practice both techniques as each has its own purpose, and you should keep practicing both after you get your licence. <S> Just keep in mind that the short/soft field technique has much less room for error, so make sure you know what you're doing! <A> It depends. <S> You should not be afraid to use whatever power setting is necessary to maintain a proper glide path. <S> Especially with full flaps, when you get low and slow you might need a lot of power. <S> The answer about the Soft-Field and Short-Field landings is excellent, and goes to the point that "it depends. <S> " <S> I looked in two POHs. <S> The POH for a 1981 C172RG doesn't mention whether normal landings should be done "power-on" or "power-off", which to me means it is my option. <S> For comparison I also looked at the POH for a 1979 C152, which says, "Normal landing approaches can be made with power-on or power-off...." <S> However, it says that "actual touchdown should be made with power-off and on main wheels first. <S> " <S> I was taught to always keep my hand on the throttle during landings and use as necessary. <A> Are you referring to a power/unpowered approach, using power during the flare, or using power as the wheels touch the ground? <S> A few considerations (without giving an actual set-in-stone answer) <S> On approach: 1) approaches without power (commonly called "dead-stick landings) are OK, but if you end up just a little short, it's a bad time to discover that your engine has stopped during that descent. <S> At minimum, give it a little power periodically to confirm it's still responding. <S> 2) cutting power at altitude and gliding the whole way down introduces a lot of cooling (less heat from combustion and friction within the engine combined with increased airflow). <S> Most (but not all) agree that rapid temperature changes reduce engine life. <S> 3) from a speed perspective, maintaining a cruise descent from several miles out will get you there faster than cutting the engine closer and being limited by Vno, Vne, or RPM (which will still be high on a fixed prop aircraft with the throttle at idle on a steep descent) during flare and touchdown: 1) with more flaps and less power, your approach angle will be steeper. <S> With power and a lower flap setting, the shallow approach angle will be more forgiving for newer pilots who are still fine tuning their flare and touchdown. <S> I had trouble getting really smooth landings with full flaps and no power, and found that with lower flap settings and a tiny bit of power, I'd hear the wheel bearings spinning before I felt the landing. <S> This can be useful for a student to gain more spatial awareness of the height of the aircraft over the runway, and can be a good stepping stone into greasing perfect landings in any configuration. <S> 2) of course, more flaps and less power lead to a shorter ground roll. <S> So don't have a crappy approach and run out of runway. <S> 3) keep in mind that your landing configuration will change depending on situation, and being able to adjust to the situation is very important. <S> 30+ flaps in gusty crosswinds can create more problems than the solve, and tailwind landings with full flaps can be interesting as well. <S> Source: <S> c172 owner, commercial / instrument rated, skydive pilot (in c182 and other airframes)
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For a soft -field landing on the other hand, it's normal to carry a little power in order to touch down as gently as possible and avoid sinking into the runway surface.
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What is the section of the fuselage below the wings called? Is there a specific name for the protruding section of fuselage beneath the wings? Im talking about the area where the landing gear bay often is. In the photo it's where the red Emirates logo is painted. source Some older airliners don't have them, such as the A300 source <Q> The outer covers at-least, are called wing to body fairings in this Airbus document - 'Airbus Future Composite Wing'. <S> Wing to body fairings; image from Airbus Future Composite Wing <S> Elsewhere, the covers are called belly fairings by the manufacturers themselves , and also in the US patent US 20060065784 A1 - Aircraft provided with a belly fairing, and corresponding belly fairing. <S> Anyway, the fairings enclose the center wing box and the main landing gear wheel well. <A> In the trade this part is generally called "belly fairing" because that term is shorter and more specific than older names like "center wing fairing" or "wing-to-body fairing" or "wing/fuselage fairing". <S> See this AV article about an AD for the A380 , for example. <S> Belly fairing expresses better that the fairing is mostly below the wing-fuselage intersection. <S> The older expressions were already used for the usual fillets between wing and fuselage which became standard in the 1930s. <S> When it was learned that in transsonic flow the clever shaping of displacement bodies can reduce drag, the fairing grew over time. <S> An important benefit is the added space for storing the main gear. <S> The usual French name for it is "carénage ventral", which is a pretty straightforward translation of the English expression. <A> Finally is a fairing of the junction between both components, fuselage and wing. <S> The intention of this fairing is to reduce the drag created by the junctions. <S> Essentially this fairing is located in the "belly" of the airplane.
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So, the usual name is "belly fairing".
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How can the Cirrus Vision jet be cheaper than its competition? Cirrus Vision SF50 costs USD 2 million, compared to USD 5 million for comparable private jets. How is Cirrus able to offer a jet at such a substantially lower price? What compromises are customers making when buying this plane versus a competing one (Eclipse Canada, Cessna Citation M2 and Embraer Phenom 100 as per https://www.usatoday.com/story/money/2017/07/06/price-cutting-private-jet-shakes-up-aircraft-market/102607220/ ). <Q> I read an article on the SF-50 recently published in AOPA Pilot and, to be honest <S> the Cirrus Jet is not even in the same league as the other aircraft mentioned. <S> People think 'oh it's a jet for $2 mil <S> - I want one' but remain fairly ignorant of exactly what that means compared with other jet aircraft. <S> Depending on payload, the Vision has about at 600 NM range at its max cruising speed of 300 KTAS, burning a stiff 84 gallons/hr. <S> It sounds enticing to an SR-22T owner looking to upgrade, but consider that high end turboprops like the TBM-9XX are leaving you in the dust by at least 20 knots and using 40% less fuel to do so. <S> Ranges of approx 1200 NM are possible, depending on payload, but at an economy cruise of 240 KTAS, making it faster than the owner's old SR-22T but slower that nearly all turbobprops and probably more expensive to operate. <S> The Vision is also not RVSM certified, limiting operations to 28,000 ft. <S> As a yardstick for comparison, an Embraeer Phenom 100 with a similar sized cabin, at roughly twice the cost of a Vision is capable of over 400 KTAS (Mach 0.70) at FL410 with an 1100 NM range with alternate and IFR fuel reserves. <S> Ther are other items that aren't immediately visible but play an important factor in the cost difference, chiefly cabin environment. <S> The Vision's pressurization isn't on par with similar jets, probably being limited to a 5-6 psi cabin differential, yielding around an 8,000 ft cabin altitude at 28000 ft. <S> The Cirrus is spacious compared with <S> an SR-22 but it's nothing impressive when it comes to light jets <S> and it's not even in the same league as larger jets. <S> Many of the systems do not have the creature comforts of the big boys e.g. <S> The Cirrus still uses a castering nosewheel as opposed to NWS equippped on most jets, etc. <S> The Cirrus represents a solid, if somewhat expensive, upgrade from the SR-2X aircraft. <S> Just don't expect it to be a personal 747; it's not and you do get what you pay for. <A> Most of its competition has 2 jet engines. <S> Jet engines are very expensive. <S> The Vision only has one engine! <A> The SF50 was designed to meet a gap in performance between high end turbo props and the 4 to 5 $M Jet. <S> So its not supposed to be as fast, or as high, or fly as far as the Phenom 100. <S> The comparison to the TBM seems a little biased. <S> We highlight a range scenario where the SF50 is heavy and at max fuel burn and then attempt to compare it to an aircraft with a lighter load lower power setting with the statement "depending on payload, but an economy cruise...". <S> If we were to compare apples to apples and go max power and max gross on both aircraft <S> , im sure that economy cruise would go right out of the window. <S> Thus putting the SF50 squarely where Cirrus intended it to be in the first place. <S> Not as fast or high as the more expensive options, but not as slow and low as some others. <S> As for the difference in cost, there are several factors that come along with production of not just another engine, but the nacelle and material to structurally mount the thing, design and engineering labor to make that work, additional labor cost t mount it, test it and any maintenance or warrant programs that may be associated with it, flight testing single engine aerodynamics and flight characteristics, certification, and lets not forget the obligatory profit that has to be attached as well. <S> After all, no one makes airplanes for charity do they? <S> As has been stated already, Does that make up for the total difference in cost? <S> Most likely not. <S> But my response is just a shadow of the reasons why other jets would carry a higher cost.
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The primary differences in performance between the Cirrus and other light jet aircraft is that it's much slower and suffers from 'short legs'.
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Why does the Zapata Flyboard Air UL consume so much more fuel/hr than the Mosquito Air? They are both ultralight and abide by FAA ultralight reg 14 CFR part 103. The Mosquito Air is an ultralight 1 person helicopter whereas the Zapata Air UL is a micro jet turbine powered 1 person ultralight hoverboard. They weigh the same and both only carry 5 gallons of fuel as this is dictated by part 103. The 5 gallons will last 1 hour of cruise flight time on the Mosquito while only 8 minutes on the Zapata. Granted we are dealing with different technologies here and different fuels (Zapata uses kerosene, Mosquito uses avgas) I was surprised by the fuel burn difference. The bare physics tells us that equal masses should require the same amount of thrust, thus energy, to hover in place where lift equals weight. Kerosene has similar energy density to avgas. And, a jet turbine is supposed to be much more efficient than a 2-stroke, 2 cylinder gasoline engine. The Mosquito boasts of a 64hp engine "with the highest power to weight ratio on the market today". The Zapata company seems not so much concerned with the gas guzzling fuel consumption. The 2 companies seem to have different priorities here, so I'm guessing the fuel efficiency of the Zapata could be improved. Still, this is a huge difference that is difficult to understand. <Q> It's the difference between jet engines and propellers. <S> It is a lot more efficient to accelerate more air to a low velocity, than it is to accelerate less air to a higher velocity. <S> For fixed wings, the only reason to use jets is if propellers hit their speed limit, when the tips break the speed of sound. <S> The Mosquito Air burns through its fuel a lot faster than 1 hour when it stays in hover all the time. <S> Cruising in a helicopter makes the fuel consumption a bit more similar to fixed wing: the rotor blades start to act more like wings and can use airspeed to reduce induced drag. <S> Still less efficient than fixed wing cruise, but more efficient than helicopter hover. <S> The Zapata Air UL is always in a hover, and has no wings, and is a jet. <S> It never gets the increased efficiency effect of forward flight that a rotor gets. <S> And jets are really very inefficient at low speeds! <A> First, let's compare apples to apples, and compare the Flyboard to the Mosquito XET, the gas turbine powered version. <S> The Mosquito XET with it's 90hp Solar turboshaft engine consumes around 8.5 gph, while the Flyboard with six small turbojets is more like 38-40gph. <S> Gas turbines are more efficient when they are made larger, which is the primary reason that large twin engine airliners are pushing out four engine airliners for international travel. <S> Far more efficient usage of fuel, now that the larger twins are getting ETOPS certification. <A> I know this post is a little old, but I happened to find this post while trying to find out what turbines Zapata uses. <S> There seems to be a misperception of how helicopters fly/hover compared to how a turbine engines produce thrust. <S> Helicopters actually do NOT fly by thrusting/pushing air down, although that is, in part, a result of what is going on. <S> Helicopters create LIFT via the profile of the rotor blades and the angle of attack which varies according to operator input (at least on the bigger boys). <S> As I'm not a helicopter person, I don't know if tiny copters like the Mosquito can actually vary angle of attack, which makes the mechanism quite a bit more complicated. <S> If you look at a copter blade profile, it's generally the same as an airplane wing. <S> The faster it spins (and therefore moves through the air), the more LIFT is generated, and eventually enough lift is generated to lift/propel the copter. <S> A turbine engine provides THRUST, and it is the THRUST that lifts/propels things like Zapata's board.
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Aside from the greater efficiency of propellers over pure jet exhaust, also consider that the XET has a single gas turbine engine, while the Flyboard has six much smaller gas turbine engines. Hovering flight is particularly demanding on fuel consumption.
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Can an airline reject a passenger for being overweight? I have a Cessna 172S and despite having 4 seats in the cabin, I cannot take 3 more passengers besides myself as the pilot with a full tank of fuel due to safety in weight balance issues. As the pilot, I'm 100 lbs overweight. Hypothetically, we can imagine a situation where a small regional carrier using a turboprop can have only one seat left but the length chord from center of gravity for that seat may cause an unsafe weight balance for the aircraft loading if the passenger is very overweight. In that case, if not other solution can be found, could the airline reject to passenger for the motive of their weight? <Q> Yes. <S> If carriage of said person on a particular flight would cause the aircraft to be overloaded or outside of its CG envelope, the airline has full right to refuse them passage for safety reasons. <S> It would be illegal under Part 121 and Part 135 to do otherwise. <S> Practically speaking though, most large commercial aircraft have such great payloads that this would not happen on a frequent basis. <S> Now the airlines may charge said person for an additional seat costs because of their size and girth. <A> There appears to be some debate as to whether this practice is legal. " <S> Customer of Size" is a politically correct industry term. <S> For example, the written policy at United Airlines requires a passenger to purchase an additional seat, if the armrests cannot be put down and stay down, regardless of whether a family member is seated adjacently. <S> US Air's policy was to attempt to accommodate a customer of size, when there is additional seating on the plane. <S> Should this be a potential issue, travelers should contact the airline in question, as policies may change without publication. <A> When the aircraft is going to be overweight, then yes, the airline can only take what weight the performance numbers will support. <S> That's somewhat uncommon, but it can defintely happen when takeoff performance is limited (hot day, short runway, full airplane, etc) or when the landing weight will be at the maximum allowed landing weight (full airplane + significant fuel load required at landing due to requirements for an alternate airport, for instance). <S> (More on this topic and how the numbers work in this answer .) <S> As far as a passenger being overweight, that's less likely to be an issue, simply because most airlines (in the US, certainly -- this may apply less in other countries) use an average weight multiplied by the number of passengers, rather than weighing each passenger individually. <S> While the difference between four ballerinas and four linebackers in a C-172 is very significant, that same difference among 100+ passengers on a commercial airliner just evens out over everybody else onboard. <S> So there isn't really a case where the airline would say <S> , we can't take this passenger (weighing 300#) <S> but we can take that passenger (weighing 100#), because we only have 250# of weight left. <S> Either you can take one more passenger, or you can't. <S> Doesn't matter what he/she weighs. <A> At least from what I've seen, most airlines will board the passenger. <S> If they have concerns about weight and balance, they'll typically deal with that by rearranging luggage or (if necessary) <S> leaving some behind to be carried on a different flight. <S> When I lived in Colorado Springs CO (runway at 6187 feet elevation), this was fairly common if you were taking off on a hot afternoon. <S> In one case I recall, they even removed most of the carry on luggage from the aircraft--but they still took nearly all the passengers. <S> At least to the best of my recollection, the only passengers who were left behind were those who refused to part with their carry-on items. <A> http://www.aviationqueen.com/?p=2585 Vilma Soltesz [...] three airlines — Delta, Lufthansa and KLM — refused to let her board on flights from her vacation home in Hungary to her permanent home in New York City, allegedly because she was deemed too overweight (at 452 lbs.) to fly. <S> Mind you <S> she was so overweight <S> they had physical problems boarding her. <S> It was not like the gate agent said "you are overweight, we won't carry you" but still. <A> Since your question was more concerned with balance (weight distribution) than total weight, the point about safety still applies. <S> However, if it were actually an issue, I suspect they could reassign seats to put the big guy closer to the middle. <S> I recently heard a pilot announce that we would be a little late because they had to move some luggage around for better balance. <A> In the U. S., ANY business has a right to refuse ANY consumer for ANY reason (with certain exceptions). <S> However, due to business reasons, an airline will force you to purchase another seat. <S> In the case of a small airline, they could put you on another flight. <S> Discrimination against consumers by businesses is permitted by law in the U. S., albeit <S> , it's not wise for business. <S> The exception is disabled persons with service animals. <S> And they must meet certain criteria before service is refused to them.
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Airlines have rejected passengers for their size, perhaps more than their weight, specifically for being unable to fit into a passenger seat.
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Is there anywhere one can buy or find plans to build a human powered aircraft? I was surprised to find that only two Gossamer Albatrosses were built. Is there any way to get or build an aircraft like that today? (I don't mean design your own). <Q> Yes, contact Todd Reichert, PhD, or Cameron Robertson at Aerovelo Inc . <S> They have designed, built, and demonstrated the first human powered vertical aircraft at the University of Toronto, of which they are alumni, and they won the Sikorsky prize of $250,000 for it. <S> They have aero- velomobiles that can smoke the albatross. <S> Note <S> : The ability to get airborne in these Ultralights is heavily dependent on the weight and athletic ability of the human operator. <A> For 20,000 USD You can paraglide on a good day and not need any power except for that of Thermals and wind. <S> If you really want to have something human powered, then after the chute costs, you can attempt a pedal-based propellor. <S> all chute equipment will run ya about 5,000-10,000 USD, depending on the source, leaving more than half available for constructing your strange propellor. <S> That said, I highly doubt that any useful thrust will come of it <S> ; it'll weigh more than it's worth. <S> The sad truth about human power is that it's not very good . <S> It's so bad in fact, that it's not worth using in any aviation-related practicality. <A> Plans for Gossamer Albatross and Daedalus are available if you search for them online. <S> But skills required to build a usable aircraft require some talent and great patience. <S> Depending where you live, materials can be pricey. <S> Personal experience:I have been working on my own HPA design for >25 years (yes). <S> I have found that the successful builders are often happy to give you pointers - so find out who they are, and try email them! <S> (I am not going to cause them spam by listing emails & names!) <S> Building such a plane (on your own?) is an intense labour of love - fraught with great obstacles. <S> It will require great tenacity and an ability to withstand ridicule and disinterest from friends and family. <S> Speed and maneuverability (Musculair), You may be able to find the plans... <S> Those were the very best (real working examples), so far. <S> There is yet to be be a practical HPA for sport and recreation. <S> Prizes for one who succeeds!
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Easy flier (Daedalus), plans are out there, just google...
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Is it better to shut down the engine(s) or leave it (them) running when a gear up landing is imminent? Is it better to shut down the engine(s) or leave it (them) running when a gear up landing is imminent? I noticed that the pilot in this video chose to shut down his engine before touching down during a gear up emergency landing. However, in Pilot Operating Handbooks, the recommendations seem to be mixed. For example, the Cessna 210 POH, Page 3-11 says: Touchdown -- SLIGHTLY TAIL LOW. Mixture - - IDLE CUT-OFF. Ignition Switch -- OFF. Fuel On-Off Valve -- OFF (pull out). On the other hand, the POH for the Piper Arrow III PA28R-201, Page 3-14 recommends shutting down the engine before touching down: 3.lSb Gear Up Emergency Landing (3.Sd) When committed to a gear up landing, CLOSE the throttle, move the mixture to idle cut-off , and shut OFF the ignition, battery master (BATT MASTR), and alternator(ALTR) switches.Turn OFF the fuel selector valve. Seat belts and shoulder harness should be tightened. Touchdown should normally be made at the lowest possible airspeed with full flaps. What is the reason for this variation? Is there some advantage to touching down one way vs. the other? I've have noticed this question: How to execute a gear up landing on aircraft with low propeller? However, I do not believe this question duplicates that one. While consideration of the propeller would be one factor in deciding whether or not to shut down the engine, it certainly would NOT be the only one. <Q> There's two schools of thought. <S> Gives you the option to go around <S> Keeps the procedure simple and allows the pilot to concentrate on a good touchdown <S> Keeps the dynamics of the airplane predictable and familiar to the pilot <S> Personally I'm with the keep the engine on school of thought. <S> The last thing I want to be doing when I'm trying to make a smooth landing is reaching for all sorts of knobs and levers, and having to reach the fuel cutoff valve in the inconvenient places that piper likes to put them, and then learning how the airplane behaves without engine power for the first time. <S> As soon as I touch down I am pulling the mixture, cutting off the fuel and killing the mags and the master switch, but until then I'm going to concentrate on making it the smoothest landing in the history of manned flight. <A> Prior military Flight Engineer, current aeronautic contractor employee here. <S> In the KC-10 , engine shutdown on contact with ground is dictated in order to minimize potential fuel spill and fire hazard. <S> I would imagine that many aircraft have different procedures dictated by their design and engineering features such as landing gear and engine configuration. <A> Both actions quoted result in engine off landings. <S> Repairing a prop strike on just the motor can easily cost 1/3 the price of a motor plus a propeller. <S> Saw a video of a guy landing gear up in a twin, he shut it down after he knew he had the runway and bumped the starters to put the props horizontal. <S> Saved at least 40 thousand dollars doing it. <A> I fly a low-wing, 4 engine turboprop. <S> We would shut down the engines by cutting off fuel, but not feather the props prior to hitting the ground. <S> There are several reasons for this. <S> 1) <S> The fire will go out in the engine, reducing the potential for fire. <S> 2) <S> The RPM of the prop and engine will be drastically reduced, for us it will probably drop to about 35% of normal operating RPM. <S> This reduces the rotational energy, and how badly the prop blades throw fragments when they hit. <S> On our plane the inboard props will hit before the outboards. <S> We also would clear personnel from any seats near the prop plane of rotation or else <S> they're probably going to get hit. <S> 3) <S> We don't feather the props because they are more likely to just bend or break off the tips if the blade angle is flat. <S> If they are feathered, they might tear the gearbox and engine off the plane entirely. <S> This is a measure to limit damage to the airframe, not really a concern about cost savings. <S> There is an awesome video on YouTube from the show Ice Pilots of a Lockheed Electra (very similar to my plane) landing with one of the mains up. <S> They followed basically the same procedure I mentioned and walked away with a lot less damage than I would have expected. <A> You mostly don't need to shut down fuel with aircraft with fuel tanks on the top but lets be on the safe side. <S> This is what I would do (I Am not that great in landings): <S> Aircraft Cessna 172SP <S> Near landing means 250Meters behind the aiming point <S> Full flaps on near the landing VSI is lower than HSI Nose little bit up Near stall speed <S> I Would shut down the engines and cut the mixture in order to minimize odds of getting fuel burned. <S> Then I would try to stop on the field as fast as possible. <S> You will not need to shut down the engine withing 250Meters of the aiming point on aircraft with fuel tanks on the top but do that procedure as n habit. <S> Also you wont need engines on a properly planned landing unless you are an aircraft carrier pilot that is afraid of your tail hook not catching the arresting gear.
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The shutdown the engine school's view is that shutting the engine down lowers the fire risk by cutting off the fuel and engine ignition spark. First is the keep the engine on school because keeping the engine on: Gives you more control of the airplane
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Is it a literal hood that's used to simulate IMC? I know this is a basic question, but a lot of Q&As on here talk about being "under the hood" to simulate IMC. My question is, is this a literal hood? Can someone please explain what this actually means to a non-pilot? <Q> When you read or hear the term "under the hood" as it relates to simulated IMC, it may or may not be an actual hood. <S> The FAA does not require a hood, instead the FAA calls for a "view limiting device." <S> Often the view limiting device used is a hood such as the ones depicted below. <S> However, other view limiting devices can also be used, such as glasses with an opaque coating that limits your view such as the ones depicted in the last picture below the hoods. <S> Checkout <S> this "superhood" at Sporty's ! <S> This is the type I used for my IFR certificate back in the day. <S> It is commonly still referred to as "under the hood" or as "hood-word", but as you can see these are not a hood. <S> There is a name brand of glasses like these called "foggles." <S> And most people refer to these as "foggles", although, these, are a different brand. <A> Yes, old style view limiting devices were typically a light plastic hat like device, which was translucent, to simulate clouds I suppose. <S> It was typically on a pivot so it could still be worn while the view was not limited. <S> It was called a hood. <S> Today a popular replacement is white with a clear cutout for viewing instruments, and it fits on glasses or sunglasses. <S> Foggles are more common, and I have students make them out of safety glasses. <S> Newer view limiting wear was less expensive, and tends to work better with headsets than a traditional hood. <S> Years ago, I used a pair of industrial safety glasses with translucent tape, to be my view limiting device. <S> I also put translucent tape on the side shields <S> They were more comfortable than what was commercially available for pilots at the time. <A> With this one, everything was under the hood. <A> Yes, most pilots practice flying in simulated instrument condition using a view limiting device, sometimes in the form of a hood, though the newer translucent eyeglasses e.g. Foggles, etc are becoming more and more popular for this purpose. <S> Another method which is preferred by the US military and other militaries are out the world for instrument training <S> is a retractable curtain which covers all the windows or canopy enclosures in an aircraft, preventing the student pilot from looking outside the airplane.
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This is another type of view limiting device that can be used to simulate IMC.
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How do you know which fuel an aircraft uses? Other than the decals on the plane, how would you know what fuel to use in an aircraft? Where is this limitation documented? For some aircraft, does this limitation include some sort of substitute fuel for emergencies? For example, I have heard that if Jet A-1 is not available, some aircraft may have approved emergency fuels, such as AvGas. Where would this information be found? <Q> The actual fuel type limitations will be listed in at least two places: the aircraft type certification data sheet (TCDS), and the limitations section of the aircraft Flight Manual, Operating Handbook, or equivalent. <S> The fuel placards placed at the fuel filler ports might not list all approved fuels, or may state "Type X fuel only" when additional fuels may in fact be approved. <S> These placards should be understood as a precaution against inadvertently fueling with an unintended or wrong type of fuel. <S> In some cases ignoring these placards can have fatal consequences . <S> Some aircraft do indeed have approved emergency fuels. <S> This information would also be found in the limitations listed above. <S> For example, the TCDS for the Beechcraft King Air B200 with PT6A <S> series engines is lists the following for normal approved fuels: <S> Fuel <S> JP-4, <S> JP-5 (MIL-T-5624); JP-8 (MIL-T-83133); JET A, JET A-1, and JET B conforming to <S> P&WC S.B. 1244 or ASTM SPEC. <S> D1655; in addition for B200 and B200C Chinese No. 3 Jet Fuel. <S> See NOTE 6 for emergency fuels <S> Note 6 in the TCDS reads as follows: <S> NOTE 6 . <S> Emergency use of MIL-G-5572: Grades 80/87, 91/98, 100/130, and 115/145 are permitted for a total time period not to exceed 150 hours time between engine overhauls. <S> It is not necessary to purge the unused fuel from the system when switching fuel types. <S> Likewise, the EASA TCDS for the King Air B200 lists the same limitations. <S> The Flight Manual for the King Air B200 also lists these limitations, as applicable, as well as some additional altitude constraints when using emergency fuels due to electric boost pump requirements. <S> In contrast to the actual fuel limitations, the placard placed at the fuel port for the King Air B200 lists very little of the actual limitations: <S> Source: <S> Beechcraft King Air 200 Maintenance Manual <A> As an example, the Cessna Caravan, with a PT6-114a engine can run on Jet A or other fuels, such as 100LL. <S> The information is not always on placards. <S> If a replacement engine has been installed, there will likely be a supplement with the STC which will cover alternate fuels and any limitations. <S> Pilots normally refer to POH and not maintenance manuals and type certification data. <S> Therefore the POH or it's equivalent is the first place I would look. <S> Besides, when you need to use an alternate fuel, the volumes of manuals and type certification data may not be readily at hand. <S> Addendum <S> #1Some aircraft, such as recip singles may have a STC permitting use of mogas, as an example. <S> In these cases the STC will have an operations supplement for the POH or equivalent. <S> This was actually a fairly common alternative fuel 20 years or so ago. <A> You know what fuel to put in your (light) aircraft, the same way as you know what fuel to put in your car - you've done it before <S> and you know to lift the right nozzle at the bowser! <S> For larger aircraft/airliners, chances are there is a person whose job it is to refuel your aircraft, and they will likely know very well what fuel to use. <S> If they don't they would ask, or look up the correct fuel from somebody who does know. <S> There are a few things to help you remember, such as placards next to the fuel cap <S> The pipework/shut off at the bowser might also have a placards/indications/color-coding. <S> A for emergency fuel <S> , that is part of flight planning - you calculate how much fuel you expect to use and add an amount on for emergency/contingency . <A> Placards only tell half the story, check the flight manuals for the rest of it <S> The placards at the fuel port will indicate what the primary or preferred type of fuel is: For spark-ignition reciprocating-engine aircraft, 100LL aviation gasoline is the primary certificate fuel, and that's what the factory placards will likely say. <S> Some aircraft may have AFM or STC provisions for the use of other types of gasoline (such as other grades of avgas, or oxygenate-free mogas), but this will likely not be included on the placards. <S> Some may be modified to use standard road diesel or blends of road diesel and jet fuel -- the placards won't mention this, but the AFM will. <S> Smaller turbine (turboprop and jet) engines also are primarily fueled using Jet-A or a military equivalent fuel, and this will be on the placards. <S> They can also often burn aviation gasoline or avgas/jet mixes but under operating restrictions that will be mentioned in the AFM. <S> Large turbine engines will require jet fuel, and kerosene-based jet fuel at that -- they cannot run on wide-cut jet fuels such as Jet-B or JP-4, likely due to boiloff issues. <S> These aircraft take enough fuel, though, that the only fueling systems capable of handling them are dedicated to jet fuel anyway. <S> Fuel ports help, but aren't the total solution <S> Jet fuel dispensers are supposed to use a wide, rectangular nozzle that is too big to fit into an avgas plane's fueling ports, thus preventing all but the most determined from misfueling an avgas-only plane with jet fuel. <S> However, a few aircraft are retrofitted with turbine engines without changing the fueling ports, some older aircraft may have large diameter avgas ports due to the flows needed, and some turbine helicopters do not accept the standard jet fuel spout (J-spout or "Hoover spout"). <S> Hence, some jet fuel dispensers are fitted with narrow "rogue" nozzles, creating the very misfueling hazard the J-spout is supposed to prevent.
