subreddit
stringclasses 11
values | text
stringlengths 246
28.5k
|
|---|---|
askscience
|
Former pool store employee here: we do! All employees are trained on not storing different types of chlorine (or any sanitizer) next to one another, and to make sure to tell customers not to mix it when buying. With cal hypo and tri-chlor (among others), we also would tell customers not to mix either one in a bucket first, due to the heat caused by the reaction with water. This was basic training before any employee was allowed to talk to customers.
Cal hypo specifically we were told was very dangerous to mix or spill, and to store it at least five feet from any other sanitizer.
|
askscience
|
How does 1 person write all that nonsense without reading a single word I wrote???? The manufacturer (for that matter the entire world since these reactions have been known about for decades and studied in depth already by scientists around the world) already did the research and posted warnings on the containers tell you not to mix those products. And linking partial pics instead of the full label is just trashy of you.
|
askscience
|
So force is just mass times acceleration as depicted in F = m*a. Since you are interested in a falling object the main source of acceleration is gravity. On earth gravity is relatively consistent and the variations that exist are negligible. Thus F = m*g, where g is roughly 9.8 meters per second. So a falling object will always exhibit a force of
F = 9.8*m (neglecting all forms of wind resistance etc). So the real variation in falling objects in this scenario is the mass. Things with larger mass exhibit more force when falling than things with smaller mass. When you add in the variation of height of free fall it doesn’t change the acceleration or the mass so force remains constant.
|
askscience
|
[As an aside, if you want to have a character like \* show up, you need to type an escape character like \ before it; e.g., \\\*. This is because reddit interprets \* differently from regular characters, to allow for some formatting. One asterisk marks italics, two marks bold, and three marks bold italics:
\*italics\* gets rendered as *italics*
\*\*bold\*\* gets rendered as **bold**
\*\*\*bold italics\*\*\* gets rendered as ***bold italics***
So, because you tried to write F=m\*a, followed by text and then F=m\*g, what you got was F=m*a, followed by italic text and then F=m*g.]
|
askscience
|
It's not the fall that kills you, it's the sudden stop at the end.
The gravitational force is mg, but that's pretty harmless. The higher the fall, though, the longer gravity has to speed you up.
When you hit the ground, your velocity has to go back to zero in a very short distance (say, 1 metre). The ground pushes back on you to do this. The faster you were going, the harder the ground has to push, and the more damage it can do.
Worse, gravity affects every atom of your body the same, but the ground is only pushing on the bits of you touching it. So the force from the ground distorts your shape, breaking skin, stressing bones, moving organs around and pressing them against each other, just generally doing stuff your body isn't happy with.
|
askscience
|
First, because I tent to ramble, TL;DR: The higher you fall from, the more kinetic energy you build. Your body has to absorb all of that energy to come to a stop.
Ok, so...for the following calculations, I'm ignoring air resistance and terminal velocity, just to simplify things a bit.
Kinetic energy (the amount of damage a projectile is capable of inflicting) is equal to one half the mass of the projectile, times its velocity squared.
The acceleration due to gravity near the Earth's surface is equal to roughly 9.8 meters per second squared.
What that means is, for every second an object is falling, you add 9/8 meters per second to its speed. After one second, 9.8 m/s. After 2 seconds, it's 19.6 meters per second. After 3, it's 29.4 meters per second. And so forth.
Ok. Now that we got that out of the way...
The higher you are, the more seconds you're falling. The formula for how long you fall from a given height is h = .5a * t^2. H is the height of the fall, .5a is half the acceleration (4.9, in this case), and t is time in seconds.
So, for a hundred meter fall, it's ~ 4.518 seconds.
Ok, so now we know how long we're falling.
4.518 * 9.8 = roughly 44.276 m/s.
A 10 kg mass moving at 44.276 m/s carries 5 * (44.276)^2, or 9801.998 joules of energy.
The same mass falling half the distance, or 50 meters, carries roughly 4900 joules of energy, if I'm doing the math correctly.
In both cases, that's how much energy your body has to absorb on impact to come to a stop. Well...your body and the ground, but still.
Now, I don't know how many joules it takes to shatter a femur or detonate a spleen (which is almost, but not quite exactly what would happen in either scenario), but I'm pretty sure it's less than 4.9 kilojoules. That's a bit more than a gram of TNT (If I did the math correctly) for a 50 meter fall, according to Wikipedia.
|
askscience
|
That's not true. Force is an instantaneous property, it doesn't make sense to talk about it over a time period like that. If you simplified things drastically and assumed you stopped instantly when you hit the ground, then both acceleration and force would be infinite. The property you are looking for is impulse, which, like momentum, is what you deal with when you are talking about forces, accelerations, etc. over time periods. For example: how far does a baseball go when you hit it? You need can't get the answer just from force. You need force + time, i.e. impulse.
|
askscience
|
A high impulse is only dangerous over a short time i.e when there is a high force, similarly a low impulse over a very short time is also dangerous. The magnitude of force applied is what matters. if you stopped instantly on hitting the ground then the force applied as you said would approach infinite which would kill you, if there was a slower stop then the impulse would be the same but the much lower force would mean you survive
|
askscience
|
The RWR (radar warning receiver) basically can "see" all radar that is being pointed at the aircraft. When the radar "locks" (switches from scan mode to tracking a single target), the RWR can tell and alerts the pilot. This does not work if someone has fired a heat seeking missile at the aircraft, because this missile type is not reliant on radar. However, some modern aircraft have additional sensors that detect the heat from the missile's rocket engine and can notify the pilot if a missile is fired nearby.
|
askscience
|
I mean you don't really need it to be autonomous
​
\- stick a couple of camera pods onto the plane. one on top, one on bottom, that can swivel just like a real pilot's head, and have them follow a drone pilot's head movements. Have the drone pilot's view switch between the two pods automatically based on where he's looking so he's never obstructed by the nose or wings of the plane
\- equip each camera pod with two colour cameras for depth perception, two low light cameras for night flying, and an IR camera that can overlay hotspots on to the colour/NOD picture (some [civilian NVG sets](http://www.nitevis.com/images/DSNVG_Image_03.jpg) already do this) so all the hot bits like enemy plane exhaust or incoming missile exhaust glows red
\- put your best fighter pilots in command of these things, who can now fly with better situational awareness and no G-force restrictions (other than what the airframe can handle), and can take control of any plane on the planet instantly (although obviously the closer the better, before they have to deal with input lag). They can get shot down as many times as you like and you'll never lose them, and can even switch to take control of the next reinforcing set of fighters if the first set the were flying were shot down, so you basically have aces flying every plane, especially in low intensity conflicts where the chances of more than 10 of your planes being in immediate combat at any time is low
​
Pretty much the main drawback is it isn't a closed system. Something can jam the signal between the pilot and the plane much more easily than jamming a self contained AI program that's already in the plane instead of being transmitted to it
|
askscience
|
Not sure if anyone had mentioned this but there was a US jet shot down in I think was Bosnia by an anti aircraft gun with radar detection. The jets were flying the same path so the Bosnians locked on to the jets once or twice to make the pilots think the the system that can tell they have been locked on was malfunctioning. Then they shot one down, there’s a doco on YouTube.
|
askscience
|
This isn't exactly how it went. Some did feel that way, but ultimately parachutes basically doubled your odds of dying. You could only use them if you bailed out of your plane while it was straight and level, as far as I remember. And they were unreliable, being designed for stationary balloons, not planes that were on a crash course. Your odds were legitimately better if you attempted a controlled crash, which is a lot less dangerous at the low speeds biplanes flew at. Germany was the only country to have parachutes on planes and they did not work very well.
Experienced pilots were very hard to come by. For many countries, pilots had a **much** higher death ratio than men in the trenches. It was in everyone's best interests to keep them alive as effectively as possible.
|
askscience
|
How do you communicate between the plane/cameras and the pilot?
There’s a signal that has to be sent (high bandwidth as it requires video at a minimum, and likely sound as well).
This communication is not instantaneous. It likely needs to be encoded and beamed to a satellite in space, then beamed back to the pilot. The pilot needs to make his/her decision based on what is seen or heard. Then the pilot needs to input his commands.
