In movies like Top Gun, you often hear a cockpit alarm go off alerting the pilot that an enemy has “locked on” to him and is about to fire.
What’s the definition of a missile “lock” and how is it different from merely being painted with targeting radar?
How does the target’s warning system know it’s been locked in? How it know what’s going on in the opponent’s cockpit?
Again, in the movies there’s a fair amount of acrobatics on both sides to achieve and/or avoid a lock, but as soon as the lock is made, it seems that further acrobatics don’t help the target much. If that’s an accurate portrayal, why is that the case?
In the case of radar-guided missiles, the targeted aircraft can detect the radar emissions of the missile (or the aircraft using its own radar to ‘paint’ the target).
The radar or infra-red seeker in the missile operates in a narrow ‘cone’; in theory, the targeted aircraft can avoid the missile by moving out of its detection area. Modern missiles are smarter than that, though, and can ‘predict’ (or at least make an educated guess) where the target has moved.
From what I understand, once the target is in the “cone” (as mentioned by Crusoe), the missile has the best chance to hit. However, if a lock-on is achieved and, before the attacker has fired, the defender moves out of the cone, the attacker must attempt another lock-on. If the missile is fired as soon as lock-on has been achieved, then the targeting systems on the missile take over; the missile, usually being more maneuverable than an aircraft, can then easily (well, more easily) track the dodging aircraft.
how come the air force hasn’t come up with backwards firing missles. I would assume that if the chase plane’s missle is sending out a radar signal trying to ‘lock on’ to the target plane, then wouldn’t you be able to launch a missle backwards which would follow that signal home?
There were plans for rear-firing missiles, but it does assume you’re happy to let someone sit behind you and get a free shot. I would imagine most engagements are head on, or at least not straight chases, so every rear-firing missile you have is one that can’t be fired forwards. They’re probably not very aerodynamic to carry that way, either.
Also, a lot of radar-guided missiles carry their own radar, so once fired the enemy aircraft can shut his radar down and bugger off. I believe the AIM-54 Phoenix missile used by the US Navy’s F-14s has a home-on-jam capability, so it can trace radar jamming signals back to their source.
You only have so many “slots” to fit missiles on a plane, though. Forward firing missiles are generally more useful than rearward firing ones. Besides, you want to give the pilots a positive outlook… outfit them so it’s assumed THEY will always be chasing the enemy, not the other way around.
There still are plans as far as I am aware (I don’t think they are scrapped). The Russian Air Force does have rear-firing AA missles.
As well, once its it locked and fired the areobatics really would start. The pilot is then flying for his life, trying his best to outfly and spoof the missle.
I cannot recall how the Pheonix tracks but I am pretty sure that even the AIM-120 AMRAAM isn’t autonymous (sp?) right after launch… but it is after several seconds. It will attempt to be if the host radar is shut down prematurely though… or some damn thing like that.
Well, what do you know. The Russian Sukhoi Su-35 “Super Flanker” prototype has been tested with rear-firing missiles, with a cone over the engine to prevent instability problems.
IARC, during the Falklands War (/Malvinas Conflict) RAF Nimrods (Maritime Patrol Aircraft (MPA)) were “totin’ heat” in the form of Sidewinders on outer wing stations. They were pointed (and would launch) in an aft direction targeting any fighter type aircraft that might be in a tail chase looking for an easy missile/guns kill. While Nimrods are a derivative of the DH Comet jet airliner, they’re no real match for any single seat tacair without an enhanced and innovative protection package.
There are several other methods for defeating an attacking IR/radar guided missile that include IR and RF jammers, IR decoys (“fireworks”), and maneuverability.
I’ve never seen a popular movie about air combat with modern aircraft that was remotely accurate. Watching Top Gun to learn about fighter aircraft is as bad as watching Die Hard to learn the correct way to shoot. That said A-A missles fall in one of the following three categories.
Passive: Sidewinder infra red guided “heat seeking” missles. There is nothing being transmitted to let the target aircraft know that it’s being tracked or locked. Contrary to popular belief the AIM-7 is not designed to fly into the engine it is tracking, it’s actually designed to miss by a narrow margin. The seekerhead has a circular sensitivity rather than a spot. Newest 'winders have side looking laser emitter detector pairs for a proximity fuze. When it’s along side the aircraft it’s tracking the expanding rod warhead is designed to throw chunks of metal into the intake. This makes the engine distintegrate from the inside, hopefully throwing turbine blades through the fuel tanks. The Sidewinder has a very tiny warhead so it needs all the help it can get. Historically the AIM-7 is the most effective A-A missle we have. In the jet age it has more kills than guns and all other missles combined.
Note: Sometimes a winder is launched in expanded aquisition mode where it is slaved to the radar of the launch plane. The missle may be totally passive but the radar lock is detected by the target.