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Aerodiesel (compression ignition reciprocating-engine) aircraft are typically fueled using Jet-A, and thus will have that on the placard. The POH is normally where this is documented.
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Has anyone ever been penalised for buzzing a control tower? Has there ever been a pilot who was caught and penalised for performing a "circus stunt fly-by" next to a control tower? To clarify the question: I mean legal actions took place; for example arrested, license revoked, attended a court martial (if the person is in military service) the action must have been unapproved, possibly illegal. Pre-arranged fly-bys, such as air-shows, or the ones used to film Top Gun, do not count. <Q> Well, there's always someone. <S> In the mid 1950’s, Arthur Godfrey was preparing to take off from Teterboro Airport in his private DC-3. <S> He requested a take off on a runway which was into the wind. <S> The tower refused his request and instructed him to use a runway which had a sizeable crosswind. <S> He complied, but he buzzed the tower, almost running into it. <S> The tower personnel dove for cover and reported him. <S> After a long hassle, Godfrey had his license suspended for six months. <S> And he wrote a song about it . <S> Back then, you lost your license. <S> If you try that stunt now, your chances of ending up in a black site are frighteningly real, as Shaun Lees, an amateur pilot found out : ... <S> (Lees) chartered the helicopter from another airport, landed at Coventry, where his actions effectively closed it down, then flew toward the control tower. <S> Hovering close to it, he announced over the radio, "you are going to see the very worst of my flying", then started to circle. <S> He got sent to the jail for three years, with ... <S> Judge Marten Coates told Shaun Lees, a 41-year-old electrician, what he had done was "practically an act of terrorism". <A> Not a control tower, but how about the press box of a university football stadium... while a game was being played. <S> During the University of Florida vs. Kentucky football game in November, 1985 a B-25 buzzed the field. <S> SUN 11/24/1985 HOUSTON CHRONICLE, Section 3, Page 16, 2 STAR Edition GAINESVILLE, Fla. - A World War II-era bomber that buzzed a stadium during a university football game was making its final flight before being turned over to Smithsonian Institution, its owner and pilot says. <S> "It was a perfect day. <S> We had made several passes in the country, and the airplane felt good," John Marshall said. <S> "It was a last hurrah - the airplane is going to the Smithsonian. <S> She had a good home in Florida, and we wanted to say good-bye." <S> Marshall, a radiologist who lives in Ocala, could lose his pilot's license and be fined $1,000 for buzzing Florida Field, where 72,000 were attending the Florida-Kentucky game. <S> The pilot acknowledged that he violated a Federal Aviation Administration regulation that requires planes to maintain a 1,000-foot altitude when flying above a crowd. <S> But he said there was "no malicious intent" involved. <S> The B-25, named "Carol Jean," which appeared in the movie "Catch- 22" as "Luscious Lulu," was received eagerly by officials at the Smithsonian's Air and Space Museum. <S> "We have long been searching for a B-25. <S> We've been purposely holding back to find a good one," said Tim Wooldridge, the museum's aeronautics department chairman. <S> Edit now that I've got <S> my 2 accounts merged... <S> I was there at the game. <S> It was AWESOME! <S> I was down closer to the field, so <S> I'm not sure if they actually got below the edge of the stadium or below the roof line of the pressbox/skybox <S> (The Swamp was much smaller then). <S> A former coworker (now dead for 10 years...) claimed to have been in the plane as a passenger and that they were below the level of the press box and actually dipped down into the "bowl" of the field, but I doubt the truth of those statements. <A> Probably not what you are looking for, but Flight Lieutenant Alan Pollock beat-up the Houses of Parliament and flew under Tower Bridge in London in 1968. <S> He also 'visited' a number of RAF airfields at low level and inverted. <S> He was arrested, put on a charge and invalided out of the RAF rather than court martialed
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In January 1954, American TV and Radio personality Arthur Godfrey buzzed the Teterboro control tower with his Douglas DC-3 , resulting in the suspension of his license :
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Is there any technical reason that prevents installation of a jet blast deflector at Princess Juliana airport? A jet blast deflector (JBD) or blast fence is a safety device that redirects the high energy exhaust from a jet engine to prevent property damage and injury. Regarding the incident on July 13, 2017 at Princess Juliana Airport , I see no jet blast deflector installed. Is there any technical reason that prevents installation of such a safety device? <Q> Large airplanes like 747s must touch down pretty close to the near end of the runway, which is right at the edge of the beach, a blast deflector would be a serious hazard if an airplane came in a bit too low. <S> Here's what I'm talking about: A static deflector would be extremely close to the path of the landing gear. <S> It could theoretically be possible to install a retractable one, however sand does not make a good building surface and therefore it would be real engineering challenge. <S> It seems much more likely that the authorities, if they do anything, will install more fencing or other barriers to deter people from getting so close rather than install a blast deflector. <S> This would be cheaper and achieve the same effect. <A> To answer your question directly, the only technical limitation would be the height of the blast deflector due to landing aircraft, but otherwise there is no technical limitation. <S> Landing aircraft have to land beyond the displaced threshold which is indicated by the arrows. <S> The beginning of the runway is located 500 ft beyond the fence (see google maps photo below), so a 6 to 8 ft tall blast deflector at the fence would pose little risk to landing aircraft, while at the same time deflecting the jet blast from the departing aircraft that are allowed to use the displaced threshold for takeoffs. <S> They could build a modified jet blast deflector that is no higher than the chain linked fence that separates the airport from the public beach, it would reduce some of the blast that is received at ground level where people are standing. <S> They could make a deflector that is a little shorter than these: However, this is a pretty big tourist attraction, and there are plenty of warning signs. <S> Its no different than people going on vacations to Yosemite, every year someone slips and falls to their death while walking on a slippery trail to see one of the water falls. <A> One also needs to remember it was not the jet blast that killed this unfortunate lady (condolences to family), but rather striking the rather awkward and hard retaining wall behind her. <S> Similar incident... <S> Although a small deflection fence would not be a bad idea, and could be built to be no higher than the current chain link fence, the least they could do is remove the hard wall that is the real killer.
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An immobile jet blast deflector could not be built far enough away from the runway end to be safely clear of the landing path.
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What happens if Marine One's rotor blades fail? While I was reading news, I came across this image of Marine One : This is Sikorsky UH-60 Black Hawk Citation of Image 1 Citation of Image 2 On a closer look, I see there are two big exhausts just under the blades at the top of Marine One. And there is also a big wing at the end of Marine One. I know I would be wrong, but I am not sure about it: I thought these two things are inter-related to each other in case of rotor failure, i.e if the rotor fails then the exhaust would pump out air backwards like a blast giving it forward thrust, and the wing at the end would help it in direction or upward/downward thrust balance (just like in F1 racing cars ). Essentially making it work like a plane for some time until it lands safely. I tried searching about it, but could not get information about it. I did come across an older Marine One image whose exhaust is too small and is at the side rather than at the back and this does not have a wing at the back: This is Sikorsky SH-3 Sea King Citation of Image 3 Citation of Image 4 I have 3 questions: Why is the exhaust at the back of new Marine One so big now? Why is there a wing at the back of the new Marine One ? What would happen if rotor blades of Marine One fail ? Citations <Q> No helicopter can fly if the blades fail. <S> The overwhelming majority of the lift produced, required to counter gravity, is from the blades. <S> There is some lift from lots of other parts of the helicopter but all combined, nowhere near enough to keep it flying. <S> The blades are also required to manoeuvre the helicopter. <S> The wing at the rear is called an horizontal stabiliser and its job is to push the tail up or down, depending on the load and speed of the helicopter, to keep the fuselage more or less level throughout the operating range of the craft. <S> Marine One would simply plummet if the blades failed. <A> To answer the other questions... <S> Why is the exhaust on the Blackhawk so much larger than the Sea King? <S> One reason is - the Blackhawk has larger engines, 1500hp as opposed to 1200hp. <S> The primary reason, though , is dispersing the exhaust heat, making the Blackhawk a harder target for heat seeking missiles. <S> Note the fairing above and around the exhausts, also part of the heat disperson system. <S> Why does it have a wing on the back? <S> This Q/A thread suggests it is tied to airspeed, not the cyclic, for stability reasons. <S> As for a main rotor blade failing... <S> yes, <S> you're pretty much dead if that happens. <S> One reason helicopters cost so much more per hour to operate than aircraft is the more rigorous maintenance and inspection schedule, especially on the main rotor and blades. <S> Fortunately, main rotor failures outside of the blades hitting something due to pilot error are extremely rare. <A> I served as a Helicopter Crew Chief on a Sikorsky H-34 helicopter in Vietnam and I agree that blade failures are incredibly rare on properly maintained aircraft. <S> On most helicopters the main structure of the blade (spar) is hollow and contains pressurized gas — usually nitrogen. <S> Before each flight, the Crew Chief and Pilot check a gas pressure indicator on each blade. <S> If a crack develops in the blade, the gas will leak out and likely indicate a problem before there is a failure. <S> Military helicopters are designed to work very hard and handle a great deal of stress. <S> Marine One probably has a very easy life compared to its counterparts in the rest of the world. <S> I’d say it is a very safe aircraft.
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It is also most probable, and this what usually happens, that if one blade fails, or is lost, the resulting imbalance in the heavy, fast rotating rotor assembly leads to instant breakup of the aircraft.
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What is the difference between a glider and a sailplane? The words "glider" and "sailplane" seem to refer to similar or the same type of aircraft. In particular, the Wikipedia articles " Glider (aircraft) " and " Glider (sailplane) " seem to be describing the same kind of aircraft. What is difference between a glider and a sailplane, if any? <Q> The sailplane article is focused around sport and recreational planes. <S> The aircraft article describes a wide variety of aircraft, not simply planes, like hang gliding and paragliding. <S> Which makes sense - one is about aircraft, so it has the aircraft moniker. <S> The other is specifically about planes, which are a subset of aircraft, and thus have the sailplane moniker. <S> There was an idea of merging them in 2011, <S> but it failed . <A> From the FAA Glider Flying Handbook , pages 1-3 and 1-4: <S> The Federal Aviation Administration (FAA) defines a glider as a heavier-than-air aircraft that is supported in flight by the dynamic reaction of the air against its lifting surfaces, and whose free flight does not depend principally on an engine. ... <S> Another widely accepted term in the industry is sailplane. <S> A sailplane is a glider (...) designed to fly efficiently and gain altitude solely from natural forces , such as thermals and ridge waves. <S> Older gliders and those used by the military were not generally designed to gain altitude in lifting conditions. <S> (Emphasis mine) <A> There does not appear to be any formal definition I can find, but if one observes the aircraft that are typically described as a 'glider' or a 'sailplane'... <S> Sailplane is generally used to describe an unpowered aircraft that is optimized to remain airborne by taking advantage of thermal currents. <S> Typically lightweight, typically with very long wings. <S> Schweitzer is a well known maker of sport sailplanes. <S> Aircraft described as 'gliders' are usually WW2 aircraft for getting troops and equipment onto unprepared ground, hopefully in one piece. <S> They were used for airborne assault in pre-helicopter days. <S> Examples: Waco CG4 , Airspeed Horsa , DFS-230 , ME-321 . <S> (the ME323 Gigant was the powered version) <S> All were expressly designed to be towed to their destination by powered aircraft, and make short glides onto unprepared ground, to deliver troops and equipment. <S> Also, rocket propelled aircraft such as the ME-163 were described as a glider, when their fuel ran out. <S> Not sailplane. <S> Finally, quite a few aircraft under development in the pre-CAD era were first flown as unpowered versions. <S> Those experimental aircraft are always referred to as 'gliders'. <A> "Glider" is the broader term, including everything that would normally be described as a "sailplane", and also including many other aircraft such as troop-carrying assault gliders , and ultra-low-performance training gliders like "primary" trainers and training gliders adapted from light airplanes such as the Piper TG-8 , and rocket-powered gliders such as the ME-163 Komet , and even the Space Shuttle. <S> "Sailplane" generally confers a connotation that a given aircraft is intended to actually gain altitude in soaring flight. <S> Yet there are also some craft called "gliders" that are specifically intended for soaring, yet would never be called "sailplanes". <S> These include weight-shift controlled hang gliders, and paragliders. <S> As an aside, being ultralight aircraft, note that these aircraft do not actually fit within the glider "category" as defined by the FAA. <S> If a given aircraft is not generally shaped like a streamlined, efficient version of a conventional airplane, or is not guided by a pilot using a fairly "conventional" aircraft control system, it will probably not be called a "sailplane", no matter how well it can soar. <S> There are also some aircraft that most people would agree may fairly be called "sailplanes" as well as "gliders", yet would not fit within the "glider" category as defined by the FAA because they are ultralight aircraft. <S> An example would be the Archaeopteryx foot-launchable sailplane . <A> I have no issue with either answer given. <S> That said, I think this question deserves an answer "from the street". <S> I got my glider add-on in the summer of 2016, started training for it in the summer of 2015. <S> I belong to a 100+ member glider club in the United States, of which 85 percent have their glider certification/ <S> add-on, 20 percent are CFIs and quite a few have flown gliders for 40+ years. <S> Due to the nature of our club, during my training I flew with 15+ different instructors. <S> And, of course, given the "stand around and tell war stories" nature of glider operations, I've talked glider flying with most of my fellow club members. <S> During all flights I have undertaken and observed, the primary goal was ALWAYS to "remain airborne by taking advantage of thermal currents." <S> (though we don't call them "currents"). <S> The exception, of course, is training flights, where the primary objective was learning to fly gliders. <S> All of this said, I have NEVER, not once, heard the aircraft we fly refered to as a "sailplane". <S> On the contrary, the word we use to refer to what we fly is glider, exclusively. <A> The term "glider" has many usages. <S> It can mean any unpowered object, from lizards to underwater craft, supported by wings and able to convert part of its downward motion into significant forward motion. <S> Most commonly it describes any unpowered fixed-wing aircraft, some of which have quite steep and short flight paths. <S> The more streamlined gliders can soar, which is a form of gliding in which rising air currents are used to sustain flight more or less indefinitely. <S> Such a soaring glider is commonly called a sailplane. <S> Then there are the specialist technical definitions, such as that used by the American FAA certification authority. <S> Many glider clubs exist and most of their planes are of the sailplane class of glider, however they are typically referred to as gliders by their owners and pilots.
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Glider refers to an unpowered aircraft that isn't necessarily optimized to remain airborne in the non-towed state.
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In the US, what can be done at an airport when volunteering hours? I am a 15 years old and need volunteering hours for my course work. I am a aviation enthusiast with knowledge of the industry and love for anything that flies. I decided to fulfill my hours at a local airport because I would be helping others doing what I love. I am from Florida, and I know this is the greatest place for all aviation related things. The tasks I would like to perform at my local airport are fueling, taxiing aircraft in and out of a ramp, and help with other airport operations. Is any of this possible? If anybody can give me any idea on how to do this. I also like any advice to help me further my volunteering path with other aviation related tasks. <Q> Commercial airports are challenging for volunteers because of security, if you want to do anything beyond the security barrier (ie where the interesting stuff is) then you need to be cleared and supervised, and that costs time and money. <S> There may be opportunities at small airports, which don't have the same security concerns. <S> Most won't have any established volunteer positions, it would be more of a case of talking to the airport manager or someone running an FBO and asking if there's anything you could volunteer for. <S> Ask politely, wait a few days, then follow up with a phone call, if they know you're genuinely interested (and polite, sensible, not likely to run into a propeller) they might be willing to offer something to you. <S> One last thing, if anyone asks you to get a bucket of propwash it's an old aviation joke. <A> Working as a volunteer at an airport may be problematic, because almost everything at most airports is (a) a for-profit enterprise, and (b) involves liability. <S> Those factors make it more likely to use paid, trained, accountable employees instead of volunteer temporary help. <S> That said, there are aviation-related volunteer opportunities out there if you can expand your criteria a bit. <S> Aviation museums tend to do lots more with volunteers, and that would be the first place I'd suggest looking for leads. <S> You won't be fueling or taxiing aircraft, but working around docents with a career of aviation experience, you'll pick up a wealth of stories & advice. <S> Best of luck in your search! <A> Civil air patrol . <S> They fly GA aircraft in service to the nation. <S> Technically an auxiliary of the Air Force, they do search and rescue, disaster relief, aerospace education, a cadet program, homeland security, assisting law enforcement, all sorts of things. <S> And yes, they have a youth program. <S> Aviation museums. <S> And one that many people overlook, naval aviation museums. <S> Like the USS Intrepid, Midway, Hornet etc. <A> I would go to your local airport and contact the manager. <S> Many airports have a public space, and most of the ones I've been to could definitely use some attention. <S> You could see if there are touch up jobs you could do there. <S> I'm wondering if railings need new paint or new signs could be placed. <S> Paint parking stalls. <S> Replace tie downs. <S> Others have mentioned liabilities working around aircraft. <S> I don't image you could do much that involves being near or interacting with planes without waivers and training... <S> Also, lots of airports like to host events. <S> I've been to many of these and there is often a lot going on. <S> I'm sure there is a way to volunteer there, even if its just taking tickets at the gate or guiding visitors. <S> Good Luck
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Some large airports may have volunteer greeter positions (i.e. "Which way to baggage claim C please") available, but I'd start with museums for a closer connection to fliers & flying machines.
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Is there any flight school that uses jets as part of their training program? Is there any flying school out there that use "jets" as part of their training program? I mean like a Cessna Citation or Phenom. <Q> Yes, Lufthansa flight training in Bremen uses the Cessna Citation CJ1+. <S> D-ILHA <S> D- <S> ILHB <S> D-ILHC D-ILHD <S> D-ILHE <S> The KLM flight academy used to have Cessna Citations, but I think they no longer use them as part of the training. <A> It's rare (and EXPENSIVE) <S> but there are a few flight schools which offer primary flight training in the Embraer Phenom 100 and Citation Mistang aircraft. <S> Angel City Flyers in Long Beach, CA (KLGB), is one such flight school. <S> Bring your banker; it's going to cost $1000+ per flight hour plus fuel and instructor fees! <S> Another place is the National Test Pilot's School in Muroc, CA. <S> Their 11 month Masters of Science in Test Piloting course will make you an accredited test pilot and log flight time in over 30 aircraft, including jet fighters like the Saab 35 Drakken. <S> Tuition is $960,000!!!!!! <A> The facility used to be used by Singapore Airlines for their pilot training. <S> Great location! <A> The Swedish Air Force uses the Sk 60 jet (Saab 105) as its only trainer , including initial training. <A> For initial training, I don't think there is any flight school or Air Force in the world that will let you begin in a jet. <S> At the later stages however there are some programs that incorporate jet time. <S> But generally speaking most pilots in training programs don't fly jets until joining the airline.
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I believe Lufthansa's ab initio course uses a Citation as the final stage before joining the airline. FlightOptions at the Sunshine Coast in Australia have a Level D Citation Mustang simulator, and a real Mustang as well.
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Do pilots need a clearance to go around? I have read about the missed-SFO-accident and watched the 2:22 movie . I want to ask about going-around (or canceling takeoff) when the pilot is fully aware of an emergency that the tower is not (or is late at acting). According to the reconstruction of the real missed-accident done by the news: Air Canada pilot was on final cleared to land, but instead heading to taxiway for reason that will be explained after FAA & TSB investigations Tower did not notice and did not complain, clearance was still ok Pilot double-checked with tower because he saw lights on the ground Tower double-confirmed clear to land Other pilot on queue said "where is this guy going?" Tower requested go around Air Canada flight crew initiated go around. The order of the last two events is currently not clear and subject to investigation. In the movie both ingoing and outgoing pilots are scared by the sight of each other but ATC Dylan doesn't command action until the last moment, while clearance to land and take off is still granted for both. It is clear that in the movie ATC has failed and pilot(s) are aware of a real danger that affects the safety of flight operation. Like a driver sighting an animal on the road and braking (or worse moosing) without calling the police first. I am no pilot, I understand that flight is definitely different from driving. And I also enjoyed my time on MSFS virtual flight school. I said the above because I know it could be disappointing for experienced pilots. I want to ask for my culture/curiosity: when a pilot is cleared to takeoff/land but sees a legitimate reason to cancel the maneuver (e.g. stop/go around), can he simply advise the tower that he is doing that or must continue as earlier instructed? AFAIK when an indicator indicates failiure at < 80kt speed the pilot can immediately cancel takeoff, otherwise is required to continue. My idea is that the Air Canada pilot could have told the tower something like "we are now fully thrusting and going around because I am not sure about the safety of this landing, please give me further instructions for looping" by his initiative. This is allowed in the MSFS simulation (you can open virtual ATC radio and announce missed approach even a few feet above ground, they will tell you how to loop over the circuit asap). Is it allowed in reality, or do pilots need a clearance to go around? <Q> No, and this applies to any pilot, not just an airliner pilot. <S> After the pilot has been cleared to land (or even if you're landing at your own discretion at an untowered airport), he can decide to go around instead of landing if he's dissatisfied with the approach for any reason . <S> The pilot might need to abort the landing for reasons the tower can't possibly know about, such as a gear unsafe indication, failing to achieve a stabilised approach, not making visual contact with the runway, or some distraction within the cockpit. <S> And even in the case of a reason the tower should be able to tell - such as another aircraft infringing the runway, lining up on the wrong runway by accident, or birds on short final - the pilot must still go around if he thinks it's not safe to land, without waiting to be told. <S> The same applies to taking off. <S> Even after being cleared to take off, the pilot must not take off if he thinks it is not safe to do so, even if it's for a reason the tower should know about, such as a runway obstruction or a take-off clearance on a crossing runway. <A> The pilot of an aircraft is responsible for the safety of the flight. <S> If he wants to go around or cancel takeoff, he can and will just do so. <S> The purpose of ATC is to provide a service to help the pilots, not to tell them how to do their job. <S> More technically speaking, when a flight is cleared for an approach, they are also automatically cleared to fly the associated missed approach. <S> The Air Canada pilot did not notice he was lined up for a taxiway before the pilot on the ground said so. <S> Because the taxiway is parallel to the runway, this would have been very hard to see from the tower. <S> The tower did nothing wrong, since they cleared the flight to land on the empty runway. <S> It's hard to say why the pilot lined up for the taxiway instead. <A> If a pilot decides to go-around for any reason, he can intiate a missed approach without making any radio call. <S> There is a good reason for this. <S> The decision will usually be made late in the approach, either because the decision height has been reached without visual contact, the approach has become unstable, or some other safety issue has arisen. <S> All these situations require immediate action by the flight crew. <S> However, it may not be possible to contact ATC at this point. <S> The frequency may blocked by other people speaking or the pilot may simply be too busy to make the call until his aircraft is safely established in the climb. <S> That is why there is a standard missed-approach procedure specific to each individual runway at major airports. <S> This will have been designed to ensure separation from other traffic should a go around be required. <S> In multi-crew operations the pilots will have briefed the missed-approach procedure before arrival, so both will have a clear understanding of what needs to happen without having to scrabble around the approach charts. <S> For example, the standard missed approach might require a straight-ahead climb to 3,000ft and then a right turn to take up the hold over a navigation beacon. <S> If ATC sees that the aircraft is going around before a radio call is made (as is often the case <S> ) they know the crew will carry out the standard missed approach procedure unless advised otherwise. <S> The crew will then call at the first opportunity to confirm the go around and give their intentions. <A> Seconds can make the difference between safety and disaster, once a pilot recognizes a situation where a go-around is required they are expected to initiate the maneuver immediately. <S> Once the pilot has established a positive rate of climb and followed the immediate go-around actions they will then contact ATC and inform them they have gone around. <A> A clearance gives the pilot permission to do it, but the pilot is not required to do it. <S> Moreover, a go-around, or missed approach, can be executed at the pilot's discretion whenever he or she is not comfortable about anything. <S> I have some flying experience myself <S> and I have executed go-arounds for all kinds of reasons, some not serious at all. <S> I have also aborted takeoffs before for several reasons. <S> In neither of these cases did I ever request permission. <S> The general rule is "if in doubt, go around." <S> A pilot tells ATC that he or she is executing a missed approach (only after you have dealt with more serious matters), they don't ask for permission. <S> On approach to land, the crew usually also prepares to go around, just in case they need to. <S> Pilots study the missed approach procedures for an airport and are ready to execute them whenever needed. <S> Furthermore, a pilot can disobey an ATC instruction, if obeying the instruction would jeopardise the safety of the flight.
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A pilot does not need to get clearance for a go-around.
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Is it appropriate (legal) to request practice instrument approaches in IMC? I have always requested practice instrument approaches while maintaining VFR (with a safety pilot or instructor). But I was wondering if there are any issues (legal or otherwise) with requesting multiple approaches in actual weather at the end of a short IFR flight. Assuming, there are no safety or controller workload issues. In other words, assuming weather is well above minimums and controlling facility is not busy (during off peak hours). I realize I could just make multiple missed approaches, and get the extra approaches that way, but that is not what I'm asking. <Q> Certainly you can request practice approaches in IMC on an IFR flight plan. <S> ATC will accommodate aircraft on a first come, first served basis. <S> It is legal, and appropriate if ATC can accommodate it based on traffic (or noise or NOTAM restrictions). <S> Of course there will be some difficulty if you attempt to do practice approaches at Los Angeles (LAX) or New York (JFK). <S> ATC would not likely accommodate this at these or similarly busy high performance aircraft airports. <S> But again, unless it was otherwise restricted (e.g., noise abatement requirements or NOTAM restrictions) you can certainly request this type of IFR/IMC handling. <A> Approaches in actual IMC aren't really "practice": you're an IFR aircraft doing IFR stuff, which just happens to be multiple instrument approaches. <S> It isn't anything to be ashamed of - everyone in the system learns by doing at some point. <S> The controller you're talking to may be a trainee, too, and learning something at the same time you are. <S> It's nice to be considerate and not show up in the middle of an inbound rush to a major airport (or even an airport close to a major airport, since controllers are responsible for a wide area <S> and you'll be part of their workload regardless...), <S> but they get paid to provide a service and you're entirely within your rights to request multiple approaches. <S> Military aircraft do that all the time - for example, a B52 coming back from a 7-hour training flight may spend another hour <S> or two doing approaches with a civil approach control before landing. <S> Just tell ATC what you want to do, and pay attention in case they issue alternate missed approach instructions. <A> If you have an instrument rating or are under training from an IR rated instructor then there's no problem asking for as many instrument approaches as you want. <S> It's good training to fly in real IR conditions rather than simulated. <S> There's nothing like real cloud to concentrate the mind. <A> You will have to be an instrument rated pilot with an IFR equipped aircraft and file a local IFR flight plan with your intended route of flight and approaches with terminations. <S> Along with full motion simulator time, this is a good way to maintain IFR currency, especially if you live in an area with frequent and harmless IFR conditions <S> e.g. low stratus clouds free of icing, embedded thunderstorms, etc. <S> in addition flying multiple approaches and holds, one right after the other, is more work intensive than a real IFR CC flight in IMC.
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They absolutely will let you fly practice instrument approaches in IMC. It would be very much against the rules to fly in instrument conditions without an IR though.
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How much FOD hazard can a Styrofoam drink cup pose? So, the Collings Foundation and their touring warbirds were in town recently, and we went to visit them. While out on the ramp though, my father managed to lose one of the Styrofoam coffee/drink cups the FBO provides (for their complimentary ice water and iced tea, of course). How much FOD hazard could that runaway Styrofoam cup pose, considering its relative lack of hardness and stiffness/strength compared to most other FOD hazard items? <Q> Probably very little. <S> There's the very slight chance that it could stuck on a pitot tube or some other terrible scenario in a Final Destination type film which, coupled with another issue, could cause a problem but again very unlikely. <S> The underlying hazard is the attitude towards FOD in general. <S> It's a bad habit to build complacency towards any FOD sitting on a parking apron or letting it "get away". <S> If it's SAFE to pickup the FOD then it should be picked up. <S> It's possible the next time someone ignores a cup, it could have been used by a wayward mechanic to hold a sticky chemical that would ruin a pilot's windshield and his day if it smacks and smears on the glass on takeoff. <S> Again very unlikely but why risk it! <A> If any engine fails due to a foam cup it was already failing. <S> Obviously you never want fod on the flight line <S> but there's a significant difference between soft and hard fod. <A> Shredded by a propeller may end up in a pitot probe and clog it. <S> Best example of this sort of small thing big trouble is the coin in the elevator mechanism that happened a few years ago to a glider (no damages or whatsoever, luckily).At my club <S> we had a passenger losing an earring while in flight and quite a bit of take apart followed....
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Chances of it causing a real damage are slim but not at all negligible.