The time between each signal sent and received isn’t trivial. It takes time on the magnitude of seconds.
I’m not a fighter pilot, but I imagine if I’m a second or two behind the fight with a human enemy, the enemy that’s seeing and experiencing everything firsthand is going to win.
|
askscience
|
The real problem here is not cost its the lead time training a new pilot and experience loss from losing the first one.
An F35 takes 41,000 man hours to build but can be built in a couple of weeks. Pilots take 2.5 years to train meaning your down a pilot that entire time. Additionally training that pilot is going to tie up the time of both the machines and other pilots you still have decreasing operational effectiveness. Furthermore, if you lose too meny veteran pilots you will begin to lose the institutional knowledge of how to effectively fight in the planes.
TL;DR: Replacement of pilots carries a logistical cost that makes sacrificing a plane to save the pilot appealing despite the price tag.
|
askscience
|
That's if you send it to a satellite in space
if you only used these drones in areas with supporting aircraft to bounce the signal, similar to AWACS planes now, except with the function of just collecting drone signals and sending them to nearby airbases with drone pilots, say, ones in a 500 mile radius from the drone for minimum lag, that delay would be tiny.
​
it would still be there, but even just seeing the red flash of a missile launch from your IR camera will gain you back more reaction time than you lose, and having the situational awareness and maneuverability advantage a drone could give you will always be better, because instead of having to quickly react to bad situations like losing sight of the guy you were fighting to the background and then being surprised when he shows up in your blind spot, you just won't have to react to to those situations because he'll be showing up on your thermal the entire time and you don't have a blind spot, so you wouldn't lose sight of him in the first place
|
askscience
|
that's the other downside of human controlled drones
You have to make a system for that drone to communicate with the guy on the ground hundreds of miles away. That system will almost definitely have to include a "middle man" to capture the signal, restrengthen it, and make sure it isn't blocked by the mountains or the horizon. This middle man will probably be a plane, so it has as few signal obstructions as possible, and each plane will probably be bouncing the signals of an entire area of operation's worth of drones, with maybe another one or two planes up in the sky as backups if that ones has problems
​
you take those communication planes out or find out a way to jam them, even in a way that just decreases the number of updates per second a pilot gets, and the strength of your entire drone force in that area goes down massively
|
askscience
|
Because a plane that is returning to base is a plane that is not performing useful duties.
I can understand the concept of what the other guy was saying, but I have a different idea.
If we have systems that can detect those things, why not design a plane that has a small turret that can fire small rounds at the incoming rockets? I wouldnt want it automatically firing, but target tracking would be good.
Maybe even slowly work on it until it is automatic, but idk.
How dumb is my thought? Or is that basically just what chaff is?
|
askscience
|
sure, but then now you have to add extra space and weight for them and their life support, and their ejection system, and their controls, and you can no longer undeniably out-turn any enemy human piloted plane just by not having to worry about pilot blackout, and you again face the possibility of the pilot not making it out alive to use all their combat experience to win the next fight they get into
​
I totally get where you're coming from, and I'm sure the main reason the F-35 *didn't* end up being pilotless was because they had this same discussion and determined it just was too risky at the time of development with there being too much lag or too many links in the chain that were vulnerable to electronic warfare or just outright destruction of those communication pathways, but it's just cool to think of the advantages and disadvantages of each system, and what it would take to make a different system viable
|
askscience
|
No, the problem with AA missile is that they can turn harder and accelerate faster then a fighter.
However, missiles are limited in size and hence in fuel and every mile and every maneuver wastes precious energy.
So an aircraft has two ways to defeat a missile.
* Miss-guide
* Waste energy
By wrong radar targets(caff, decoy), wrong infared targets(IR Flares) or Jamming. On the other hand there are evasive maneuvers that try to waste as much energy as possible(sharp turns) or in some cases even outrun the missile.
This however all depends on energy the missile has left. A 60mile missile may intercept a target after 40 miles and only have enough energy to turn sharply once. The same missile might be almost unavoidable at 20 miles.
Even though getting closer means the attacking fighter is more exposed to incoming fire.
It all depends on the situation.
​
|
askscience
|
I don’t know of automatic maneuvers, but fighter pilots are trained in maneuvers that the body can’t handle for special situations. For instance, some high g turns to evade SAMs can cause so much blood to leave your head that the pilot is temporarily blind. If you listen to recordings you can hear some pilots time the maneuvers to know when to level off and regain vision or breathing. Or their wingman will tell them when to level off.
|
askscience
|
My issue of drones in war is the removal of the human life as a cost. A society that doesn't experience loss of life when they make war will inevitably become corrupt and become a threat to the world at large.
Nothing more than tyrants who order the deaths of their enemies without fear of reprisal who've become numb to the horrors and suffering they inflict. Sooner or later, they'll see their enemies as sub human and won't hesitate to use more and more extremely destructive measures such as nukes.
|
askscience
|
UAV Engineer here, there are several interconnecting factors.
 
1. There is a huge debate and a lot of moral and ethical issues if a machine is given the power to decide whether to "take the shot" and possibly kill a human being.
2. You can put a human at the other end of the computer like at a desk in base. But comms tech have limitations such as latency and fixed lag. This will hinder the agility of the drone. Imagine playing FPS with a constant lag, it is REALLY incapacitating.
3. Comms jamming. Makes your entire fleet/squadron useless. (Then the Qn: how about fully autonomous and self-localized computing w/o comms. Ans: See point 1 and point 4)
4. Dogfighting. The AI required for LIVE dogfighting is very complex. Flying in free space with just control surfaces is VERY different from Computer game simulation.
 
Edit: formatting
|
askscience
|
Infrastructural hurdles aside, situational awareness is possibly the next largest issue, for both manned and autonomous operational schemes. Looking down a straw is fine for relatively level flight, comparatively slow targets, and effectively safe skies--not so much for near-peer adversaries in contested environments. The lack of vestibular and proprioceptive input with current ground control schemes is also another potential consideration--core senses that to a certain degree do play a role in situational awareness and split-second combat decision making.
Being able to rapidly process and synthesize the amount of information needed to form a coherent picture of the space and situation around you is difficult enough for human pilots, requiring considerable training and the ability to adapt and function with an incomplete picture. We'll likely have trained software systems that effectively duplicate human combat pilot capability eventually, but that is definitely not an easy challenge.
|
askscience
|
This is the key advantage of armed UAVs. None exists at the moment (that I'm aware of), but if pilots were removed from fast jets, those aircraft could pull significantly more Gs than a manned aircraft and would have a much better chance of dodging ordnance.
The reasons this hasn't been done yet are:
1. There are serious legal and moral questions about allowing robots to make autonomous combat decisions; and
2. There are some things that humans can do better than algorithms - such as cooperate and make 'intuitive' decisions.
|
askscience
|
Radar works by directing energy at something and then picking up the signal that's bounced back - as in /u/Terr_ example, the flashlight sends out a beam of light energy and your eyes pick up the light reflected off whatever the beam hit.
Electronic Attack (a component of EW) works, among other ways, by detecting the flashlight being pointed at it and returning fire with one of those old searchlights from WWII, effectively blinding you, except with electronics it fries the circuits, destroying the sensor.
|
askscience
|
to piggy back on Crudboy's comment.
radar's have two main modes of operation - search & track. Imagine you're in a pitch black area, you can see that someone has a flashlight and they're sweeping it side to side - that's search mode.
now imagine they're pointing the flashlight in your eyes and keeping it there as you move - that's track mode and what is called radar lock.
the RWR system can tell the difference and will warn the pilot when the mode changes
|
askscience
|
The days where aircraft were dogfighting and dodging around the sky are long gone. Fights between modern jets happen at great distances. The definition of a *short range* air to air missile is a missile designed to kill a target at *30 kilometres or less.*
If flares and chaff won't save you, a barrel roll won't either. Planes are comparatively fragile and missiles aren't designed to actually hit a plane. They use proximity fuses to explode when near a plane, which is all it needs.
