how does a missile work? (1 Viewer)

[felix_suwarno]

i watched behind enemy lines earlier today. the missiles acted like torpedoes. the f18 had to dodge them a few times, yet, they keep coming back.

compare that to top gun!

is it the way missiles work these days? what guided them to get back to their target when they missed the target once?

 

[Bruce Hedtke]

is it the way missiles work these days? what guided them to get back to their target when they missed the target once?

Heat. The jet's exhaust is what the missile locks onto. A sudden turn will cause the missile to "lose" the target, but only momentarily. I don't recall the film that well, but didn't they shoot their own missiles into the ground to start a fire and draw the incoming missile away from their exhaust?

Bruce

 

[Danny R]

Its not just Hollywood stuff. There are several missiles that have limited reacquisition capability if the original lock is maintained long enough and the missile misses at its first intercept. If a missle has this capability, then it usually also has IFF (identify friend/foe) sensors as well to prevent it from backtracking toward the launching craft.

The Redeye and Stinger are some examples, and are simular to the Russian SA-7 Grail.

Other missles are actually controlled from the ground, and can be redirected while in flight.

Topgun I believed used sidewinders, which once the lock is gone, just continue onward.

Many air-to-air missles however won't have close misses. They are programmed to explode at the closest intercept point, with the goal of not actually impacting the target, but sending a cloud of shrapnel toward it.

Targetting is done by infrared, radar, or by remote targetting from the ground or air which lights up the target in a way the missle can detect.

 

[Grant B]

ICBMs are a whole different beast.
Trident II uses star charts loaded into the flight controls to guide itself to a point in space.
Very early in development it was realized that if a chunk of the earth was blown away;terrain maps would be useless.
The missile will impact that point in space even if the earth doesn't exist anymore.

 

[DustinDavis]

Some of it was Hollywood, though. Notwithstanding any reacquisition capability, your average missile intended to shoot down a plane will fly several times faster than the plane itself, won't it? In the movie, they are shown "running away" from a missile. Don't get me wrong, I loved the movie but I had a laugh at that one.

 

[Danny R]

I haven't seen the movie, so I'm unsure what you mean by outrunning the missile.

If they mean simply putting on the afterburners and flying faster, then this is totally hollywood. Anti-aircraft missiles fly much faster than the fastest aircraft, and can perform tighter turns as well since they don't have a human limited by g-forces onboard.

However if the missile is fired at extreme long range, it may be possible to put enough distance between you and it so that it runs out of fuel before it gets to you. However I believe most targetting systems wouldn't get a lock until the target is well within their range anyway, so I doubt how often this could be done here as well.

 

[felix_suwarno]

"Anti-aircraft missiles fly much faster than the fastest aircraft, and can perform tighter turns as well since they don't have a human limited by g-forces onboard. "

i dont think so. most air / ground to air missiles are capable of flying at mach 4. a super hornet is mach 1.8, maximum.

how can you maneuver your body when you are flying at mach 4? i find it hard to believe when a fast flying missile could find its target again after missing it.

i read an article many years ago. air to air combat doesnt count in minutes, but in seconds ( sorry my grammar sucks ).

unless a USAF officer confirmed it, i wouldnt believe that jetfighters could outrun or "dogfight" a missile.

 

[NickSo]

Heres what i found on HOWSTUFFWORKS.com:
http://www.howstuffworks.com/cruise-missile.htm

"Anti-aircraft missiles fly much faster than the fastest aircraft, and can perform tighter turns as well since they don't have a human limited by g-forces onboard. "
i dont think so. most air / ground to air missiles are capable of flying at mach 4. a super hornet is mach 1.8, maximum.

Aren't you two agreeing here? looks like you're saying the same thing:
Antiaircraft missles are faster than aircrafts...

 

[Cam S]

Oddly enough I JUST finished watching this movie, and I really enjoyed it. They didn't fire rockets into the ground to divert the SAM's but they jettisoned their own fuel tanks, pretty cool actually. They didn't seem to "outrun" it, but they did seem to out maneuver it.

 

[Hakan Powers]

I havn't seen the movie so I'm not sure what types of missiles you're talking about. Air-to-Air or Surface-to-Air?
A2A missiles come in various sorts but none that I know if will miss a target and come around for a second try. They might "reaquire" a target if aquisition (sp?) is lost in flight though.
The AIM-9 Sidewinder is heat seeking, IIRC the AIM-9P variant is rear aspect only while the AIM-9M is all aspect, meaning it can lock on to a targets IR signature from all directions.
The AIM-120 Amraam (Advanced Medium Range Anti Aircraft Missile) is a radar guided "fire & forget" missile. The launching plane feeds targeting data to the missile before firing and the missile itself (I think) uses radar for final guidance.
Generally though, missiles don't behave as in hollywood

 

[Hakan Powers]

Cam S,

jettisoning fuel tanks isn't done to divert incoming missiles. It is done to loose the extra weight and thus gain manouverability and performance in a dog fight.

