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Why aren't contra-rotors used on the V-22 Osprey? The Osprey has 38 ft (11.6 m) rotors in a rotating nacelle on each wing. The rotors are powered via a gearbox as in usual turbo-pro fashion. Is any reason that is obvious that smaller contra-rotating rotors wasn't adopted. It is noted on Wikipedia that the rotor diam...	Aerodynamically, co-axial rotors can deliver a higher end thrust than a single rotor of the same diameter, at the expense of less efficiency: But it would be an impossible engineering challenge, the Osprey is pretty complex and had plenty challenges to solve as is.
Can you identify this airplane? Im thinking the window sequence and the shadow (possible a prop?) Might be your best help. My dad bought this photo and him nor I can figure it out. I work at a dang airport, too! TIA. <Q> It was a strategic bomber used by the US in the Pacific theater of World War II. <S> The lower row ...	It's most likely a Boeing B-29 Superfortress . If I were to guess I'd say the picture is of the B-50 at the Pima Air Museum.
Is it unusual for an aircraft to flash its landing lights in sequence? Walking this evening I looked up and saw a plane which I assumed was on approach to Liverpool John Lennon. When I looked carefully I could see that as well as the anti-collision strobes it was flashing two lights in sequence. I assumed they were the...	In addition to helping the pilots to see ahead of them when on the ground in dark conditions, landing lights help to make planes more visible to others.
Can a missile be fired when a fighter jet is inverted? Is there an attitude limit for firing a missile from a fighter jet? Can the pilots fire them when they're pulling Gs, or inverted? <Q> The combat advantage of fighters (as opposed to heavier-payload bombers) is their maneuverability, therefore a missile delivery re...	Firing a missile while manoeuvring also depends on altitude of aircraft, type of missile and effectiveness of seeker.
How can I create a map of all paths of flights incoming to an airport in a given day? Is there any where I could find a map overlaid with the paths of all flights that came into a given airport on a given day? I've found a lot of maps that show the current location of all flights, or the path of a single flight, but ...	The gov't published approach charts are here https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dtpp/
Is "Tally-Ho" used in ATC radio communication, specifically in the UK? This question Are "Tally-ho" and "no joy" acceptable ATC terms for civil operations? concerns the use of the phrase "Tally Ho" to mean "target in sight" in civilian air-traffic-control communication. It was largely answered (and somewhat asked) i...	I have never heard "tally ho" used in civilian aviation and it not a recognised phrase so should not be used. A civilian ATCO would not think positively about anyone using that phrase.
Are there any ILS approaches in Class E airspace? When descending on an ILS you can descend to 100' above the TDZE if you have the approach lighting system in sight. Cody Johnson wrote an article explaining how one pilot mis-interpreted what the rules allowed him to do, descended below 100' when there were obstructions...	Visalia, CA (KVIS) is an uncontrolled airport with a Class E surface area and an ILS with 200' minimums.
Why does a clean configuration lead to the generation of greater wingtip vortices? "Slow, heavy, clean" are the three major conditions generating stronger wing vortices. It's very clear how "slow and heavy" aircraft create stronger vortices, but why a "clean" configuration generates stronger wake turbulence is less cle...	A clean wing configuration is designed for the cruise condition, where there is lots of airspeed to generate lift and we want to keep induced drag to a minimum.
Can a contra-rotating helicopter simply tilt its entire rotor set instead of using a cyclic? I was reading this interesting question and, per answer #1, a normal helicopter cannot do it because gyro effects would probably mean the body of the heli would tilt more than the rotor. So now I think about contra-rotating ...	So yes for a very small helicopter, it should be possible to tilt the main rotor for cyclic control, without hydraulic power assist. The gyroscopic effect will work against you and I have in mind no way to move a so big part of the Mass of the helicopter.
How can hang gliders and paraglider pilots prevent stall? Aircraft and gliders usually have instruments to measure air speed and angle of attack, which should be monitored to prevent stalling the aircraft. However, it seems that most paragliders and hang-gliders lack such kind of tools. How do the pilots avoid stalli...	I imagine hang glider pilots will feel and hear the wind, and be aware of the pressure on the control bar.
How does an aircraft recharge its batteries? I assume aircraft have batteries that power up all electronic devices on board. But how are these batteries recharged? When the aircraft is on the ground, it can be connected and recharged in the airport, but mid flight? Is there a way to charge the batteries in the air ? N...	The aeroplane's electronics are driven by the battery which usually gives us 5-6 hours of operation time I guess, however, with the installed alternator -- given they are not broken, the batteries get recharged mid-flight and once in a while on the ground using battery chargers too -- batteries should be detached in or...
Would a gimbaled, always horizontal cockpit be beneficial to fighter jets? Would it be possible to have a spherical cockpit that was gimbaled in jets such as fighters so the pilot was always upright. With all controls in the cockpit wirelessly communicating with the rest of the jet? Wouldn't this be an advantage as ...	So, no, you don't want the pilot to be level and upright all the time, often the pilot will deliberately make themselves not upright because its safer and more pleasant.
