Often in the movies we see a torpedo homing in on a sub, or a heat-seeking missile homing in on a dogfighter.
Suppose we had an ace pilot who is a master of escape-and evade, trying to shake the tail.
How long does a rocket fly or a torpedo swim until it runs out of gas?
Depends on the missile being used (torpedoes vary too but not as much).
The AIM-54 Phoenix missile has a range of 100 miles. The AIM-9 Sidewinder missile has a 22 mile range. Stinger missiles have a five mile range.
The US Mark 48 torpedo has a range of about 30 miles (it varies depending how fast the torpedo is set to run at).
Missile ranges are a bit more complex than ranges on firearms or artillery because missiles are not that much faster than the aircraft they’re fired from or chasing after And since air thickness varies greatly with altitude, so does air resistance which works against range.
If a source (e.g. wiki) says the range of an AIM-9 is 22 miles, that means something about like this:
Assume two airplanes headed towards each other at high altitude and high speed. One fires when the other is 22 miles away dead ahead. The target keeps coming straight at the shooter. The missile and the other aircraft meet in the middle maybe only 15 miles from the point of firing and by then the shooter is only 7 miles away from that meeting point. When the missile does get to that point, it’s almost out of oomph and any maneuvering, even a gentle bank, by the target would cause a miss.
So about 7 miles of the 22 was covered by the target driving into the missile, about 7 miles-worth was covered by the speed the launch aircraft gave the missile, and about 7 miles-worth was covered by the missile accelerating ahead of the launch aircraft. Given these airplanes are going somewhere around 7 to 10 miles per minute we see the time of controlled flight is on the order of one minute maximum. In the case of AIM-9, the motor burns for a fairly short time and the missile coasts most of the way to a target at max range. For close-in shots the missile will still be thrusting all the way to intercept.
Conversely, if the target and shooter are traveling the same direction with the shooter trailing the target, and the target is fast and the shooter is slow, and the whole engagement is taking place near sea level, the effective range will be much less.
After firing the missile will first have to accelerate to match the target’s speed, then get faster than the target’s speed. The whole time the missile is slower, the target is getting farther away. Once the missile is faster it will begin to close the distance. If it’s pushing through thick air down low it may not get that much faster than the target. Nor will it accelerate as well as it could at high altitude. Once the motor burns out the coasting phase will be short before the missile once again slows below the target’s speed and begins to drop farther behind.
For something more like AIM-54 which was more of a cruiser, the motor burned at high intensity briefly to get the missile up to speed, then reduced to a lower thrust to drive a long distance out to the target.
The same kinds of issues about intercept geometry, maneuvering, and altitude still play.
IIRC the AIM-54 would climb to very, very high altitudes and then drop down on the target from above making use of all that potential energy it has. I have a dim memory reading somewhere the way pilots defeat this missile is to fly straight up in a corkscrew at the missile as it is diving down at you. Of course this missile was meant primarily to take down long range bombers which can’t really do that (maybe it was the AMRAAM…very vague memory of it).
There are surface-to-air missiles with a range of 400 km (249 miles):
If by “how long” you literally mean how much elapsed time (not how far), at the S-400 missile’s speed of Mach 6, this would imply a flight time of roughly three minutes.
“Dogfighters” are frequently shot down by surface-to-air missiles, but if you mean only air-to-air missiles they vary from a few mile range up to 200 miles, although the really long range ones are intended more for bombers and support aircraft than fighters. The flight time in this case might be up to three minutes: R-37 (missile) - Wikipedia
For torpedoes, the Mk 48 ADCAP has a range of up to 27 nautical miles (31 statute miles): Mark 48 torpedo - Wikipedia
This would imply a roughly 40-minute running time at maximum range.
Re “heat seeking”, if you literally mean only missiles which exclusively use heat-seeking, this would generally be short range. Radar guidance is typically used for medium and long-range missiles. However some surface-to-air missiles use multi-mode seekers which begin with radar guidance then switch to infrared for the terminal phase. Examples are Patriot PAC-3 and THAAD, but they are generally intended for anti-missile operations not anti-aircraft. That PAC-3 definitely has some anti-aircraft capability (however limited) because its warhead includes a “lethality enhancer” for that target type.
Missiles like the original heat seekers just chased the fire, so as the aircraft maneuvered, the missile had to follow suit and try to stay locked on and catch it. Not anymore.
Now the best ones calculate future position as they close and fly towards the anticipated meeting point, “cutting the corner” so to speak. This reduces the number of times the target can change directions and get away with it.