Direct hit missiles are mostly reserved for tanks and other armour. Easy targets with thick skins.
|
askscience
|
Well what you're suggesting is essentially an air-to-air capable drone, and they are in development. However, you vastly underestimate the cost of training pilots. Even purely from a monetary standpoint, it is a significant percentage of the cost of a 5th gen fighter. Not only that, but the turnaround times on training versus replacement are vastly different, you can't just train new pilots like you make new planes. Finally, if pilots know that as soon as they get in the plane, there's a good chance their own plane will kill them if they engage in aerial combat, then they probably won't engage, or they won't join, or they will just refuse to get into the plane.
Wildly impractical. I know I wouldn't get into a car as a driver if you told me in an emergency situation it will perform a manoeuvre automatically that may kill me.
|
askscience
|
You are correct. With the advent of computer aided stability systems, fighters can be designed so that they are unstable. First (US) aircraft to do it was the f-16,which...had a few bugs early in development that caused several mishaps and earned the aircraft the moniker "lawn dart" because it had a tendency to nose down and crash with its tail in the air.
Between that and advances in auto pilot systems (mostly on the civilian side), you could make an aircraft that could take off, fire weapons at a target, return, and land with little human help. But that is a far cry from the situational awareness required in combat, which is why our drones still have humans at the controls.
|
askscience
|
Yes, back in Vietnam the idea that a missile only plane the F-4 Phantom was used. This quickly was found to be a very bad idea because the missiles used at the time weren't as accurate as advertised and there were more MiGs than the F-4 had missiles. A hard point attached external gun was added to the F-4 and every fighter jet since has had a gun in its design. The only exception to this that I know of is the F-117 but that wasn't a true fighter as it had no air to air ability and due to fuel constraints only could carry one bomb for actual missions.
|
askscience
|
Most fighter aircraft now carry a cannon of some variation. Some countries have thought about "equipped for, but not with" a cannon, with the intention to put it on if necessary later. But it turns out the cheapest way to maintain the aircraft balance was to just buy the gun to put in.
The F-35 is one of the first new fighters to be designed without a gun, but a gun pod is available for the variants that don't have an internal gun.
|
askscience
|
> Plus going unconscious is not good. There's no "it's okay he's just knocked out" in real life.
Passing out due to a temporary lack of blood to the brain is not amazing for you, but if it is for a short period you will be absolutely fine. It's not at all equivalent to being knocked out by blunt force to the head.
I have no idea whether modern fighter planes can, will or should do automatic manoeuvres that make their pilots unconscious but the idea isn't absurd just on the grounds that "going unconscious is not good".
However my amateurish guess is that a missile that just has to move itself and a little payload of explosives will always outrace and outmanoeuvre a plane that has to carry a pilot, weapons, ammunition, fuel for it all and so on.
|
askscience
|
Hi, RF radar engineer here. Modern cruise missiles are extremely hard to out-manoeuvre, something that movies and games get wrong. Missiles hone in on the infra-red wavelengths emitted from the engine. Special systems called Infra-Red counter measures (IRCM) use lasers to ‘blind’ missiles by shooting them with infra red signals at a higher power than those emitted from the aircraft. This allows them to be set of course and steered away from the aircraft. Its such an incredibly effective technique that an aircraft equipped with an IRCM system should never have to perform an evasive manoeuvre.
Edit: first sentence originally said ballistic missiles, I of course meant cruise missiles.
|
askscience
|
When a Radar locks a target, this is what's called STT or Single Target Track mode. The Radar focuses all it's energy on the one contact in order to receive near real-time range, speed and position information (Sometimes other information too). This is detected by the RWR as a large, continuous radar waveform. Each radar produces a different waveform, which is how threats can be identified.
Once a missile is fired, depending on the type of missile, the radar waveform my change again to 'illuminate' the target for a semi-active radar homing missile - or to send additional data to an active radar homing missile to update it on the enemies position. The RAR can listen to the waveform and decide what the threat radar is doing.
Not all missiles require a radar to lock a target to fire, however. Some missiles can fire on targets that have merely been scanned by the radar, and not locked. A good example of this is the AIM-54 Pheonix missile used by USNavy F-14 Tomcats.
|
askscience
|
Missiles are generally more maneuverable than the planes they are fired at. They are lighter, faster, and have a higher thrust to weight ratio. Imagine - is there anything that a tanker truck could do to avoid a motorcycle determined to catch it?
Even more interestingly - missiles (generally) don't "touch" the airplane and then blow up like a hand grenade - or an RPG where there is a "button" on the nose that makes it blow up when it touches something. Rather missiles can tell how far away they are from the plane, and when they get within say a hundred feet they explode projecting a cone of shrapnel at the plane. Imagine if instead of trying to grab the Road Runner from atop an acme rocket, Wile E. Coyote instead had a shotgun and as soon as he got close he blasted the Road Runner with the shotgun.
|
askscience
|
Drones in full rate production right now are designed for long-duration loitering and are therefore pretty low-speed, mostly turbo-prop. They're also almost all used against ground targets (although i think an MQ-9 got an air-air test kill the other week).
​
Lots of air-superiority UCAVs are being developed, but none are particularly far along.
Oh, and in the important bits of UAV operation they're directly piloted by humans, avoiding the moral conundrum of letting machines decide to kill humans. Air-air combat would be challenging to achieve without automation, due to satellite latency and general importance of speed in being successful.
|
askscience
|
I'd think it'd be doubtful too, but not because for not knowing how long the pilot would be out. If the choice is between getting hit by a missile and blacking out for a variable amount of time then blacking out is the easy choice. The bigger problem would be the risk of false positives. Having the plane automatically take control from the pilot and perform a maneuver that has a high chance to cause them to black out would be a dangerous system to have installed. It could also be something that is targeted directly. Tricking a plane to knock out its pilot could be highly beneficial.
However I could see such a system as something that the pilot could initiate.
|
askscience
|
I swear I saw a video of a head position/vitals/response detector that would apply power, keep the nose up, sound an alarm, shake the stick and possibly waggle the wings a little to prevent the plane from *crashing* if a pilot in a single place plane went lights out. Any fighter pilots here?
Not far fetched as these days the pilot flys the computer (FBW) and the computer flys the plane. Also I have read that nowdays, any fixed wing plane that can land on a carrier, can land *itself* on a carrier.
|
askscience
|
The probability of a hit in that mode is very low. The target would need to be maintaining the same height and speed as the view the amraam seeker has is quite small. The money maker is AWACS led targeting. Radar off aircraft fires on the target having been data linked it's location by an AWACS hundreds of miles away. AWACS continues to data link the missile until the seeker sees the target. Target can't act against the AWACS as it is too far away.
|
askscience
|
So I had an opportunity to talk to an F-16 crew chief when they first arrived. Fly-by-wire is what you guys are talking about. Pressure on the stick is translated to movement by the computers to move control surfaces. He told me when the A models first arrived the stick was rigid and the pilots had a very difficult time judging how much control input they were giving the aircraft. It led to over Gs and botched maneuvers and injuries. One of the very first upgrades they have the aircraft was to add very slight movement to the stick. It fixed the issues.
The F-22 also had some mishaps during testing. It has porpoised down to the runway and iirc a programming error during a test flight multiplied the pilots inputs by a high multiplication. He went to level the nose out and it pulled negative 13 Gs and he went to correct it and it pulled positive 11 Gs. All in like 1 second. He passed out and the plane went into a holding pattern at an assigned altitude until he came back. Plane structure was fine other than the hard points had minor cracks and the pilot has busted blood vessels in his eyes.
Edit: as pointed out my phone auto corrected fly-by-wire to fly-by-night. It's fixed now.
|
askscience
|
Negative, all evasive maneuvers are accomplished by the pilot. Usually the other pilots flying together will verbally tell a targeted pilot to "break left/right" in order to dodge the missile by turning harder than the weapon can.
The only exception might be terrain avoidance used for flying low to the ground. I'm not sure if fighters have this system (TCAS), but I know most of our heavy aircraft do (at least in the military). My knowledge is limited, I only work bombers.
|
askscience
|
It's important to note that an RWR can only tell the pilot about things it can detect a difference in - you'll really only get a lock warning if the aircraft locking you up switches to single-target mode (where his radar directs all it's energy into one target only). If he stays in scan mode and let's his computer "track" your position digitally, you won't get a lock tone, just the scan warnings.