What are the differences between the SR 71 variants? I read that all SR 71 blackbirds were different, what was different with each one and is one regarded as superior to the rest? Why? <Q> Like every military aircraft built over the years, the aircraft evolve. <S> So to address the aircraft's history and all variants...	If you measure them in surveillance equipment or range, SR-71 would come out on top.
Is it normal for instantaneous GLOC to occur at 5 G's? Is it normal for a trainee to have an instantaneous G-force induced loss of consciousness (GLOC) at 4-5 G's in a light military trainer aircraft like Socata TB 30 Epsilon, after doing a manoeuvre sequence? <Q> That sounds really unlikely to be a G-LOC. <S> That u...	I would recommend to see a physician about this.
Could the V-22 Osprey be used as a close air support platform? I saw the US was looking for a new close air support plane. Why do they not use the V-22 Osprey ? It is able to travel slowly and could carry more weapons than an A-10 , for example. <Q> Can it be? <S> Sure. <S> Let's take a look at what it would be ...	The speed, altitude and maneuverability of the platform will never be ideal for integrating into fixed-wing A/C formations, nor will they confer the ability to out run or out fight even the most outdated of adversary fixed-wing A/C in an unescorted role (an A-10, for example, is more than an match for a V-22 air to air...
Are tower simulators used in civil ATC training? Pilots use cockpit simulators, what about training of air traffic controllers working in control towers? Control tower of Québec / Jean Lesage airport (CYQB). Source . How do they train? Are there full visual simulators with runways, taxiways, radio traffic, etc? T...	The answer is yes, tower simulators are indeed used in civil ATC training. the answer is yes they're available.
How are aircraft shipped to their customers? This is sort of the inverse of this question . I was looking at the Boeing facility in Renton, WA in Google maps, and I realized, the airport is across the (Cedar) river from what I assume to be the construction facility. The Boeing facility in Everett, WA is also across H...	They are flown to their customers by either Boeing or pilots from the given airline.
Is a compressor blade slowing down the airflow or accelerating it? When a jet aircraft flies at maximum speed, are compressor blades actually a barrier to the air flow, or is the airflow accelerated by the compressor? <Q> are compressor blades actually a barrier to the air flow, or is the airflow accelerated by the co...	The compressor blades of the rotors accelerate the airflow and impart a momentary velocity increase.
Where does the difference between calculated and actual groundspeed come from? I'm a paragliding pilot. At school we learn that the trim speed of a paraglider is about 38km/h airspeed, the accelerated airspeed is about 45km/h and the minimum airspeed is 22km/h - being inside the weight range of the wing. If I fly with...	It depends on the difference between the predicted wind speed for the winds aloft vs what was actually up at that altitude at a given time.
Is the old paint removed before applying a new one? I've heard that paint on large airplanes weigh 250+ kg. When an aircraft gets a new owner, do they remove the paint that was previously on or simply paint over it? If it is removed, how is it removed? What is the correct procedure for painting/repainting an aircraft...	When a new paint-over is done, the aircraft must be weighed to determine the new weight and CoG. Small partial paintings can be made without the need to weigh the aircraft, but unfortunately I don't know what are the limitations. The paint can then be scraped off with plastic tools or removed with a pressure washer, an...
Is there a standard format to exchange airspace information in electronic form? I am looking for information about airspace definitions. On maps they look great and a pilot has no problem reading maps and NOTAMs, but what about autopilots? Do they use some kind of standardized interface/database? If it exists, where i...	The majority of GPS navigators and FMS have a dataloadable navigation database. ARINC 424 is an international standard file format for aircraft navigation data maintained by Airlines Electronic Engineering Committee and published by Aeronautical Radio, Inc.. The Aeronautical Information eXchange Model (AIXM) was design...
Is this a famous aviator / airplane? This may be a little off topic but I could not find a better community or website. I have two photo postcards with a man in front of a plane. Pretty sure it's Charles Lindbergh but an exhaustive Google search for anything related visually has only turned up another picture of CL wi...	They are indeed of Clarence Chamberlin (a contemporary of Lindbergh) and were taken on June 15, 1927 at the Stuttgart-Boeblingen Airfield in Germany.
Why do buses at some airports differ from conventional ones? Why do buses at airports differ from conventional ones? Why do they have such wheels or cover wheels at all? Source . <Q> Apron buses are dedicated to transportation in the airport area, the one your show is located near the air museum at Salzburg airport /...	Protecting the wheels also keeps clear the space needed to lower the bus, and prevent accidents.
Why has the range of movement of the control surfaces changed over the past year? During the annual inspection on our glider, we discovered that the maximum downwards extension of the right aileron (i.e. full left stick) was outside the manufacturer's tolerance. The measured value was 32mm and the manufacturer allows 4...	One of the linkages in the pushrod system could be loose. Possibly an obstruction somewhere, causing it to not move through its full range because it gets blocked by something.
Which 'pusher' propeller aircraft have been used in active military service? The only 'pusher' aircraft I know of that has been used in active military service is the SAAB 21. There are several prototypes out there, but I can't see that any others were used. Which, if any, other aircraft are there? Maybe the Japanese ...	Flying boats with single pusher propeller: AD Flying Boat ; Aeromarine 40 ; Curtiss Model F ; Hansa-Brandenburg CC and W.18 ; Lohner L ; Macchi M.3 and M.5 ; Grigorovich M-5 and M-9 ; Beriev MBR-2 ; and Supermarine Walrus Various German bombers, each with two pusher propellers: Friedrichshafen G.II and G.III ; Gotha G....