Dennis
Medium-range air-to-air missile spend most of their time gliding. The AMRAAM is meant to burn for about six seconds, but can then fly ballistically for a long way. The maximum effective range is much shorter than the maximum kinematic range, because by that range the missile can hardly manoevre without losing all its energy. The Russian Adder missile stretches its fuel with a “sustain” burn which gives it a shorter maximum range, but means it burns for longer and can react to manoevreing targets for longer. The European Meteor missile uses a ramjet so it has a much longer effective range compared to maximum range, at least in theory.
It’s certanly possible to dodge incoming missiles. Dump ordinance, increase speed and climb.
I think a factor is that there isn’t really much dodging, as far as I understand it as soon as the missile detects that it has overshot the target it detonates, so even if it was manoeuvrable enough to turn around and come back it doesn’t.
The documentary Behind Enemy Lines notwithstanding. 
That’s mixing several issues.
As you rightly say, almost no antiaircraft missiles can pass the target then turn around and take another pass at them.
The missile typically doesn’t actually want to impact the target; it’s more effective to pass a few feet away and detonate there. See Continuous-rod warhead - Wikipedia for more on warhead & corresponding fuze design.
Almost all fuzes are designed to function at or just prior to the point of closest approach, however close that is. In general the fuze is set to function at a max distance that’s a bit bigger than the warhead is likely to be effective. e.g. if the warhead is good out to 100 feet, the fuze will trigger as long as the point of closest approach is less than, say, 120 feet. A miss farther than that will not trigger the fuze. The thinking being that getting a lucky wound on the target is better than nothing.
But all that doesn’t mean “dodging” doesn’t have a role to play. A maneuverable target like a fighter will be maneuvering aggressively to avoid the missile if the pilot sees it coming. Meanwhile the missile will be actively counter-dodging trying to get to where it thinks the airplane will be when their paths eventually cross.
Early on that can be the target trying things like descending to hide behind a hill to interrupt a radar track, or putting a bright cloud in the visual background against an IR missile. As well, chaff and ECM are used to counter radar-guided missiles while lasers and flares are used to counter IR-guided missiles.
In the mid-course phase, and especially after the missile is coasting as blindboyard described, any maneuvering by the missile greatly reduces its range. If the target knows what’s going on he can weave first one way and then the other. Which causes the missile to overreact as it tries to fly to where it thinks the target is now going. A couple of violent weaves can knock many miles off the range of a coasting longer-ranged missile. Maybe enough range that it falls from the sky before it gets to the target.
At the last ditch phase, the missile is typically closing on the aircraft at a high relative speed. The missile may have a lot of G capability, but turn radius is speed^2 / G and the extra speed means the missile makes relatively wide turns.
So the trick is to keep an eye on it and make a very sharp max effort turn when the missile is close enough that its best effort to turn to follow you won’t be enough for it to get close enough for the fuze to function. Even if you don’t evade it completely, you’ll be contributing to increasing the miss distance which may be the difference between your jet coming apart or just being wounded.
Bottom line: dodging is very much part of missile countermeasures.
There are more plays in the playbook but this post is long enough already.
Yes sorry, I phrased that poorly, thank you 
One thing I have wondered. In the movies, flares and chaff trick the missile into detonating prematurely. So there’s this big flashy explosion and our heroes fly away safely. Shouldn’t the missile have a fuse that detects the mass of metal of an airplane or something to prevent such trickery from working?
Without going into what’s in movies, depends on the missile and fuse. Some early air-to-air missiles such as early Sidewinders had passive IR proximity fuses, so those could conceivably be made to detonate by an IR decoy. Likewise the radar proximity fuses typically used on early SAM’s might be simple enough for a chaff cloud to cause them to initiate.
But in general the idea of such decoys was or is to make the missile miss outside lethal radius rather than prematurely detonate it. Also most AA missiles have end-of-run fuses so they detonate before hitting the ground if they miss.
But the whole history of missile guidance systems and fuses v countermeasures is a book length topic, and a lot of the most relevant recent examples would be classified, or simply unknown*. To stick with US AAM’s just as examples, the AIM-120 has a radar proximity fuse, recent AIM-9’s have active laser fuses. It’s reasonable to assume both are relatively difficult to fool as are the seekers, but can’t be assumed it’s impossible. Some antiaircraft missiles also rely on directly hitting their targets.
On earlier point of weapons being decoyed and coming back for a second pass, this isn’t very plausible for a/c target, but some antiship missiles are programmed to try it, and so can Mk.48 torpedoes. They are after targets which will have moved a lot less (and limited to two dimensions in case of a surface ship) by the time they try again.
*nobody necessarily knows how the latest missiles and countermeasures would fare against one another.
Here’s mine.
[quote=“Bear_Nenno, post:14, topic:784337”]
Here’s mine.