With a hostile Russian aircraft, the IRST sensor won't trigger the RWR at all, so even if you know he's there, you won't know if he's planning to shoot until he does.
|
askscience
|
It's actually quite an interesting problem and there's a bit more to it than just maximum G's. In a nutshell to directly answer your question in order to keep them a light as possible aircraft are designed to break only a bit higher than the the pilot breaks. As a result the maximum G this theoretical system can turn at before the plane falls apart around the unconscious pilots is really only a bit higher than what the pilot could tolerate anyway.
The question of "if it would actually help anyway" is really, really complicated; missile guidance and control is a really fun topic.
For some numbers, most fighter aircraft airframes are designed to withstand a maximum maneuvering loading of say 15gs and this is sensibly based in human endurance; there's no real reason to design it any stronger and that would make it much heavier.
A SAM or air to air missile can maneuver at >60g.
An aircraft simply cannot hope to purely "out G" a missile. No pilot or airframe can survive 60g.
However! That is not the only determining factor of if the missile can maneuver to hit. Turn rate is a function of velocity squared and G loading. Turn Rate = Velocity^(2)/(gravity * G loading).
This means that, for example, an F15 at cruise speed can actually turn a smaller radius than than an AIM9x at its top speed despite the fact than the missile can maneuver at ~5x higher G's.
However Mk2! Consider than the AIM9x's motor has burnt out shortly after launch and so its technically gliding into the target and so has probably slowed down a fair bit by the time it's reached its target. Does that put it in a situation where it can now out turn the aircraft? Maybe, maybe not.
However Mk2 Mod 0! Turn rate isn't the only determining factor for if the missile will actually hit the target. A very basic terminal guidance algorithm is called Pro-Nav (short for proportional navigation) guidance. This guidance algorithm basically holds the angle that the missile sees the target as a constant. If this angle is constant then the missile is tracking the most efficient course into the target at that point in time since it must be closing purely in distance.
What this effectively means is that because the missile is chasing the target it doesnt need to turn as fast. Does that put it in a situation where it can now hit/get close enough to the aircraft? Probably, maybe not.
This is where the tricks a pilot can come into play. If the missile is a long way off, in Pro-Nav a course change by the target will require a correction for the missile; and this uses energy of which the missile has a finite amount of, and the jet has fuel to spare. A bunch of jinking could make these corrections burn the kinetic energy of the missile up hopefully enough that it runs out of steam before it reaches the target.
However Mk2 A2! Missiles nowadays don't purely rely on Pro-Nav guidance and will use some other mid course guidance algorithm before swapping to a terminal guidance algorithm like Pro-nav. This is where the GNC engineers earn their wage. We are just as aware of the ways to try and defeat missiles as pilots are (probably more so!) and have no intention of letting them have an easy time dodging. The goal is to ignore the jinking and figure out what the pilots doing long term until you're close enough that the missiles lower turn radius but very high closing rate (from the terminal guidance algorithm) means the pilot can't maneuver out of the lethal radius of the warhead in time. Sure the pilot can maybe turn tighter than the missile, but usually the missile doesn't need to turn as much sinces its chasing and a near miss is good enough with the warheads they are carrying.
The end result is an envelope that says "This missile can probably hit this aircraft going this fast if launched from these distances and angles. Probably". The designers/analysts of these systems are *very* aware of these envelopes and are most definitely classified!
High G maneuvering to escape destruction was far more important in cannon/machine gun combat, not missile combat. If you can turn faster/tighter than the other guy close behind you, he can't shoot you. If you're interested in this sort of system, have a read about the auto pull up system on the [Junkers Ju-87](https://en.wikipedia.org/wiki/Junkers_Ju_87#Basic_design_(based_on_the_B_series)) dive bomber from WW2. That aircraft has a near system to allow the aircraft to pull out of the dive bomb run if the pilot suffered G effects. Pretty neato, and fairly unique as far as I know
Source: Am aeronautical engineer and have worked on missile seeker guidance algorithms
Tl;Dr Aircraft aren't designed to take much higher G's than the pilot and theoretical system wouldn't really help that much given how missile guidance works.
|
askscience
|
>This quickly was found to be a very bad idea because the missiles used at the time weren't as accurate as advertised and there were more MiGs than the F-4 had missiles. A hard point attached external gun was added to the F-4 and every fighter jet since has had a gun in its design.
this is half facts. yes the navy and the air force struggle with early missiles and both of them came up with 2 different way to solve it. the air force put a gun pod on it as a band aid and requesting a new version of phantom with guns meanwhile the navy built a think tank /fighter school that create a doctrine to optimize the missiles. the results are the K/D ratio of USAF phantoms were not changed meanwhile the navy K/D goes up to 12 migs to 1 phantom.
also, that fighter school is called "top gun". a name that you might know.
|
askscience
|
while BVR might be what aircombat looks like with 4th generation fighters, with 5th generation fighters, some people argue that BVR will actually be less of a thing, and WVR may actually happen a lot more often than you would think due to them being much harder to target for BVR. WVR will be significantly more deadly due to the extreme lethality of modern WVR weapons and targeting systems on these aircraft so its unlikely aircraft will truly merge and get into a turning fight - if that were to happen though, it would almost certainly have to be a 1 circle scissors fight - any 2 circle fight would likely lead to attrition as both pilots would easily be able to target and hit the other.
|
askscience
|
No. A maneuver like that would carry a significant risk of stalling the aircraft and if the pilot is passed out then there’s no way of knowing if they’d be able to recover the plane to stable flight or if they’d even be able to wake up before a crash (fun fact, when they were experimenting with the F-16 program a big problem was that the modern systems allowed for maneuvers well above what the human body could handle so they had to ad manual resistance to the controls otherwise it was too easy for a pilot to accidentally pull a high G turn stall the plane and pass out). Usually if a pilot knows there is a missile like that they will try and use countermeasures to break the lock stuff like chaff to confuse the radar, or flares to throw off a heat sealing missile ( attack helicopters do this too especially when coming in on an attack run to help prevent getting shit down by a manpad), pilots may also try and make maneuvers to break the lock such as taking a sharp enough turn that the missile can’t track it anymore or going close enough to the ground that the ambient heat messes with the heat seeking system. You also want to keep the conscious and aware since they might have to eject immediately either after they’re hit and they realize they can’t limp back to base, or if the pull a maneuver to dodge the middle that results in an unrecoverable loss of control. A lot of the modern stuff is kinda stuck in a theoretical lurch though as we haven’t really seen large scale air to air combat between near peer forces since Vietnam, so who knows exactly how well modern missiles and countermeasures will actually work.
|
askscience
|
Those corrections are because fighters are typically designed to be *un*stable. Meaning, any disturbance will actually push the plane further and further out of equilibrium rather than return to it. Maneuverability and stability are opposites; the more stable your airplane is, the less maneuverable it will be, and vice versa. Correcting for this requires constant minor control inputs to fix any disturbance before it gets out of control. Think of trying to balance a stick or something upright in your hand. This is *exhausting* for a human to do on by itself, let alone on top of any other high stress task for hours on end, so the fly-by-wire systems constantly adjust the control surfaces by itself to hold the fighter steady.
|
askscience
|
It's possible but not likely that it would be immediate death. Anti air weaponry is typically low explosive because it doesn't take much damage to take an aircraft down, just damaging it significantly is good enough and the goal. Also in most combat scenarios, the missile will hit the engines.
Also, I'm not sure the aircraft is going to be able to out maneuver the missile, what you would hope for is to somehow maneuver quickly enough to get out of sight of the missile's tracking system. However that won't really happen considering the missile can out maneuver the aircraft and is much faster than the aircraft as well.
|
askscience
|
Those systems do exist. The JU87 Stuka famously pulled out of dives on its own (provided the pilot clicked the bomb release button while the dive brake was deployed). It wasn't hugely precise, but it could pull harder than the pilot, allowing for a lower and more accurate release.