What's the meaning of "straight and level"? Indeed a very strange question. My understanding of straight and level is: The aircraft is flying at a constant heading and constant altitude, and maybe at a constant speed, and this has nothing to do with the aircraft attitude. However I was reading this in " Big Red Toda...	In the airplane flying handbook the FAA defines straight and level flight as Straight-and-level flight is flight in which heading and altitude are constantly maintained.
What procedures are followed for a planned landing in a field? If an aircraft was making a planned landing in a field/sports ground/other large flat area what landing procedures would be followed? My thoughts are that it would be very similar to a non-towered airport, with self announcing and flying a bit of a pattern...	The first act is usually a low pass to inspect the conditions and determine the best landing direction (if there is more than one option), assuming that the winds will allow it.
Why does this regional jet have its air brakes wide open before touchdown? I was looking at a detailed picture of a plane while following its path on Flightradar24.com. Here is the Avro RJ45 I am talking about: I wonder why its aerobrakes at the empennage seems wide opened before touchdown. What I remember from all ...	Commercial jets and military fighters tend to be quite 'slippery' and require drastic throttle reductions to slow down without the use of speedbrakes. It allows better speed control
I overboosted an engine in a Mooney 231 - do I need to do an inspection? I have an intercooler, but no wastegate. Manifold pressure was not controlled on takeoff and went to 50. The max is 37! If overboosting doesn't really exist because the relief valve opens, then how did the gauge even get to 50? It was at that le...	I would say that you should definitely have the engine inspected. The relief valve may have failed.
In which phases of flight should the carb heat be turned on? I have about 200 flight hours in a fuel-injected C172. I have just jointly bought a C152 with a carburetor and I am getting used to using the carb heat. I am scared whenever I hear stories about engine failures due to carb icing. What I know is to turn CH on...	Leave the carburetor heat on until the engine run smoothly.
Is it dangerous to do a skidding turn to lose altitude without increasing airspeed? I was taking some lessons in a light sport aircraft in South Africa a few years back, my instructor taught me something which I had never seen or heard of before or since. We went through an emergency scenario in which we had to make an...	That said, as a maneuver (on an aircraft that slipping is allowed with) it is safe and normal use of flight controls. A skidding TURN is dangerous as it creates a much greater speed differential between the wings, prompting a poor soul to "hold the inside wing up" with aileron.
How can dynamic and static pressure be explained? How exactly do you explain dynamic pressure? If someone asked me what the ASI reads, I would say it reads the dynamic pressure, which is the ram air pressure (total pressure) - static pressure = dynamic pressure But would explaining dynamic pressure as "the press...	Static pressure is the weight force of the mass of a column of the atmosphere all the way to space resting on the base area of this column.
What is profile drag? I know about induced drag, parasite drag, form drag, skin drag, wave drag, and interference drag. But I don't encounter the term profile drag often, and I can't find a good definition of it. Is profile drag the same thing as form drag? If not what is it? <Q> The composition of total Drag as it i...	Profile drag is the combination of form drag and skin friction as it results from the cross-sectional area, or profile, of the aircraft, presented to the relative airflow.
Why don't drones use ducted fans? If efficiency of converting battery power to lift or thrust is paramount, why don't drones use shrouded or ducted fans, instead of unshrouded propellers? This is the only image I could find to clarify what I mean by " ducted fan ": Image source (public domain) My thoughts: An e...	The reason not many drones use ducted fans is efficiency.
What is the typical angle of attack aircraft fly at and at what angle of attack do they stall? At what angles of attack do aircraft typically fly at? How much of a margin is there before aircraft stall due to an increase of an angle attack due to factors such as gusts or rotation of the wing section due to deformation?...	The critical angle of attack when an aircraft goes to stall usually is about 15 degrees, mainly depending of the wing plane form, flight Mach number, the wing section profile and flaps position.
What would be the airspace class when no vignette is visible on a US VFR sectional chart? If a airport doesn't have a pink vignette nor blue vignette on a VFR sectional chart, but the airports around this particular airport has pink vignettes, would this airport's Class E start at 1200 AGL or would this airport be Clas...	As long as the airport you are talking about "near airports with pink vignettes" is not under the pink vignette, then G extends to 1200 AGL.
Would an Aero L-159 Alca air frame be able to withstand a supersonic engine? Aero L-159 uses a Honeywell F124-GA-100 turbofan engine. First question is, can it be fitted with any modern supersonic jet engine? If YES, why isn't Aerovodocody doing that? If NO, why? <Q> By 'supersonic jet engine', I presume you mean a...	It is not designed either aerodynamically or structurally for supersonic flight.
Would a stationary WWII fighter fall on its nose with full throttle and brakes on? Would a stationary WWII fighter fall on its nose with full throttle and brakes on? It's a general question, but I am interested in the Republic P-47. <Q> ( Wikimedia ; arrows and CG icon are my additions) P-47 side drawing. <S> The th...	If the static thrust or the elevator moment is high enough, it could happen.