[/QUOTE]I’d love to see a computerized reconstruction or something of what happened. It’s certainly dramatic but the actual visuals make the special effects of Dr. Strangelove look good.
This.
The missile might or might not detonate as it passes the flare or chaff cloud. It certainly wouldn’t detonate prior to closest approach to the decoy or target aircraft, whichever happened first.
The hope is simply that A) the missile chases the decoy, B) ideally the missile fuze doesn’t trigger when it goes by the decoy, and C) if it does trigger, the decoy and target are far enough apart by then that the warhead effects don’t reach the target aircraft.
Any depiction that the missile detonates in response to a decoy just appearing somewhere out in front of the missile is bunk.
Having said that, missile / aircraft intercept can involve some pretty wildly dynamic 3D motion. Even an accurate 2D depiction of the 3D motion can look plenty misleading to amateur audience members. OTOH, Hollywood only inserts as much reality into any scene as is necessary to tell a good story; excess reality is a detraction, not a benefit to good story telling.
So the upshot of this that I am getting is the best way to ensure a kill is to make sure the first time the pilot realizes he is under attack is when the missile detonates next to his A/C? Cause if he gets warning, he has a good chance to survive and a skilled pilot can make it even better odds?
Isn’t this one of the reasons why BVR combat has proven to be less than promised? Since RWR can tell the pilot he under attack and he can take evasive actions.
Submarine and dogfighting movies of 10-20 years ago or more relied on what we would now call primitive technology. Point, shoot, and hope.
If I were designing missiles or missile defense systems today[sup]*[/sup], I would have the following at my disposal:
Missile design: A video camera with modern software would have no problem differentiating between a submarine or plane and countermeasure chaff. Think size, shape, motion. And…you’re running out of fuel in 2 seconds? El-blamo and you might get lucky – what do you have to lose?
Countermeasure design: How can you make the missile miss? What can it not do? Can it climb as fast as your plane? Can it turn as fast? Can you fool it into thinking a cloud is your plane? How long can it go without running out of fuel? Can you shoot it in the vital organs? Confuse the guidance system? Offer it a free cruise in the Bahamas?
We’re a long ways from WWII point & shoot tech.
For sure an oblivious target maximizes the missile’s chance of success. Conversely, a well-warned target, and especially one that can catch sight of the incoming missile, can do his/her best to defeat it.
In both cases we’re talking an incremental / decremental percentage over what’s already a percentage shot. The total number of publicly reported genuine AAM missile vs. fighter engagements is still a small enough sample that it’s hard to reach statistically valid conclusions. e.g. if current stats give us an 80% expected success rate in the generic case, than an oblivious target may add 10% whereas a perfectly flown defense may subtract 10% to the odds on this particular engagement.
BVR adds a host of obstacles to reliable kills.
Not least of which is the simple kinematic reality that from the attacker’s POV, shooting as early as possible is best, but in many cases that early shot affords the target a guaranteed miss if he simply promptly turns tail and runs. The problem is akin to that of the old duelists: upon turning to face the opponent, do you shoot quickly and perhaps miss, or take more time to aim carefully and perhaps get shot while still aiming?
Beyond all that, if there are 10 things that have to go right to score a kill after launching an AIM-9 from an established tailchase, there are 100 things that have to go right score a kill with an AMRAAM launched head-on at an opposite direction target too far away to see. All in all it’s a very complicated process being done under severe weight and power consumption restrictions in a violent physical environment.
Imaging seeker design is a current area of interest.
OTOH It’s easy to forget that a fighter sized target at 10 miles is a tiny, tiny dot. The angle subtended by 50 feet at 50,000 feet range is on the order of 3 arcminutes. And the atmosphere is not completely transparent to any of UV, visible, and IR. Optics can make up for some of that, at the expense of field of view. Unless you add intelligent zoom. Which is another incremental problem for your weight, power and complexity=reliability budget. To say nothing of your $ budget.
Once the target gets close enough to start resolving shape then imaging intelligence can play a large role in the end game and fuzing logic. As you suggest.
Putting both of my last two posts together, by far the best defense to missiles is to prevent the enemy from every getting off a shot. Once there is iron in the air things get ugly quickly if you’re the target.
BUMPED.
Interesting reading on the Syrian-USN engagement. Now a 40 year ol fighter bomber like the Su-22 really has no chance against a Super Hornet,but according to sources an AIM9X (i.e the latest Sidewinder) was fired first and the jet evaded. It was then taken out by an AMRAAM shot at close range.
According to the above source
If the latest AAM can be decoyed by a 40-year-old flare dispenser; is that not A Very Serious Problem? Or was a testament to the Syrian pilot’s skill?