Some modern fighters like the F16 and F/A18 trialed systems that would save the pilot from hitting the ground completely automatically. Called GCAS, there's [footage of it saving a pilot who blacked out on youtube](https://www.youtube.com/watch?v=WkZGL7RQBVw). I'm not sure of its current status, it may be in widespread use already.
|
askscience
|
Realistically there's not really any chance you'd be in a position for it to happen.
But, a Heatseaker has a IFF (identification friend or foe) before launching the missile, after firing the missile it is locked onto its target and will go after that, but if it looses the infrared lock (or something hotter comes along), it will go after the next heat source which can be a friendly plane as the missile only cares about the heat source of whatever its following once launched and has no distinguishing abilities on its own.
The main issue with the missile hitting the aircraft that launched it isn't that it can't happen due to mechanics, but it's somehow physically doing some movie type maneuver to make the missile curve round and hit the plane that launched it
|
askscience
|
Yes, but you CANNOT skip the 2.5 years in any way, whereas 41K man hours means that if you have 41 people doing 60 hour work weeks, you're done in 4 months. It doesn't scale indefinitely, but it does scale.
Also, the supply of skilled pilots is considerably more limited than the supply of materials to build fighter jets. Just the amount of people that can handle the G-forces a figher pilot must already limits the amount.
​
|
askscience
|
In real life, the idea is always to avoid a strike. Either through electronic warfare, blinding the missile, decoys, or maneuvering. Possibly soon, it will involve destroying the incoming missile.
Thoughts on defense against ground based anti-aircraft defenses have varied over the years. Initially it was all about going higher and faster. See the transition from B-36 to B-52 to B-70.
Then it was thought that the SAMs had gotten too good for that to work, so they decided to try low and relatively fast (but still subsonic, because it's hard to move supersonic down low). Turns out this is a mistake for two reasons: SAMs weren't actually that good, as evidenced by the later stages of the Vietnam war, once doctrine caught up with reality. Low and fast doesn't give you as much time to think of options as high and fast, because the missile doesn't have as much time to hit you. And going low exposes you to a lot more potential anti-aircraft fire. The big expensive SAMs required for defense against high altitude bombing might not work so well down low, but you can give cheap SAMs to a bunch more people, and even use stuff otherwise considered obsolete (radar guided artillery cannons).
This last problem wasn't realized for a while (not until OIF, roughly). It wasn't what spurred the idea of every fighter being Stealth, but it definitely didn't hurt. SAM defense now is mostly: try to avoid where it's defending, and when you can't, make sure the SAM site isn't there to be defending.
Heading for the ground might still be helpful, but more for being able to turn your potential energy into kinetic energy in order to run away better.
|
askscience
|
Fighters rely on several things to evade radar guidance systems.
1. Radar jamming. Some more modern aircraft radars are capable of entering a “jamming mode” where they can interfere with the incoming radar signal. The F-22 Raptor and F-35 Lightning both have this, and some other older US fighters have been upgraded with it.
2. Pilot evasive maneuvers. A fighter jet will never be completely out of the control of its pilot, even if the automatic pilot is engaged, mostly because of the idea that you always want a *person* making decisions about when to employ a weapon system.
3. Chaff. https://en.m.wikipedia.org/wiki/Chaff_(countermeasure)
Basically a short range projectile that contains metal or plastic fragments that can disrupt missile radars.
|
askscience
|
He has a safety harness keeping him strapped to the rocket. When he fires he is knocked off the harness and cooked in the rocket's exhaust as the safety harness keeps him tied to the rocket. The rocket races forward straight while the road turns and slams into the side of a cliff - exploding and cracking the side of the cliff. Wile E. Coyote peels off the side of the cliff, and falls down onto the desert floor below with a little mushroom cloud. The force of his impact expands the cracked cliff face and a huge chunk of rock detaches and falls down, right onto our unfortunate predator.
|
askscience
|
easy - if the radar signal power level fades in and out - it's sweeping (looking for a target). if the signal is strong & continuous it's locked on targeting you.
Edit - clarification on fades in and out...when the enemy's radar is pointed at you, the radar signal will be clear and distinct, when it points away from away from you the signal will be weaker and somewhat fuzzy since what you are sensing are jumbled reflections.
|
askscience
|
Not out of the realm of possibility in the near future. As it turns out, however- airplanes are designed with the pilot in mind. The airplane is usually stressed to 8-10 G forces- about the same as the pilot. Combine that with the short duration of the maneuver and it’s unlikely that the maneuver would incapacitate a pilot. The F-16 currently has “computer in the loop” flight controls which help prevent controlled flight into terrain (CFIT) via Automatic Ground Collision Avoidance.
|
askscience
|
The f18 super-hornet knows if you pass out though. If you release grip on the sticks it will just fly straight and level. This is not what that plane wants to do, without the flight computer if you took your hands of the sticks for long it would just tumble out of hte sky. They also auto launch, so when you are comming off the carrier the pilot doesn't actually control the aircraft. You will see they actually hold onto the handles during launch and only grab the controls after they start to pull up off the end of the ship.
|
askscience
|
Public knowledge? No. In reality? Probably.
Despite what people say here g force recovery times are fairly reproducible and consistent for a trained pilot. Modern jets monitor their pilots internals and can fly themselves for the most part. From an engineering perspective there's no real reason why the jet cant make the maneuver and fly itself until the human regains control.
That being said you could just make the jet fly itself with no pilot but to answer your specific question yes I'm sure this technology exists in a lab somewhere. I'm also sure it's in use in some aircraft.
|
askscience
|
I don't think that's accurate either. The A-10C, for example, has multiple countermeasure modes; Manual, Semi-Automatic, and Automatic. In the automatic mode, the CMSP will automatically select the correct counter measure profile based on what the system *thinks* was shot at you, and then automatically dispense those countermeasures without the pilot having to do anything.
Semi-Automatic mode will automatically select the counter measure profile for the pilot, but the pilot will have to manually press a button to begin dispensing counter meausres.
And in Manual mode, the pilot has to select both the counter measure profile and manually activate it.
|
askscience
|
Perhaps you're envisioning a situation like a dog fight or near range shot where the attacker and target both are aware of each other. Future combat might not be like that.
A stealth fighter might not turn on their radar at all because doing so also gives away their location. They might rely on passive data or data from other aircraft. Firing from >50 miles away. The missile turns on radar last mile or so. But yes according to public data, bvr shots have a ~60% kill rate.
|
askscience
|
While you are technically correct “cone of shrapnel” isn’t a valid way to describe the warhead action of a missile, depending on the missile type it could be a radial fragmentation (bunch of metal cubes blown out in a circle around the missile), to continuous rod (basically an expanding buzz saw rotating at high speed).
Again depending on the missile depends on the warhead (and even different models of the same missile can have different warhead types), and my comments reflect knowledge of US based missiles only.
|
askscience
|
To clarify one point: the RWR cannot always detect when the radar has switched from scanning to a lock because there are different ways of locking up a target. The RWR generally knows when the aircraft has been locked because the locking radar narrows the radar sweep so instead of scanning the area immediately around the target, for example, once every two seconds, it scans that area several times per second and continually adjusts the focus of the sweep to keep it centered on the target.
Modern "conventional" (versus even more modern active electronically scanned array systems) radar systems can guide active radar homing missiles (i.e. those with their own onboard radar in the seeker) within the shorter acquisition range of the missile (a little over a few miles) with only a "soft lock," which involves having the aircraft's onboard computer extrapolate target movements. The target can't tell the difference, so you don't know when you're locked/launched on versus just being scanned until the missile seeker goes active very roughly ~10 seconds from impact. This is all very fuzzy information, though, since all of this is still largely classified and it's hard to find definitive public information.