Do parking brakes lock the wheels and airframe together? ( YouTube ) Wildcat undercarriage. For planes with non-truck undercarriages, can they be rotated around the lateral axis of the main landing gear with the brakes applied without causing translation? My answer is no, they must be locked and there must be trans...	If the brakes are applied, but the wheel's position is not fixed to the ground, the aircraft will rotate round the wheel's point of contact with the ground.
Is it technically possible to have nuclear-powered hot-air balloons? Could a balloon use non-fissile isotope, like Pu-238, to heat air in the envelope to stay afloat for years? let's put political and health related problems aside, and consider if it's technically possible at all. Say, as an unmanned, high-altitude sc...	Lockheed Martin is developing a very promising device . It is unlikely that a balloon could use Pu-238 to heat enough air in the envelope to get airborne since Pu-238 is not powerful enough for that.
Can a US airline add an employee passenger as crew? Suppose an airliner flight is full with passengers and the airline staff realize afterwards that there are employees who the airline wants to send to their shifts using that flight. The airline staff decides to ask for volunteers to surrender their seats in exchange ...	If the employee is a pilot FAR § 121.547(c)(3) allows off-duty pilots to fly in a jumpseat on the flight deck, so there would be no need to make them an active crew member.
Why doesn't the US have a flag carrier airline? With the recent United Airlines fiasco, I was reading up on their history and the airline industry and to my surprise I found that United Airlines is not the US flag carrier. In fact, the US does not have flag carrying airline at all! All this time I thought UA was the na...	A flag carrier is a transportation company, such as an airline or shipping company, that, being locally registered in a given state, enjoys preferential rights or privileges accorded by the government for international operations.
Do pilots have their own in-flight entertainment? Besides flying the plane and talking to the person in the other seat, what other forms of entertainment are (also legally) available to pilots while on the job? I'm thinking of 'activities' like reading, listening to music, watching a movie, or... playing a flight simu...	And many IFDs and integrated GNSS navigation systems often offer XM weather and XM Radio services through subscription that pilots will use to listen to XM radio, as this SR-22 pilot making a flight out to Camarillo, CA does. Use of visual entertainment such as movies, television programs, video games, etc., is not all...
Why do all commercial aircraft have carpets? When flying I noticed that all the commercial aircraft I have been on use carpets as a floor covering. But why? If you fly in an older aircraft it looks worn out and it is susceptible to stains etc. Why do they not use one of the hard flooring options like linoleum? <Q> hel...	Furthermore a lot of people take their shoes of during long flights and a carpet feels in this situation a lot more comfortable.
Should I record my helicopter and autogyro time in separate logbooks? I have been flying autogyros for some years now, and I am out to do my license on UL helicopters. I bought a new logbook to log all time in helicopters separately from autogyros. Is that correct? In a few days I will also be taking some lessons in ...	Log your time in whichever logbook is appropriate. Get one logbook for each category/class of aircraft you intend to fly.
Does the FAA dictate that bridges are closed for the Thunder Over Louisville airshow event? A big tradition here in Louisville is "Thunder Over Louisville". This starts the celebration for the Kentucky Derby. 'Thunder' is an airshow, fireworks, fair, concerts, and a nice day out along the river. This event leads to the...	So, in short, the FAA cannot close the roads, however it can regulate the airshow which would require the organizers to abide by the FAR's.
Does the tailwind component always have the same absolute value as the headwind component? If we are on course 360 and we have crosswind from 020 at 20 kts...does the amount of head wind on this leg equal the amount of tailwind on the reciprocal course (i.e. 180)? To amplify the question with an example: TAS: 260k...	Yes, the intensity of the tailwind will be the same than the intensity of the headwind.
What is this ring-shaped device behind this DC-8's jet engine? What is this ring-shaped device behind this Douglas DC-8 's jet engine? ( YouTube ) <Q> ( airliners.net ) Ejector on the Rolls-Royce Conway of a DC-8. <S> It's called an ejector. <S> Introduced in c. 1958 by Douglas for their DC-8, it is extended du...	It's an ejector and was fitted on the DC-8's equipped with JT3C, JT4A or RR Conway engines.
What is the physical meaning of Mean Aerodynamic Chord? I have not been able to find a consistent definition of what it really is. I have come across definitions such as: "Physically, MAC is the chord of a rectangular wing, which has the same area, full aerodynamic force and position of the center of pressure at a gi...	The mean aerodynamic chord is only identical to the mean chord for rectangular wings.
Can a passenger drone perform auto-rotation? ( Source ) The Dubai Drone is an Ehang passenger drone planned to start commercial services in July 2017. If there is a failure, can such an electric multi-copter auto-rotate a landing? I'm wondering, if an electric motor would even allow auto-rotation, and if the...	A drone with fixed wing propellers such as the one you describe can not autorotate. If a single motor fails, it's not unsafe (supposedly).