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How long can an average aerobatic plane sustain 0g? How long can an average aerobatic plane sustain 0g safely? <Q> An aerobatic aircraft (as well as any aircraft) can sustain 0g until the pilot pulls up, the aircraft hits the ground, or reaches terminal velocity. <S> In order to sustain 0g <S> the aircraft must be accelerating towards earth at $9.8 m/s^2$ (meters per second squared). <S> That means there isn't much time before the aircraft reaches its maximum speed. <S> Once the aircraft can no longer accelerate at the same rate of gravity, then the occupants will no longer feel 0g. <S> In sky diving (and physics) <S> this is called terminal velocity, which is the velocity at which air friction prevents the object from falling any faster. <S> Acceleration is change in speed, so naturally you don't have to be going straight down to be accelerating towards the earth <S> (we're talking about vertical speed). <S> If you are going up at 200kts and begin to decelerate at exactly $9.8m/s^2 <S> $ you will "feel" like you are in 0g (free fall) even though you are continuing to go up for a few seconds. <S> But this will only last for a few seconds before the aircraft momentarily reaches its apex and you and the aircraft begin moving towards the earth. <S> If the aircraft can match exactly the acceleration of gravity, then you will continue to feel weightless (i.e. 0g). <S> But you can't continue to accelerate indefinitely towards earth without either reaching terminal velocity or exceeding the aircraft's maximum speed. <S> So the limit of the sustained 0g flight is the pilot pulling back on the yoke and climbing to prevent the destruction of the aircraft and death of all on board. <S> However, even if the wings broke off of the airplane, and you were plummeting towards the ground in the fuselage of the aircraft, you would only remain weightless so long as the fuselage continued to accelerate towards the earth at $9.8m/s^2$. <A> The longest possible 0 <S> g <S> experience is on a parabolic Flight <S> http://www.asc-csa.gc.ca/eng/sciences/parabolic.asp . <S> As Devil07s great answer explains the time a plane can fly "at 0g" depends on its vertical speed at start of the 0g time. <S> Lets take a typical air acrobatic plane . <S> Its maximum speed is 220knots <S> ~ <S> 400km/h .The plane looses some speed before entering the flight pattern (until it reaches 45° pitch) and gains some more speed before reaching 0° pitch after leaving the pattern, but lets ignore that for the ease of the calculation. <S> At the moment the plane enters the parabolic Flight pattern with 45° pitch its vertical speed is IAS/sqrt(2) = <S> 400km/h*1.414 = <S> 283km/h = <S> 79 <S> m/s <S> Choosing a higher pitch will create a higher entry speed by calculation but the entry speed will also be reduced by the longer "rotation time" and structural limits of the plane. <S> Now it follows the parabolic Flight pattern until it reaches the culmination point (0km/h vertical speed): time = speed/acceleration = <S> 79 <S> m/s / 9,81m <S> /s² = <S> 7,9s <S> The plane needs exactly the same time to reach the "exit speed" of 400km/h. <S> Therefor the total time an Extra EA-300 can fly in 0g is approximately: 15 seconds . <A> That depends on a whole heap of things. <S> Zero g is experienced during a ballistic trajectory. <S> Wikipedia lists as time spent during ballistic flight:$$ t = \frac <S> {2 \cdot V \cdot <S> sin\theta}{g} \tag{1}$$ with V = <S> starting velocity in [m/s] and $\theta$ the starting angle. <S> The equation is valid for vacuum, which would be equal to our situation where thrust continuously equals aerodynamic drag. <S> For any velocity, if we want to maximise time spent we need to start at 90 deg, as this plot shows: time in seconds as function of starting angle at starting speed of 100 m/s. <S> But that creates a bit of a practical problem at the apogee, the aircraft will fall back tail first, do a hammerhead, and we're not in zero g anymore. <S> So let's take an angle fairly close to the maximum where the pilot could maintain parabolic flight using his incredible skill: 60 degrees. <S> Image source <S> We're in an aerobatic aircraft, which is a very wide range actually: jet fighters are fully aerobatic as well. <S> If we take a typical Red Bull Air Racer as one delimiter and an F16 as the other one, we have a speed range of between 100 and 600 m/s. <S> For a ballistic flight path starting at 60 degrees, we get the following flight time as a function of starting speed. <S> Between roughly 18 and 106 seconds.
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At some point, if you had enough altitude, the drag (wind friction) on the fuselage would prevent it from continually accelerating towards earth and you would reach an equilibrium speed where the force of gravity equals the force of drag and you would no longer feel 0gs.
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What are the effects of an increase in altitude upon ESHP of a turboprop engine? This is one of the questions in the ATP material: What effect will an increase in altitude have upon the available equivalent shaft horsepower (ESPH) of a turboprop engine? A) Lower air density and engine flow will cause a decrease in power B) Higher propeller efficiency will cause an increase in usable power (ESHP) and thrust C) Power will remain the same but propeller efficiency will decrease I chose (C) but the correct answer was (A). Could anyone explain why? Isn't the whole purpose of a turbocharged engine to sustain engine power at high altitude (below critical altitude)? Why does lower density at high altitude cause a decrease in power? <Q> You have confused a turboprop engine with a turbocharged engine. <S> They are very different and have very little in common. <S> A turboprop engine is powered by a turbine engine geared to a propeller. <S> Turbine engines have less power available at higher altitudes so answer " <S> A" is correct. <S> A turbocharged engine is a piston engine which is fitted with a small compressor driven by exhaust gas pressure. <S> The compressor (turbocharger) can increase manifold pressure to restore sea level power at altitude. <S> (Turbo-normalized) <S> A turbo charger can also supply greater than sea level manifold pressure for more power. <S> (turbo-supercharged) <S> Both types of turbocharged piston engines can maintain full rated power as they climb, but they will eventually reach a limit where full power can no longer be maintained. <A> Because the performance of a turboprop engine, like any other air cycle heat engine, is directly proportional to the density of the air moving through the engine. <S> Denser air means more working fluid in a greater amount of energy can be obtained from it by combusting it with fuel. <S> As you rise in altitude, the air becomes less dense and the amount of work that can be obtain from a given volumetric flow rate of air becomes less and less the higher you climb. <S> This also lowers the equivalent shaft horse power that one can obtain from the turboprop engine, as it both reduces the shaft horse power to the propeller as well as the jadditional et thrust from the exhaust. <S> Manufacturers of turboprop engine sometimes compensate for this by flat rating the turboprop engine. <S> That is, the fuel control unit for the turboprop presets the amount of output power that the engine will produce. <S> The gas core of the turboprop may be able to produce much more power at sea level or at lower altitudes than you can obtain with a full throttle command from the cockpit. <S> The maximum amount of power the gas core on a flat rated turboprop can produce at sea level at standard atmosphere is referred to as the engine's thermodynamic power rating. <S> A flat rated engine will continue to produce a uniform power output as the aircraft continues to climb until the flat rated power output is equal to the thermodynamic power output of the engine at the current flight level. <S> If the aircraft continues to climb, the engine's power output will begin to decrease. <A> The turbocharged piston engine also produces less power at altitude due to less air entering the cylinder. <S> Both have a compressor, and some effects of altitude on power generation are indeed similar, but the design conditions differ due to the great differentiator: weight. <S> A turboprop engine's weight increases much less as a function of max power at sea level, than that of a piston engine. <S> The turboprop can be designed for cruise conditions, and take the surplus of power at sea level as either: a bonus, so that much more power is available at sea level and power output decreases gradually with altitude; a liability for the gearbox, so that power limitations at lower altitude are applied by the FADEC. <S> If the same approach was followed for a piston engine, the weight penalty would be much higher than for the turbine engine. <S> So piston engines are designed for maximum power at sea level, and this power is maintained as long as possible with increasing altitude, by pumping in more air through the super/turbocharger. <S> Note that the turboprop with derated power and the turbocharged piston have very similar characteristics, both deliver a constant power as altitude increases, up to the critical air pressure... <S> The weight advantage of turboprops over piston engines was demonstrated in the 1960s by the conversion of the Cessna Skymaster into the Conroy Stolifter: the two Skymaster piston engines produced 155 hp less and weighed 117 kg more than the single TPE-311 turbine engine that replaced them. <S> Image source Image source
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The turboprop engine produces less power at altitude, because the mass stream through the engine is smaller: there is less air.
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Is it legal for a balloon to land at a US international airport? Assuming the winds directed a hot air balloon near a US international airport, and the pilot has no other choice than landing, say near the runways/taxiways, would they face legal trouble/fines? <Q> Assuming the winds directed a hot air balloon near a US international airport <S> By this I assume you mean <S> a major airport in class B or C (possibly even D) airspace. <S> An "international" airport is simply one that is an airport of entry and maintains customs officials and processing ability and may or may not be a "large/major" airport. <S> would they face legal trouble/fines <S> This depends on how the balloon is equipped. <S> This advisory circular on ballooning would indicate it is legal to enter all airspaces in a balloon. <S> There are of course some practical problems here such as the fact that as a balloon you can't really divert around an airspace if you are not granted clearance. <S> If there is no safe landing space and the wind is blowing such that your only option is to enter the class B <S> you may be stuck declaring an emergency, or at least getting back on the radio and explain whats going on. <S> Some FAA officials may consider this poor/dangerous flight planning (since you should have looked at the wind prior to departure) and you may end up in some trouble for that. <S> From the Balloon Hand Book <S> As a general rule, balloons do not freely operate within Class B airspace. <S> Equipment requirements are the same as for Class C airspace; however, due to air traffic congestion, the balloon pilot requesting entry to Class B airspace will likely be denied entry, as ballooning operations inside the Class B airspace constitute a potential traffic conflict.... <S> But legally you can and the FAA prefers you coordinate before hand, Should it become necessary for operational reasons to fly through Class B airspace, that flight should be coordinated at least one hour prior, as provided for by 14 CFR section 91.215. <S> It is permissible, and perfectly legal, to operate a balloon under the lateral limits of the Class B airspace. <S> Same applies for class C, Balloon operations in Class C airspace, <S> while technically feasible, are usually not advisable <A> What you are describing sounds like an emergency. <S> In an emergency a pilot can take any reasonable actions necessary to ensure the safety of aircraft and occupants. <S> As others have mentioned there might be some other reasons for legal action, but since your question only refers to the landing of a balloon at an international airport, I will assume no other regulations were violated. <S> So, if no other regulations were violated up to the point that the balloon pilot had "no other choice" but to land at an international airport, then I would argue that the pilot could avoid (legal trouble/fines) either with a clearance from the tower(unlikely), or a declaration of an emergency. <A> A balloonist always has a choice of when he can land. <S> He must carry enough fuel on board to remain aloft until a safe landing area can be reached. <S> There is no way a busy control tower would allow him to land in the middle of the airfield. <S> He might be granted clearance to fly through the control zone but would never be given clearance to land. <S> If he was out of fuel, he would declare an emergency and accept the consequences. <S> (Legal trouble/fines)
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As mentioned in the comments you need a transponder and a 2 way radio to enter certain controlled airspaces (usually those surrounding big airports) and if the balloon is properly equipped it would be allowed to enter and utilize public resources such as airports and landing areas.
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Why do military pilots report "gear down" during their traffic calls? I've noticed that military pilots will often say something along the lines of: <airport> traffic, Basher 5-2 left base, full stop, gear down . Why the additional "gear down" call? Shouldn't it be implied that if you're landing full stop, you'd want the gear down? And similarly, if the gear isn't down, wouldn't an emergency call be more appropriate? To be clear, I'm not asking why it's a good idea to check to see if the gear is down, I'm asking why military pilots broadcast the fact that they've checked. <Q> 1 <S> In the U.S., for Military aircraft, ATC is required to: "Remind aircraft to check wheels down on each approach unless the pilot has previously reported wheels down for that approach". <S> [ref: [FAA Order 7110.65W] , para. <S> 2-1-24] <S> Normally, the phraseology suggested in your question would reflect the pilot's response to this ATC reminder. <S> (For example: "[call sign] Check Wheels Down, Cleared for [whatever]" ) <A> Other answers mention "it's the rules" without specifying why the rules are what they are. <S> Civilian airplanes are for the most part assumed to be in proper working order after a flight, unless it is known otherwise. <S> Military flight hardware may have experienced 8-9 G loads, supersonic airspeeds, ground fire, attacks from other aircraft, been subject to an EMP, and likewise for the frail meatsack at the helm. <S> One cannot assume that all components are working properly after a mission. <S> Additionally, civilian aircraft usually do not carry high explosives which could turn a belly scrape into a fireball. <S> Very recently a (non-American) military aircraft had an ordinance issue when landing (gear down) with undeployed payload. <A> Why do military pilots report “gear down” during their traffic calls? <S> (Example of a regulation here ). <S> I spent a few years teaching military flying. <S> Military aircraft have been flying for over a century. <S> There have been enough gear up passes 1 over the years that the habit pattern of checking and calling the gear (in any aircraft with retractable landing gear , which is the vast majority of military aircraft, and all primary trainers) has become a standard. <S> I've noticed that military pilots will often say something along the lines of: traffic, Basher 5-2 left base, full stop, gear down. <S> Not understanding how this is a problem. <S> Why the additional "gear down" call? <S> It's not "additional." <S> Shouldn't it be implied that if you're landing full stop, you'd want the gear down? <S> It's not a matter of "wanting" the gear down <S> , it's a matter of reporting that you have lowered the gear and that you have checked and confirmed that it is down. <S> And similarly, if the gear isn't down, wouldn't an emergency call be more appropriate? <S> Not by default. <S> If it isn't down because of an oversight, it would be appropriate tolower it <S> and then either go around and try again, this time with thegear down, or if confirmed down before landing, land. <S> That willvary with the situation and the SOP of a given squadron/wing. <S> If it won't come down , then you don't call for a landing until you have tried to get it down, possibly making a low pass to see ifsomeone can provide you with a gear check (maybe your indicator isbeing tempermental) and then, if the gear won't come down, declarean emergency and attempt the procedures for your gear up landing. <S> Usually you'll be asking for such crash and rescue as is available to be ready, in case things go sideways. <S> 1 <S> A gear up pass, what is it? <S> An attempt to land with the gear up when they should have been down. <A> For USAF pilots of retractable gear aircraft, it is a required call. <S> Per Air Force Instruction (AFI) 11-202 Volume 3, General Flight Rules : 7.7. <S> Landing Gear Reporting Procedures. <S> Retractable gear aircraft will report gear downstatus to ATC or runway supervisory unit after extending the landing gear. <S> This report shallbe made during any approach prior to crossing the runway threshold. <A> There are a lot of "safety" procedures in the military that aren't done in the civilian world. <S> Even in the civilian world there are differences. <S> Each airline even has its own safety procedures and even write their own manuals. <S> "Check Gear <S> Down/Gear Down" is just one of them that the military established long ago as a precaution to avoid stupid mistakes that are very avoidable. <S> Call <S> "Gear Down" and actually look at the gear lights to be sure you have 3 green. <S> No one wants to be the one idiot that forgot the gear. <S> As has been mentioned, in two pilot civilian cockpits this is done between the pilots. <S> It gets very busy in the traffic pattern and stupid mistakes happen. <S> "Gear Down", as well as the many other SOPs, keep it all standardized and helps make sure that its always done the same way by everyone, everywhere. <S> In a huge organization like the USAF such things are very helpful when you have personnel constantly training, coming and going and transferring etc. <S> Similar calls are "call the ball/roger, ball", "feet wet/feet dry", <S> "fence in - check fuel flows are good, fuel levels are good, IFF is stdby, oil pressure good, fuel tanks and oil system pressure off ( in case you take a hit ), PC system all good <S> , weapons selectors set, weapons master off <S> , chaff/flares are armed, etc..." <S> (when crossing the hypothetical "fence" into hostile territory when on a combat mission ). <S> Another neat one is calling "Base Plus" when climbing above Controlled Airspace above 60,000 feet which can still be heard from time to time. <A> After up to 12hrs of flight the operational fatigue may lead to dumb mistakes, it is not uncommon at all to see gear up landing amongst those who think they are too cool for the checklist.
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It is not a procedure exclusive to Military aircraft, also gliders report "gear down and locked" when entering the downwind. Because it's what they are trained to do.
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Can a supersonic aircraft have winglets? In order to have laminar flow over the wings which helps in friction drag reduction, a number of airfoil designs have been proposed from the past to the latest 737 winglets. But if we design a laminar flow wing for supersonic aircraft, the wing should be very thin which will end up with stall and speed related problems. So, I am curious that if we add winglets on supersonic aircraft, will it be helpful other than for its drag? If so what are all the problems we need to consider? <Q> This has been (and thus can be) done and there is some current research on it as well. <S> The <S> XB-70 Valkyrie had dropping wing tips that added stability at high Mach speeds as well as allowed the plane to ride on its own shock wave . <S> It also effected trim drag, The repositioned wingtips also reduced the area behind the airplane's center of gravity, which reduced trim drag. <S> The downturned outer panels also provided more vertical surface to improve directional stability at high Mach numbers. <S> You can check out this podcast episode <S> that interviews some of the people at NASA doing various research projects including wingtip control systems and other interesting applications in that space. <S> You may find some info in this book on supersonic wing theory . <S> This thread <S> (and you know how accurate the internet is) has some interesting points on the matter. <A> Research has been carried out into this area, for instance the Computed Fluid Dynamics tests that NASA carried out on highly swept wings in supersonic flow . <S> They reached the conclusion that winglets can have positive effect on lift/drag, but it is of course highly dependent on the wing shape and profile. <S> From the report: winglets can be designed and aligned in supersonic flow such that little or no performance penalty will be incurred relative to a wing of equal projected span. <S> alteration of winglet length, sweep, and camber may not be as critical as the toe angle or the orientation of the winglet relative to the wing. <S> winglets with negative dihedral and toe in were found to typically outperform similar winglets with positive dihedral. <S> One of the configurations studied is below: NACA 1402 base wing with 65 deg leading edge, and the best winglet found. <S> One of the recommendations made is to put further research into dual use of winglets, if they are useful for yaw control at supersonic speeds. <A> The projected European spaceplane Hermes did indeed have winglets. <S> Those were needed for drag reduction in the landing phase. <S> So they did not help at supersonic but at subsonic speed. <S> Without the winglets the energy would had bled off too quickly during rotation so the descent could not be stopped in simulations. <S> The spaceplane without winglets was in essence impossible to land. <S> Only by lifting the subsonic L/D above 5 with the help of the outward canted winglets did the simulation result in smooth landings. <S> Artist impression of Hermes spaceplane (picture source ) <A> Even if they can, would they be practical? <S> Many combat aircraft use the wing tips to carry short range missiles or other light weight stores. <S> You'd lose those hardpoints. <S> Plus you'd introduce more complexity into the wing, especially if you rely on them for stability, making the aircraft more vulnerable. <S> Also, I've not done the calculations but many combat aircraft have wings that have a large taper <S> , winglets may very well be only marginally effective with such a wing design. <A> There are 3 types of drag: Friction drag Induced drag Wave drag <S> In low speed flights, first two are responsible for the total drag created. <S> Wave drag is usually neglected as it is very less compared to others. <S> Winglets are provided to reduce the induced drag. <S> Now, in case of the supersonic aircrafts, wave drag creates most of the total drag as the shock wave creates enormous drag. <S> Friction drag and wave drag are proportional with the velocity , and induced drag is inversely proportional to the velocity of flight. <S> In case of supersonic flight, due to the velocity, the induced drag is going to be very small that it is always neglected. <S> And most supersonic aircraft are military fighter jets, and fuel efficiency in the military is not a priority <S> By the way, this answer is from a Quora question found with a quick Google search. <A> The North American XB-70 <S> Valkyrie was a Mach 3 bomber which had variable-geometry winglets. <S> Their purpose was most unusual in that they turned vertically down to help reduce drag during supersonic cruise, and returned to horizontal to increase the wing area for takeoff and landing. <S> The wing of the Valkyrie was a waveriding delta. <S> The engine intakes formed a central underwing body which created a strong shock wave. <S> The wing leading edge was angled such that at cruising speed the shock front ran out along the wing just behind it. <S> All the wing behind it was subject to an increase in air pressure, creating a substantial amount of extra lift and improving the lift/drag ratio of the wing. <S> When the shock met the downturned winglets, it was reflected back under the rear of the wing creating even more lift and improving cruise efficiency even more. <S> The winglets also provided additional directional stability just when it was needed, as this normally reduces at high speeds.
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So yes winglets are possible on a supersonic aircraft, but are rather decoration then useful.
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Why are there no 4-winged airplanes? With larger wings comes more drag. So why don't large planes have 4 smaller wings instead of 2 very long ones? <Q> Biplanes are a thing and have been since the earliest days of flight. <S> However, they fell out of favour because they actually have more drag than a corresponding monoplane. <S> Not only do you need essentially the same amount of wing <S> but there's also the extra supporting structure. <S> Alternatively, if you're thinking of two wings one behind the other then the turbulence from the front wing will dramatically decrease the lift of the second. <A> With larger wings comes more drag . <S> True, because the drag is a function of the wing area <S> A: $$ D = <S> C_D \cdot <S> \frac { <S> 1}{2} <S> \rho \cdot <S> V^2 <S> \cdot <S> A $$ <S> Now the question is: over how many wings will we distribute this wing area? <S> The classical biplane is a thing of the past, however there have been incredibly clever aircraft builders who have looked at the long coupled canard configuration. <S> This one really makes a lot of sense: Image source <S> So to answer your question: there are aircraft with two wings. <S> It's just that people don't buy them, and go for boring old Cessna's instead. <A> I think there are could be a couple of reasons why one wing is the norm. <S> Firstly, from an induced drag perspective a longer wing, if structurally possible, will provide less drag than a shorter, fatter one. <S> The longer the aspect ratio (the ratio of wingspan to the cord (width) of the wing) <S> the less effect the wingtip vortices have. <S> Secondly, as mentioned in another answer, a wing behind another wing sees disrupted flow. <S> How this flow is disrupted could be hard to predict when designing the aircraft <A> Biplanes and other multi-wing configurations suffer from the airflow coupling of the wings. <S> Specifically, lift is due to deflection of the air downwards by the wing. <S> Another nearby wing now is dealing with deflected air, reducing its possible lift. <S> As mentioned earlier, the real lift function depends on span per unit lift, regardless of how many wing (or horizontal tail) surfaces are involved. <S> A Cessna wouldn't fly with 36 one-foot wings...
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You need a certain wing area to support the weight of the aircraft. For over 80 years, the answer has been: one wing (the two wing halves make up one wing).
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Is there a landing gear system that extends automatically to prevent belly landing? To my knowledge, most aircraft with retractable gear are equipped with a landing gear warning system that makes repetitive beeping sounds in case the pilots try to land without the gear down. I imagine big jetliners like Airbus and Boeing would have a far more advanced landing gear warning system, but does any of them have a landing gear system that extends automatically if the pilots fail to extend the gear and continue their descent for landing despite the warning? <Q> The simple fact is that an unintended gear deployment could be catastrophic, as it has a profound impact on the flight dynamics of the aircraft (one of the reasons there are warnings for both retraction and extension). <S> The benefits would be marginal as checking gear down is part of the bread-and-butter procedures for all retractable gear aircraft. <S> Keep in mind adding some automation to an aircraft has far ranging impact, just off the top of my head adding automatic gear mechanism would require: Standardization of the automation Modification of procedures Training of pilots, and then re-certification of pilots Training of maintenance crews, and then re-certification of the crews Possible change to the maintenance schedule of aircraft Certification of the new system by the regulator <S> and you would still need a backup / redundant system; and now you are back to the manual controls. <S> I can imagine this being implemented in remote piloted or autonomous aircraft though; as an additional workload relief. <A> It has been tried before. <S> At higher airspeeds this system was overridden by a separate pneumatic system which deferred control to the cockpit selection handle. <S> This system did have its drawbacks, most notably being there are times where a pilot wishes to keep the gear retracted regardless of airspeed for performance reasons. <S> A fatal crash involving a PA-28 caused by an increase in parasite drag from the gear automatically extending caused Piper to subsequently issue an AD requiring all PA-28s and PA-32s with the automatic gear extension systems to be fitted with an emergency override, allowing the pilot to continue to command the position of the gear with the cockpit selector handle regardless of airspeed. <S> I suspect most GA aircraft and transport category airplanes never implemented such a device because the risks of an inadvertent gear up landing were outweighed by the advantages of having the ability to select the position of the gear for operations in all areas of the flight envelope. <A> Adding such automation is not what the manufacturers want to be doing. <S> It is additional work and costs money. <S> It is another system that might fail. <S> This is not a trivial matter. <S> There are lots of variables to take into account. <S> Complex rules would have to be made when to extend gears. <S> For example when ditching in water we don't want gears to extend. <S> As the pilot may not be aware that the gears are retracted, now we have the possibility to not know that they are automatically extended. <S> Aircraft manufacturers would probably just issue a bulletin reminding pilots to operate the landing gear when needed. <S> Accident investigators would probably want to eliminate the reason that lead to the omission of a checklist item (proper sleep etc.). <S> Sidetracking a bit, but sometimes automation fails: <S> When flying some Boeing aircraft, the pilot should be able to know that when some sensor reading are different between pilots' displays, the autopilot & autothrottle might get erroneous data and shouldn't be used. <S> Planeloads of people have died because of pilots' inability to connect the discrepancy of sensor readings to the erratic behavior of the aircraft. <S> Meanwhile, an Airbus A330 flew into thunderstorm, had its pitot-tube frozen for a short duration, and after receiving conflicting information disengaged the autopilot. <S> The pilots needed just to fly straight forward, but one of them panicked and stalled the aircraft, killing everyone onboard.
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Piper's PA-28R and PA-32R aircraft were equipped with an automatic landing gear extension system which would automatically extend the landing gear below 85kts regardless of the position of the selector switch in the cockpit.
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When departing IFR, when do I switch from Tower to Departure? When departing IFR from a Class D airport, must you wait until the Tower instructs you to change to Departure? <Q> When operating within class D airspace (operating Air Traffic Control Tower) pilots are to maintain communication with the tower until instructed otherwise. <S> Remain on the current frequency until instructed to change. <S> Here is an except from the pertinent regulation (FAR Part 91): §91.129 <S> Operations in Class D airspace. <S> 2) Departing flight. <S> Each person— (i) From the primary airport or satellite airport with an operating control tower must establish and maintain two-way radio communications with the control tower, and thereafter as instructed by ATC while operating in the Class D airspace area; Note: <S> It should be noted however, that in the U.S., departing IFR military turboprop/turbojet aircraft (except transport and cargo types) will be instructed to "change to departure control frequency" before takeoff . <S> [ref: FAA JO 7110.65 , paragraph 3-9-3 a. 2.] <S> This requirement allows pilots of single-seat high-performance aircraft, as well as certain other military aircraft, the ability to avoid being distracted by changing to another (e.g., departure control) frequency immediately after takeoff. <S> Further, many military fighter type aircraft used to have (probably some still do) <S> radios positioned in the cockpit in a location that requires looking down or moving the pilot's head/eyes in such a manner that might cause momentary disorientation, which is not a good idea right after takeoff and close to the ground. <S> U.S. military control towers and some (perhaps most) joint-use military/civilian control towers have an "override" frequency (same frequency as the departure controller uses), for use in case some emergency situation that occurs just before, during, or immediately after departure requires urgent communication with the pilot (e.g., engine fire on takeoff noted by the tower, or similar type situation). <A> You should never leave a control frequency without an explicit instruction to do so. <S> This can be a literal instruction (the controller telling you to contact another unit/frequency), or a procedure described in the AIP. <S> For example, at some airports, a part of the description of the standard instrument departures read "When passing 1000 ft, contact Departure on 124.975" or similar. <S> Here is an example from Copenhagen, Denmark: <S> That's the beauty of flying as a controlled flight - you don't need to worry about which frequency you should be on, the current controller will always hand you over to the next one when required. <A> Yes, no frequency changes until instructed. <S> (unless previously requested and approved, which seems unlikely on an IFR departure) <S> The phrase is typically, "N12345, Over to Departure. <S> G'day" <A> Since you are IFR, in your question, you do as told. <S> Which means as instructed or as cleared. <S> If a SID is applicable, you conform to the SID, unless cleared otherwise. <S> If you are VFR, which you said you were not, then the game is different. <S> In general the do as instructed / cleared applies, but some new nuances come into play. <S> For example, VFR, you need only maintain tower com while in Class D, so leaving Class D, you can go where you want. <S> May not be considered polite, but if you think you are forgotten, and they are really busy, you might just go. <S> They will see that you checked in with departure at most facilities. <S> Common courtesy is to let the tower hand you off, or prompt them for a hand off.
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On an IFR flight departing from a tower controlled airport, the tower controller will instruct the pilot when to change frequency to contact the next controller (the IFR Departure Controller). Unless such a procedure is in place, you wait until the tower changes you to the next frequency.