I have no idea how this works with AESA systems since they scan ridiculously fast all the time.
|
askscience
|
Yes, but most missiles will burn through all its fuel in matter of seconds. After that, it'll lose its speed quickly. If the pilot have ample warning time, a proper maneuver can force the missile to bleed its speed to the point that it can no longer catch up with the aircraft. Missiles don't "chase" planes the way movie portrayed, unless the targeted aircraft is very close to the launching point, the missiles will basically be "gliding" toward the aircraft by then because after the burnout, it no longer have the power. It'll be more like a tanker truck encountering an out-of-fuel motorcycle that still have a lot of momentum from prior speeding.
|
askscience
|
Taking it a bit further, different radars operate on different frequencies. You can tell what kind of radar is pointing at you based on that. In the flashlight analogy, you could think of it as color of the light (that literally is the frequency of the light actually). And if you know that a green light is a search radar, and a red light a guidance radar, you can then know if you're targetted or just being spotted.
Taking what /u/__redruM said also, its important to note that besides just exposing you, radar exposes you at much further distances than its capable of seeing. Again, the flashlight analogy works well. A flashlight really only illuminates everything for a few feet in front of you, but someone a mile away might be able to see the flashlight when its pointed in their direction. The person with the flashlight can't see this other person, but this other person can see them (or at least the light of their flashlight). Radar works the same way.
|
askscience
|
Not sure about missiles, but the technology is there to terrain avoidance. Auto GCAS (ground collision avoidance system) has already been credited with saving a number of pilots.
"Once the program recognizes the aircraft is likely to crash, it prompts the pilot to evade either a ground crash or a controlled flight into terrain situation. If no action is taken, Auto GCAS assumes temporary control, engaging an autopilot maneuver to roll the aircraft upright and initiate a 5-G climb, diverting the plane and pilot out of harm’s way.
After putting the aircraft on a safe trajectory, the system then returns aircraft control to the pilot."
https://www.acc.af.mil/News/Article-Display/Article/1026196/point-of-recovery-ground-collision-avoidance-system-saving-pilots-lives/ article about it
https://youtu.be/WkZGL7RQBVw video of it in action, referenced in article. You can tell when the pilot passes out based on his breathing. You can hear another pilot yelling "two (his callsign sully-2), recover" as he dives below the "floor" of the exercise, 12,000 ft (numbers on the right side). The x across the screen with "fly up" is the auto GCAS kicking in, with an audible tone and verbal warning "pull up." The other pilot calls "knock it off" (cease activity due to a safety concern) and tells him to "get yourself back above the floor" (return to the airspace they're cleared to be in)
|
askscience
|
The radar warning receiver is simply a series of sensors that are capable of measuring the wavelengths/frequencies of incoming emr (electromagnetic radiation). They are capable of sensing emr in the range of the electromagnetic spectrum that is used for radar, and they send the raw data to a computer in the plane.
The computer is able to take parameters such as frequency, wavelength, and power, and identify not only what mode the radar that is painting the aircraft is in, but what type of radar it is, and from that information what type of plane is locking you up or searching you. The way this is accomplished is a combination of really good programming, and military intelligence to gather information on enemy radar systems and their specific radar signatures. I'm not sure the exact methods they use to build databases of different radar patterns, but I'm sure there is a huge amount of human effort and money that goes into the construction and maintenance of an RWR system.
​
|
askscience
|
'any danger' is too broad of a hand-wave my dude.
even 'medical danger' is broad enough to include the uncertainty in recovery latency resulting in further weapons vulnerability, aircraft malfunction, and crashing.
Yes we know 'knocked out' doesn't imply death, except in totally complicated scenarios or something.... like being in a plane, hurtling through air at supersonice speeds, that may or may not have just evaded a missile, it relies on you waking up within a 100ms-2s to qualify as 'fault tolerant'.
|
askscience
|
Yeah, missiles have gotten a lot better, on both sides. The F4 occasionally ended up in gun range in very large part *because the Migs needed to be in gun range*. Both sides use missiles, now.
Most fighters still have guns mainly because they're occasionally called to fire at soft targets where a missile wouldn't be appropriate, like strafing an enemy ground position or shooting down a non-threatening air target that isn't worth the cost of a missile.
|
askscience
|
The sensors for detecting IR missile launches are generally looking for a UV burst as the rocket motor ignites, rather than a heat signature. While IR missiles aren't particularly long range, they're likely launching from multiple kilometers away and detecting a small heat signature at that range with a wide field of view system is seriously difficult. On the other hand, picking a bright flash of UV (that tends not to come from many other sources) is relatively easy.
Of course, this can be taken advantage of. If someone on the ground was to be say, arc welding, it can set off the IR warning system within a limited range.
|
askscience
|
The Russians were working on a HUGE (like 1,500 lb) anti-radiation missile with a 400km+ range specifically for the purpose of engaging AWACS (and possibly tanker, homing in on emissions like TACAN) aircraft.
Even if they couldn't reliably kill AWACS it would force them to evade and be less effective. I'm pretty sure the program ran out of money before anything was fielded but the concept wasn't totally ludicrous.
Another plan that I don't think ever got beyond planning was a turbine powered cruise missile-like first stage with a solid rocket second stage that lit off when near the target.
|
askscience
|
And to extend it to stealth/radar cross section: imagine you're wearing a white t-shirt. You'll be seen much sooner than if you were covered in all black clothes. That's the difference between radar reflective and radar absorbent material.
Now imagine you're covered in mirrors carefully angled away from the guy with the flashlight. That's stealth shaping. The nightmare there is you have to make sure that every edge is perfectly fit so it doesn't glint.
|
askscience
|
I would not be surprised if we find that we need a second human either in the aircraft or remotely to be a drone/sensor/weapons operator and the pilot does piloting.
Managing the cloud of drones that operate sensors, carry additional fuel and/or weapons and fly on hostile airspace is a complex task. Some of the theories blending drones, stealth fighters and non-stealth weapons trucks is interesting. Can't wait to see how it all settles once the technologies mature.
|
askscience
|
Adding to this, the RWR does it magic by analyzing a radar transmission mainly through its frequency and pulse rate. It will compare this data with a library of known radar signatures and present this information to the pilot. If an unknown radar signature is encountered, I imagine some sort of heuristics is used. There is little to no information in this area that is available to the public for obvious reasons. The frequency and pulse rate of a search radar is generally not the same as they are for a radar that is used to "lock on" to a target. Certain frequencies are good for searching for a target but not good enough to guide a missile to hit a target. Other frequencies are just the opposite. You can see evidence of this in articles about stealth detecting radars. They never mention how good it is at shooting down a stealth airplane. Pulse rates are generally higher when a radar is "locked on" to get the most up to date information to get the best chance of hitting a target with a missile.
Just having a RWR does not automatically mean a pilot has a clear picture of all radar activity in the area. During the Yom Kippur War, the SA-6 made its combat debut and spanked the IAF because they did not have any information on its radar signature. The effectiveness of a RWR is mainly dependent on the signature library. A library is worthless if there are no books in it. One can imagine how some of these signatures were acquired and what is required to keep this information up to date.
​
|
askscience
|
Generally no, there are various ways of reducing/eliminating interference, to allow friendly forces to recognize their own signals, and to hopefully prevent enemies from spoofing or jamming. There are a range of frequencies available, schemes that may jump around or sweep across frequencies, ways of coding the signal to make it stand out, and equipment able to detect which direction a signal is coming from.
While you could jam a target's radar systems, you probably wouldn't try this at the same time as attempting your own radar lock, unless you were certain the two systems wouldn't interfere with each other. There is also the risk of weapons being trained on anything emitting radar (e.g. anti-radiation missiles).
|
askscience
|
It is avoidable for ground sites, thats how the Serbian air defence network was able to do so well with essentially obsolete equipment vs NATO air power during the breakup of the former Yugoslavia.
Just because they didnt WIN (yeah, winning vs any coalition involving the USAF, let alone their allies aint happening unless you're a nuclear power) doesnt take away from the achievement of what they did do, which was drastically reduce the effectiveness of NATO's airpower during the campaign.
|
askscience
|
To piggy back on tasteslikesardines comment. The search radar is pulse and the tracker is CW (at least on the last system I worked on). We used to set the radar to work before fitting it on the type 42 destroyer. One way to test the tracker was to scan for a nice fast flying aircraft and get a missile lock on it so the tracker could track. This worked fine and didn't upset anybody until the air-force started flying over. The tornado crews were not happy when the alarms all went off. I later worked with one of the navigators and he told me the adrenaline rush was very difficult to come down from and that we were very lucky they never flew with live missiles because they would probably have just fired on us as an auto response. We still thought it was funny. Ground crew don't often get one up on the fly boys.
|
askscience
|
> The pulse radar range of the AWACS is over 400mi
Is it true the AWACS could focus on a plane and dial up the power until the electronics are all fried and the pilot can no longer sire children?