How did the 747SR fly from Qatar to London? The following photo on the Boeing 747 Wikipedia article reads: Qatar Airways 747SR-81 landing at London Gatwick Airport in 1996. How did the 747SR manage this flight [on a regular basis]? The only range information I can find for the SR (short range) is from ANA's fle...	Assuming favorable winds, it is reasonable to believe the airplane could make the flight nonstop with IFR reserves.
How can seagulls slide in the wind without flapping their wings? There are a lot of seagulls in a park near where I live. Sometimes I can see them somehow "sliding" forward or backward diagonally when flying against the wind, however, their wings aren't flapping. What are the flight mechanics behind this? Can gliders ...	Some birds 'harvest' energy from the wind gradient.
Can a low flying jet fighter lift water? Can a low flying but super fast jet spray water from the surface of the ocean? I've seen this visual effect done many times in movies. It's often done to highlight supersonic speed just a few feet above the water. Do the laws of physics even come close to this being plausible?...	A fast, low-flying jet may create some shockwaves (not to be confused with the "vapor cone") that would disturb the surface of water, or some updraft that sucks up spray, but nowhere near the massive amount of water depicted.
How can two planes be on the same taxiway facing opposite to each other? Curious to know how two planes can be on the same taxiway facing opposite to each other at the same time? Please have a look at the satellite view of the following coordinates in Google Maps: ( -27.369843, 153.126482 ) <Q> The taxiway is being us...	A controller made a mistake and cleared two aircraft onto the same taxiway at the same time.
What is the best word for lateral translational movement in a rotorcraft? I'm talking about movement left and right without changing attitude. This is a motion that can be done with a quadcopter and to a limited extent a helicopter (I presume). On a helicopter a left/right movement of the cyclic will command a roll m...	The term I preferred was "slide" In our NATOPS manuals, and in our trained procedures in both Search and Rescue ops, and cargo ops, in the Navy the crewman would call for us to "slide left" or "slide right" as he positioned us over the pick up point. This movement is called a sideward hover.
What is the Scaling Factor in ARINC 429? I'm a newly appointed engineer in an avionics company and have been tasked with preparing a report on ARINC429. I understand most of it, and I certainly find it simpler that 664, but I still can't manage to wrap my head around what "Scaling Factor" is.No resource on ARINC429 I h...	The scale factor (which I'll call $Range$) is usually the value given, unless a $\pm $ is used, i.e. $\pm180$ for labels like heading, in which case you would use the highest value (180).
How to fly to an uncharted airport? I'm learning X-Plane 11 and started to use an add-on called FS Economy. One of its missions is to fly to small airports that I can't find on skyvector, so I'm unable to plan a direct flight. I usually fly to the nearest charted airport, and fly using the GPS from there. Not know...	As a frequent flyer to uncharted airports, I simply use a VOR radial and distance when filing.
Is there a specific relation between sideslip angle and yaw rate OR how sideslip angle depend on yaw rate? Since, yaw rate is controlled via rudder and sideslip angle can also be controlled by rudder, I want to know if there is any dependence of sideslip angle on yaw rate in fly by wire aircraft as I am working on the ...	No, there is no specific or dependent relationship between sideslip angle and yaw rate.
Did any aircraft ever use stick twist for rudder control? Did any aircraft ever use stick twist for rudder control like some joysticks for video game flight simulators? <Q> Yes, the RAH-66 Comanche FBW system used a twist control for the yaw channel. <S> It had no rudder pedals. <S> (Yes, a helicopter is an aircr...	The RAH-66 Comanche used a twist in the pilot's stick to control the rudder/yaw inputs.
What is that black pod on the left wing of a TBM? What is the black pod on the left wing of a TBM ? ( Source ) <Q> That is the front of the housing which encloses the 10" GWX70 Color Weather Radar antenna. <S> Here are some close up shots of a TBM depicting the weather radome. <S> Source: <S> Own work <S> N...	As stated above, it's a dielectric blister fairing which houses the antenna for the GWX70 weather radar.
Do airlines have freezers? In the latest twist to the case of the dead rabbit, an anonymous "airport worker" has told a reporter that it was killed by leaving it in a freezer locker , contradicting the accounts of United executives who have claimed the rabbit was well treated. United also hastily incinerated the body...	[Depending] on the nature of the goods to be transported, [ULD's] may have built-in refrigeration units.
Do helicopters need to use yaw pedals to fly a coordinated turn? I recall years ago, when I took a helicopter tour, I noted the pilot simply moved the cyclic left or right to bank the helicopter and initiate a turn. No pedal input was made whatsoever, and the ride seems completely fine. In many fixed wing aircrafts, i...	It could be that the helicopter you were in was travelling at a high enough rate of speed that a large (or any) correction was not needed to maintain proper alignment.
Do flight regulations prohibit sleeping on the floor of an airliner? During a recent trip in a Finnair A350, a couple traveling together was occupying 1 row of three Economy Comfort seats. During the 12 hour flight, one of the couple stretched out on the seats, the other one on the floor in between the seat rows, leg r...	I do know it's not allowed on QANTAS (and Jetstar), Emirates, American, Virgin Blue, or North West (now defunct). Also mentioned was the danger to passenger in case of turbulance, etc, the comparison with sleeping on the back seat floor of a car in motion was mentioned vis a vis unexpected swerving or breaking.