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Why did the F-104 Starfighter have a T-tail? The F-104 Starfighter was launched in 1954, nine years after WWII. It had short stubby wings and a T-tail. According to wiki , the short stubby wings caused inertia coupling and the T-tail reduced this. My question is: is that really the reason why the F-104 had a T-tail? How does that help reduce inertia coupling? EDIT @aeroalias answer has many of the reasons for the T-tail. Had edited the question with some additional info, it was suggested to put this in an answer instead. <Q> The initial preliminary designs had the horizontal tail in multiple locations (including in-line with the wing and cruciform), before settling on the T-tail by December 1952. <S> The reason for selecting the T-Tail is given by Glenn L. "Snake" Reaves, Lockheed Production Flight Test Pilot in the F-104 <S> Test Pilot notebook as <S> The high tail position was selected ... after extensive wind tunnel tests (which) proved that the location was necessary to obtain optimum stability and control about the pitch <S> axis throughout the wide Mach range. <S> The position also results in minimum transonic trim changes while accelerating to supersonic. <S> Another advantage was that the high tail on the swept vertical fin reduced interference drag. <S> While the problem was inertial coupling was quite well known during 1950's , the design of the F-104 was frozen during the same period, so it is difficult to tell conclusively if that is the reason for F-104 having a T-tail. <S> The test pilot notebook also has some explanation about how the T-tail reduces the problem of inertial coupling: <S> If we now consider two facts about these rolling maneuvers, it will become clear how inertial coupling builds up: <S> The sideslip build-up is controlled by the induced rolling moment. <S> As sideslip builds up, the centrifugal or rolling forces increase and this tends to displace the aircraft fuselage perpendicular to the flight path. <S> The T-tail controls the the sideslip build-up by inducing a rolling moment. <S> From the same document: ... the high tail position of the horizontal stabilizer raised the center of pressure. <S> Image from F-104 <S> Test Pilot notebook ... <S> whenever we sideslip an aircraft, a rolling moment is induced that resists the sideslip. <S> This induced rolling moment is generally termed dihedral effect. <S> ... with any sideslip, the restoring force acting through the center of pressure does not act through the c.g of the aircraft. <S> Therefore, a sideslip condition actuates the restoring force on the tail but at the same time, induces a roll. <S> ... <S> now that we have raised the tail and consequently the center of pressure and the positive dihedral effect has been increased considerably. <S> The T-tail reduced inertial coupling by preventing sideslip buildup. <A> The Wikipedia article lacks a reference. <S> It seems it's to keep the fin short while being effective, which reduces weight and drag. <S> A classic use of T-tails . <S> Source: General Aviation Aircraft Design: Applied Methods and Procedures , p. 973 <S> The cited Whitford I believe refers to this book . <A> @aeroalias answer contains a link to the F-104 test pilots notes, which explains: why the Starfighter has a T-tail; what measures were taken to prevent inertial coupling from happening. <S> According to the document, the T-tail provided better stability, control, and trim characteristics throughout the speed range. <S> It also provided the same aerodynamic coupling effect as wing dihedral does, that's why the wings have anhedral. <S> Inertial coupling is not an aerodynamic phenomenon. <S> It has occurred in one of the first satellites put into orbit, which was longer than it was wide, and over time started to wobble around the axis of rotation, a phenomenon called nutation. <S> Airplanes with a long wing span can maintain a high roll rate without pitch and yaw being affected - the Starfighter was the first plane with short wings, and with a high roll rate came nutation, with undesirable pitch and yaw effects. <S> And also a challenge when turning, judging from the famous phrase of a Canadian pilot: "Banking with intent to turn." <S> The T-tail is not really a solution to inertial coupling, only a longer wing span around the CoG is. <S> Inertial coupling was prevented by limiting the roll rate. <S> So contrary to the wikipedia statement, the T-tail was not primarily implemented to reduce inertial coupling.
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The T-tail did increase directional stability of the vertical tail due to the winglet effect, as did the ventral fins.
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Is there a KPI to measure average hours flown? I am working on a report for a small charter airline and I want to set a key performance indicator (KPI) to measure average hours flown. Is there a practice in aviation field to consider optimum flight hours for an airplane? An arbitrary example: Let's say I have a Boeing 767 and I want to consider if that particular model is profitable (I know it depends on payload, routes, and many other things), does it have to make an average 300 hours per month? Is there such thing in aviation? <Q> I want to set a KPI to measure average hours flown. <S> You might want to check block hour : <S> (aviation) <S> The time from the moment the aircraft door closes at departure of a revenue flight until the moment the aircraft door opens at the arrival gate following its landing. <S> Block hours are the industry-standard measure of aircraft utilization. <S> (Emphasis mine.) <S> The Wikipedia article airline cost glossary lists very common terms and KPI's. <S> One of those terms that could also be applicable to your case ( revenue passenger miles ) was asked about here: Which aircraft type flies the most annual passenger-miles? <A> Like you say, it depends on quite a few parameters. <S> You would set up a cash flow Excel sheet with cash in/cash out per month: Costs <S> Lease Salaries <S> Operational costs including certification, licensing Office/ <S> overhead Fuel Airport fees <S> Maintenance/consumables not covered by lease Marketing.advertising Revenue from ticket sales <S> Number of flights per day <S> Passenger load factor Seasonal variations Market price per ticket <S> Predicted market share <S> The companies that lease out aircraft would have filled out scenarios for you. <S> Boeing and Airbus have departments that advise prospective customers on setting up airlines. <A> Is there a practice in aviation field to consider optimum flight hours for an airplane? <S> Im not really sure what you mean by optimum hours for an air frame <S> but you could likely figure out a predicted up-time (usable and subsequently profitable) for an aircraft. <S> You can start by assuming the aircraft is in the air all the time then subtract for the following, Time to and from the gate Time at the gate <S> If you are in a cold environment - de-ice and other similar pre-flight things Scheduled maintenance <S> Some form multiplier for unscheduled maintenance issues (this number is easier to compute after some time of operation. <S> Time sitting un-used on the ground as there is no route or booking for the plane Paying everyone involved (maintenance crew, pilots, flight crew etc) small charter airline <S> For this you need to look at things like smaller turbo <S> props as they have very different cost breakdowns than a 767. <S> If you are here in the USA you also need to identify if you are planning to operate a 135 or 121 airline as the governing and rules are somewhat different which will impact cost. <A> In the 1940-1950 era a DC3 was considered to have a "good" route if it was in the air 2-3 out of 24hrs. <S> Today, airlines keep aircraft out of the gate closer to 16 out of 24hrs. <S> Total Airline Operating Cost Breakdown======================================44% is operating, includes fuel, direct maintenance, depreciation, and crew29% is servicing expense, aircraft, traffic, passenger14% is <S> reservations and sales expense13% is overhead expense, adds and adminCost per block-hour of operations = <S> ================================= <S> B757-200 <S> (avg. <S> 186 seats)Based on 1252 mile average stage length and 11.3 block-hr daily utilization CREW $ 489FUEL <S> $ 548MAINTENANCE <S> $ 590OWNERSHIP <S> $ 923--------------------------TOTAL <S> $ 2,550 per block-hr Typical costs per block hr <S> A/C Seats <S> blk/ <S> Hr seat/hr===================================DC9-30 100 $1,973 <S> $19.73 A320 148 $2,270 $15.33 <S> B727-200 <S> 150 $2,555 $17.03 B757-200 186 $2,550 $13.71 <S> B747-400 <S> 375 <S> $6,455 <S> $17.21 <S> Source
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"optimum flight hours" is keeping the aircraft in the air except for mandatory maintenance.
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What are good alternatives to sunglasses for flying? I'm a student pilot and I won't be able to wear sunglasses for 5 months... Now, how am I going to fly? I know you don't have to wear them but it's easier (brightness etc. etc.). Are there any alternatives you can give for flying? I've never tried a hat, is that a good option for the moment? Maybe it's a silly question but do sunglass contact lenses exist? <Q> I've been flying for over twenty years. <S> I've never once worn sunglasses or a hat in the cockpit, with exception of a view limiting device (i.e. hood). <S> I understand why many pilots wear sun glasses and have nothing against it, but for me I feel like it hinders my vision more than helps. <S> You can fly just fine without sun glasses. <S> One thing that might help, is to make sure you wipe down your windshield before flight to make sure its clean and clear, in order to reduce glare. <S> You should be totally fine. <S> Flying without sunglasses is like flying without noise cancelling headsets. <S> Its a creature comfort, but not absolutely necessary for safe operation. <A> The nice thing about polycarbonite windshields is that they block the bulk of the UV, which is the primary reason protection sought by sunglasses. <S> The DPE who administered my private checkride told me that he found that wearing sunglasses created a dependency on them, in his opinion. <S> I changed my ways, and concur with his finding. <S> My ophthalmologist agrees. <A> To address the question about contact sunglass lenses... Contact lenses are available with custom dyes, used for examples by actors to create eye colors not inherent to the actor. <S> Similarly, contacts can be obtained with tint which would attenuate the visible light, in a manner similar to sunglasses. <S> You should talk with a contact lens dispenser, as they will have access to the offerings of their suppliers. <A> It wasn't clear from your original post exactly why you cannot wear sunglasses. <S> I wasn't aware of any restrictions (at least in the United States) on student pilots wearing them. <S> While @Devil07 is correct that sunglasses are not strictly required for safety purposes, they do offer vital protection against damage to your eyes. <S> To quote the American Optometric Association's article Why you need sunglasses , you need sunglasses for: UV protection. <S> The sun's UV radiation can cause cataracts, benign growths on the eye's surface, and cancer of the eyelids and skin around the eyes. <S> UV radiation can also cause photokeratitis, sometimes called snow blindness, which is a temporary but painful sunburn of the eye's surface. <S> Wide-brimmed hats and caps can only block about 50 percent of UV radiation from the eyes. <S> Blue light protection. <S> Long-term exposure to the blue and violet portion of the solar spectrum is a risk factor for macular degeneration, especially for people who are sun-sensitive. <S> Comfortable vision. <S> The sun's brightness and glare interferes with comfortable vision. <S> Sunlight affects clear vision by causing people to squint and the eyes to water. <S> Dark adaptation. <S> Spending just two or three hours in bright sunlight can hamper the eyes' ability to adapt quickly to nighttime or indoor light levels. <S> This can make driving at night more hazardous. <S> I should note that I actually don't wear sunglasses... <S> I wear prescription glasses with transition lenses that provide some of the protections mentioned above. <S> You also asked about contact lenses. <S> The AOA also has an article on contact lenses that provide UV protection.
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A baseball cap might be a good idea if your airplane doesn't have sun visors.
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Why can't this blended wing body trijet airliner fly? I was told in this other question this aircraft was not real, and that it could not fly in this design. I'm now interested in knowing what would prevent it to fly, from an engineering point of view. It looks great... why is it so obvious this cannot work? <Q> As the comments point out, the main landing gear is too forward. <S> Delta wings (and blended) typically land (and takeoff) with a high nose-up, should be an easy fix. <S> Left wing is longer, again easy fix. <S> Outboard control surfaces (normally would be elevons ) are both pointing down on approach ( or is it climbing ?) <S> , tail heavy? <S> For a blended wing body, the airline still chose a tail-fin logo (backwards mind you)! <S> Natural pitch stability is required for certification, but the way it looks this design is unstable in pitch. <S> Note that all trailing flaps are deflected down, something which will generate strong pitch instability. <S> There is no obvious means by which a counteracting pitch response could be generated. <S> It looks as if payload is held mostly in the forward part. <S> While it could be balanced when empty, with any sensible amount of payload it will be hopelessly nose-heavy. <S> Related: <S> Why is there really only one basic design for passenger airplanes? <A> Passenger evacuation for one. <S> Right now, you can open some doors on the side of the tube and add more doors if needs be. <S> That's a lot more of a challenge here. <S> Also, distributing passengers to a wider area inside the body can lead to greater instances of motion sickness. <S> Passengers will generally prefer having windows, which is also a challenge for this type of aircraft. <S> Main gear should be far enough forward that most of the weight is on it, but far enough aft that the nose isn't unloaded in aft CG conditions. <S> It might be right where it needs to be. <S> You'd have to know the CG location. <S> You also need to account for an empty airplane with minimal fuel or it could tip up onto the tail. <S> Tip up. <S> A large lifting area should at least mean slower landings, but gear should be long enough or far enough aft to flare a bit. <S> You want the mains to touch first so you don't bounce or damage the nose gear. <A> That picture appears to be a photoshop assembly of real aircraft bits from common landing/take-off shots, made to fit the shape of a NASA X48, an unmanned flying test aircraft about the size of an ultralight. <S> Whoever did the photoshop job even slavishly copied the undercarriage position (but not the relative undercart length/height) of an extremely lightly built, largely empty, model aircraft. <S> It certainly can fly. https://www.nasa.gov/topics/aeronautics/features/bwb_main.html <A> I believe the challenges to using BWB as a people mover are the motion sickness and evacuation issues. <S> Soluble, but challenges nonetheless. <S> Of course, airport and runway suitability are possible issues as well. <S> Military airlift is a probable first application for BWB.
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It's not so much that it can't be done, but there are challenges.
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Would a helicopter with the blades on the bottom fly the same, if at all? I've heard that the pendulum rocket fallacy applies to rotorcraft as well. As stated above, I'm curious to know if a helicopter with blades on the bottom of the body would experience any effects from this. (Yes I know it's impractical and landing would be terribly difficult.) <Q> Yes that is possible, like the Hiller flying platform demonstrated. <S> It had two counter-rotating propellers inside a shroud and the pilot controlled his craft by shifting his body weight, like on a Segway. <S> There is no law of physics that prohibits a helicopter from flying upside down. <S> The Hiller flying platform was one of several types built in the 1950s, after it was observed that controlling an underslung rotorcraft by weight shift could be learned by untrained personnel in 20 minutes. <S> The DeLackner Aerocycle was another platform built based on this finding. <S> The idea was later abandoned due to practical issues like kicking up rocks into the rotor blades, and an at the time unexplainable interference between the counter-rotating blades. <S> The Aerocycle had a fixed rotor head, the dynamics of which were poorly understood at the time. <S> For full scale helicopters, having the rotor underneath the helicopter has the same stabilising effect on flight characteristics. <S> Stability of helicopters (and of fixed wing aircraft) is studied from the perspective of aerodynamics: the effects of wind gusts or control inputs. <S> In the hover, the speed stability ${\delta M}/{\delta{\dot{x}}}$ plays a significant role: if positive, the hover is unstable. <S> A human can learn how to control an unstable platform if the time period of the oscillation is high enough (conventional helicopter pilot), but it is much easier to fly in an aerodynamically stable aircraft (the underslung platforms intended for general infantry personnel). <S> The speed stability effect in the hover equates to a gust of wind blowing from directly forward, does then the change in moment tend to amplify or counteract the effects of the gust. <S> This can be visualised like so: Image source <S> The gust blowing on the helicopter tilts the rotor back, which tilts the thrust vector. <S> A teetering conventional rotor has a positive ${\delta M}/{\delta{\dot{x}}}$: it wants to flip backwards ever stronger, and is therefore aerodynamically unstable in the hover. <S> An underslung teetering rotor has a moment change that stabilises: it tilts the fuselage back, and due to aerodynamic coupling <S> the rotor follows back to neutral. <S> A rotor with hinge offset has a smaller stabilising moment, but a stronger fuselage/rotor coupling. <S> It is just a bit unpractical, that's all. <A> We spend all our weekends mowing lawn with these guys. <S> Courtesy: <S> Helifreak.com <S> You can find thousands of Youtube videos showing how comfortably they can do that <A> One of the first helicopters that really flew (c. 1918) was the ' Petróczy-Kármán-Žurovec ', intended to be used by the Austro-Hungarian Army as a tethered observation platform. <S> The observer stood above the contra-rotating rotors... ( Image source ) http://www.aviastar.org/helicopters_eng/petroczy.php <A> As far as I understand the aerodynamics and dynamics of a rotor wings and disk, it would actually be more stable, at least at some degree, regarding blow back of the rotor disk. <S> Since the CG of such helicopter would be above the rotor disk. <S> Rotor disk/blade aerodynamics are not that straight forward and you have a lot of other forces involved depending on the phase of the flight. <S> I'll try to elaborate more, when I get to the computer. <S> After finding my notes, interesting enough, only talks about rotor above CG condition, in hover. <S> It states: "(...) <S> rotor alone, above the CG, is dynamically unstable in hover! <S> Hovering dynamic instability problem: <S> In case of an horizontal velocity disturbance: flapping angle appears; flapping angle appears; rotor and thrust are tilted; horizontal acceleration is installed; horizontal velocity builds up untill rotor flapps in the opposite direction; The process is repeated in the opposite direction with increasing amplitude! <S> For large helicopters, the hovering oscillation period is usually long enough for safe reaction of the pilot." <S> It also talks about de Lackner HZ-1 Aerocycle: <S> https://en.wikipedia.org/wiki/De_Lackner_HZ-1_Aerocycle <S> When you are flying forward, there is a blow back force, produced by the advancing blade, creating lift, which then reflects 90° due to gyroscopic precession. <S> This make the rotor disk to blow back, that is why when you fly helicopters you are always pushing the cyclic forward, more and more with velocity (this means, more lift created by the advancing blade, due to the increased relative wind). <S> This is the only reason I am saying that it would be more stable, because the helicopter would have a tendency, in the nose dive, to blow back the disk, thus decreasing the angle of attack of the advancing blade. <S> In the case of helicopters, this also happens, which in turn they need a horizontal stabilizer in the tail, to counter the nose down attitude. <S> I don't know if I am making any sense, it is really hard to explain all the dynamics involved, but there are some good books regarding the matter of helicopter aerodynamics. <A> A way to simplify the presentation of a helicopter with the rotor assembly on the bottom is to consider the lift created by the rotors as buoyancy and therefore create a direct comparison to a ship/boat. <S> The described helicopter would demonstrate negative static stability (regardless of your discipline). <S> As the center of lift moves away from the center of gravity (think of an extreme: a 30' vertical pole with a horizontal force at the top), no force exists naturally to return the system to equilibrium. <S> The lift created by the rotors is now through a line perpendicular to the plane of the rotors. <S> When the rotors are above the center of gravity, the vertical force of gravity drives the center of gravity below the center of lift (or center of buoyancy in the ship example). <S> hope this helps.
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So to answer your original questions: Yes the helicopter with an underslung rotor would fly, and it would be easier to control than a conventional helicopter.
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Can a pilot rated in one category solo in another category without a current flight review? Scenario: A pilot is rated to fly gliders in the United States. The pilot allows his glider flight review to lapse. That pilot now decides he wants to get a type rating for the airplane category, single engine land. Question: Does the pilot have to be flight review current in order to solo in a powered airplane? (Secondary question, as long as we are at it) Does the pilot have to be flight review current in order to take the FAA practical (check ride) in a powered airplane? Note: I'm most interested in the answer under US FAA regulations, though the answer in other countries would be of interest as well. I have spent some time looking over the FARs, specifically 14 CFR 61.56 and I cannot find anything conclusive either way. I should mention that I suspect the answer to this question to be no, though I am not prepared to offer evidence to back this up. I've already seen this related question asking whether a biennial flight review is valid for any airplane category, but I don't believe it's a duplicate because that only covers the situation where the pilot is rated in both catagories. This question refers to the situation where the pilot is rated in one category, but not the other. <Q> You do require a flight review, per the Beard (2013) interpretation : <S> Finally, you have also asked whether a person operating in solo flight under a § 61.31(d) endorsement must comply with the flight review requirements in § 61.56(c). <S> With a few listed exceptions, no person make act as pilot in command of an aircraft unless within the previous 24 calendar months that person completed a flight review with an authorized instructor. <S> 14 C.F.R. § 61.56(c). <S> Section 61.56(g) provides an exception for student pilots provided the student pilot is undergoing training for a certificate and has a current solo flight endorsement as required under § 61.87. <S> Because this exception applies to student pilots, a pilot who holds a higher level pilot certificate and has an endorsement for solo flight under § 61.31(d) must comply with the flight review requirements in § 61.56 before acting as pilot in command of any aircraft. <S> Regarding the student pilot exception, others have suggested in comments that you are in fact a student pilot because you're new to the category/class. <S> However, the interpretation says you are not: <S> Section 61.81 states that subpart C "prescribes the requirements for the issuance of student pilot certificates, the conditions under which those certificates are necessary, and the general operating rules and limitations for the holders of those certificates. <S> " <S> As such, by its express language, subpart C to part 61 applies only to those persons who are seeking or hold a student pilot certificate. <S> So, since you will be acting as PIC and none of the exceptions in 61.56 apply, you need a flight review. <S> As for a checkride, the person taking the checkride is acting as PIC ( 61.47(b) ) <S> so again, you would need a valid flight review. <A> I'm not sure what the ediquite is for anwering your own question. <S> However, after seeing the extent of the discussion here, I did a bit of deaper research and finally came across <S> this from the FAA Acting Assistant Chief Counsel for Regulations: <S> The pilot is training to add a glider category rating to his pilot certificate. <S> Section 61.56(g) provides an exception for student pilots, provided the student pilot is training for a certificate and has a current solo flight endorsement as required under 61.87. <S> A pilot who holds a higher level pilot certificate must comply with the flight review requirements in 61.56(c) before acting as pilot in command of any aircraft. <S> The question of whether a certificated pilot needs a current flight review to perform solo flights in another category or class of aircraft is discussed in the Letter of Interpretation to Daniel Beard, January 9, 2015, a copy of which is enclosed with this response. <S> This, of course, deals with the reverse situation, but I would assume the same would apply for a glider ppl trying to solo for powered. <S> Thus I believe @pondlife is correct here and will click the check mark for that answer. <A> We deal with this in my glider club fairly often. <S> 14 CFR Part 61.56 provides several ways to get credit for a flight review. <S> Imagine the extreme case of a former military pilot who has only ever flown multi-engine jets - how would he/she get a flight review in any cost effective manner? <S> The answer to <S> "I don't want to spend money getting current in something I'm not going to fly again" is the FAA Wings program. <S> An actual Flight Reviews must be done in something in which you are rated. <S> That's not true for Wings. <S> So, with a little planning, the first few dual flights in the new aircraft can go into Wings. <S> Combine that with some appropriate online training and boom. <S> You have credit for a flight review. <S> Works great. <S> Now, I hope that maybe someone will see this seven months after the original conversation(s). <S> Terry Pitts, CFIG <A> Does the pilot have to be flight review current in order to solo in apowered airplane? <S> It's even worse than that. <S> In the US, a commercial airplane pilot with a gazillion hours who retires and lets his biennial flight review and medical certificate lapse cannot solo a glider, even under an instructor's supervision, without either taking the steps necessary to take that BFR in an aircraft for which he is already rated, or surrendering his power ratings and applying for a student pilot's license. <S> In other words, that pilot is in a deep hole compared to a novice who can simply apply for a student pilot's licence and then solo under his instructor's supervision. <S> One way out of this dilemma may be the "Wings" program, as stated in another answer.
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Per 61.56(c), the pilot in question must have a current flight review to perform solo flights in a glider during training.
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Do promotional flight routes have a historical precedent? Right now , a Dreamliner is flying a rather strange path over the USA (see below). The plane took off from Boeing Field airport near Seattle, and is 'drawing' a virtual copy of itself on the map of the USA before flying back home. As flight trackers are a relatively recent phenomenon, I was wondering: is this the first time something like this ever happens, or is this a tradition in aviation which I'm not aware of? Permalink for the flight. <Q> Back in 2012 they wrote 787 and the Boeing logo: Planes have been drawn before by others as well. <A> One of the first examples I recall of this sort of thing was when a Gulfstream aircraft wrote "GV" over the US in 2007: <S> One could say that this has been a "tradition" for at least 10 years now. <A> It turns out Boeing has done this earlier this year as well; on February 11th, a 737 MAX painted the letters M A X over the North-Western states: <S> (source: Boeing's Twitter account ) <A> Probably best to note that it's not really "promotional" -- Boeing had to do an 18 hour endurance test of the Trent 1000 TEN engines so they were going to be up there flying around anyways. <S> So why not have some fun with it? <S> When those pictures came out it wasn't in a Boeing press release, it was some people who noticed by watching FlightRadar24 and other sites :)
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It's not the first time they do it.
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Why are fuel tanks in the wings filled first, and why are they used last? When fueling airliners, why is fuel filled first in the tanks in the wings and then the center tanks? And why do they use fuel from the center tanks first and then from the tanks in the wings? From my research I've found the purpose is not to give too much stress to the structure of the wings, but I don't understand exactly how it works. How does having fuel first in the wings and leaving it last in the wings help protect the structure of the wings? <Q> It's for wing bending relief (for cantilevered wings ). <S> As the generated lift bends the wings upward, the weight of the fuel will counter that. <S> As the plane loses weight in-flight due to burning fuel, so does the need for wing bending relief (less weight → less lift), that's why the wing tanks are the last to be used. <S> For context, a Boeing 777-200ER can hold 29 tonnes of fuel in each wing, and each wing measures ~27 metres and is self-supported. <S> Example: <S> Let's say in our airliner each wing tank holds 100 units (200 total for both tanks), and the center tank holds 200 units, and you have a flight that needs 200 units of fuel. <S> Incorrect scenario: By filling only the center tank, the wings will bend a great deal (maybe even beyond their design limit). <S> This is not good, and even if it is within the design limits, the repeating [avoidable] stresses will shorten the plane's lifespan . <S> Example for order of use (schedule): <S> Our flight needs 300 units, based on the above, we will fill the wing tanks, and fill half the center tank. <S> Correct order: <S> By emptying the center first, we have extended the duration of the wing bending relief. <S> Incorrect order: <S> By emptying the wings first, we lose the wing bending relief, while the plane is still heavy. <S> Related: <S> How is fuel stored and routed on a trijet with one engine at the tail? <A> Having all the payload of a plane concentrated at the fuselage creates a large bending load on the wings in order to support that weight. <S> Storing fuel in the wings allows some of that weight to be placed at the same place where it's being supported, in the wings. <S> Distributing the weight into the wings reduces the loads where the wings meet the fuselage. <A> A minor point - keeping less of the flammable fuel in the body has a safety benefit. <S> Using up what's in the body first helps keep it further away from the crew and passengers. <A> Probably the main reason why fuel is put into the main wing tanks first is because on some airliners (if not most) the engines are fed directly from the wing tanks. <S> Some airliners have to pump the fuel from center tanks into the wing tanks before the engines can utilize the fuel. <S> So for example, if the flight requires 10,000 pounds of fuel, and each wing can hold 5,000 pounds, plus the center tank holds an additional 5,000 pounds, then you don't want to start in the belly tank, because you'll end up with 5,000 pounds in the belly, and 2,500 pounds in each wing. <S> Then the flight crew will have to do a fuel transfer in flight of 5,000 pounds from the belly tank into the wings. <S> Imagine if the flight only required 5,000 pounds and you started in the center tank. <S> You would end up with the full fuel load in the center tank. <S> When the flight crew arrives to take the plane they will have to transfer fuel into the wing tanks before take-off. <S> If you are topping off the aircraft, it won't matter if you fuel the belly or wings first. <S> However, another consideration, which is not part of your question is weight and balance on the ground when the aircraft is empty. <S> Some aircraft like the older DC8 has like 8 or 10 fuel tanks in various locations, some are forward of the CG and some are aft of the CG. <S> However, the fuel tanks in the root of the wings are usually slightly forward of CG which helps to prevent tail tipping. <A> The simplest explanation is that the wings are designed to be the load bearing structure in the air and on the ground. <S> So, you want the most weight to be in/on the wings. <S> In other words, you want to keep the weight stress on the wing structure as opposed to the fuselage because the wings are designed to carry weight. <S> Wing tanks are loaded first because: That keeps the most weight on the wings. <S> They will always be loaded. <S> Center tanks may not be fueled at all on shorter flights. <S> Fuel is then consumed from the center tanks first to keep the most weight on the wings through the flight. <A> The weight from the fuel will counter the upward bending of the wings, as nothing but the wings alone must bear the load of the cabin, and all of its passengers/cargo. <S> Using fuel from the wings last will decrease stress on wings, and the joints between the wing and cabin.
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Correct scenario: By filling only the wing tanks, the weight of fuel in the wings will counter the bending of the lift. In a crash you'd prefer the fuel to not ignite, but of the two locations, its better burning out by the wings than inside the main fuselage.
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What's the point of separating the Alternator and Battery switches? What's the point of having a different button for the battery? Why does the alternator turn on simultaneously with the battery? I need an easy and short explanation, if possible. <Q> I will expand a bit on @Noah Krasser's answer with some situations where you would want one or the other. <S> FWIW under-volt scenarios are typically far less of a problem than over-voltage scenarios. <S> Bad Voltage Regulator : <S> Alternators vary their voltage output with RPM. <S> This keeps your systems power supply at a constant voltage, typically at the cost of some power in the lower end. <S> These things can and sometimes do fail, if they fail in such a way that the alternator is at a high RPM and putting out a voltage that could be potentially harmful to your avionics you are going to want the ability to cut it off while still drawing from your battery. <S> Battery Short <S> : More often than not batteries are stored in the tail section of GA planes or potentially anywhere. <S> If the cable chase leading to the battery develops a short you may want the ability to cut the battery circuit out while still having the ability to power you aircraft from the alternator. <S> Thermal Runaway : <S> Batteries can runway on you and cause an over-volt issue. <S> Again in flight you are going to want to be able to cut it from the system. <A> Short and concise answer: <S> Imagine there is a problem with the alternator. <S> You have to shut it down. <S> Now there is only one button to turn off both the alternator and the battery. <S> You just want to turn off the alternator, but you would also lose your radios, the GPS, everything. <S> Is that what you want? <A> In addition to the other answers, most modern alternators have stator and rotor coils. <S> One generates the electricity, the other consumes current to generate a magnetic field. <S> When driven by the engine, the current consumed is a small fraction of the current generated. <S> However, when you first power up your machine you really do not want the batteries delivering current to the alternator till after the engine is started and running or you will reduce the amount of battery power available and eventually drain the battery. <S> As such, having the ability to completely disconnect the alternator is a good thing.
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To keep your system operating properly a voltage regulator is installed on the alternators direct output.