 

[felix_suwarno]

"i dont think so. most air / ground to air missiles are capable of flying at mach 4. a super hornet is mach 1.8, maximum."

what i meant is, it is not possible to be maneuverable in high speed. dont you know that it is really hard to change direction in mach 4?

"Air-to-Air or Surface-to-Air? "

in this case, ground to air.

 

[Paul Jenkins]

Anti-aircraft missiles fly much faster than the fastest aircraft

the old SR-71 can fly Mach 3+ and can outrun/outfly most anti-aircraft missles if memory serves (mainly due to its speed and height (85,000+ foot ceiling at Mach 3+ makes it VERY difficult to shoot down...))

We have a SR-71 replacement that has never been declassified and is rumored to top Mach 4+ and exceed the SR-71's speed and height records... [rumor, of course...]

 

[Danny R]

i wouldnt believe that jetfighters could outrun or "dogfight" a missile.

The best one can hope to do would be to fool the missile's sensors, using chafe if its radar guided, or a flare if its a heat seeker. I think actual "dodging" is mostly hollywood.

dont you know that it is really hard to change direction in mach 4?

However its much harder for the Hornet flying at 1.8 to change direction than it is for the missile, even though the missile is going twice as fast.

This is because the Hornet is limited by the frail cargo onboard, namely the pilot. A turn going at that speed will black the pilot out. The missile on the other hand is only limited by inertia and aerodynamics.

We have a SR-71 replacement that has never been declassified and is rumored to top Mach 4+ and exceed the SR-71's speed and height records... [rumor, of course...]

True, but then the SR-71 and any replacement are survellance craft, and not combat. An enemy isn't as likely to worry about shooting it down, because they know it doesn't shoot back. Besides which I believe satellite survellance has overtaken the SR-71's mission in any case.

 

[AjayM]

jettisoning fuel tanks isn't done to divert incoming missiles. It is done to loose the extra weight and thus gain manouverability and performance in a dog fight.

Well in the movie they dumped the tanks so they would explode and put a large heat source for the missles to lock onto. Which of course worked for a couple of the missles.

In reality, the heatseaker is a pretty low end missle, they do fly fast and are fairly manouverable, but if you can evade it you probably don't have to worry about it because it won't come back trying to find you. They also have limited range, like that 2-3 minute fight with the missle probably wouldn't really happen.

As to the BLackbird, it was height and not speed which kept it from being a target of ground missles, mix that with the speed and you have a plane that is hard to shoot down. Once an SA gets shot at the plane, it has to climb to 70,000ft and catch the plane which is cruising along at M3.2, I had just read a website about the Blackbird and it's role against the sat images, the sat is usually quite a bit better, but the Blackbird always seems to get called back to duty when something happens (for instance the gulf war it came back).

Andrew

 

[felix_suwarno]

"However its much harder for the Hornet flying at 1.8 to change direction than it is for the missile, even though the missile is going twice as fast. "

yea, i agree. but as far as i know, when they are doing dogfight, they never exceed mach 1. otherwise their planes wont be able to maneuver at all.

 

[felix_suwarno]

"Well in the movie they dumped the tanks so they would explode and put a large heat source for the missles to lock onto. Which of course worked for a couple of the missles. "

no, according to the director's commentary, they just needed to drop them so that the plane is lighter. it exploded because there was still fuel inside.

 

[Jack Briggs]

Felix: You ask a question about how missiles work, and you proceed to disagree with everybody who answers you. What, exactly, are you hoping to achieve here? You have been given some pretty accurate responses by several people who were kind enough to answer your initial question. JB

 

[CharlesD]

As far as the possible SR-71 replacement goes, I wouldn't be surprised if it exists. (BTW if it doesn't exist the SR-71 would be the only plane to be taken out of service with no better replacement)

Sure satellites can replace many roles previously taken by surveillance aircraft, but the sats are not always in the right place at the right time, and whatever instrument is on the sat can get better information from 10 miles up than it can from 22,000 or 200 miles up.

 

[Philip_G]

yes but sats don't risk lives, I imagine there are a few sats in geo-synch orbit over key locations just hanging out 24/7
BTW for reference for an SR71 to make a 180 at full speed takes an area of roughly half the united states. Not only is the bank pretty limited (I hear) the faster an A/C flies the slower it turns, that is true of all airplanes, a piper warrior in slow flight spins like a top (56 knot airspeed or so)
edit: man I can't type tonight. Must lay off the crack.