I think I read that in a Tom Clancy book. He talks about them using it as a way to express displeasure (you're getting too close to the mother ship!) without shooting them down and starting a war.
|
askscience
|
I have a family and am the primary breadwinner. I understand that it is supposed to be a 'threat' but it is something I couldn't do.
Just yesterday I went to see a doctor for it as I was referred to them, and their response to 'Ive had physical therapy, which made it worse, ive had muscle relaxers, which didnt help, ive had nerve relaxers, which helped only a little, a mixture of the two which worked but made it hard for me to make it to the bathroom, much less function at work, ive had several different anti inflammatories because 3 differwnt doctors thought it was a swelling of a muscle aggrivating a muscle at the base of the head that was aggivating the nerve cluster. Thosr never helped. Ive also been perscribed a medication for nerve pain and depression, but after two weeks i couldnt handle the insomnia, the mini blackouts, the dizziness, the heat waves, and the like. Ive also had 2 injections of some steroid which made things worse, and had Xrays and an MRI which showed nothing.'
And the fucker responded with 'Its your posture, im gunna refer you to a physical therapist, and give you a steroid injection for today'.
I kinda just threw in the towel on the whole institution for the moment. I guess I will work like always, maybe black out from pain every once in awhile, lose tons of sleep to the pain, but ill be damned if Im gunna put more money into getting told 'Hey theres nothing wrong' and have to deal with those symptoms anyway.
Maybe ill get into illegal narcotics (/s). More than likely though ill just be miserable and depressed though. And its tough to explain to people that I usually hover around a 3/10 pain for a normal day, but that usually goes up to a 6 by the end of the day, and can hover at a 8 or 9 for several days at a time, and that the pain is depressing me, not some sycophantic self loathing (though i figure we all have our fair share of that)
Sorry for the wall. Felt like venting.
Have a good day m8.
|
askscience
|
It's the R-37, its operational range is somewhere between 150-400 km. While 400 km is doable for a missile that large, being able to target an AWACS from that distance is unrealistic since an interceptor's radar can't hope to match AWACS' huge radar. The launch would definitely be noticed.
R-37 is reported to have a speed of around Mach 6, or about 2 km per second. So if an AWACS is exactly 4 km, it'll still take almost 3 minutes and a half for the missile to travel that distance (and I'm ignoring the fact that the missile will already ran out of fuel like a third of the way before and is just "gliding" at this point), I wouldn't doubt that even a 707 could evade a missile very low on energy from that range with that much warning time. The escorting fighter would be throwing chaffs to distract it away as well.
It is possible to build a cruise missile that can targeted other aircraft, however, those will have a large RCS and could be shot down by an escorting fighter. That's why the idea doesn't really lift off.
|
askscience
|
Satellites will only have a limited window of visibility as they pass over, possibly not enough to coordinate the engagement. You'd also need a lot of them to have sufficient coverage. Closest I've read to that is signals intelligence satellites detecting the radar emissions of warships. As they're slower moving, you can lob a missile in their direction (from an undetected submarine for bonus points) and it'll generally be in the right place when it arrives.
|
askscience
|
No worries! I would hate to see someone wander into trouble because they thought it’d be safe.
The difference is send versus receive. Pilots want to know when they’re being targeted by shoulder launched weapons as well as big SAM sites. As to how the pilot or the aircraft responds, I would hazard to guess is based on aircraft configuration, model and experience. I would imagine, since the frequencies of police RADAR are known, it is negligible these days.
The effective range of many modern police RADAR units are usually around a mile, but the actual range the beam can travel is significant (technically infinite, until reflected, refracted or absorbed). This is usually why car RADAR detectors go off for no explicable reason.
|
askscience
|
At peak output they will only be producing 17 per month for the F-35. What is the max they could feasibly produce per month? 50? Let's say 50 planes per month for 2.5 years. That is 1,500 aircraft produced at a cost of $120 billion.
Individual pilots may take longer to train but you can train thousands of them at a time if necessary. Over the same 2.5 year period you can train 1,500 pilots for just $3.9 billion, a tiny fraction of the cost of the aircraft. Let's include the statistical total value of a human life which is between $7 and $9 million. Let's say they are all really exceptional people worth $18 per head. That is a total net value to society for 1,500 pilots including training investment, lifetime support to include college, and total lifetime potential future earnings of $30.9 billion dollars.
I'm not saying we should view human life as an expendable commodity ever but as a statistical matter for war planning on average an 80 million aircraft is worth 4 to 7 times as much as the pilot that flies it.
|
askscience
|
Humans and chimps mate all the year round so there’s not really a season where it is favourable for mating. If there was a particular bad time of year for babies to be born i.e. depths of winter in the arctic circle then it would be common sense make things easier by not mating 9 months earlier but this is a conscious decision and not a biologically driven. Anyone who has tried for a baby knows there’s a few days every month when the chances are highest when the woman is in oestrus which is probably the closest thing to a mating time.
|
askscience
|
What you're describing are [tangent circles](https://en.wikipedia.org/wiki/Tangent_circles). The circles touch at exactly one point.
Algebraically, we can write the equations of the two circles as:
(x - x_1)^(2) \+ (y - y_1)^(2) = r_1^(2)
and
(x - x_2)^(2) \+ (y - y_2)^(2) = r_2^(2)
where the first circle has center (x_1,y_1) and radius r_1, and the second circle has center (x_2,y_2) and radius r_2.
If we look for values of x and y that satisfy both of these equations, there are three possibilities:
1. There are no solutions. The circles do not touch.
2. There is one solution. The circles are tangent.
3. There are two solutions. The circles overlap.
|
askscience
|
But what is the value of the point at which the touch? That’s always bugged me.
The only equations I have seen basically are to determine whether or not they touch. And that’s the basic answer I get from a lot of math teachers. But what is the value of the point? Can it even be measured, or would that be an example of a value not zero, but just above?
|
askscience
|
It's not permitted. Two figures are considered litterally "the same" in that case. I'm afraid I can't explain it better than this since english is not my native language. e.g.: two squares having the same size and the same (obv bi-dimensional) position on the plane are exactly the same object on the plane, unless you are switching in a 3d space where two squares having same starting two coordinates and size may float one on top of the other (from a top-down perspective). In that case "the same" square would be a square with all the equal three coordinates. Same for a 3 object.
Sorry if I made any confusion. Maybe someone else can be more clear :)
|
askscience
|
I am hoping that someone who Knows will post. I've only seen the "trick someone into sticking their arm in" method. If we could lure mosquitoes into drinking from tubs of blood, it seems to me that that provides a method for annihilating mosquitoes. Some Africans bleed their cattle rather than slaughtering them. So that's half of the job done, right? The other half is putting something into the blood that will make the mosquitoes die or fail to breed. Maybe HFCS. (j/k)
|
askscience
|
Idk why it was tagged as math, but even still, I would assume, not necessarily pool, that was more of an example, but, sphere or circle. Either is the same. But when you talk about a point, a point has to have value, either 0, which means there is no point, or 0.0000001(with infinite zeros) being the smallest amount of contact possible, which technically, should be an infinitesimal, correct?
But the question remains, if two perfect circles, or spheres, are tangent, there is contact, so the value, so to speak, cannot be zero. That would mean they are not tangent.
They touch, meaning, the circumference of each touch, but how much touches? If they were tangent squares, than, whatever the value of a side is, would be the value of which they make contact.
|
askscience
|
>a point has to have value
Define "value." There's a mathematical concept of "measure" which is probably closest to what you're trying to say.
>either 0, which means there is no point
Why can't there be a point? Points have 0 length, width, or height. In terms of measure, a single point has 0 measure. In fact, there are infinite collections of points which have 0 measure.