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How do seaplanes do run-up checks without brakes? Usually on run-up you want to check the response of the motor when changing for example the carb-heat (if existent). At least we did so on my intro flight (yey!). To prevent us from rolling onto the active runway we (obviously) held the brakes. Now I wondered how pilots of floating planes and flying boats prevent movement on pre-takeoff checks. Additionally most images I found from flying boats they usually have more than one engine. Similar question here: How do pilots prevent swimming circles as one engine is started and the other(s) is/are not? I scanned this FAA document from this related question but that is mostly is about landing (which is interesting as well but I assume that as in the linked question the airframe and especially the water resistance take care of that). <Q> I'll limit my answer to single-engine seaplanes as I've never flown a multi-engine seaplane. <S> Typically there is no need to stay stationary in the water when doing a run-up. <S> Just do it while taxiing to your takeoff path, or you can do it on your takeoff path. <S> If the takeoff path isn't long enough to do the run-up and then continue along the path for the takeoff, you can turn around, taxi back along the takeoff path, and then takeoff. <S> At typical run-up power settings, if you hold full up elevator, the airplane will simply mush along on the water since you won't have anywhere near enough power to get it up on the step. <S> In other words, you won't be going very fast. <S> When giving floatplane instruction, one of the first things I tried to impress on students was to not think in terms of the constraints of straight, hard-surface, defined runways, taxiways and the like. <S> There's no need, typically, to taxi in a straight line, make well-defined taxiing turns, and no need to takeoff in a straight line. <S> Once away from the dock or beach, the airplane is going to weather vane unless you actively oppose that, and that weathervaning is going to have a component caused by the current, if any, of the water you're on. <S> In my experience, most of the time the takeoff path was either dictated directionally (a river) or pretty much wide open (lake or reservoir). <S> For new students in my area, reservoirs were preferred. <S> Then just takeoff. <S> I never flew a twin-engined seaplane, but I see no reason why you couldn't bring both engines up to the run-up rpm <S> , do the checks on one and then the other. <S> While checking the mags, carb heat, and props, there would be a little asymmetrical thrust, but not enough that the rudder couldn't handle that. <A> Aircraft on ski's have the same problem, and the answer is relatively simple... <S> They do an abbreviated run-up on the go. <S> Even if the aircraft has a constant speed propeller, many can't feather the propeller enough to completely prevent motion. <S> There are a few piston light aircraft that have a feathering prop, and one that I know of that can actually reverse . <S> This takes some practice, to be able to throttle up to your run-up RPM, do a mag-check, carb heat check, and prop check (for constant speed), but can usually be done in less than 30 seconds, or as little as 10-15 seconds for an experienced pilot. <S> The hard part is dividing your attention between not running into anything and completing your checklist. <S> Remember, it actually takes quite a bit more power to get an airplane moving through the water than it does to move it on land. <S> Some float equipped <S> airplanes have problems taking off from glassy water because they don't have enough power to get up "on the step", or planing the floats (so they have to run back-and forth over their wake to get up). <S> So while 1700 RPM on land basically means you'd be taxiing at 40 knots, on the water it is much slower, and doesn't accelerate as fast. <A> Float planes have variable pitch propellers , meaning that the propeller blade can be angled so that it does not provide any forward movement at all, or even turned backwards so it pushes the airplane backwards a little bit. <S> When the engines are started, or during run-up tests, the propeller pitch is set so that it does not provide any thrust. <S> When flying, the propeller pitch is adjusted to provide differing levels of thrust for take-off, climb, cruise, or descent. <A> Answer 1: WATER RUDDERS <S> As to your question about the "swimming circles" the answer is that the floats have deployable rudders that provide directional control of the aircraft when in the water. <S> They should be retracted before take off as they can be damaged at high speed. <S> They are linked to rudder peddles <S> so you just use a little opposite rudder, if needed, when you have asymetrical thrust situation. <S> Answer 2 <S> : RUN UP during TAXI <S> The run up can be performed while "plowing. <S> " Plowing is a method of taxing a seaplane that produces a lot of water drag on the floats--basically its a tail low position. <S> The pilot can further encourage this nose high attitude by applying full back pressure (up elevator). <S> This accomplishes increasing drag on back of floats and keeping the nose as high in the air as possible, because water can do serious damage to a propeller at high RPM. <S> According to the FAA's Seaplane manual FAA-H-8083-23 (Ch4 p.4-12): " All checks are performed as the seaplane taxies, including the engine runup. <S> Hold the elevator control all the way back throughout the runup to minimize spray around the propeller. "
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More often than not, it was a matter of getting a short ways off the dock, do the checks other than the run-up while moving away from the shore at a 90 degree angle more or less, lift the water rudder, bring the stick all the way back, and do the run-up, all the while letting the aircraft weathervane into the wind.
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Can you report a crash landing on an emergency frequency even if you are not at the airport? You see a crash landing near the airport but you're in a car, no other planes have reported the status of the plane, and Approach can no longer contact the plane. Can you report the crash on an emergency or approach frequency to the tower? <Q> If you are in a car, you probably don't have the full picture. <S> Chances are, if the accident happened "near the airport", emergency services are probably already on the way. <S> This is because the pilot would have been communicating with ATC, and would probably have indicated that he was in trouble before the actual accident. <S> Even if the pilot did not have time to notify ATC, if a plane suddenly "dissapears", search and rescus will be initiated. <S> Don't overcomplicate things and try to get in touch with ATC - just dial the emergency number directly, and they will know what to do. <A> Yes, you can. <S> If you have an aviation handheld or a ham radio in your car, you can call the tower. <S> FCC rules allow you to use any frequency in an emergency. <S> The catch is that you are supposed to exhaust other means first, so if you have a cell phone you should call 911 first. <S> Note that this is only FCC rules. <S> Your local jurisdiction might still arrest you for interfering with police or fire operations if you, say, were to report the crash on the local EMS repeater. <S> It's doubtful, though, so long as you do what you are told and are concise. <A> I think you might have been trying to ask "Can you report a crash landing on an emergency frequency from your crashed aircraft even if you are not at the airport, and you don't have a mobile phone or have no mobile coverage?" <S> It's unlikely an ATC radio facility will be reachable on the ground more than a few miles from an airport, so the Answer would be " <S> yes you can", but <S> your message would need to be received by (high-flying) aircraft in the vicinity monitoring the emergency frequency, and I am not sure many aircraft do so anymore. <S> You would be better off trying to contact an aircraft on an your last used ATC or uncontrolled field channel (like 122.9) that might be intercepted by an aircraft in the vicinity.
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In any case, if will do no harm to call the normal emergency services (dial 112 or 911 in some countries).
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What regulations are in place for ultralight vehicles flying over US national parks? A flight instructor i met with recently said that flying ultralight over national parks is a crime. The law section of the powered paragliders bible has nothing on parks. One would think that commercial vehicles wouldn't be needing to plan around parks above a certain altitude. But ultralight vehicles may have different regulations. After further reading into the book, it says "almost all state and federal parks prohibit launching aircraft and ultralights except at airports." Nothing about flying though <Q> The use of mechanized items, which UAS, ultralights and other aircraft are considered are prohibited from Congressionally Designated Wilderness areas. <S> That designation does not appear on a sectional chart, but can be queried from the supervisor for the park or forest. <S> As far as I know, overflights, particularly those by manned aircraft are not prohibited, but launch, recovery or operation from the wilderness area is prohibited. <A> We have a similar question about Yosemite and the same general answer would apply to any other national park. <S> For ultralights specifically, the regulations are in 14 CFR 103 which has only a few very simple restrictions on where ultralights can operate. <S> 103.15 says you can't operate over a congested area or a crowd of people and other restrictions <S> are the obvious ones <S> : don't fly near airports without ATC approval, don't enter restricted airspace, and do follow NOTAMs. <S> That means that - as with the Yosemite question above - it comes down to whether the national park in question is a congested area or not. <S> Realistically, most parks where you might want to fly an ultralight probably aren't, so it's very likely that you can fly over them at any altitude you like: <S> part 91 doesn't apply to ultralights, so the minimum altitudes mentioned in the Yosemite question wouldn't matter. <S> There's also AC 91-36 to consider, which requests pilots to stay voluntarily above 2000' AGL. <S> I don't know whether it's meant to include ultralights <S> (it's a part 91 AC) <S> but it doesn't really matter because the general guidance is definitely applicable to anything that flies: <S> The intent of the 2,000 feet AGL recommendation is to reduce potential interference with wildlife and complaints of noise disturbances caused by low flying aircraft over noise-sensitive areas As you already mentioned, there might be restrictions on taking off and landing in a park or other public areas (that's an issue for seaplanes , helicopters and bush pilots too), but those would be non-FAA regulations. <A> Pilot regulations are under part 91. <S> Violations are under part 61. <S> You might be flying under part 103 but the answer is <S> yes and ultralight vehicle is not a certified aircraft but the answer is yes <S> you are still required to follow the federal minimum prescribes under CFR the codified federal rules. <S> Just because your meeting the requirements of part 103 does not mean those are the only requirements. <S> An ultra-light is considered a vehicle. <S> But an ultra-light is still an aircraft. <S> There are different types of aircrafts. <S> Don't get mistaken and and up foot dragging down the highway. <S> Because I promise you I've seen in 20 years <S> I've seen plenty guys end up with some images of over $1,000 and having their equipment taken because they don't gain the concept.
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There are no regulations that prohibit operating an ultralight (or any other aircraft) over a national park.
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Strange plane-shaped object at UK airport A friend sent me the following image, spotted at an UK airport. Do you have any idea what that might be? It looks a bit like MD-11/DC-10 transport case, but i have no idea. Is something like this used to transport airplanes? <Q> That's a training rig for airport fire crews. <S> They can usually be set on fire through whatever controlled means and the crews can practice approaching and working around aircraft. <S> In fact, after a cursory Google it's either the one at Heathrow or is near identical to it. <A> Here's the one at Amsterdam Airport: Image source <S> Some of the fire trainers, if not most, have a replicated interior as well so that procedures can be trained for going into the plane, in realistic heat and smoke circumstances. <A> This is a dummy aircraft used for training firefighters. <S> I believe that it's coloured green so that random observers don't think that it's a true emergency.
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That will be a fire trainer, for the airport fire fighters to practise procedures for different types of fire and smoke events.
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What is the purpose of a wing Yehudi? Apart from covering the landing gear leg, the Yehudi also increases the wing root cord which allows the build height for the root to increase for the same wing relative thickness. This is useful as the wing has its highest stresses in this area, it is where the wings bending moment is at its highest ( leehamnews.com ). I don't understand the text in bold. Apart from landing gear 'packaging'. What are the advantages of the Yehudi? Aerodynamic or otherwise. ( commons.wikimedia.org ) An early jetliner without the Yehudi. I'm also interested in the etymology. <Q> Mitteneffekt <S> The pressure fields of the left and right part of a swept wing interfere at the center, causing a drop in lift. <S> The Horten brothers called this " Mitteneffekt ", and it was never properly translated into English, so the German term is used. <S> The Hortens increased chord at the center trailing edge of the wing, reducing local sweep and increasing the area for lift creation. <S> This helped to fill the "hole" at the center and at the same time allowed them to better enclose the pilot. <S> Lift distribution over unswept and swept wing (picture source ) <S> The same is achieved with the reduced training edge sweep at the wing center of airliners. <S> Since this part is occupied by slotted flaps, the rounded trailing edge contour of the Horten planforms is not possible there, so a straight line is the best solution. <S> Structural Efficiency <S> Large wings need heavy spars , and saving some spar weight goes a long way in reducing lift requirement and, consequently, drag. <S> While smaller airplanes do not profit much from an increased wing root thickness, larger ones can save hundreds of kilograms by increasing their root thickness. <S> Since the flight Mach number must not suffer from this thicker root, the simplest solution is to extend the wing chord at the center. <S> (Sorry, the link leads only to a library, but the thesis gives extensive proof.) <S> A nice side effect is the increased space for housing the landing gear. <S> Separation Control Interference between fuselage and wing will cause separation there to start earlier than on the clean wing. <S> Also, the superposition of the flow fields of fuselage and wing will cause shocks at a lower flight Mach number. <S> Therefore, aerodynamic efficiency both at low and high speed is increased when the local lift coefficient drops near the wing root, so the flow has more margin before shocks or separation start. <S> By increasing root chord over what is required for an elliptic lift distribution, the local lift coefficient can be lowered while the circulation distribution stays elliptic. <S> Flap Effectiveness With an unchanged leading edge sweep, Mach tolerance is not much affected, but the lower trailing edge sweep is very helpful for increasing the effectiveness of the trailing edge flaps. <S> Regarding the word "Yehudi": This is the first name of a famous violinist , but I do not connect it with a wing planform. <A> The straight bit of trailing edge at the inboard section of swept wings is indeed to house the undercarriage, without having to interrupt the rear spar structure: behind the rear spar, outside of the fuel tanks. <S> The top view in the OP is of a caravelle with engines mounted at the rear fuselage, with a relatively much shorter landing gear. <S> Image source <S> If this gear housing would just be a bit of extra skin cladding, the local wing profile would have: a lower sweepback angle, decreasing drag divergence Mach number. <S> a lower wing thickness, increasing drag divergence Mach and (partly) compensating for decreased sweep angle. <S> That's aerodynamics. <S> An early solution to this was seen in the B737, where the leading edge was kinked as well and the average thickness increased proportionally, maintaining more or less constant profile geometry. <S> Image source Aerodynamic optimisation of the wing root is a very complex procedure, and half a century after the design of the 737-200, CFD enables much more extensive aerodynamics testing. <S> Wing root optimisation is a bit of a dark art, with parameters including: Increasing local twist. <S> Forward shift of the point of maximum thickness. <S> Extra thickening of the root section: for low wing aircraft, part of the root section lacks the upper surface where the drag divergence shock are created. <S> On the etymology: I've never seen it referenced as a wing yehudi before, only as a trailing edge kink :) <A> There are some people on here that have much more technical knowledge about this, but just from the words of the text you are asking about it seems that they are saying that the wing can be built "fatter" (i.e. the distance vertically from top of wing surface to bottom of wing) when the chord (distance from leading edge to trailing edge) is increased. <S> The wing root chord, is simply the chord (distance from leading edge to trailing edge) at the root of the wing (where it connects to the fuselage). <S> It seems to make sense that being able to build a fatter wing where it has the highest stress would be beneficial for improving structural strength.
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Structure wise, a low wing thickness at the root is not desirable, because that is where the highest bending moments are: the more distance we can get between upper and lower skin, the lighter we can construct.
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What performance issues/symptoms can a pilot expect while taking off above MTOW? Lately I've been flying a Cessna 162 Skycatcher , primary as a cheap way to build time towards the Instrument Cross Country requirement and my glider club's hours requirement to tow gliders. One issue with the 162 is it's relatively low Useful Load. Here are some figures relevant to my question: Maximum Takeoff Weight: 1324 Equipped Empty Weight: 857 Useful Load: 467 Weight of full fuel: 24*6 = 144 Weight of 3/4 fuel: 18*6 = 108 My Weight: 215 Max Weight of passenger full fuel: 108.24 Max Weight of passenger 3/4 fuel: 144.24 Note: All Weights above are in pounds(lbs). Because weight is an issue with this plane and almost any passenger I would consider bringing along, there is a diagram in the FBO's flight book that can be shown to the person fueling that depicts points inside the tanks that denote full, 3/4, 1/2, etc: Last week, I did a flight with a 130 pound passenger. On the first refueling I was sure to show this diagram to the person filling to ensure he only filled to 3/4. I generally make it a habit to inspect the tanks after fueling to ensure they have not gone over the asked for amount. Takeoff was normal with no noticeable degradation in performance. Note: the fuel gauges in the 162 tend to show the same value whether the tanks are full or 3/4 full, with no noticeable decrease until until values go below 3/4. We then proceeded to fly roughly 1.5 hours to another airport. At that airport, I went through the same routine but (in a hurry of course, isn't that how most mistakes are made!) I did not follow up to ensure he had not "overfilled" the tanks. On takeoff, I noted a notable (though by no means catastrophic) degradation in performance: I needed more runway to rotate. I could not climb above 55kts (Vx/Vy in the 162 are 57/62). As I was able to climb at a safe enough airspeed, things seemed to stabilize and I had no other issues, I chose to proceed with the return flight. Performance for the rest of the flight was fine with no extra RPM needed to cruise or do later climbs. It wasn't until I was thinking about it later that it occurred to me that the refueler might have filled my tanks to full. So my question is, do these symptoms sound indicative of being overweight? Or, more generally, What performance issues can a pilot expect while taking off above MTOW? Note: I have reviewed several questions related to this, including: Can a commercial airliner be too heavy to take off? Does weight and balance of an airplane matter more on takeoff? Questions tagged with weight-and-balance However, I didn't find a question dealing specifically with the performance degradation felt by a pilot taking off above MTOW. Update After thinking on this a bit more, reading some of the answers and talking it over with my daughter (the passenger mentioned and a pilot in her own right), I'm leaning towards a different conclusion. Since I was first checked out in the 162 last winter, this was the first time I'd had a passenger. My first takeoff was from KJYO (5500 feet runway length / 390 ft elevation), whereas my second was from Eagles Nest (W13) (2004 ft runway length / 1436 ft elevation). My new theory is that what I felt on the second takeoff was the added weight I wasn't used to since I've flown the previous 20+ flights alone. I believe I didn't notice this as much on my first takeoff because I had much more runway to work with. Nonetheless, I think the question and answers are still relevant/useful. <Q> Firstly, you did goof up by not checking what the refueler did. <S> Your life depends on that fuel, and in light aircraft the gauges are notoriously unreliable. <S> We've probably all done it <S> but we shouldn't - always check! <S> However going off your figures you might have been what, 20 pounds overweight? <S> That shouldn't cause such a massive decrease in performance. <S> MTOW isn't an on/off switch. <S> It's a point that has been selected as the maximum allowable limit - with a safety margin built in. <S> You should never exceed MTOW even by a bit, but if you do you will (hopefully) live to see your kids birthday thanks to that margin. <S> I've flown a C172 right at MTOW (actually about 5kg under but close enough). <S> Acceleration is slow, meaning you use more runway. <S> Rotation actually feels normal thanks to ground effect, but once you leave that you notice a degraded climb performance. <S> If you're over MTOW these effects are the same but amplified. <S> If you are very overweight, you will climb in ground effect but will struggle to go much higher than 20-30ft. <S> As for your flight though, it could have been affected by a tailwind or high temperature/low atmospheric pressure. <S> What was the temperature like on the second leg? <S> Vy will theoretically get you the best climb rate even above MTOW <S> so it doesn't make sense that you could climb below but not at that speed. <S> Maybe there was something localised affecting the ASI, or, if I may be so bold, your technique on the day wasn't 100% :) <A> It's possible you were overweight, a longer takeoff roll and degraded climb performance are definitely symptoms, however there are other possibilities as well, for instance a higher density altitude. <S> Assuming you are in the northern hemisphere and therefore in summer, a couple of hours can make a big difference temperature-wise, and therefore to your density altitude can be much more than you might expect. <S> Let's compare a sea level airfield at standard pressure when it's 50 degrees F (11C) versus 90 degrees F (32C), <S> at 50F the DA is about 450ft, at 90F <S> it's closer to 3000ft (dew point dependent). <S> An airfield at 1500ft elevation at standard pressure and 90F temperature would be 4700ft density altitude. <S> A high density altitude also makes for a much longer takeoff roll and decreases climb performance. <S> It's possible you may have been both a shade overweight in hot and/or high conditions, which would make for an uncomfortable beginning of the flight. <A> Provided that you don't run out of runway, you will probably get unstuck, but perhaps then you won't be able to fly above ground effect. <S> The MTOW figure has usually a considerable margin of tolerance, but a pilot should follow the rules exactly, and consider it an absolute limit... <A> Yes, MTOW is there to save your neck, BUT - there will come a time when you decide that it is necessary <S> to exceeed/ignore it, for whatever reason seems good to you. <S> Each situation needs careful analysis. <S> Understand that MTOW changes with temp / density alt/wind/Rw length /rw <S> slope/ <S> even safety margin inherent in the a/c design, such as power reserve amd wing section polar. <S> We are talking extreme situations, such as PNG mountain strips, <1700 length, 5000'high, 25 C, and passengers determined to fill by volume. <S> Older designs often have a bettter margin than more modern types. <S> DC3 have been known to get away with 200% of useful load, a popular usa light 2/4 seater was fatally overweight, inquest found that it would have been overweight with pilot and zero fuel, not the pilot, 3pax, luggage and full fuel they attempted T <S> /O with. <S> I have flown a seriously OW Aztec, but I had lomg sealed strips both ends and leaving the high country behind. <S> I didn't calculate TOW, didn't want to frighten myself. <S> The Aztec wasa great bush type.
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Overweight of 20% useful load can usually be accomodated by technique, you need to know flight in ground effect, use of thermals and, of course, fhe terrain ahead.
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How do military radars detect the type of an aircraft? How do the military air defense radars and aircraft radars detect the type of an aircraft and enemy or friendly information? <Q> This depends on the type of radar system and its intended application. <S> You can find a nice bit of history on it here . <S> The early radars could not tell the difference between aircraft types, any kind of movement was coordinated beforehand on the friendly side and anything that was not pre-arranged was considered foe. <S> The early Doppler systems that resided on the DEW Line could be trigger by as little as a dense flock of birds. <S> The early radar data from the DEW Line was processed on the SAGE system a very early (very primitive) system for coordinating a great deal of weather, radar, and flight information. <S> After WWII and through out the cold war era newer tech was built to solve the issue of coordination. <S> The modern Identification Friend Or Foe system that is now in use provides at least some way to pick apart radar targets. <S> With the advent of modern computer processing and the ability to analyze radar returns beyond staring at a scope <S> it is possible to determine (with great certainty) the make of an aircraft by its radar signature (and in some cases thermal signature). <S> Also known as Radar Cross Section . <S> Everything ( even stealth planes ) have a radar cross section and once a cross section has been identified it could be used again to check against future pings. <S> One could go as far as to say there is some historical precedent around this. <S> The general idea of "if it comes from over there is one of them, if it comes from over hear its one of us" is very much how radar worked for a long time and the identification of the actual plane was less important than identifying that it was there. <S> If an unidentified target entered a radar area and did not identify its self, over the radio, with some kind of transponder and or at a preordained time it was intercepted. <S> Not until visual identification was made was it not longer considered a threat. <S> Here in the states by 2020 the civilian world will be sending speed and position data via ADS-B OUT to supplement (and potentially replace) radar returns. <A> Classic radar works by reflection radiowaves of objects. <S> The time it takes for the radiowave to come back to the radar, determines the distance. <S> Depending on how many of the transmitted radiowaves are being reflected back, you can determine the approximate size of the object. <S> If an object is moving, the distance will vary, and you can calculate the speed. <S> That is how they did it in the early days of radar. <S> Nowadays, detecting the type of aircraft, is done with transponders. <S> The aircraft itself will broadcast its type and position. <S> Traditional radar is only used as backup on most airfields if a transponder fails. <S> Military uses ofcourse are different. <S> Norad will monitor the skies for instance for any objects that cannot be identified by tranponder signals. <S> And stealth planes will not show up on radar anyway, and will ofcourse need to identify themselves using a secure transponder. <A> Radar can only detect position and speed of objects. <S> The amount of reflected energy may be used to estimate the size of the object, but other factors also have an impact on the amplitude of the radar echo: shape, roughness, paint, apparent angle. <S> Size and speed give a clue to the class of aircraft. <S> Friendly aircraft are known, or respond, or announce themselves. <S> Silent unknown aircraft are potentially hostile.
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You could make an educated guess as to what type of aircraft is detected by radar, based on size and speed.
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Is fuel moved around during flight on a passenger or cargo plane? If so why? Is fuel moved around during flight on a passenger or cargo plane? If so why? Is balance an issue? <Q> Maybe This is dependent on the air frame and varies from plane to plane and not all planes have capability of moving fuel although most large planes do. <S> The Concorde moved fuel all over the place from its 13 tanks to cool the nose cone as well as trim the aircraft. <S> It was perhaps one of the most complex implementations of such a system and kept the flight engineer quite busy. <S> ( source ) <S> Here is a layout of how it was used to control trim. <S> ( source ) <S> For any of this to be possible the aircraft must be equipped with cross-feed abilities. <S> On larger planes this is fairly common, in case of a single side leak the cross feed valve is usually kept shut but since engines can have slight variances in fuel <S> burn the pilots may need to cross feed every so often to balance the plane out. <S> There is a nice overview on 737 fuel systems here. <S> ( source ) <S> In small, often single engine aircraft fuel management is generally left up to the pilot. <S> There are often multiple tanks which can be individually selected and must be rotated in flight every so often (30 min usually). <S> Since some planes are prevented from drawing from "both" tanks, the switch has a lot to do with not running a tank dry in flight. <S> This article overviews weight and balance fairly well. <S> Often times quantity of fuel is more important than location. <S> Most modern airliners store the fuel fairly close to the CG (in the wings or belly for that matter). <S> The Concorde's unique delta wing design led to a fairly different use case than your run of the mill jet. <S> Some of the balance issue is solved within the tank using baffles which keep the fuel from sloshing around too much but allow it to flow freely around a fairly large tank when need be. <S> You can find the full text of the FAA's book on fuel systems here. <S> Here is a neat video of how to actually cross feed fuel. <A> The A330 has trim tanks in the horizontal stabiliser, and so does the A380. <S> In the A380 fuel transfer occurs automatically, unless a fault occurs of course in which case the flight crew will initiate the fuel transfer. <S> From the A380 FCOM: <S> The fuel system stores fuel, monitors the quantity and temperature of fuel in each tank, and controls fuel transfers to: Supply fuel to the engines and to the Auxiliary Power Unit (APU) Maintain the Center of Gravity (CG) within limits <S> Reduce structural loads <S> Control refueling and defueling Enable fuel jettison, if necessary. <S> There are 11 tanks that store fuel. <S> The feeder tanks: <S> Contain a collector cell of about 1,300 kg that is kept full in order to be able to maintain engine fuel feed at negative g. <S> Are positioned such that a rotor burst does not affect them. <S> Fuel transfer takes place from inner tanks first, then mid, then trim, and outer wing last to maintain wing bending relief. <A> In 747-100/200 aircraft, takeoff was accomplished tank-to-engine (meaning each engine was fed from it's corresponding main tank). <S> After takeoff the fuel burn schedule called for center tank fuel to be used after takeoff until exhausted. <S> This was done by turning on jettison/override pumps in the center tanks that put fuel from the center tank into the common fuel system ducting used for refueling and for jettisoning at a higher pressure than the tank-to-engine pumps. <S> The center tank was that tank that was typically used to bring the CG of a tail heavy freighter to within limits, which is why the zero fuel weight CG of a 747 was checked and why fuel used to balance the zfw was considered ballast and not available to burn. <S> Three-engine ferry flights were allowed, as were continued flights after a single engine failed. <S> In these cases the flight engineer would periodically transfer fuel out of the failed engine's tank to the other side. <S> The TWA 800 accident in the late 1990s complicated center tank fuel usage, but that's another topic. <A> In addition to Andrew Morton's comment regarding moving from tanks to engine. <S> It is sometimes also possible to move it outside of the plane, i.e. Fuel Dumping . <S> This is used to reduce weight of the aircraft to be able to land without overweight. <S> And also for "Dump-and-burn" maneuver (dumping and igniting with the afterburner) to create a big flame for visual effect during air-shows.
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Fuel can be stored there to balance the aircraft - without trim tanks the stabiliser would be set to produce lift to balance the plane, and this causes extra drag. Yes fuel is moved around, and balance is indeed an issue.