Why do some fighters have two engines? Some countries (e.g. Russia) develop fighter aircraft (e.g. Sukhoi ) with 2 engines. Is it for maneuverability, or is it because they can't build an engine that would meet the power requirement? <Q> Taking the Sukhoi Su-35 <S> for example, it has two engines, each capable of ...	The main reasons for selecting a twin engine design are: Slimmer design, two smaller engines make for a slimmer profile than one big engine.
Can the APU provide emergency thrust? By David Monniaux (Own work) [ GFDL , CC-BY-SA-3.0 or CC BY-SA 2.0 fr ], via Wikimedia Commons Many larger airplanes have gas turbine APUs ( auxiliary power units ). It seems that their exhaust is oriented to the rear and might provide some thrust. How much thrust does an APU...	Practically speaking, APUs are not sufficiently powerful to provide the thrust necessary to maintain level flight.
Why do some aircraft have pods on their wing tips? By JetPix [ GFDL 1.2 or GFDL 1.2 ], via Wikimedia Commons Why do some aircraft have pods on their wing tips, like this Cessna 414? <Q> Wingtip pods or winglets differ in installation reason from aircraft to aircraft. <S> Here is a non exhaustive list of possible re...	Weight at the end of the wing will offset the bending of the wing due to lift.
How is an ILS approach conducted when following a heavy aircraft? I'm following a much heavier aircraft on an ILS approach to a large airport. Ideally I'd like to stay a bit above the glide path and land late, both to avoid the turbulence and also get off the runway quicker. Is that actually a good idea, and how woul...	Basically you can fly above the glide slope as you have assumed but you should always take precaution as it cant be known if the leading aircraft is at or above slope.
What's the reason for pilots wearing uniforms? Just came across an interesting answer to a question on uniforms for PPL Human Performance and Limitations: Pilots wear uniforms: a) so they can be easily recognised b) so that they can be perceived to be important c) so that they can feel important Apparently the cor...	Airline pilot uniforms started being used by Pan Am in the 1930s to make the pilots look more professional and experienced which would calm nervous fliers down.
What is the fatigue life of a fuselage based on? The fatigue life of the fuselage is based on the number of what? Pressurization cycles? <Q> Most (large) aircraft life times are measured in cycles. <S> "Aircraft lifespan is established by the manufacturer," explains the Federal Aviation Administration's John Petr...	Aircraft used on longer flights experience fewer pressurization cycles, and can last more than 20 years.
What were the U.S. Air Force's first 2-crew fighter planes? The Navy has had 2-crew planes since at least as early as 1944 with the Grumman F7F Tigercat but when did the U.S. Air Force adopt 2-seaters. Does the Navy prefer 2 crew and the Air Force prefers 1? Was the McDonnell F-101 Voodoo one of the first AF 2-crew? <Q...	Depending on what you consider a fighter, the Northrop P-61 Black Widow night fighter entered service with the USAAF in 1944 with a crew of 2 or 3 (pilot, radar operator, and optional gunner). In the WWI and interwar era, a few biplane fighters carried an observer/gunner; the Berliner-Joyce P-16 introduced to the USAAC...
How much lift is created by a half-sized rotor? I wonder if lift is directly proportional to the diameter of the rotor disc. For example, if an engine spinning a 26 ft diameter rotor can lift 635 kg, will a 13 ft diameter rotor using the same engine lift 318 kg? The power absorbed by the rotor is the same in both case...	For the hovering rotor, the stationary case, it can be safely assumed that the lift $L$ is a function of the input power $P$, the diameter $D$ of the rotor and the air density $\rho$.
Where can I find registration information of a private aircraft registered in Germany? Is there any way (website, database etc.) where I can get the registration information of a privately-owned general aviation aircraft registered in Germany? (Germany has pretty extensive privacy laws, but it would seem that aircraf...	According to the German wikipedia the Luftfahrtbundesamt (LBA, the German Civil Aviation Authorities) cannot publish the information for data protection law reasons.
Is a one foot landing possible? This video shows an aircraft touching down like a helicopter on some gravel, is this possible or is the video a fake? Are there any other videos out there? Facebook video Similar one on YouTube <Q> It's a STOL (short takeoff and landing) plane, landing in strong headwind. <S> It's ...	The videos you reference are real.
Why are holding patterns in an oval shape? Why are holding patterns in an oval shape? Why not circular or more square-like? <Q> I don't have any definitive information on why the oval shape was chosen. <S> However, it seems to me to be the most practical shape given the navigational equipment available when holding pat...	Flying a circular pattern makes it more difficult to keep track of where you are in your head (no glass cockpits, indeed no HSIs Basically, the straight legs of the track allow the gyros to settle down again after a turn, and (just as importantly) allow the pilot to check that the instruments have settled down again, b...
Why are autonomous vehicles not used at airports for on-ground services? Autonomous vehicles have been around for over an decade, other industries such as the maritime industry have already been using unmanned vehicles at ports. Curious to know why airports are reluctant to implement this despite the clear benefits it ...	Autonomous vehicles are great, but they do not fit to an airport.