>0.0000001(with infinite zeros)
This is not a valid real number. Every digit must occur a finite number of places after the decimal. At what position does the 1 occur?
>infinitesimal
Infinitesimals are generally not considered to exist in standard real analysis (essentially the study of real numbers and functions on the real numbers). There are ways to formalize the concept, but for non-experts its best to forget about them entirely.
|
askscience
|
You won't find your answer because you're using mathematical models to describe physics, without taking into consideration the validity of your models. In maths, there is only one point. In reality, you'll never have a perfect circle, and you need to take into account elasticity, perhaps even quantum phsyics to study the very close point of impact, for all I know. There will always be a reason why it'll never truly be a point of impact. It's like trying to apply 1+2+3+.. = -1/12 to your everyday life. It holds some value but you've got to be very careful about how to use your mathematical results in the reality.
​
That being said, it's considered as a point for physics, and you can calculate the distribution of energies with a -point- of impact. But again, it's just a model. Not reality. Reality is, your circumference is practically impossible to determinate, as there are too many factors.
|
askscience
|
Yes. The given age of the universe is in the frame of reference of minimal motion relative to the cosmic background radiation. This means that if we look left, right, up or down we can't tell the difference between the temperature of the background. If we had a large motion it would be blue-shifted in some directions and red shifted in others.
It is also given relative to being in an area with no strong gravitational fields.
If you were travelling with a high speed relative to the background you could calculate a different "local" age of the universe.
If you were stationary in a strong gravitation field and you would also calculate a different age of the universe, however this would not help you much, as you would be dead.
|
askscience
|
No, because strong in this case refers to how strong gravity can be. Just as 600km/s ( our speed relative to CMB ) is crazy fast in comparison to 0m/s, but basically a rounding error in comparison to 300,000km per second, so is 11.2km/s ( escape velocity of earth ) basically 0 in comparison to the escape velocity of a neutron star (100,000 to 150,000 km/s), the strongest gravitational field one can be stationary in.
|
askscience
|
>If you were travelling with a high speed relative to the background you could calculate a different "local" age of the universe.
>If you were stationary in a strong gravitation field and you would also calculate a different age of the universe, however this would not help you much, as you would be dead.
Given the length of a human life and the necessary speed/acceleration to achieve the first option, would this really be less deadly than the second option?
|
askscience
|
You should see the NASA sat loop of the winter, spring, summer, fall cycle of vegetation dying then growing but instead you see the Co2 levels dramatically rise and by mid summer you se O2 levels dramatically rise.
Pretty awesome satellite loop.
Edit: I’ve posted the link three times but I had somebody PM they are not showing up, the links. I’ll try this...
https://youtu.be/x1SgmFa0r04
https://youtu.be/2BWWrJr6TJw
Can you all see this???
Edit: now I can see the messages people are posting pop up on my phone but as soon as I tap to see they are gone. Something is going on.
|
techsupport
|
So my gaming PC is relatively new, I built it about two years ago. It’s always run without any issues but today it decided to go Awalt.
I turned on my PC and went to the widows login screen and put in my password but as soon as I was in my home screen my mouse stopped working. It’s a wired mouse that I’ve had for years but the light on it turned off and it wouldn’t move the cursor. I disconnected it and connected it to another PC and the mouse worked fine. I tried connecting it to other USB ports on my pc but I had the same issue. I then decided to turn the pc off and on again but when I turned it on again it gave me a prompt saying there was no signal input, it also won’t respond to my keyboard.
TLDR: my pc won’t respond to anything plugged into it
|
techsupport
|
I clicked on a link today and some people said this was a keylogger i scanned the URL on virustotal but i dont really understand much about this stuff i would appreciate if anyone could tell me if this link is safe or not. Here is what i got when i scanned it.
http://imgbc.com/images/U6FY3FK/
Serving IP Address
95.142.32.180
Status Code
200
Body Length
5.55 KB
Body SHA-256
21e48444e3251b11b8e9f2a640e7d180e030bf779809f986f386b9f8893c8c0c
Headers
connection: keep-alive
content-type: text/html
date: Sun, 02 Sep 2018 21:41:11 GMT
server: nginx
transfer-encoding: chunked
vary: Accept-Encoding
x-powered-by: PHP/7.1.21
|
techsupport
|
I've done everything I could to prevent updates beforehand, and it sitll faield on me.
I had the update disabler service running.
I had the windows update service disabled and set to no retry.
I had stopped updates from the task scheduler.
I had applied all Windows Update registry settings I know of.
I had set a metered connection.
And probably more.
I NEED to stop this update from installing. What can I do, right now, that would stop it from installing, and prevent it from happening again? I'm in a position right now that I can't afford an update, and this is my number one priority. As you can tell, I took preventative measures, and it still found a way through. I cannot explain how desparate I am. How can I stop this update?
|
techsupport
|
So I'll start with I have the basics of networking down, I've been through network+, started dabbling in cisco ios, but know absolutely nothing about networking on the scale of an ISP.
So here's where the meat is, I live in an area where we have a "private" ISP, as in, not comcast or TWC or something, and for the last week or so I started noticing some weird behavior from my home network, my google homes would often say there was a problem, and games would drop connection randomly, but I never lost any packets, I had a ping test running for like 1000 iterations, and had 0% packet loss. Speeds were exactly what they should be, but still just weird stuff was happening, my security cameras upload clips of motion to the cloud, and they were coming in corrupt. I tried a new router, then eliminated the router and connected to the modem and was still having issues, such as one game in particular wouldn't connect. So I finally tried connecting to a VPN, and suddenly, the game connected, I wasn't getting horrid DNS resolution times randomly (which I had tried different DNS servers both at my computer and at my router, to no avail), everything worked perfectly...
So I went out and bought a router that has a VPN client so I could blanket my network with the VPN, and suddenly my google homes are working perfectly again...
My question is this, how the hell did a VPN fix my issue? Is it something with their routing? One person said that they got someone to tell them that they were taking the Data Blockers (apparently used to keep internet only customers from getting cable?) off everyones lines, as that was part of the issue? I feel like there's enough I don't know about the infrastructure, that the info about the data blockers could honestly go either way, it could be related, or it could be BS.
I know this is a crazy long post, and ultimately, it doesn't matter, they say they know what the issue is, but I'm just supremely curious, and I really want to know what they fucked up. I'm making an assumption of course that they fucked something up, because their whole operation seems to be poorly managed.
If I haven't given enough info for someone with behind the scenes knowledge to make a guess, I'm sorry, please let me know if there's something else I could give you.
|
techsupport
|
I've put my PS4's IP into the DMZ. Didn't work.
I've forwarded all the ports listed on portforward.com. Didn't work.
I drilled a hole in my floor to run an ethernet cable directly into my router. Didn't work.
I bought a new router. Didn't work.
I recently switched ISPs from Xfinity to a local company that runs my city's municipal fiber network. I called them and they said there was nothing they could do since I wasn't using their router.
I'm completely at a loss. I don't know what to do. Please send help.
EDIT: After some tweaking and troubleshooting, I got a call back from my ISP, which is a miracle considering it's Labor Day. Basically they have everything locked down tight on their end so I have to pay a couple extra dollars a month for a static IP address. Thanks everyone for taking the time to respond! Your help was very much appreciated!
|
techsupport
|
So I got this "system mechanic" program I saw recommended, thinking it'd clean up my pc a little bit. Well it fucking did.
Started up the pc today, what do I see?
Everything has been restored to what's basically a fresh install of windows, my desktop's all fucked up, seemingly random icons are still there (I had like 40+ icons, like 10 were left, I don't know by which criteria).
All of my settings are gone (stuff like not adding -shortcut when you create a shortcut).
The "downloads" folder from quick access has been defaulted to "default" I guess, making me think I lost all my downloads, but no for some reason it just made the other one default.
I lost all my documents in the my documents folder.
Lost all of the browser settings. Literally. Like I reinstalled firefox. Also chrome and IE even though I don't use them.
What can I do at this point?
Edit: System restore fixed a lot of shit, I spent an hour fixing up the numerous small problems it didn't fix (like only being able to access reddit for some reason, every other site would get stuck at TSL handshake).
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.