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How high does the ground effect last? Up to which height is the ground effect still significant enough to be taken into account? Would this height be sufficient to actually fly above the ground, overcoming at least trivial obstacles like trees? The early transatlantic flights were done with heavy loaded planes that had difficulties taking off (only at the end of the runway, and only just). Could it be that these planes were flying within ground effect for rather extended distances, before picking enough speed to complete the take off? <Q> There is no height at which ground effect is switched off. <S> It just becomes less and less effective. <S> There are two factors which determine how strong ground effect is. <S> : <S> Height relative to wingspan <S> : The downwash cannot move into the ground so the induced flow field around the wing is distorted. <S> In a first order approximation, the wing affects mostly the air which flows through a stream tube with the diameter of the wing span. <S> For an explanation see this answer . <S> Once the height is above one semispan, the distortion of the flowfield comes to an end. <S> Trailing edge height relative to wing chord. <S> For very small heights, the gap between trailing edge and ground becomes small enough to more or less block the proper exit of the flow below the wing. <S> The result is an increase in ram pressure on the lower side and further distortion of the flow field such that the stagnation point moves down and the suction peak of the nose flow becomes stronger, adding nose thrust and reducing drag. <S> Moving up further will also weaken the first effect until at a height of one semispan the flow will be very similar to that of the airplane out of ground effect. <S> To illustrate how much happens on the last centimeters (or feet), look at the two pictures which I took from this YouTube video : <S> In the top picture the wing is clearly closer to the ground than its semispan, but the vortices from the flap edge trail straight behind the plane. <S> Now move forward to the lower picture when the trailing edge is maybe half a chord above the ground. <S> Now the trailing vortex is swept to the side because the flow, which is compressed below the wing, expands when it exits the gap between wing and ground. <S> Additionally, the downwash becomes a sidewash, because it has no space below the wing left in which to drop. <S> This should demonstrate that most of the ground effect happens when the ram pressure below the wing builds up. <S> Once the trailing edge is less than half the wing chord from the ground, this part of ground effect kicks in, and the aircraft sees a significant reduction in drag. <A> I remember studying that ground effect happens within one wingspan. <S> Although it reduces when you gain altitude. <S> As mentioned in FAA’s Pilot <S> ’s Handbook of Aeronautical Knowledge : <S> When the wing is at a height equal to its span, the reduction in induced drag is only 1.4 percent. <S> However, when the wing is at a height equal to one-fourth its span, the reduction in induced drag is 23.5 percent and, when the wing is at a height equal to one-tenth its span, the reduction in induced drag is 47.6 percent. <S> It is also referenced here : <S> But, it really reduces your drag when you're within 20% of your wingspan to the ground. <S> At that height, your wing only generates 60% of its normal induced drag. <A> Ground effect height is primarily a function of the airfoil, and the "ground" surface. <S> Smooth desert lakebeds have "better" ground effect than forest tree tops. <S> Calm water is better than open water for smoothness. <S> As I recall, there have been several times where planes have operated in ground effect for substantial distances, such as military aircraft loosing engines at sea. <S> So to the OP questions <S> : The general rule is that 1/2 the wingspan is the practical limit of ground effect. <S> My spin is that the surface of the ground, and the airfoil, vortex and downwash factor into that distance. <S> Obstacles such as trees are not practically overcome by ground effect. <S> Numerous documented instances have historically occurred where aircraft have extended operations over large bodies of water with engines out, or lower power settings, using ground effect. <S> As fuel is burned off, sometimes the ceiling of the aircraft will increase notably. <A> Although it depends of the characteristics of the wings (shape, wingspan,...), as you said it can be useful to gain some lift. <S> I would say from 5 to 10 meters (for a medium sized plane), the effect loses a lot of its efficiency. <S> Unfortunately, I have no mathematical proof to back this up. <S> I don't know if you ever heard about them, but ekranoplans use almost exclusively the ground effect to "fly", however, they can't gain altitude like an actual plane would do. <S> As @mongo stated, smooth surfaces are much better to take advantage of this effect. <S> More examples of Ground effect vehicles here
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Ground effect only begins to show up when you're within one wingspan of the ground. When moving up from zero height, ground effect diminishes rapidly because the gap between trailing edge and ground opens up and the ram effect vanishes.
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Is it practical to use ground effect to extend range in an emergency? Imagine a piston engine airplane (let's say a DC-3) flying at cruise speed and altitude over a calm sea, trying to reach an unreachable airstrip straight ahead, just above sea level. Fuel is very low and ditching may occur at some point even if highest lift to drag to consumption ratio is achieved. Would a ground effect low horizontal flight increase the range? That could mean ditching closer to the shore, and getting help sooner (or even landing safely). If yes, is it also the case for a modern jet airliner usually cruising faster and in a much thinner air, and are there some emergency procedures or regulations about that? <Q> When flying close to the ground, there is an important reduction of induced drag, the larger the closer to the ground one flies, so the airplane needs less engine thrust to keep a given airspeed. <S> Anyone who has made a low pass over a long runway may attest this... <S> I remember reading that it was often used by carrier planes returning from a mission low in fuel... <A> There has been an incident with a propeller machine where one engine failed. <S> Cause the other engine would run hot while keeping the altitude, the pilot decided to descend till he reach ground effect to reduce the stress of the one last engine. <S> Also the pilot asked the passengers to throw out their luggage to reduce the ballast. <S> Finally they flew over one hour in ground effect and reached land. <S> A modern airliner would most likely glide cause of the much higher cruise height. <S> See Gimli Glider and Air Transat Flight 236 <A> During glider training, I was taught to use ground effect to my advantage if I was going to come up short on final. <S> It's been a long time, but my recollection is that I was taught to get to ground effect efficiently (no drag devices out, appropriate airspeed), and then ride in it as close the ground as is safe until (hopefully) reaching the runway. <S> A glider in a clean configuration can go a long, long ways in ground effect. <S> I was also taught to maintain some excess energy on final, to speed up through significant sink, etc. <S> Riding in ground effect was a "when all else has failed" measure.
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Flying in ground effect is a nice way to save fuel and extend the range.
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Are planes assigned different climb angles from the airport by the tower? Clearly the angle at which planes take off and climb depends on lots of things (mountains, residential area, aircraft type, wind) but when watching planes take off after another from the same runway, I have the impression that similar aircraft climb at different angles right after another. So I'm wondering it this is a measure to increase the distance between two planes quickly after they leave the airport? Such that every other aircraft is asked to leave flat'ish (within what the plane and regulations allow) and others more steeply? The question occurred to me at GVA (single commercial runway). This is about the initial climb angle, not their course heading. <Q> There can be many reasons. <S> Flights taking off one after another: have different destinations have different weight and balance have difference in wings and wingtips <S> have pilots with difference in skills got different takeoff directions by ATC are trying to avoid wake turbulence <S> Off all the reasons I mentioned above, perhaps wake turbulence might be playing more role about difference in takeoff angle. <S> There are a ton of questions about wake turbulence , which is worth a read. <A> Referring to the takeoff pitch angle differences, they are often due to aircraft characteristics or situational things, like potential wake turbulence, or known obstacles. <S> consider an F-18 putting out full afterburners on takeoff. <S> That pilot could go straight up, no problem. <S> At my flight school on the other hand, someone was training in a home-built LSA (I don't remember the type) <S> that I swear had a max fpm climb rate in the TENS. <S> (joking, somewhat). <S> That little plane had to do a LONG and SLOW climb. <S> Anytime in the pattern behind him was laughably interesting, having to extend the pattern in all sorts of ways. <S> That was fun for a newbie trying to learn how to land in the first place. <S> Aside from that, departures vary for safety and often convenience, keeping planes out of trees, wake turbulence, and other planes. <S> Planes with short takeoff rolls can usually get above obstacles (50') or wake turbulence effects before most of the runway is taken up, allowing for a shallow climb. <S> Other planes might require more runway, leaving a steeper climb required to clear obstacles. <A> Separation is achieved primarily by lateral distance. <S> If there is a risk of collision (e.g. an aircraft has just taken off, and the landing aircraft executes a go-around), ATC will issue a different heading to one of them. <S> The initial climb from the runway is hand flown by the pilot; even if conditions are the same, different pilots might have climbed the aircraft at a different angle. <S> Besides, there are quite a few factors which will influence the initial climb you observed: <S> A heavier aircraft will have a higher Vr, which will delay rotation. <S> An aircraft heading to a farther destination will carry more fuel and be heavier, even compared to another aircraft of the same type. <S> If the aircraft is empty (e.g. positioning flight), the pilots can probably climb faster. <S> If the fuselage is long (e.g. 777-300) and the pilot pitch up too much, it will have tail strike. <S> Company SOP may require the pilot to "pitch up to X degrees" for passenger comfort. <A> A climb rate/angle assignment will not be assigned, altitude only. <S> The standard climb rate is 200 ft/nm unless otherwise published, but ATC won't verbalize the published climb rate unless queried. <S> The closest thing to your question would be the assignment of a departure procedure. <S> DP's have a required climb gradient based on the departure runway to ensure obstacle separation or satisfy noise abatement procedures.
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Planes have different speeds for best climb, and that will result in different take off angles. No, planes are not assigned a specific climb angle by the tower upon takeoff - the tower will not instruct an aircraft to "climb at FPA 4 degrees" or "climb at 1200 feet/min" .
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Why are empty pylons weighed down? ( airplane-pictures.net ) Airbus A330 no engine option. Why are empty pylons weighed down? The plausible answer is to maintain the correct center of gravity. But why not just load ballast pallets in the forward cargo compartment, like those used on tail heavy planes on ferry flights? On airliners.net there is a theory (plus debate) that states another reason is to relieve the load on the wingbox, which I would imagine would also decompress the landing gear (I don't see how). Lastly, I remember on a TV documentary it was stated that the reason is so the wing would not deform upwards (again I don't see how). <Q> Your reason 1 is correct. <S> Why not pallets? <S> This would produce the same center of gravity location, but a different mass distribution. <S> Clearing this configuration even for being loaded and pushed around is more effort than simply placing the ballast where the mass of the engines would go. <S> Now all clearances are valid and the aircraft can be handled much as one with the engines in place. <S> Next, engines are only installed shortly before delivery or first flight. <S> The cost of capital is too high to install them any sooner. <S> (airbus.com) <S> Example of clearances that would be affected by non-standard mass distribution. <A> You're correct- <S> it is to maintain the center of gravity within limits and to prevent the possibility of tipping over. <S> As for why weights in pylons and not ballast, this method is quite simple. <S> You can simply hang the weight of the engine on the pylon and the aircraft will behave as it there is an engine (weight and c.g. wise). <S> In case you want to load ballast, first you have to calculate the ballast to to be loaded based on the location. <S> In some cases, the cargo compartments may not take the load at all- for example, in case of A320 neo, each PW1000G weighs around 2.8 tons, while the forward compartment is limited to 3.4 tons . <A> You want to handle the aircraft as it was initially designed. <S> This means that even though you could have proper CG location with internal ballast, you might fall out of design elsewhere, like in mass distribution. <S> For example, consider the location of the engines vs the landing gear. <S> There definitely were a lot of design considerations in choosing how to support the aircraft on the landing gear. <S> It appears the gear are inboard of the engines (or where they normally would be) in the image shown. <S> By instead moving all the weight inside the plane, you would be creating a different bending stress distribution, as all the engine mass, originally outboard of the gear, is now very much so inboard. <S> As a dramatic (more fun) example, imagine a scenario in which the ground crew, having fun with the plane, somehow managed to load the ballast in the correct CG location, but all the way out on the wing tip . <S> I hope you could see that the wing wasn't originally designed with the necessary structure to support that weight all the way at the tip. <S> The tips would droop down to the floor (if the wing didn't totally fail), and then scrape all the way to the next hangar area... :) <S> Imagine then tossing the keys of your bent or drooping A330 to your dumbfounded buyer. <S> "She's all yours".
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Without the ballast the aircraft would become a taildragger .
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Can pilots wear glasses/corrective lenses inside the cockpit? I was wondering If I could wear corrective lenses/glasses inside the cockpit If I have a certified class 2 medical certificate? <Q> Yes. <S> See Title 14 <S> §67 Medical Standards and Certification. <A> According to the FAA , yes. <S> For a Class 2 Medical: <S> Distant Vision: <S> 20/20 or better in each eye separately, with or without correction. <S> Near Vision: 20/40 or better in each eye separately (Snellen equivalent), with or without correction, as measured at 16 inches. <S> Intermediate Vision: 20/40 or better in each eye separately (Snellen equivalent), with or without correction at age 50 and over, as measured at 32 inches. <S> Notice <S> the "with or without correction". <A> According to the CAA in the UK , Class 1Refractive error(1) <S> At initial examination an applicant may be assessed as fit with: (i) <S> hypermetropia not exceeding +5.0 dioptres; (ii) myopia not exceeding -6.0 dioptres; <S> (iii) astigmatism not exceeding 2.0 dioptres; (iv) <S> anisometropia not exceeding 2.0 dioptres; provided that optimal correction has been considered and no significant pathology is demonstrated. <S> BUT there are a long list of exceptions and further conditions that may well disqualify you anyway. <S> And the requirements for a class 2 medical are stricter, add limits on top of this.
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All current classes of FAA-issued medical certificates allow for the use of corrective lenses in the cockpit.
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Why on weather surface charts high pressure is blue and low pressure is red? Is there any relation with the temperature of the air or is it just a standard procedure? <Q> Red/blue for pressure is in no relation to surface temperature. <S> Storms develop where the pressure is very low. <S> Red being associated with danger is a good color choice for low pressure. <S> Storms are created when a center of low pressure develops with a system of high pressure surrounding it. <S> Low pressure is also associated with decreased aircraft performance, both lift and engine power. <S> See below and find the strongest storm system. <S> ( Source ) <S> Blue for cold and red for hot is used for coloring the weather fronts : ( Source ) 1. <S> cold front 2. <S> warm front 3. <S> stationary front. <A> High pressures are associated with stable weather, sun, blue skies, absence of wind... <S> Hence, it's no wonder that low pressure is indicated in red, and high pressure in blue... <S> Socialist-minded people do strongly object... <S> For them, the red color is a symbol of revolutionary progress... <A> "From high to low, look out below." <S> Pilots use this mnemonic to remember that when flying from high pressure into low pressure, the altimeter will read higher than actual altitude, which can be dangerous. <S> (also true from high temperature into low temperature). <S> I don't know if it was by design, but I've always associated the red low pressure with danger, because flying from an area of high pressure into an area of low pressure can result in flying lower than indicated on the altimeter and also <S> , low pressure is usually associated with less than desirable flying weather. <S> Additionally, high pressure is often associated with blue skies. <S> So maybe that is the rationale, if there even is one. <A> Lows are composed of warm rising air; highs of cold sinking air. <S> That's why highs are represented by blue, which equates to cold air, and lows are represented by red, which equates to warm air. <S> Again, this is aloft, near the top of the troposphere, not at the surface. <S> This website explains the sinking and rising aspects of highs and lows.
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The colors of high and low pressure areas are chosen to represent what occurs aloft, not at the surface. The red color is universally associated with evil, suffering, blood, fire... Low pressures are associated with rain, storms, even with hurricanes and tornados...
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Which civil airport has the longest runways in total? It's quite easy to google information about which civil airport has the longest runways, but what I'm really looking for (and having a hard time to find) is which airport has the longest runways in total - I mean if you add up all the lengths, disregarding the direction - which one be the winner? <Q> Best I can find, within the US, is KDFW with 80,403' of total length. <S> Second seems to be KDEN with 76,000'. <S> Glanced at KORD, and with mental math it comes up to about 71,000'. <S> Most other major airports are well behind all of these, mainly because they don't have as many long runways as DFW and DEN. <S> Somebody else can consider Russian, Chinese, and Middle Eastern airports <S> -- I don't have the chart sets handy for those. <S> May be worth converting this to a community wiki answer if any of those places give interesting results. <A> Based on my current navigation database (AIRAC 1911), the following 20 airports have the longest total runway length: <S> KDFW : <S> 7 runways with a total length of 80,403 ft (longest 13,401 ft) <S> KDEN : <S> 6 runways with a total length of 76,000 ft (longest 16,000 ft) EHAM : <S> 6 runways with a total length of 63,688 ft (longest 12,467 ft) KORD : 7 runways with a total length of 62,342 ft (longest 13,000 ft) <S> KDTW : <S> 6 runways with a total length of 57,713 ft (longest 12,003 ft) <S> KEDW : <S> 4 runways with a total length of 56,143 ft (longest 21,119 ft) (not civilian) <S> LTFM : <S> 4 runways with a total length of 51,508 ft (longest 13,451 ft) <S> KIAH : <S> 5 runways with a total length of 50,403 ft (longest 12,001 ft) <S> CYYZ : <S> 5 runways with a total length of 49,955 ft (longest 11,120 ft) <S> LEMD : 4 runways with a total length of 49,761 ft (longest 13,711 ft) <S> KATL : <S> 5 runways with a total length of 49,389 ft (longest 12,390 ft) <S> ZSPD : <S> 4 runways with a total length of 49,212 ft (longest 13,123 ft) <S> ZBAD : <S> 4 runways with a total length of 48,556 ft (longest 12,467 ft) <S> LIRF : 4 runways with a total length of 48,272 ft (longest 12,802 ft) PHNL : 6 runways with a total length of 48,264 ft (longest 12,312 ft) <S> LFPG : 4 runways with a total length of 45,085 ft (longest 13,780 ft) <S> KJFK : <S> 4 runways with a total length of 44,990 ft (longest 14,511 ft) <S> KLAX : <S> 4 runways with a total length of 43,829 ft (longest 12,923 ft) <S> KLAS : 4 runways with a total length of 43,800 ft (longest 14,515 ft) KMCO : 4 runways with a total length of 43,010 ft (longest 12,005 ft) <S> In Europe, the winner is Amsterdam Schiphol (EHAM) and in Asia, the winner is Shanghai Pudong (ZSPD) . <S> In total 11 out of the 19 civilian airports listed above are in the United States. <A> Qamdo Bamda Airport (ZUBD) has one runway that measures 18,045ft.(5,500M) <S> long
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The highest average runway length of the 19 civilian airports listed above has Istanbul Airport (LTFM) at 12,877 ft. As Ralph J said in his answer , Dallas/Fort Worth (KDFW) comes first (also worldwide) due to the large number of runways (also highest worldwide, together with KORD).
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What aircraft is this flying near Greenford? I live in the suburbs of London in Greenford (near RAF Northolt Base) and today I heard a droning sounds which, albeit from my limited experience, sounded like a propeller plane. I checked my generic flight radar application on my smart phone, no result. I then checked the ADS-B tracking website which identifies most military aircraft that aren't flying covertly but, again, no result. I did manage to take a picture of the aircraft and it looks like a small passenger turboprop plane - so any ideas about what aircraft this is and why it wouldn't be showing up on any radars? It does not seem like a stealthy fighter jet by any means. <Q> Spy planes!!! <S> Looks like I found an answer after two years when I came across a blog called 'secret bases'. <S> "Keen MI5 spy plane spotters should continue to lurk around RAF Northolt. <S> A company formed by former elite RAF pilots, 2 Excel Aviation, actually based at Sywell Aerodrome, Northamptonshire, is now performing those spooky Northolt tasks, as part of its Scimitar special projects team. <S> They are using Piper PA31 Navajo aircraft "G-SCIR" (ModeS 40729C), "G-SCTR" (ModeS 40029D) and "G-SCMR" (ModeS 40729E) — <S> all registered to 2 Excel in February / March 2017. <S> They joined regular "sneaky-beaky" craft "G-UMMI" (ModeS 400C86) which is regularly spotted with special communications equipment attachments. <S> All three RAF Northolt Piper Navajo PA31 craft had been purchased by 2 Excel from Mike Jones Aircraft Sales Inc in Murfreesboro, Tennessee, America, who specialise in Colemill Panther conversions for performance and safety boosts. <S> G-SCTR previously carried registration mark N331DB. <S> G-SCIR had been supplied with tail number N522AW and G-SCMR had previously carried N27773. <S> Military aviation enthusiast Alan Warnes blogged on the subject in August 2017 on his Warnesy's World website, but strangely he only noted two out of the three Piper Navajos and missed G-SCIR. <S> Curious, as the three registrations all took place at the same time – February / March 2017. <S> The London Evening Standard's Business Pages reported on my findings in an article headlined <S> "Lift Off: Home Office privatises MI5 spy plane operations"." <A> A long shot, but perhaps it's an Avro Anson , a true "old timer" from WWII and used by the RAF no less. <S> Image credits all from Wikipedia <A> I'm going to hazard a guess here, but that's likely the best you will get unless someone tracks down a photo of a plane with a matching paint scheme. <S> Here's my thought process: tapered, low wings <S> engine nacelles are almost as long as the nose, which narrows things down a bit engine nacelles are relatively large in size, so it's... probably piston engined probably <S> fairly small, maybe 6 passengers? <S> vertical tail looks swept horizontal tail is placed low, and is at least as wide as the engine nacelles fuselage tapers from the trailing wing root to the tail <S> Image credit: AOPA <A> Given its proportions and size, as well as the shape of the wing platform, I might guess a Beech King Air C90.
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As far as I can tell, it looks an awful lot like a Beechcraft Baron .
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Are there any helicopters with ejection seats? Are there any helicopters with ejection seats? If so, how is the clearance problem with the rotating blades solved? <Q> Many years ago I read about the Kamov-50 helicopter family <S> * being the first helicopters equipped with ejection seats. <S> And Wikipedia verifies my memory: <S> It is the world's first operational helicopter with a rescue ejection system, which allows the pilot to escape at all altitudes and speeds. <S> In the same article for the same helicopter it is mentioned that Before the rocket in the ejection seat deploys, the rotor blades are blown away by explosive charges in the rotor disc and the canopy is jettisoned. <S> Also, if you want to count experimental helicopters in, Sikorsky S-72 RSRA may be another one. <S> Here is an interesting video , demonstrating the blades being blown away, and ejection of the pilots. <S> As a side note, in the article I read in an aviation magazine many years ago, it mentioned a synchronization of the seat with the blade rotation so that the seat passes between the blades. <S> It was based on a working principle similar to the middle machine gun that some WW2 German airplanes were equipped with that fired the projectiles between the propeller blades. <S> Judging from the fact that I read it somewhere in the late 90s where the project was still new and developing, as PlasmaHH pointed out, that was probably more a thought rather than a fact. <S> * Kamov 50 and its variants/successors like Ka52 <A> Image source <S> The Sikorsky S-72 Rotor Systems Research Aircraft had ejection seats, as shown on this video . <S> Like the Ka-50, it blew the rotor blades off first before ejecting. <S> This article mentions a crash of a Mi-28 in which one pilot died: <A> As others above have stated, the Kamov KA-50 family is fitted with an ejection seat. <S> First the blades are separated from the blade sleeves, which remain attached to the mast (rotor hub). <S> a few fractions of a second later, the conventional upwards firing ejection seat is launched, using extraction rockets tied to cables to drag the seat clear of the airframe. <S> This cutaway image shows it to reasonable effect. ' <S> 46' indicates where the blade separates from the sleeve. <S> The little sketch of the smoke on the lower right blade shows the separation, and the '18' and '19' show the extraction rocket. <S> KA-50 <S> Cutaway image <S> Digital Combat Simulations's (DCS) line of computer simulations models the ka-50, including the ejection seat. <S> I'm sure there's video from the game online somewhere. <A> The Mi-28 doesn't actually have the ejection seats, the Mikoyan constructor bureau follows a different approach: they've created energy absorbing seats and landing gear to protect the pilot in a crash. <S> Kamov does install ejection seats in their helicopters, a.o. in the Ка-52. <S> It blows off the rotor blades and shatters the upper glass windows to make the way clear for pilot ejection. <S> One can see the white cord with explosive on the upper window of Ka-52 on the pictures (there is a white zigzag-like cord on the bottom of the pilot window): <S> Testing of the part of the system Ad from Rosoboronexport
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The Mi-28 was supposedly designed with an ejection seat system that fires its crew out the side and downward.
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Why wouldn't a helicopter ejection seat eject sideways? Or forwards? This question got me thinking . Ejecting from a helicopter is necessarily more complicated than ejecting from a fighter jet or other fixed-wing aircraft. The answer to this question states that ejection-capable helicopters blow the blades first, then the canopy, then eject the passengers. This seems to me like a lot of explosions above your head, which seems only slightly preferable. Why not eject the passengers either sideways or forwards? <Q> Well to me it seems that in your question you consider the helicopter flying straight and level and clear of any terrain. <S> Well that's not true <S> so let's take each case separately: <S> Eject forward <S> That seems like the most dangerous option to me. <S> What if you are into CFIT ? <S> The ejection system will actually "spit" you into terrain with your helicopter's speed plus the speed of the acceleration. <S> Ouch. <S> Even if you survive this, the point is to escape the helicopter. <S> And guess what its trajectory is: forward. <S> Also consider that the free stream works against you so you will need more acceleration to get away of the incoming helicopter. <S> Finally, right in front of you there is equipment like dashboards machine guns sensors et al. <S> that need to get out of your way before you go. <S> Eject sideways That sounds a least dangerous option. <S> But what if the helicopter is banking to one of the sides? <S> If the crew is seated side by side do they have time or even the option, "I go first <S> you go after"? <S> Also bear in mind that attack helicopters' nature is to fly low and maneuver a lot. <S> So there are high chances to be low and bank at the same time when in need to eject. <S> So the above 2 leave you with one option: eject upwards. <S> But then you have one (or maybe 2) <S> big propellers rotating above your head. <S> But that's "easy": you get rid of them the same way you get rid of the canopy and then eject. <S> Once the blades are released, the centrifugal will do what it knows best and the blades will be out of your way in no time. <S> Well, hopefully. <S> Considering the "too many explosives above ones head", it's not rare practice to use explosives to get rid of things that are in the pilot's way like for example the canopy . <S> That's been around for a while. <S> But changing the trajectory of escape that will be a new concept and it will need lot's of testing. <A> Because of a high chance of being launched into terrain, not because it would be worse for the body. <S> The human body can actually withstand more g's in forward and sideways acceleration than in upwards acceleration. <S> When accelerated upwards, the blood cannot reach the brain and eyes and very soon a glucose deficit will cause loss of vision and/or of conscience. <S> Colonel John Stapp pioneered building up this knowledge between 1945 and 1958, by exposing first a dummy and then himself to accelerations up to 46.2 g. From <S> this fascinating article : <S> Stapp was subjected to tortuous conditions, but more importantly, he survived. <S> His team showed that humans could withstand forces in excess of 30G deceleration and just as importantly showed that seats, harnesses, and cockpits should be designed to withstand these forces as well. <S> And Stapp had suffered a complete red out and was just barely conscious. <S> The jolt burst nearly every capillary in his eyeballs, he was blinded, but his retinas did not detach. <S> He slowly regained his bearings and within a day his vision was back to normal. <S> Results of the research of this brave man: <S> Forward acceleration up to 20G is perfectly survivable. <S> Sideways acceleration has little influence on consciousness, but does have significant impact on supporting muscles for the head. <S> So the head must be fixed in sideways position before ejection. <S> Upward acceleration is more taxing than in x- or y-direction, with problems occurring at 4-5 g depending on onset and duration. <S> A typical Martin Baker seat creates accelerations of 12-14g but for a very short time. <S> Downward acceleration is tolerated the least well by the body. <S> Image source <S> So for the body, x- and y-accelerations pose fewer problems than z-accelerations, provided that the head is supported for sideways acceleration <S> - the Formula 1 style may be too restrictive for helicopter pilots though. <S> The main practical problems are therefore altitude and attitude. <S> Upwards is a better direction! <A> In both cases, you must be sure to "outrun" the helicopter blade. <S> Your seat must go fast enough to avoid you getting a new haircut. <S> This might be problematic because of violence of the acceleration, especially if you eject sideways. <S> In addition, helicopters tend to fly low so you might hit terrain or simply not have enough altitude to land safely. <S> I'd rather have explosions above my head and eject safely than ending like a pancake or minced meat.
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Backward acceleration is much more taxing to the body. The first F-104 Starfighters had downward facing ejection to avoid the T-tail, however they fly quite a bit higher than a typical helicopter.
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What are the benefits of a non-orthogonal (scissor) tail-rotor? Why is the tail-rotor of some helicopters (e.g., Boeing AH-64 Apache) made of non-orthogonal (scissor) blades? What are the aerodynamic benefits (or any other benefits) compared to the orthogonal cruciform option? ( Source ) <Q> ( Source ) <S> The comments and answers already say it's for noise reduction. <S> What's more intriguing is the how: The blades are not coplanar (image). <S> The tail-rotor of the Apache rotates clockwise (video) when viewed from the port side. <S> The nearest blades (nearest plane) to the viewer are the leading blades of each group. <S> A group is two close blades regardless of plane, e.g., 1 and 2 as labelled above are a group, 1 is leading. <S> The thrust of the tail-rotor is being directed away from the viewer (port to starboard), which means the viewer is looking at the pressure side of the rotor. <S> Below on the left is what it looks like from behind the Apache. <S> This arrangement allows the trailing blades (2 and 4) to miss the wake from the ones ahead of- <S> (and closest to-) them. <S> (Own work) <S> Left: <S> Apache; Right: coplanar normal spacing. <S> View is from behind and thrust is left to right. <S> This L scissor configuration, as it is known, where the lower blade is leading yields more thrust due to the better interaction. <S> Based on extrapolation of the test results and calculations, the increase in thrust over a conventional four-bladed rotor of the same dimensions is about 10%. <S> Rozhdestvensky attributes Bell's failure to come to similar conclusions to their use of a very small model. <S> And quieter, too Noise measurements during flyovers were made with a Havoc having the four-bladed scissors tail rotor and the three-bladed tail rotor from the Hind . <S> The two rotors made about the same noise at low speed but at high speed the scissors rotor was quieter. <S> The primary reduction was in the "broad-band" frequency range from 600 Hz to 2000 Hz. <S> Much of the noise at these frequencies is due to the effects of the tail rotor working in the confused wake of the main rotor. <S> The scissors rotor apparently acts more like a two-bladed rotor in this situation. <S> ( Helicopter Aerodynamics Volume II , p. 72.) <A> Image source <S> The tail rotor of the Apache consists of two 2-bladed teetering rotors, referred to as scissor rotors. <S> This unusual configuration was first implemented by Hughes Helicopters in the late 1960s for reducing the noise of the OH-6 helicopter. <S> The OH-6 had a single twin blade teetering tail rotor, which Hughes wanted to rotate slower for reducing noise levels. <S> In order to maintain the same thrust a second identical rotor was mounted, which could not be placed at 90 degrees due to interference. <S> The resulting twin teetering scissors rotor had a good noise profile - <S> our ears are less sensitive to lower frequencies, and the scissor rotor dominant frequency is two per revolution instead of 4 per revolution for the 90°. <S> The Hughes team minimised new inventions, and implemented this solution for the Advanced Attack Helicopter competition of 1972, which they won. <S> The blades in the Apache tail rotor are mounted at 55 degrees, reducing the harmonics and the pressure levels in the sound profile. <S> Source (page 69) <S> From <S> this reference : <S> The four-bladed tail rotor is unusual in that, rather than the blades being evenly spaced at 90° intervals, the blades are spaced at 55° and 125° angles. <S> This Mindef reference describes experiences with the original configuration of the AH-64, which had a T-tail. <A> I believe its to reduce the noise, here is a partial info <S> http://theses.gla.ac.uk/619/ <S> The complex flowfield which is associated with a rotor wake gives rise to the multitude of aerodynamic interactions that may occur during rotorcraft operation. <S> These interactions may give rise to undesirable noise and lead to an unacceptable performance degradation,
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This allows for significant reductions in noise.
