: how does a air-air missile track an aircraft that is constantly changing it’s direction while also traveling supersonic?
In: 321
[removed]
the missile is much faster and can turn far quicker than the aircraft. so much so that a simple program of “point nose towards heat source” is probably enough to get the missile to hit (or explode nearby causing the fragments to hit the plane)
Simplest to explain is probably a heat-seeking missile.
On the nose of the missile is an infra-red camera that sees a hot object as a bright spot. When flying the missile guidance system has one simple rule: “Keep the bright spot in the center of the camera’s view”. If the bright spot is in the center, the missile is pointed straight at the target. If the bright spot is off to the left side of the image the missile needs to turn left to bring it back into the center of the image and be pointed back at the target.
The main trick for tracking aircraft is that the missile can turn **MUCH** faster than a plane that has a squishy meatbag in it.
Tracking depends on the missile. Fox 1 and Fox 3 missiles use some form of radar tracking, which is where you emit radio waves and scan for an echo. If you detect that echo, that means there’s something to bounce the waves. Measure how long it took to return and you can calculate distance to the target because you know the speed of radio waves. If you measure the difference in frequency from what you emitted you can also discern how quickly they’re moving relative to you through the Doppler effect. If you know all this, and you track the target’s angle relative to the radar you have all the information needed to calculate it’s exact position and velocity relative to your missile. You can calculate the target’s trajectory from all these values and tell the missile where in that trajectory to go so that it will hit the target.
Infrared missiles are simpler, they listen for infrared waves and point themselves at the brightest heat source. They have no way to tell distance to the target so they simply follow it until they hit, or until they run out of velocity.
[removed]
The missile has a camera in the front with a lens that lets it see a wide angle of view. The camera is tuned to see infrared (heat), and then fines of a jet are hot so the camera sees a big white spot that that it aims for. Electronics in the missile tell it to steer the missile so that the bright spot is always in the middle of the view (straight ahead). If spot moves away from the center, the missile’s electronics adjust its direction. It steers by moving little fins on the missile like a plane steers by moving its flaps and aileron. The missiles are designed to be faster than jet fighters and they can turn much quicker too (because of G forces, a pilot can pass out if they turn too quickly and missiles don’t).
This why air-to-air missiles are so deadly and so fantastically expensive. The missile costs 10 times the yearly salary of the person that fired it, but it can bring down a plane 25 to 150 times its cost.
Very very complicated math
No mere mortal can understand it except those who have studied math.
air air? do you mean anti-air?
Infrared sensor on nose of missile
As soon as it, say, detects the infrared signature going to the right, it twiddles its nozzle to the right so it steers that way etc
That’s why flares work as a deterrent, they confuse it thinking there’s a hundred little planes in a cloud that it needs to track
(Pretty sure there are other ways but this is the simplest one)
All the other explanations here are missing one crucial point: the missile arrives from a distance and it has a broad field of view—be it radar or infra-red, doesn’t matter, but what does matter is that it can “see” the target against a wide background and can make a *minor* correction for each *major* maneuver that the target makes.
Think of it like this.
You’re running on foot through an open field from a bandit that’s chasing you on horseback. If you run in a straight line, you’re doomed, right? So your only chance is to try to go to either side and hope that you’re able to jump away from the bandit.
But if you start turning to the left, the bandit will see you doing so and will guide his horse to the left immediately. He won’t have the horse run along your path, but will try to cut you off—to intercept you as you’re turning left. You’re at an inherent disadvantage because whatever you do, the bandit will adjust against what you’re doing. And in order to chase after you, he will need to make a very slight turn to the left for each significant turn to the left you make yourself.
Yet another way to think of it is to imagine a right-angled triangle.
C
|
____|
A B
As you see, in order to get from point A to C going through B, you need to make a sharp turn of 90 degrees and cover the distance AB+BC. But now imagine adding the hypoteneuse. The bandit (or missile) needs to make a much slighter turn to get from A to C directly and the distance of AC is shorter than AB+BC.
And on top of that, since a missile doesn’t have a human body in it, it can maneuver with G-forces that exceed what a human being can handle, which—to continue the bandit analogy—makes it very hard to jump away from the missile at the last moment, since the “bandit’s horse” can turn on a dime.
But just to be clear: missiles in real life don’t chase after planes as if they’re Wile E. Coyote and the Road Runner. A missile’s job is to intercept the target. If it misses, it’s done. So if you do jump away from the bandit and his horse (for example, because you throw sand in the horse’s eyes—the metaphorical equivalent of chaff and flares), you’re safe. Until another bandit comes after you.
Edit: Let me add—[this is an example](https://youtu.be/ITwA9M2Qtcc?t=196) of how a missile (a SAM in this case, but same principle) *does not work*. It’s not able to chase a target through so many maneuvers in such a long time, if for no other reason than simply because it won’t have enough fuel.
Latest Answers