Was the F-4 Phantom the only fighter to be in service for the US Navy, Air Force and Marines? As is stated here : Furthermore, the F-4 came in both ground- and carrier-based models and served in the U.S. Air Force, Navy and Marines. The only other frontline fighter to serve in all three services before or since i...	The FJ Fury is actually a Navy/Marine derivative of the Air Force F-86 Sabre. F-15 Eagle/Strike Eagle (Air Force) Sea Dart (Navy) F-10 Skynight (Navy/Marines) F-11 Tiger (Navy) Variants of the Northrup F-5 were also used by all services, although mostly in adversary training roles.
Was differential thrust used in the P-38 to improve turn performance? In the P-38 Lightning could differential thrust be used to improve turn performance ? If so what was the procedure ? <Q> According to WW2 pilots, no. <S> Aside from the dangers in adjusting 1600hp on one side of the aircraft on the fly in the midst o...	But yes, differential thrust was used and was a trick up the sleeve of 38 drivers.
What's the UX in modern airliner avionics for diversion choices, and does it integrate to autopilot? This question mentions a flight that had to divert, in that case to Iqaluit (YFB) . I was wondering: in modern large airliners, what is the user interface like when diverting? How is the case of "what is the nearest...	On a Boeing 777, the pilot can select to have nearby airports displayed on their navigation display (ND).
Which engine type requires the shortest take-off run: a turboprop or a turbofan? If two fixed-wing aircraft almost identical except for the engines, one turbofan and one turboprop, which one would need less runway to take off? <Q> Even with similar weight, turboprop and turbofan aircraft will have different design char...	Everything else being equal, and for the same engine power, a turbofan will need more distance, since turboprops give more thrust than turbofans at small airspeeds.
How many four-engine commercial passenger jetliner types are currently in use? Just heard following somewhere: It is easy to distinguish four-engine passenger jetliner type, because there are only three of them: if it has "hump" upper deck then it is Boeing 747, if it has two decks then it is Airbus A380, otherwi...	The BAe 146 is a 4 engine regional airliner, and you could add to your distinguishing features "has a T-tail, must be a 146".
What can trigger the ELT on GA aircraft? Does the Emergency Locator Transmitter (ELT) on smaller aircraft activate automatically in case of an accident? If so, what triggers it? Is it a certain amount of G's that triggers it or are there other parameters taken into account? <Q> There are four different types of ELTs:...	An ELT which is rigidly attached to an aircraft and which is automatically deployed andactivated by impact, and, in some cases, also by hydrostatic sensors.
As a plane gets slower, why does a certain bank angle make you turn faster? In the video "Maneuvering during Slow Flight" the narrator states that while flying slow the airplane will be less responsive to aileron and other control inputs. He also says that the plane will turn quicker at a certain bank angle than it wou...	So the simple answer is that there is less energy (acceleration * time) spent in turning a slow object than a fast object.
Is it legal for an SEP airplane to fly above its service ceiling? Let's take a Cessna 172R for example. According to the POH this airplane has a service ceiling of 13,500 ft. I know that the service ceiling is the maximum altitude where a 100 foot per minute climb can be maintained.So that would mean that it can techn...	But there's no actual regulation, as far as I can see. The only clear case I can think of would be if the POH says that the service ceiling is an actual limitation and you shouldn't operate above it.
How can you identify the upwind side of a thunderstorm, and why should you fly there? When flying around a thunderstorm, it is advised that you fly in the upwind portion of the thunderstorm. First off, how do you figure out which side is the upwind and downwind of a thunderstorm? Second, why fly in the upwind? <Q> The ...	Typically the downwind side has a much higher probability of hail.
Why does it feel like a plane accelerates just before touching down? On commercial flights it often feels like the plane gets faster just before touching down. What creates that sensation? <Q> The aircraft flares just before touching down. <S> It descends with a constant velocity, and just before touching down pulls th...	As the plane descends into ground effect, it may actually accelerate if the engines are producing enough thrust, since in ground effect the plane requires much less power to keep "flying".
Is it possible (not practical) to create a liquid nitrogen jet? Would it be possible (though not practical) to create a jet that runs on liquid nitrogen that is heated, creating the expansion effect? I believe nitrogen takes up 674 (about) times as much space in gaseous form as in liquid, but if it were somehow evenly ...	In the end you're going to need a large generator running some kind of fuel to produce the electricity needed to cool the liquid nitrogen, heat it up in the engine, and prevent icing on the nitrogen pipes.
Why were the speed records set by seaplanes in the early thirties? For nearly all of the 1930'ies, the fastest aeroplanes were all of the seaplane category (as opposed to landplanes, to use the terminology of FAI ). Presumably, the designers of the two categories had access to more or less the same technology (engine...	So again, no source other than books like The Aviators, but I would say funding in the Navy was higher and aircraft carriers weren't yet perceived by the navy as a whole as the dominant force they became in the early years of world war 2 (hence the pontoons).
Can you file an open-ended IFR flight plan? Say you are doing an instrument training flight with a CFII and you are practicing IFR navigation. You will be taking off and returning to the same airport, but you are not certain exactly where your CFII might have you go. For instance, your CFII wants to see how you handle ...	You usually file a local IFR for this kind of flying, usually with a flight plan indicating the airports you will be flying approaches into or other details about your flight.