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Does weight affect the fuel burn calculations in a light GA airplane? When calculating fuel burn in say a Piper Archer, I usually just use the conservative estimate of 10GPH, but, does the weight of the aircraft affect my fuel burn? Assuming I have full fuel and am taking off a max takeoff weight, will I still burn the same amount of fuel in 4 hours as I would if I took off with only myself in the plane and full fuel? <Q> The engine doesn't care how heavy the airplane is (or how well it is flying), but you might. <S> As long as you are cruising around at a particular altitude and power setting, then the engine is going to consume fuel at the same rate. <S> A heavier airplane will require increased lift, which will induce greater drag, and will have a lower forward airspeed as a result of that same power (assuming it is not so heavy that it prevents you from maintaining altitude). <S> If on the other hand you have a particular airspeed you want to maintain, then the power needed for that speed will depend on weight. <S> Lower weight, less power necessary, less fuel flow required to supply the power. <A> More weight means the plane will need more lift, and more lift implies more drag. <S> For example, and for a constant airspeed, an increment of 10% in weight will mean 10% more lift, achieved by increasing the AoA, and that will mean 10% more drag too. <S> The power required will be 10% higher also, implying 10% more fuel consumption... <S> For heavier loads, the relation would not be so (approximately) linear, because the airspeed will be probably lower, the AoA higher, and the induced drag far higher. <S> Thus, the power required (and the fuel consumption) will rise disproportionately. <A> In short, yes. <S> However the limited flight envelope and useful loads for these kings of airplanes combined with limited increase of induced drag will only decrease speed a few knots or so between the airplanes empty weight and maximum takeoff weights. <S> This only translates to a couple of extra gallons in fuel savings. <S> To compensate for this, the OEM approved performance charts and flight planning literature in the AFM are usually done at the maximum takeoff weight of the airplane for conservative purposes; the airplane may perform slightly better in optimum conditions but manufacturers err on the safe side for the average private pilot. <A> Short answer is: you would burn more fuel. <S> 1 <S> You need more energy to counteract gravity during the climb. <S> 2 <S> Your POH (part 5) might explain how to calculate the new required fuel.
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At a given speed, a higher mass requires more lift, and more lift implies more drag, more drag requires a higher power setting to achieve the same speed, and a higher power setting means a higher fuel flow.
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Where can I get information about the FAA "restricted like" license to fly a N aircraft in Italy / Europe? I have recently bought a N-REG C172 in Italy since 2008 and in fact I have been told by the Italian NAA that my EASA License will be valid limited for flights in Italy. I understand if I wish to fly in other EU countries I should apply for a FAA "Restricted like" License which I can obtain symply by giving a short english language check in recognized FAA offices in Italy. Any Idea about this "restricted" option? Whom should I ask to get more info? <Q> I don't know what an FAA "restricted" license is, but I guess it may be a foreign-based license issued under 14 CFR 61.75 ; see this answer for more information. <S> It's an FAA private license that's linked to your Italian one and <S> it gives you all the privileges of a regular FAA private license, including operating N-reg aircraft anywhere in the world. <S> But note that if your Italian license has more restrictions than the FAA one (e.g. no night flying) <S> then you still have to obey those restrictions. <S> The process to get one is described here <S> but I believe you have to physically visit an FAA office in the USA to get it. <A> The license they are talking about is an FAA license issues on the basis of your Italian one, provided that license is up to an FAA standard. <S> See @Pondlife's answer for some links, and here's one on the AOPA website . <S> The FAA license would be restricted to the privileges of your Italian one. <S> For example, if you do not have privileges to fly at night on your Italian license then you would not be able to fly at night. <S> If your Italian license defines the day as being shorter than the FAA you'd have to use the Italian definition. <S> To get one you have to show up in person at an FSDO unless the Italian FAA equivalent has an agreement in place where they can validate identity, etc. <A> I'm just back from FSDO in Hempstead near NYC with my temporary license and would like to give a feedback to anyone interested. <S> follow instruction @ <S> https://www.faa.gov/licenses_certificates/airmen_certification/foreign_license_verification/ <S> obtain verification letter from FAA Schedule a meeting with your FSDO inspector follow instruction given by FSDO to log in application @ <S> IACRA website <S> https://iacra.faa.gov/IACRA/Default.aspx when visiting take your IACRA credentials with you + logbook + license and medical certification During the meeting at FAA-FSDO you are required to complete your application in front of the FAA inspector and electronically sign (that's why you need your credentials) and prove your Logbook registrered hours as well <S> show original Medical certificate and License, FAA will aslo verify your English knowledge ,in my case a nice conversation about general subjects with the two FAA gentlemen I had in front of me <S> You will finally be issued a Temporary permit valid 120days <S> Your definitive "restricted" FAA License will be delivered to your home address within 90days <A> I suggest you to double check the information that "EASA License will be valid limited for flights in Italy". <S> Is that specifically mandated by the FAA? <S> Here in Italy is absolutely commonplace to have D and G registered aircrafts and fly them, also internationally, with EASA or Italian licenses.
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Your license will give you a permit to fly an N aircraft only where your original License is considered valid (Europe) and according to ratings and limitations of your original license
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How much weight does a thrust reverser add? How much weight does a thrust reverser add to an engine? Let's take the CFM Leap 1B as an example, which powers the new version of the Boeing 737. This engine can produce up to 130 kN of thrust for takeoff, and has a dry weight of 2.78 tons. I could not find how much weight is the thrust reverser system. Closest thing I found was this FlightGlobal article which at least talks about it, but doesn't give numbers. One purpose of this question is to compare it to old-school drag chute system. I will open a separate question on that. <Q> For the LEAP-1B example, the weight you found is a dry weight that does not include the reverse system per the type certificate . <S> Such weights are very hard to come by, even from the respective system manufacturer. <S> However, statistical data can help. <S> [Studies] conducted by General Electric Aircraft Engines indicate that the thrust reverser system accounts for more than 30 percent of the nacelle weight (not including engine) for an engine having a fan diameter in excess of 100 inches. <S> This could be as much as 1500 lb [680 kg] for a GE 90 class engine. <S> As for the nacelle, an older NASA paper says the weight is in direct relation to its surface area constructed from simple cylinders. <S> [For the nacelle, the surface] area is used to correlate weight, and, rather than introduce the complexity of the actual nonaxisymmetric shape of the nacelle, simple cylinders are assumed, using the fan diameter, the turbine diameter, and the lengths from the previous section. <S> [And] a unit weight of 17.1 t <S> o 19.6 kg/m2 appears reasonable. <S> From the same paper, here are some examples for the weight of the reverse systems of different engines: <S> Since the CF6 days manufacturers were able to reduce the weight of the nacelle and its components due to the " extensive use of composite materials ." <A> Chapter 6.6.1 deals with thrust reversers, and mentions that the weight is considerable: between 15 and 20% of the bare engine weight, with the higher region being for high bypass engines like the Leap <S> 1B. Wikipedia lists the weight of the 1B as 2,780 kg. <S> If we take the mid region of percentage due to improved technology since the book was written, the resulting guesstimate for the weight of the 1B thrust reverser is 0.18 * 2780 = around 500 kg. <S> Plausible if we consider the complexity of the system. <S> The book also mentions an alternative means of thrust reversal for turbofans, the same one as used for turboprops: fan pitch adjustment, developed by the Dowty Rotol company early enough to be mentioned by the book. <S> This mechanism weighs about half of that of the thrust reverser, amounting to about 250 kg, and has of course the advantage of being able to optimise blade pitch during cruise and take-off. <S> Rolls Royce has announced plans for adjustable fan pitch for the next generation engines. <A> It obviously depends on the engine and airframe involved. <S> For example, in case of Hawker 700, the aircraft with thrust reversers , ... has 248 pounds less useful load than a Hawker without reversers. <S> As the Honeywell TFE731 used in the Hawker weighs around 734 lb, this works out to about 17% of the engine dry weight. <S> The thrust reversers seem to be classified as a structural component . <S> In case of present generation high-bypass turbofans, this value will be on the higher side due to various other factors like acoustic liners for meeting noise requirements (which the TFE31 doesn't). <S> So, 15-20% appears to be extra weight due to the thrust reversers.
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According to NASA , the reverse system of a GE90 class engine can weigh upwards of 30% of the nacelle weight. The detailed weight of the components of the Leap 1B are elusive to find at the moment. There is statistical data available in pre-design books, such as Synthesis of Sub-Sonic Airplane Design by E. Torenbeek.
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Why has Boeing used mini winglets on the 737-200? I found mini winglets just in B 737-200. What's the differences between mini winglets and the blended ones which Boeing uses in more recent versions?(picture source ) <Q> When originally Richard Whitcomb of NASA developed the winglets, he developed the split winglets with one above and one below as shows in image below: The one above starts at 0.4x chord from the leading edge. <S> For a test program on KC-135 tanker, which I suppose was first application of the winglets, they used the type of winglets shown in the question: <S> Conceptually there is no difference in the "mini-winglets" and the "Blended winglets" <S> While I think almost all the wingtip shapes are more or less of same efficacy, I can think of couple of reasons for variations seen among various aircrafts - One is patents taken for some shapes would force other OEMs to come up with different shapes. <S> Second is weight of the wingtip vis-à-vis the reduction in fuel burn. <S> Typically winglets reduce fuel burn by ~3-8% but in some cases, the increased weight can off-set majority of the fuel burn or even prove to be more than compensating for it, especially on shorter hauls. <S> I think it would be difficult to say make any generalised comment on this. <A> Adding winglets to an existing design puts stresses on the existing spar ends that they weren't designed for. <S> Fortunately, they're stronger than may be necessary at the ends due to mechanical implementation requirements, allowing some additional load. <S> But a "full size" blended winglet should be designed in from the start to ensure sufficient strength, minimal weight and avoidance of aeroelasticity (flutter). <A> Boeing 737-200s are comparatively old and the winglets developed for them are not by Boeing, but by a third party, as noted by b737.org.uk : ... <S> 737-200..., fitted with mini-winglets. <S> This is part of the Quiet Wing Corp flap modification kit which gained its FAA certification in 2005. <S> The other types of winglets in B737s- blended wing winglets in 737-800s, the AT winglets in 737 MAX and Split Scimitar in NG 737 (through there is some overlap here) were all developed by Boeing (with others) and are available from production units and also as retrofit.
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One may be able to make a lighter blended winglet using co-bonded, co-cured composite structure as compared to the short winglet mentioned in the picture which with say bolted joints might end up heavier.
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What's the precise meaning of "landing south (north, east, west)" in STARs? "JetBlue six zero two leaving flight level two one zero descending via the Ivane Two arrival landing south." Does "landing south" here mean the aircraft will be landing on the runways north to south? <Q> Depending on conditions, they could come from the opposite end of the runway, and would be "landing north. <S> " This is also referred to as "south flow/operations." <S> If you look at a chart for the IVANE FIVE shown below, you can see why this is important. <S> The runways at KCLT are primarly oriented north/south. <S> The aircraft will enter the approach at MAJIC from the northeast. <S> If landing south, the arriving airplane will fly IVANE BABZE HEELZ and needs to be at 6000 feet when they reach HEELZ north of the airport. <S> Approach control will then turn them south to land. <S> If landing north, they will fly from IVANE to GIZMO and follow the approach down to the south, and don't have to be at 6000 until they get down to ESENE. <S> After reaching JATAB approach turns them north to land. <S> Telling the pilots which direction they will be landing lets them know which route to follow on the approach and helps them plan their descent. <S> If approach hasn't provided a runway yet, they can also know which runways they can plan for. <S> Source . <S> This is the best I could find for the IVANE arrival. <S> The MAJIC ONE isn't RNAV, the CHSLY THREE would seem to be the applicable RNAV procedure from the northeast. <A> Landing south means that they will be using a southerly heading runway. <S> I.e. landing on rwy 18 rather than 36. <S> The landing directions will be indicated on the STAR. <S> For example the chart below for Charlotte. <S> Depending on which runways are in use the flight will take a different branch of the STAR. <S> Since they aren't given a specific runway assignment yet they will report in with the general direction they expect to be landing. <S> They are usually given this by the en route controller. <S> If not the ATIS will tell them what runways are in use. <S> If the northbound runways (36L/R/C and 5) are in use, they are "landing north" so when they reach waypoint MANGY they will turn left to a heading of 273° and expect the controller to give them vectors after GATEE waypoint. <S> If the southbound runways are in use they will be "landing south" and will continue on the STAR until INNOR wp. <S> This lets the controller know what they should expect the aircraft to do until they are told differently. <S> Usually when they check in they will be given a specific runway assignment, but it's possible the controller won't have a specific runway yet, so they will follow the correct branch of the STAR until they are given that assignment. <S> That's why they have the general "landing north" or "landing south" designations. <S> In this example, if they are landing south they need to have a specific runway assigned by the time they reach INNOR because they must either turn right toward rwy 23 or continue straight toward rwys 18L/R/C. <S> It is possible, due to a shift in wind or noise abatement change, the airport could have changed directions (or the en route controller could have given them incorrect info). <S> That's why they must tell the controller at check in which direction they are going to go. <A> One arrival may have multiple routings after a branch point, and when ATC assigns the arrival and the descend-via clearance, they have to specify which branch is to be flown. <S> As an over-simplified example, let's say that the arrival starts at AAA, then flies east toward the airport to points BBB and CCC, which is the branch point. <S> When the airport is landing to the south, aircraft turn north (i.e. onto a downwind leg) and proceed to point NNN and OOO, and then a vector toward the (southbound) final approach course. <S> When the airport is landing to the north, after CCC the arrival would have the aircraft turn south (again, onto a downwind leg) and fly to point SSS and TTT, and then a vector toward the (northbound) final. <S> Each of these points might have an associated altitude and/or airspeed, and the clearance to "descend via the ___ arrival landing north" and "... <S> landing south" tells the pilot which set of points (AAA-BBB-CCC-SSS-TTT-vector, in the "landing north" case, or AAA-BBB-CCC-NNN-OOO-vector in the "landing south" case) he's cleared to fly, along with their associated speeds/altitudes.
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"Landing south" means the planes are facing south as they land.
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Explain how the infrared flame detector work? For fire detection systems, such as for engine fire detection, how does the infrared flame detector work? <Q> When a flame ignites the various types of materials burn at different strengths, intensities, and <S> -what we care about- wavelengths. <S> In the visible spectrum we can describe a flame as red or blue which can be simplified flames discrete wavelengths. <S> The IR sensor can detect the wavelengths given off outside that visible light spectrum. <S> This helps eliminate sources like a technicians flashlight from setting off a pure visible optical sensor. <S> An example from Wikipedia shows a distribution of this emission. ! <S> Fire spectrum <A> There a several types of IR sensors. <S> The simplest measure a point and radiometrically read the object temperature. <S> Other sensors like room occupancy sensors read the ambient temperature but don't care about the ambient temperature. <S> Rather they have lenses which create a series of apertures which interrupt the sensing as a warm body moves around the sensor field of view. <S> That interruption rate range is thresholded to sense the expected periodicity of the event (eg a human moving in a room). <S> Both types are employed in aircraft fire detection and in some other systems like gensets. <S> If there is a particular sensor model of interest, the manufacturer specs on that sensor will tell you if it employs a lens to detect motion. <S> A third variant is to sense the ambient in an area with one wide view sensor and use a second sensor to read a localized temperature in an area of interest. <S> If the sensed differential exceeds a threshold then the sensor system shows a triggered event. <S> Fire detection methods such as ionization measurement don't work well in aircraft applications as they are suspectable to airflows changing concentrations and therefore the sensing threshold. <A> Flame Detectors Optical sensors, often referred to as flame detectors, are designed to alarm when they detect the presence of prominent, specific radiation emissions from hydrocarbon flames. <S> The two types of optical sensors available are infrared (IR) and ultraviolet (UV), based on the specific emission wavelengths that they are designed to detect. <S> IR-based optical flame detectors are used primarily on light turboprop aircraft and helicopter engines. <S> These sensors have proven to be very dependable and economical for these applications. <S> When radiation emitted by the fire crosses the airspace between the fire and the detector, it impinges on the detector front face and window. <S> The window allows a broad spectrum of radiation to pass into the detector where it strikes the sensing device filter. <S> The filter allows only radiation in a tight waveband centered on 4.3 micrometers in the IR band to pass on to the radiation-sensitive surface of the sensing device. <S> The radiation striking the sensing device minutely raises its temperature causing small thermoelectric voltages to be generated. <S> These voltages are fed to an amplifier whose output is connected to various analytical electronic processing circuits. <S> The processing electronics are tailored exactly to the time signature of all known hydrocarbon flame sources and ignores false alarm sources, such as incandescent lights and sunlight. <S> Alarm sensitivity level is accurately controlled by a digital circuit. <S> [Figure 17-9] Source: Aviation Maintenance Technician Handbook - Airframe - Chapter 17: Fire Protection Systems <S> (FAA)
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Infared flame detectors have an imaging sensor that "sees" infared light.
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Why aren't there any single turbofan airliner? A configuration which looks like a DC-10 , without engines mounted under the wings. Let's say 737 sized. Let's forget about redundancy security advantages of twin or quad engines, since they're obvious and not my concern about this particular question. One single engine is more efficient than two similar engines. Efficiency multiplies, two engines are less efficient, four even worse. Center of gravity problem doesn't exist since wings can be moved backward.(of course yaw stability will be corrected inherently) Modern turbofans family can provide a single stock powerful enough version to fly a 737 class size. In the event that debris is released from the engine, one canard configuration may be designed, in order to prevent hydraulic failure and loss of control. To summarize, are there (except redundancy safety concerns) any reason why there are no single turbofan airliners? <Q> Airliner designs must be certified in order to fly commercial services. <S> In the US, this means compliance with the Code of Federal Regulations, Title 14, Subchapter C, Part 25 . <S> In §25.901(c) <S> it says: <S> For each powerplant and auxiliary power unit installation, it must be established that no single failure or malfunction or probable combination of failures will jeopardize the safe operation of the airplane except that the failure of structural elements need not be considered if the probability of such failure is extremely remote. <S> It's the same for fuel pumps, instruments or even wheels: Every one has a second unit which can take over if the first fails. <S> For wheels, this is very easy to check: You will not find a single airliner landing gear leg which has only one wheel. <S> All have two wheels or more . <S> Or pilots: The minimum number of pilots for safe operation is two. <S> One can fly the plane (so she/he can land it if the other pilot is incapacitated), but two are needed to start any revenue flight. <S> I could continue that list, but I guess the concept has become clear: For every element on an airliner there needs to be a second, redundant one, except for structural elements with a very remote probability of failure. <S> This has been learned the hard way: Some of the first aircraft designed for passenger service (like the Junkers F-13 or the Fokker F.II ) had a single engine. <S> Some of the multi-engined ones even became dangerous death traps when one engine failed. <S> Military operators have fewer qualms about single engine designs , because using fewer engines improves performance and lowers acquisition and operation cost. <A> There is an aircraft with a single engine in the middle of fuselage- <S> the Northrop Grumman RQ-4 Global Hawk - <S> and it has the wingspan of a 737. <S> Global Hawk and B737; image from reddit. <S> For the engine to power an airliner the size of 737, it would have to be more powerful and huge. <S> This leads to a few issues: <S> It is going to eat up cabin space. <S> In an age where airlines are finding creative ways to squeeze more people into the available space, this is a no-go. <S> The large engine means that there should be sufficient clearance between the engine and the fuselage- else, it would result in more drag and reduced thrust, thereby reducing efficiency. <S> Increasing clearance is quite difficult for fuselage mounted high bypass engine due to weight implications. <S> Passengers in rear seats may not have a pleasant journey due to engine noise. <S> Mounting the engine in rear incurs weight penalty through various ways- <S> you have to strengthen the rear fuselage and at the same time, you lose wing bending relief, requiring strengthening <S> and you have cg issues. <S> Mounting engines above the fuselage is a not maintenance friendly either. <S> Just to note, redundancy and safety are significant issues, especially in a commercial airliner. <A> This question explains with pros and cons of dual vs single engine. <S> I think that the main reason is additional safety that comes from redundancy. <S> Apart from that an airliner has much more people on board, an airliner with its the only engine failed would be much more dangerous for the people on the ground than some tiny single engine aircraft. <A> There are a number of problems I can think of if an airliner the size of a Boeing 737 has a single turbofan engine: <S> Insufficient thrust. <S> The engine must now produce twice the power. <S> Unbalanced Center of Gravity. <S> The tail-heavy configuration would make tail strike (both during ground operations and takeoff / landing) must more likely. <S> Also, the effects of the elevator would be greatly reduced. <S> Lack of redundancy. <S> Even before ETOPS, airliners need at least 3 engines to fly oceanic routes. <S> Loss of critical controls in the event of an un-contained engine failure. <S> Many critical components, such as hydraulics, elevator and rudder, are located near the tail. <S> In the event that debris is released from the engine, there is a high chance that these components will be damaged, rendering the plane uncontrollable.
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Engines do fail from time to time, so there must be a second unit which can take over if one fails. Over time, the desire to increase safety made redundancy the supreme design principle for airliners.
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How can I get back up into flying after not flying for over 20 years? I'm a former USAF pilot and former Bonanza owner. Haven't flown private in more than 20 years, but looking to get back into it. A friend who owns a 182 and will fly with me and I know some instructors. I don't even know where my old certificate and log book is, so this is really starting from scratch. What steps do you recommend? <Q> I do not have a sanctioned answer, but I can give you my take on an overview of what I would plan for someone in your situation. <S> Your certificate duplicate can be ordered. <S> You will need a through review of airspace (things have changed), weather gathering (also changed), AIM stuff (changed runway markings, phraseology, etc.). <S> I would urge FAAST courses for various topics you might feel you can get brushed up in. <S> On the air side, if we were flying, we would do a "checkout" in the 182, covering the systems, cowl flap operation, targeted power settings, trim usage, etc. <S> A little airwork, steep turns, turning to headings, power on and off stall recoveries, emergency procedures and landings, takeoffs and go arounds. <S> Everyone is different, but the last guy, similar to you, flew C208 and stopped in 2003, and did not fly since then. <S> This summer he hit the books, watched a few videos, took a practice commercial written, and flew 3.4 hours with me. <S> I was real comfortable signing him off, and his wife, who was the concerned party, was real happy with the results. <S> Two months later we did a instrument proficiency ride, and that was a little more difficult for him, but he completed the ride in two flights and less than 4 hours. <S> Good luck and enjoy. <S> Have your instructor put a new high performance endorsement in your new logbook for the 182. <A> As long as you hold at least an FAA PPL, it should be fairly easy. <S> As a former military pilot you could easily obtain an FAA CPL in the category and class of aircraft you flew in the USAF per §61.73. <S> After that, it’s just a matter of regaining currency. <S> You will have to undergo a flight review with a CFI and receive a logbook endorsement per §61.56 plus an Instrument Proficiency Check, if you intend to fly under IFR, as required by §91.1069 and §61.157. <S> It may take a few flights with an instructor, but it will all come back to you sooner or later. <S> I would recommend reviewing your training literature you have from the USAF or obtain copies of the FAA’s <S> Airplane Flying Handbook, <S> The Pilot’s Handbook of Aeronautical Knowledge, The Instrument Flying Handbook, and The Instrument Procedures available to you for self study. <S> I would also recommend that you obtain the latest copy of the FAR/AIM for 2018 and keep that on hand for reference during these flight reviews. <S> I’d guess the same kind of inquiry could be made with the USAF for your pilot qualifications with them. <S> Oh and one other thing: did you obtain a military logbook or a civilian rating just prior to giving up flying? <S> You may see if you can obtain the paperwork from the FAA which you filed for these ratings. <S> These days everything in done on the FAA’s Integrated Airman Certification and Rating Application (IACRA) database, but any Aeronautical experience you file for application for a rating can be used as an official documentation of logged flight times. <S> I’d check on that to rebuild your logbook on. <A> You said you used to own a Bonanza <S> so I'll assume you already hold an FAA private certificate (at least). <S> Your options are: Apply for a regular third-class medical. <S> If you're in good health that should be straightforward, but if you have any health concerns then it would be worth talking to AOPA or an AME before you actually apply for the medical examination. <S> If you held any valid FAA medical between July 15, 2006 and July 15, 2016 then you could fly without a medical under BasicMed . <S> AOPA has a lot of detailed information on it that's worth checking out (and see this question ). <S> (You don't need a medical for gliders or ultralights either.) <S> You mentioned a 182 <S> so I guess you don't plan to go this route, but it's worth including for completeness. <A> You may also need to obtain a new Pilot License. <S> A rule change went into effect in 2006, that by 2010 all pilots needed a plastic license, looks kind of like a credit card, with hologram on the front, mag stripe on the back, place to sign your name. <S> 2010 was extended to 2013. <S> Can request it at FAA.gov. <S> $2 for a duplicate, free if you want your license # changed from your SSN.
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Apart from the flight training that other answers have covered very nicely, you may need a new medical certificate. Fly a light-sport aircraft without any medical at all, using sport pilot privileges . If you don’t currently have access to your certificate, but know you possess one, contact the FAA and request an duplicate copy from them.
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What are the differences between FADEC and EEC systems? Can anyone differentiate FADEC and EEC system in an aircraft Engines? As I was working related to Engine controlling. I got confused of FADEC and EECs.As per some of the doc. I read like EECs are a part of FADEC. <Q> Kind of like the microprocessor in a digital computer. <S> From The Jet Engine by Rolls Royce, 5th edition: The EEC is dual redundant with all subs-systems such as sensors, cables etc duplicated, so that a single fail leaves the system fully operational. <S> It is housed either in the airframe, or like in civil airliners on the engine, leaving it in need of protection of extreme circumstances: Temperature - ice and tropical heat. <S> Electromagnetic radiation - lightning and airport radar Engine vibration <S> The FADEC monitors inputs such as: <S> Shaft speeds Engine temperatures Oil pressures <S> Actuator positions <S> Power setting <S> and then sets fuel flow, variable stator vanes, and air bleed valves. <A> UTC's product description might help here: <S> The system consists of an electronic engine control, along with other accessories that work together to optimize fuel management and engine performance during takeoff, flight and landing. <S> In addition, we provide prognostics and health management electronics that provide more engine diagnostics and prognostics, which can alert the operator to needed maintenance actions before they become an expensive and time-consuming problem. <S> Other technologies include advanced sensing systems <S> EEC or ECU is the main component of FADEC. <S> It controls the engine actuation system depending upon the situation and the commands received from cockpit. <S> It receives data from all the sensors, commands from cockpit. <S> It processes the data and figures out what control commands need to be given to the actuation system and then execute them. <S> While FADEC is an overarching system which includes EEC and some other components in it, such as sensors, health monitoring system etc. <S> I think, a FADEC typically contains more than one EEC/ECU for redundancy. <A> EEC is a supervisory system which controls engine parameters and operation to prevent parameter exceedance (temperature, RPM, etc.),and comes into operation at certain engine speeds. <S> It has a backup in case all the channels of EEC are lost. <S> FADEC is a full authority system, i.e. it controls engine operation and parameters at all speed regimes. <S> It has no backup system.
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The EEC is the Engine Electronic Controller, the digital processing heart of the Full Authority Digital Electronic Controller.