How do I remind myself to run in-flight checklists? When flying a basic light aircraft with no "modern" instrument the pilot needs to remember to do various checks on a regular basis (FREDA every x minutes, change fuel tank every Y minutes etc.). Just flying the plane can be consuming a lot of attention (especially ...	If you are unable to use an actual timer, determine the interval of the task (for example every 15 minutes), and use your normal watch. Using a checklist allows you to not forget anything that needs to be done, like lowering the landing gear!
What is the procedure when an aircraft with an emergency can't land due to a blocked runway? This is a hypothetical scenario, but I'm interested to know if there are any regulations/guidance for what ATC should do in this situation. The hypothetical nightmare scenario: The runway is blocked by a crashed airliner and...	No, there is no standard procedure for handling a scenario like the one you describe. The procedure is to determine a course of action which will likely result in the best outcome for everyone, utilizing all resources and given all constraints. If there is another runway or taxiway available to land, the ATC will send ...
What happens when disengaging the electricity generators on a B747? This answer says: If let's say, you [...] disengage the electricity generator of every engine (which cannot be re-engaged without mechanical maintenance), [...]. What exactly happens in the aircraft when disengaging the generators and what benefi...	The disconnect button is pushed when there is reason to believe that continue operation of the generator may lead to engine damage, for example when there is a low oil pressure or high temperature indication of the IDG.
What is the efficiency of running an electric motor from a gas generator? If you were to run an electric motor from a gasoline or diesel generator, how big would the generator have to be to run something like the Siemens electric engine? Is this a viable model for replacing a heavy piston engine or is it too inefficien...	Gas-Electric (be it diesel or gasoline) is advantageous as you can drive full torque at 0-RPM which is useful when getting a giant freight train rolling but does not provide a ton of benefit to light aircraft.
Why the moment arms in x-direction are considered as -x? Thanks for anyone reading this question. I am able to understand the signs of the forces, but I could not understand why a negative sign is added to the moment arm in x-direction (please check the last line in the picture).Thank you! <Q> In your drawing, force is...	You are right, technically the equation should have only plus signs, and the value of X would be negative.
Do the pilots have to recalculate the balance when 6 passengers show up last minute in a 737? Few years ago me and my mates forgot the checkin time and were late for flight. We were late for check-in counter closure (30 minutes before flight if i'm not wrong) but the staff allowed us to go on. We had no checked luggage...	If the changes are minimal, there is no need to recalculate the mass and balance, and trim settings.
Why are fighter pilots seated and not reclined? I have always wondered about this one. Pulling high G-forces is, I assume, the most physical challenge the pilot of a high performance fighter aircraft needs to be able to sustain without blacking out or worse. Indeed, in most countries in the world would-be fighter pilo...	The tilted seat can accommodate taller pilots and increases G-force tolerance; however it has been associated with reports of neck ache, possibly caused by incorrect head-rest usage. Fighter pilots are far more reclined than you might think. A very critical device in a F1 car that allows for that extremely reclined pos...
Why is a sweeping second hand required for IFR? The reasons why a clock is necessary for IFR have been explained elsewhere , but I haven't seen the reason that the clock has to have a sweeping second hand. It seems like when timing things it would be more useful to have a ticking second hand, why is it expressly req...	The rule was written "sweep-second hand" meaning a seconds hand that swept around the main dial so that a pilot could accurately time seconds.
Where can I get airport diagrams of non-towered airports? I'm trying to find a couple of airport diagrams for right now: X26 and X59 . Neither of them are listed in the Chart Supplement or on the FAA site.All I could get were those shabby diagrams presented by Airnav and Skyvector and sorts, and Google Earth imag...	ForeFlight makes a basic airport diagram for X26 and for X59.
Can state or local laws regulate where aircraft can take off and land? Say you have as private strip, but your neighbors get tired of hearing your plane. Can the local authorities pass, and enforce a law saying you can't take off and land there? Or do FAA rules override local authority as to where you can and can't lan...	Civil Helicopter Operations are greatly stilted by local county, and municipal laws that in many cases, prohibit helicopter operations.
Why is there a helicopter visibility reduction restriction for this approach? For the RNAV (GPS) RWY 17 approach at KSMN, why does it say "Helicopter visibility reduction below 3/4 SM NA."? Looking at the LNAV, there is a 5 mile visibility requirement and if we cut that in half per AIM 10-1-2 , wouldn't there be a...	My understanding is that similar to the notation on the chart that "DME/DME RNP-0.3 NA, the helicopter notation (Helicopter Visibility Reduction less than 3/4 SM NA) is just a charting convention.
Why is an approach that relies on both LOC and PAPI not considered a precision approach? I am an aviation layman. I am reading about PAPI lighting system and it seems like it provides vertical guidance, just like the glideslope component of an ILS. Coupled with a LOC, both vertical and lateral guidance are available t...	In addition to the issue of visibility, consider that a PAPI consisting of 4 red/white lights only lets you distinguish between five different states (ranging from all red to all white), whereas an ILS glideslope component will give you a continuous guidance.

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