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How did the gyro gunsights of WW2 get the range and lead of a target? I just read this article on the gyro gunsight, but I don't understand how it computed range/position to the target and then calculated how much lead is needed. Surely it must have had radar to get range to the target? But I could only find one mention of radar in the article, and it only pertained to one particular model of the gyro gunsight. Even if so, I don't understand how a radar return is integrated with a gyro instrument. I understand that a gyro can tell you your roll angle and rate of turn in any or all axes, but the main thing I'm missing is how did it know range and position of the target? It seems only radar can do such a thing and I don't know how radar data could be integrated with a gyro way back in the 1940's. The wiki article even says that these gyro gunsights were developed "just before the Second World War". But I also noticed the article is not that well-cited. <Q> You are seriously over estimating the technical capabilities of the time. <S> The gun-sight is not much more than an intricate slide-rule. <S> The position of the projection is offset from the guns aiming point according to the gyro factors, the set range, and the fall rate of the ammo. <S> When the reticule circle lines up with the wingtips of the target you are at the right distance and angle to the target <S> and you push the trigger. <S> It assumes you are following the same flight pattern as the aircraft in front of you. <S> That is.. chasing it in a dog fight. <S> That makes it fairly limited in use and effectiveness and would be no replacement for a seasoned pilot. <S> Additional Reference Links: Aviators Database <S> Axis History Forum <S> Video: <S> Gyro Gunsight Mk <S> IID <S> CORRECTION: Upon watching the video <S> it is apparent that the implication that the aircraft must be following the same flight pattern as the target is misleading. <S> In reality the target reticule, and in effect the pilot's aircraft, needs to be turning at a rate to track the target's flight pattern. <S> Further, the range can be adjusted while continuing to track the target. <S> That all sounds a bit like rubbing your head while patting your tummy and I am sure took quite a bit of practice and an accommodating target that maintained a constant heading or turn rate in front of you. <A> Other answers here describe the functionality of such gunsights; the "calculation" was done by mechanical analog computer, made up of gears, cams, shafts, and linkages. <S> Here's part of a Sperry K-3 gunsight computer from a B-17 (inherited from my father, who liked collecting strange gadgets, now decorating my kitchen): <S> Additional information on the mechanical gunsights and bomb sights of the WWII era can be found here . <A> I don't understand how it computed range/position to the target and then calculated how much lead is needed. <S> Reading the Wikipedia article you linked, it didn't, but both assertions are unsourced. <S> The distance was estimated visually by the gunner through a visual aid: a reticle to match to a target plane's known wingspan (to adjust the sight for the target's distance) <S> i.e.: the gunner would know the target wingspan, and its size in the reticle at a given distance, the mismatch would allow the estimation of the distance. <S> The lead was based on gyro information (hence the instrument name): <S> It is important to note that the information presented to the pilot was of his own aircraft, that is <S> the deflection/lead calculated was based on his own bank-level, rate of turn, airspeed etc. <S> The assumption was that the flightpath was following the flightpath of the target aircraft, as in a dogfight, therefore the input data was close enough. <S> Personally, rather than "calculated" I expect that some sort of mechanical linkage was moving the floating reticle around based on the relative position of gyro and airplane. <S> The video found by Trevor confirms that this is the case. <S> Starting at 2:00 we are told that: given the range, the gyro corrects only for the rate of turn the pilot has to manually adjust the gyro correction for the range (at 4:15 we are told that the renge adjustment does not alter only the position of the reticule, <S> bu also its diameter, to reduce the errors deriving from manually estimating the range) <S> the pilot can also select the base size of the reticule to match the aircraft being chased (4:35) <S> The full procedure with the correct sequence of settings and adjustments is described starting at 5:42
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You had to feed it information about the target size/aircraft type and it used the gyro information from your own aircrafts turn rates to project a reticule circle on the glass.
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Is it normal practice to use 25 degrees of flaps when taking off at max weight in a PA-28-181? I recently started renting a plane ( PA-28-181 ) from a new flight school and had to get checked out before I had the "OK" to rent. I had brought 2 family members with me during my checkout because... They wanted to experience a small plane for the first time My intentions with the plane were to have the option to fly with a full load of passengers (which I couldn't do in the planes I was used to flying) so I wanted to experience what flying at max gross weight was like. During the checkout, while in the runup area going through my checklist, the instructor encouraged me to go back through my checklist. Eventually after hearing this suggestion multiple times and not understanding what he was hinting to, he came out and said "You need to set your flaps to 2 notches because we're at max weight". I hadn't heard this before and I'm not seeing a ton of discussions about this type of thing online. His point was, the flaps would increase lift since we're heavy - that makes sense to me... But they also increase drag. Note: this was not a short-field takeoff. 5,503ft paved runway, although it was hot (90+ degrees fahrenheit). So, this leaves me with 3 questions: Is this correct? When you're on the "heavy" end of the spectrum, should you be deploying flaps? If so, what would be the proper flap setting at max gross weight? Since, in this case, the point wasn't to clear an obstacle, would you simply climb out at Vy instead of Vx ? <Q> The PA-28-181 POH I have read says to set first stage of flap (10 degrees) for a normal takeoff, and 2 stages (25 degrees) for a short or soft field takeoff. <S> I've flown PA-28s quite a bit <S> and I've never heard any suggestion of using 25 degrees for a normal takeoff. <S> At maximum weight on a hot day at sea level 5,503ft should be plenty at 10 degrees, even if you are at 4000 ft pressure altitude it should still be sufficient, <S> so I see no reason to set 25 degrees. <S> An engine failure on takeoff with 25 degrees of flap will give you less time to get the nose down, and stall characteristics are harsher with more flap. <S> If the runway was shorter I would see 25 degrees as good advice. <S> There are plenty of light aircraft pilots who don't do performance calculations before they fly, drilling 25 degrees of flap when heavy into them may just save their bacon on a hot day on a short airfield. <A> I should preface this answer with 2 prudent points <S> My first flight of a PA-28 (Im unsure the exact model) was a week ago. <S> I have roughly 250 hrs on Cessna 150/152/172 <S> The answer to all of these sort of questions pretty much always comes down to " <S> What does the POH for this specific aircraft say?". <S> That is the authoritative source of information on operating the aircraft. <S> Another useful source of information on the safe operation of any aircraft is to ask, and seek instruction, from a competent flight instructor who is familiar with an aircraft. <S> So, there is a fairly good chance that the instructor doing your check ride just knew the aircraft performance well, the airfield well, and the prevailing conditions <S> well and was advising you based on their experience . <S> There is no substitute for experience! <S> That said, it's easy enough to find a reproduction of a PA28-181 POH online - you should of course consult the actual POH of the aircraft you are flying but the general handling procedures are usually the same. <S> The POH linked mentions for standard take off <S> The [trim] tab set just aft of neutral with the exact setting depending on the loading of the aircraft. <S> Allow the aircraft to accelerate to 48 to 53 KIAS depending on the weight of the aircraft and ease back on the control to rotate to climb attitude. <S> It goes on to mention a different procedure for short or softfield take off, or a takeoff with obstacle clearance <S> The flaps should be lowered to 25 o (second notch) [...] <S> So, no mention of flaps for a normal take off even at or near maximum weight. <S> Take from that what you will - but personally I would still be listening to the instructor! <A> I'd like to add to Jamiec's excellent answer. <S> The attached POH shows that the take-off distance with 25 degrees at maximum gross weight is a few hundred feet less than 0 degrees of flaps. <S> While the current runway may have been of sufficient length for a take-off with 0 degrees of flap, the instructor performing an insurance checkout for the FBO may have wanted to instill the importance of the 2nd notch of flaps for when the pilot rents the airplane on his own and flys out of shorter runways with a full load of passengers. <S> Apparently for an Piper Cherokee Archer II <S> the increase in drag of 25 degrees of flaps is more than offset by the increased lift allowing the aircraft to lift off sooner.
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Setting 25 degrees for takeoff increases lift at the cost of drag, and risk as you are closer to performance limits.
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Why does MAP show ambient pressure when engine is shut off? Manifold pressure is the absolute pressure at the intake manifold and increases as throttle is increased and vice versa. However, when the engines are shutoff, the manifold reads ambient pressure. My question is, why does it read ambient pressure when engines are shut off when the throttles at closed? <Q> The intake manifold is where the air flows from outside into the engine, so obviously it must be open to the outside. <S> So when everything is calm, the pressure quickly equalizes and the manifold pressure is equal to the ambient pressure. <S> The non-obvious thing is actually why it differs when the engine is running. <S> When the engine is running, it sucks air in. <S> The volume of air per unit of time is proportional to its rotational speed: higher RPM means more strokes per minute and each stroke has the same displacement. <S> Now without any restriction in the intake manifold, the air would still enter at the ambient pressure (speaking of normally aspirated engine). <S> And with fully open throttle, the restriction is small enough that the manifold pressure is indeed only a little below ambient. <S> It is only as you close the throttle that you create significant restriction, which reduces the manifold pressure. <S> But the reduction is still proportional to the engine RPM. <S> This dependence on the RPM also means that it is not actually good indicator of the power the engine produces. <S> When you increase RPM by adjusting the mixture, the engine power will increase—because it takes more power to sustain higher RPM—but the manifold pressure will decrease—because there is more suction. <S> The same also happens when you increase RPM by advancing propeller pitch selector. <S> What manifold pressure is good indicator of though, and the reason it exists, is the engine wear . <S> The amount of air, and fuel, are proportional to the manifold pressure, and therefore so is the peek pressure when the air is compressed and the fuel burnt. <S> And the higher the peek pressure, the more wear on the components. <S> That is why there is absolute maximum you should never exceed and continuous power limit that you should only exceed for limited time on take-off or in emergency. <S> Note that the relations are further complicated in turbocharged engines where higher engine RPM also mean higher turbocharger RPM and that increases the pressure gain on the turbocharger that adds to the manifold pressure. <A> Scenario 1: engine running slow Since there is always at least one piston going down and its valve open, this increases the volume of the manifold and reduces the pressure. <S> Since the throttle is almost closed, the pressure remains low and near vacuum (low MAP), i.e., outside air is not allowed to rush in freely. <S> Scenario 2: engine shut down With the engine shutdown <S> , there is no piston action and the pressure can stabilize with the ambient <S> (the throttle valve is not air tight, that's why you can have the engine running with the throttle pulled all the way back, different story for the mixture control). <A> Image source <S> Because the manifold is connected to the ambient air via the air intake. <S> The throttle does not hermetically seal against ambient pressure differential when closed, there is no design requirement for this condition. <S> The transducer measures pressure, not pressure differential.
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With engine not running there is no suction, so the pressure can't decrease and the gauge still shows ambient pressure.
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What is the maximum speed for regulation of sonic boom noise? If fuel cost and fuel efficiency were not the issue, what is the maximum speed (air speed and ground speed) that business jets or airliners could travel at without exceeding the maximum noise and sonic boom allowed or as regulated in the USA, Europe and the rest of the world. I need to know why there are no faster business jets and for business class airliners given that private and business fliers are prepared to pay a premium <Q> Business jets are developed to different rules than airliners. <S> The biggest difference is that, indeed, fuel price and fuel efficiency are not an issue when what counts are bragging rights for the fastest plane on the ramp. <S> Their speed has steadily increased and is now at Mach 0.935 for the fastest models. <S> Compare that to Mach 0.78 to 0.85 for regular airliners . <S> Since supersonic flight over land is heavily restricted, the fastest speed would be Mach 0.99. <A> True Air Speed limit is Mach 1. <S> Ground speed is not relevant to this question. <S> The reason there are currently no flying supersonic business aircraft is that designing and building an aircraft capable of supersonic flight is very expensive and technically challenging. <A> It is 0.99 Mach over land. <S> I don't see any restrictions over the ocean. <S> Based on the top answer to this aviation SE question , I think if you can design a more stealthy hypersonic transport aircraft and fly it at high enough altitudes in the stratosphere, you may minimize the sonic boom to the extent that it is a non-issue. <S> The NASA graph in the answer shows that the XR-71 has an insignificant sonic boom when cruising at 60,000 ft MSL compared to the Concord SST. <S> Ram-jet technology would eliminate the need for the turbine compressor used on current jet engines thus allowing the aircraft to be quieter and more streamlined and stealthier.
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Supersonic business jets were proposed several times in the last decades, but so far nobody has risked to spend the money it needs to bring one design to a type certificate.
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Has there ever been a seaplane with inflatable airbags rather than traditional pontoons? Traditional pontoons are big and cause a lot of drag. It would be nice to retract them like normal landing gear but they are just too big. Has there ever been a seaplane with inflatable airbags instead? They way I imagine it is a lot like normal landing gear, with lowering struts from the wings or belly. But instead of wheels, it has a wound-up airbag that's unrolled and inflated. I think this would save a lot of drag and weight, and I'm a little surprised that this apparently doesn't exist over the 114 years or so of airplane history. Is there something unfeasible about this concept? I suppose getting propeller clearance over the water is the biggest concern, but I would think slightly long legs on the landing gear would be sufficient and well worth it to save all that weight and drag from those big pontoons. Edit: This is for the really small planes. <Q> I would think the stresses would be fairly high <S> and I dont know of any off the bat <S> but there have been helicopters outfitted with them . <S> ( source ) <S> On the drag front, this is only really a problem for smaller sea planes (C172, Caravan etc.). <S> On the large side of things when you want to reduce drag a belly land design is used like in a Grumman G-21 or even as far as the worlds largest airplane the Hughes H-4 Hercules . <A> The Goodyear Inflatoplane was used with a hydroskid <S> so technically one can say that there has been at least one plane with inflatable floats. <S> There also several ultralights that use soft floats, too. <A> The basis for the idea was that supersonic fighters were bigger and heavier than all previous fighters, and the US Navy was worried that the carriers would be too short for safe takeoffs and landings. <S> With a seaplane there was no such worry; the aircraft could simply be lowered into the sea, turn into the wind and take off, and be hoisted back onto the carrier after it had landed. <A> The stresses on an inflatable float at take-off and landing would probably have been too high for the materials of the 1920s and 1930s, when seaplanes and flying boats were economically and militarily important. <S> Another approach was invented by the Blackburn Aircraft Company in the UK: a retractable float. <S> Their B-20 experimental flying boat avoided having the deep hull that would have been necessary for propeller clearance by being able to lower its whole underside a few feet. <S> This did actually work, and the aircraft's crash was due to an unrelated flutter problem. <A> Bell did some experiments with a hovercraft setup on a Lake LA-4. <S> https://goo.gl/images/uVUFfA
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If you do a Google image search for "Bell Aerosystems air cushion undercarriage", you'll see pictures of it, as well as a DHC Buffalo and a Soviet attempt. There was an attempt made during the 1950s to build a sea-plane fighter jet with retractable water skis (the Convair F2Y Sea Dart ).
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Can the Apache detect infrared (IR) lock? Can the Apache, regardless if it's the AH-64E/D (US) or AH1 Longbow (UK), detect IR lock? I am aware that the Wildcat AH1, Merlin HC3/4 and AH1 Longbow share the same defensive systems that can detect IR missile launch. However, I have yet to find any information suggesting any of these aircraft can detect an IR lock from a fire control system of another aircraft. <Q> I think I have answered my own question from a little bit of research. <S> Warfare systems such as Laser and Radar are detectable because they are active emissions <S> (i.e. They have to make their own emission, wait for it to reflect back, then lock onto it). <S> Visual and Infrared are not easily detectable because they are passive. <A> No. <S> IR threat warning systems detect the energy from the missile. <A> The CMWS can be used in concert with systems like the AN <S> /ALQ-212 <S> to actively jam incoming infrared missiles. <S> Googling for "Apache missile warning" seems to indicate those units are in widespread consideration or use.
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The IR Launcher or TV-Guided missile only requires the targets emission to lock onto, not its own in the example above, so there is no way you can detect being locked onto. It took me a little Googling, but I found one: the Netherlands intends to equip their AH-64Ds with the AN/AAR-57A(V)7 Common Missile Warning System , a system that's capable of detecting infrared missile launches.
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What were the safety recommendations following the Aeroperú Flight 603 crash? I just watched the Mayday Air Crash Investigation about Aeroperú Flight 603 and two questions that weren't answered are: Who was responsible What caused the ATC to relay false altitude information to the pilots Has anything changed since then to prevent that from happening again? <Q> who was responsible for ATC relaying false altitude information to the pilots Not an easy question mostly because it asks (even if not directly) to put the blame on someone. <S> And although there is not an explicit rule for not doing this, I prefer avoiding it in respect to the dead and the ATCOs doing their job as good as they can. <S> I will focus on the reason behind the "false reports" and not the responsibilities . <S> The RADAR system the ATCOs use relies on aircraft systems for two things: one is to identify the flight (Mode A) and the other is to get its altitude in hundreds of feet (Mode C). <S> Now if you recall what happened, the static ports were duct taped for some routine cleaning of the fuselage and were not removed. <S> This affected the airplane's altitude indicator and consequently the altitude transmitted by Mode C . <S> So the ATCO was reporting back to the plane the same erroneous altitude the pilots were seeing in the cockpit. <S> has anything changed since then to prevent that from happening again? <S> I don't know if there was any action taken after the accident <S> but I think that there wasn't anyone needed: there is regulation (need to make some research to find it) which specifies that all "foreign" parts attached to a plane for protecting its vital parts should have a prominent red "REMOVE BEFORE FLIGHT" ribbon. <S> The duct tape was of silver non reflective color (if I recall correctly) and had no ribbons. <S> When the crew inspected the plane at night with flashlights they couldn't spot them. <A> What caused the ATC to pass incorrect information to the flight crew was that they had no reason to mistrust their own instruments. <S> The altitude information displayed to the controller was transmitted from the aircraft itself, and at the time the controller was no more aware of the issue on board the aircraft than the flight crew were. <S> The NTSB, although not the investigating authority did produce a short report which noted that: Section 12-25-01 of the Boeing 757 Maintenance Manual contains the instruction for cleaning and polishing the airplane. <S> When preparing the airplane for cleaning and polishing, maintenance personnel are instructed to prepare the airplane by taping moisture-resistant paper over the static ports to prevent the entry of any contaminant The safety advice which came from this was: <S> Ultimately the crash was caused by failure of the maintenance crew to remove the static port tape, failure of the flight crew to spot this defect on inspection. <S> (The following quotes are from here ). <S> It can be deduced from the investigation carried out that the maintenance staff did not remove the protective adhesive tape from the static ports. <S> This tape was not detected during the various phases of the aircraft's release to the line mechanic, its transfer to the passenger boarding apron and, lastly, the inspection by the crew responsible for the flight (the walk-around or pre-flight check), which was carried out by the pilot-in-command Together with failure of the flight crew to respond appropriately to the ground proximity warning system. <S> The pilot-in-command [...] made a personal error by not complying with the procedure for GPWS alarms and not noticing the readings of the radio altimeters in order to discard everything which he believed to be fictitious <S> And furthermore The co-pilot [...] made a personal error by not being more insistent, assertive and convincing in alerting the pilot-in-command much more emphatically to the ground proximity alarms. <A> I believe that for point 1 that both ATC and pilot assumed the height information on the ATC radar display came from radar trigonometry and not the reply of the transponder. <S> Neither was at fault here and this is more likely due to bad training on both sides. <S> If either had realized where the altitude information came from then the mode C transponder would have been deactivated and if the radar station tracking them was equipped with <S> to do altitude triangulation then the ATC could have provided better altitude information. <S> Incidentally with GPS being more common nowadays it can serve as a backup altitude indicator.
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Immediately review and amend, as necessary, all airplane maintenance manuals to require operators to use only standardized, highly conspicuous covers with warning flags attached in any situation in which static ports would need to be covered.
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How does 220 kN of engine thrust create the 700 kN required to maintain the altitude of an A320? On the Airbus A320, the two engines produce about 220 kN in cruise, whose weight is about 700 kN (about 70 tons). The lift / drag ratio in cruise is about 15 (likely higher), meaning in cruise lift = 700 kN and drag = 47 kN (or less). What is the accurate explanation of the figures above? How does 220 kN of thrust create the 700 kN required to maintain altitude and the 47 kN required to maintain speed? <Q> The engines only need to overcome the induced drag to remain in the air, which is a result of the lift but usually much smaller on the order of 1/20 for a modern jet. <S> This ratio is specified as lift to drag or L/D. <S> It is a vital performance statistic of an aircraft. <S> Why? <S> Wings are weird and complicated, there is not a simple 100% correct answer. <S> Only a rocket needs thrust equaling gravitational force since it has no wings! <S> (L/D = 1/1) <A> the two engines produce about 220 kN in cruise <S> A single A320 engine ( V2527-A5 ) produces 120 kN at SLC (sea level conditions). <S> Both will be 240 kN. <S> In cruise it will be much less thrust. <S> 25% of that as a ballpark figure. <S> A solid example: The CF6-80C2B1F of a 747 produces 57,160 lbf at SLC, and 12,820 in cruise (22% of SLC). <S> The thrust is much lower in cruise (less air, less thrust). <S> Except if the flight is too slow with a high nose up <S> then some of the thrust counters the weight, but for all intents and purposes, assume they are the same and you won't be wrong. <S> L/D is not a fixed value too. <S> It changes with speed. <S> At low altitudes the drag is higher (denser air). <S> In cruise the true airspeed is higher. <S> Lift depends on the true, and not the indicated, airspeed. <S> That's how less thrust can do more lift up there where the air is thin and the plane can reach fast true airspeeds. <S> The form of velocity applicable to the lift equation is the true airspeed . <S> True airspeed is defined as the actual speed of the aircraft through the air and includes corrections for density, compresibility, and instrumentation error. <S> The main issue: <S> The pulley system (now removed from question) is a one-body problem, an airplane is a two-body problem (airplane and air). <S> The air does the lifting. <A> I can't produce any equations, but the forward motion is what creates the lift. <S> If you had a completely drag-free glider and no wind it could stay in straight flight forever with all forces in balance. <S> Gravity counters lift. <S> And no drag, so no thrust. <S> The reason it must eventually come down is because the drag force slows it down. <S> Less speed equals less lift. <S> In a powered plane the thrust simply needs to balance against the drag. <S> Then all forces are in balance again, so the only force the engines need to balance is the drag force.
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In any straight-and-level flight regardless of altitude, thrust = drag.
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What is the smallest manned aircraft with four engines? What is the smallest (by operating empty mass ) quad-engine aircraft that satisfies these conditions? Current or past airplane aircraft with fixed wings, not a rotorcraft, not a lighter than air, etc 4 engines, pistons or turbines fuel as a main source for propulsion actual aircraft, not scaled model piloted by a pilot or a crew used for an actual military or scientific goal or business (not for design tests only). Added to prevent flying suits to be proposed: Need to takeoff and land under its own power. Not a worn wing (flying suit), the aircraft must have a flight deck where the pilot can be. If this one had been piston or turbine, it would be a good candidate: ... but it's an electric-powered aircraft. <Q> I present you <S> Yves Rossy's Jet wingpack , which satisfies your conditions (I know I'm pushing it, but couldn't resist). <S> Yves Rossy's Jet wingpack, By Rama <S> - Own work, CC BY-SA 2.0 fr , <S> Link <S> It is certified by FAA as an aircraft , powered by four Jetcat P400 turbojets, piloted by an individual, not a rotorcraft and used in show business. <S> According to the official site , it weighs 150 kg. <S> @ymb1's logic is correct. <S> To get to lightweight four engined aircraft with, you have to go back when the engines were not powerful enough for large aircraft. <S> Sikorsky Ilya Muromets, By www.cultinfo.ru, Public Domain, Link <S> The Ilya Muromets Type S-23 V is reported to have an OEW of around 3700 kg, powered by four Sunbeam Crusader engines. <S> Its predecessor, the Sikorsky Russky Vityaz , was still lighter, though it never saw service in numbers, sadly. <S> Of course they are not autonomous as per your requirement. <S> Why would you want a manned autonomous aircraft anyway? <A> The Short Scion Senior flying boat was powered by four 88 hp radial engines and its weight, empty, was 3,650 lb (1,637 kg). <A> I present to you a light giant (you asked for OEW). <S> One of the major reasons to have 4+ engines <S> * is if the engines are weak, and the plane is big. <S> Therefore one of the lightest will be an early 20th century giant. <S> Jets are out of the question since they are inherently heavier and most (if not all) are all-metal. <S> From the Wikipedia Category:Four-engined_aircraft , the only two planes under push configuration are both experimental. <S> That leaves us with the push/pull configuration if we are after light planes (common nacelle, fewer stress points, etc.). <S> The lightest (but not smallest) <S> I found and hence nominate is the Gotha WD.27 at an empty weight of 4,500 kg and powered by four 160 h.p. <S> Mercedes D III 's driving 4 propellers (each two in push/pull). <S> It weighs as much as 5 Cessna 182's, after all it has 4 (old and heavy) engines. <S> I doubt we can find any 4-engined fuel powered airplane under 4 tonnes (c. 1913 <S> it was possible, see comment by PK ). <S> And piston engines aren't easily miniaturized (dang it, see xxavier's answer ). <S> ( Source ) <S> Just look at it, it's nothing but a giant wing with 4 engines and two floats. <S> Reportedly 3 were built for the military for sea patrol. <S> There is not much information about it online. <S> An aircraft encyclopedia I have doesn't say much about it either, only confirms 3 were built. <S> (The smaller cousin, the WD.22 , was a prototype at 3,800 kg .) <S> * I didn't say 3+ because 3 can be a workaround for the era pre-ETOPS. <S> There's the beautiful Dornier Do 26 , but unfortunately it's over 10 tonnes. <A> The 1800 lb “Bally Bomber” is the smallest and lightest 4 engine, manned, conventional aircraft. <S> It is a 1/3 scale B-17. <A> Can I suggest the DH Heron, which first flew in 1950. <S> It was a development of the DH Dove, with a lengthened fuselage and 4 engines. <S> This (according to Wikipedia) weighed in at 3700kg. <S> DH Heron . <A> Smallest commercial jet with 4 turbines is probably the BAe 146-100. <S> https://en.wikipedia.org/wiki/British_Aerospace_146
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So, I present you the Sikorsky Ilya Muromets , the World's first four engined bomber.
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In the rare event that the U.S. DOD shuts off the GPS, what's the alternative? In the U.S., the Department of Defense along with other Federal Agencies of the Government operates & maintains the GPS . In the rarest of the events, if for any reason whatsoever, the Government decides to shut off GPS provisioning (even temporarily), what are the consequences/alternatives for the aviation industry? What percentage of the industry solely relies on The GPS to operate? What percentage of the industry has enough alternative navigation means to continue operation regardless The GPS? On a broader spectrum, I'm also curious about the aviation industry's reliance on GNSS and what could happen in cases of global disaster, wars, cyber-wars etc. (all of which are not impossible). <Q> If the GPS is unavailable, it will be quite an impact to the aviation industry. <S> All airliners in-flight will experience degraded RNAV performance, but they would make it to the destination using VORs, DMEs and ILSs. <S> For general aviation, things are not so lucky. <S> The GPS display provides an excellent situation awareness in small aircrafts; without it, navigation reverts to old school VFR and reading charts. <S> Most pilots will probably make it, but a few may get lost and end up in fuel exhaustion. <S> For airliners preparing for departure, initiating the INS is time consuming as the GPS coordinate is used as one of the startup parameters. <S> The coordinates of the gates can be looked up in airport charts, some airports also have signs which specify the GPS location; both of these take longer time. <S> Suddenly, pilots flying oceanic routes find out they need more planning for contingencies. <S> Some routes may be changed to fly VOR-to-VOR. <S> Departures around the world are going to be delayed, that is for sure. <S> Ground Proximity Warning Systems, which use GPS to determine the aircraft's location, are unable to use their terrain database to provide warnings to pilots, although warnings based on radar altimeters should still be available. <S> Basically, we are thrown back to the 80s or 90s, when GPS was not yet widely adapted. <S> Many of those navigation aids are still in use today, so the industry can still fly, but traffic capacity will be reduced. <A> There are going to be bigger issues. <S> The shipping industry is GPS reliant, the communications industry heavily relies on GPS time signals, Routing for trains, and so on. <S> The fact is that the chaos without GPS will extend far beyond aviation. <S> It will impact the network, the power grid, agriculture, mining, and so on. <S> In 1992, I had a team which proposed a smaller aircraft launched GPS system in LEO to handle such an emergency. <S> For the most part, receivers could use the LEO transmitters. <S> But if I were just worried about aircraft, then I would also have GLONASS, Galieo, and others integrated into the receivers. <S> I believe many receivers are currently configured to handle GPS and GLONASS concurrently, and employ WAAS, and the European, Japanese and Indian augmentation systems as well. <S> Things are changing, because I recently found a GPS/GLONASS receiver with WAAS and the other equivalents, with a USB interface, for $18. <S> Pretty amazing. <A> These can work with existing RNAV systems as well. <S> Other options for navigation from a failure of the GNSS service can include the following. <S> LORAN - still popular with maritime operations, LORAN is still a very accurate means of navigation. <S> Unfortunately aviation LORAN receivers fell out of favor with the advent of GPS. <S> Celestial Navigation systems - electronic sextants which can track known stars in the sky. <S> The systems can be combined with other INS and RNAV systems for improved performance and redundancy. <A> In the past, the US GPS system incorporated Selective Availability (SA), this ensured civilian users has less accurate positioning than the US military. <S> SA was switched off in 2000, and since 2007 , new GPS satellites do not have the option to switch on SA. <S> If the US military needs to degrade GPS service, it'll be done in a limited region . <S> Presumably that region will be a warzone, and will be closed to commercial and general aviation anyway. <S> If the US ever has to switch off the entire GPS system, WW3 has probably broken out. <S> Again, navigation won't be the biggest problem for commercial and general aviation in this scenario. <A> I am not sure about the current distribution in the market, but the value of other constellation owners like GLONASS or Galileo would suddenly increase. <S> Currently, due to wide usage of GNSS they aren't getting much traction. <S> In fact, the majority of cellphones currently have both GNSS/GLONASS available. <S> In fact, Russia poses additional tax if a device doesn't have GLONASS support to increase the usage of GLONASS. <S> So the only thing I see is a sudden bump in usage of other constellations. <S> My iPhone/Samsung phone would be just fine!
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Inertial Navigation Systems - current generations of solid state INS gear are highly accurate but accuracy begins to degrade with prolonged use, requiring accurate position updates from time to time. Currently IFR capable aircraft are required to retain VHF navigation radios for use with terrestrial navigation beacons.
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