Semi-active: AIM-9 Sparrows and similar only have a radar recieving section. The launch aircraft has to paint the target through the entire flight. Having a radar lock is a dead giveaway to the target that it’s being tracked. Even with all the sophisticated countermaeasures we have the F-14 was eqluipped with a device that was basically a 28 volt version of a Fuzzbuster for this purpose. The Sparrow has “head aim” and “english bias” unlike the Sidewinder. It doesn’t aim for the target, it aims for where the target will be when it gets there.
Fully active: The AIM-54 is usually launched semi-active but can go fully active at a [CLASSIFIED] range where its own mini AWG-9 radar can leave it totally independant of the launch aircraft. The AIM-54 doesn’t reaquire the launch aircraft to have a continuous lock on the target. A search sweep where the target is painted briefly for short intervals will suffice at long ranges. The missle’s computer extrapolates where the target is most likely to be the next time it is painted by the launch aircraft. When it is close enough to go fully active it has a traditional lock on the target but by then it’s hopefully too late for the target to evade.
I’ve been out of this business for a while so this info isn’t the most current. I worked on F-14 weapons systems (AWFG-9 radar, AWG-15 fire control and ASN-92 intertial navigation) in the early eighties and those systems were pretty old then.
There are differant radar frequencies used to target aircraft, one broader bandwidth one will cover a general area to light up potential targets and then this information will be passed on to a higher frequency, narrow beam targeting radar.This is the one that usually sets off the alarms since the next thing to happen is a visit from Mr A.A man.
This last is what NATO fighter flying over Iraq respond to sending out radar countermeasure devices or passive radar homing missiles.
Infra-red heat-seekers, e.m seekers(including radar) do not transmit any signal, though a few switch on their own systems for the final transition. This means you cannot know if such a missile has locked on.
Some missiles do use their own radar for the entire flight but a significant number do not.
What seems to escape me is why you have to get into the correct position for a “lock” – if the target is somewhere infront of you, and your radar can see if, wouldn’t the lock just be there. Its not like the gun where you have to point the entire aircraft…
I was told by my American History teacher that the actual damage done by an air-to-air missile against an enemy plane is much lower than is shown in movies. According to him, unless the enemy pilot is unlucky enough to be tagged by shrapnel, he should be able to eject safely and survive. My teacher’s main point was that the point of the missile is not to blow the fsck out of the enemy plane or otherwise catastrophically damage it, but just to break the enemy’s engine so as to force him to stop messing with you.
So, is this idea of missile damage correct, or is the enemy pilot actually flying for his life as bernse said?
I did my military service in the Anti-aircraft artillery as a commander of a searchradar so I believe I can provide at least some input here from a swedish perspective.
Anti-radiation missiles can also target the first type of radar (search radars) and not only the narrow beam targeting radars. When one is lit up by the targeting radar it is usually too late to launch your own missile in defence because the shells are bound to appear any second later.
Smart AA-tactics is not to light up your targeting radar until you know (based on information from the search radars) that the target is within range. That way you can fire almost instantaneously.
Padeye is correct. Hollywood exaggerates the explosive power of all missiles. Quite often they may only be a bit bigger than a hand grenade.
The Bofors RBS 70/90 missile , if I remember correctly from my military training, only has a charge of around half a kilo, but it is surrounded by thousands of tungsten pellets which perforates the target when the laser proximity fuse is set of. This will most likely destroy the engine if it is hit. It will also make un-aerodynamic holes in the aircraft which can be quite fatal if it is travelling at near supersonic speeds du to the increased drag.
If the pilot is not hit my guess is that he will fairly often be able to eject before the plane goes down.
The RBS 70/90 is quite a cool missile since it will not alert the target by locking on to it with radar. Instead it follows a laser beam that the firing unit paints the target with.
Minor correction to Padeye: AIM-9 is the sidewinder, the AIM-7 is the Sparrow.
The “cone” for the AIM-9 has grown much larger in terms of degrees over the years. It is essentially an all-aspect missile, meaning that you don’t have to be behind the target aircraft to get a lock on it. You could be at an angle or if it were slow enough, coming at it almost head-on. The use of these later-model AIM-9s proved to be a very decisive advantage for the British in the Falklands War.
The quality and capability of the AIM-7 has also improved very dramatically over the years.
As said, the actual explosive charge in missiles is surprisingly small. The key is the fuzing and the pattern of shrapnel. Generally, there is a metal ring of sorts in the warhead that expands like a watchband to make like a ring of W’s. As it expands, hopefully it cuts through the target. Depending on how the fuze is set up and how the missile and target converge, the cockpit (and pilot) can be cut through, or some major part of the target’s structure can be cut so that it falls apart. Sometimes you’ll see this in films of missile tests on unmaned target aircraft. Most usually, the damage only has to be to the target’s hydraulics, as these control the aircraft. Once control is lost, you hope you’re still “in the envelope” to eject.
The AIM-54 Phoenix weighs in the neighborhood of 1000 lbs. It is a long-range missile designed to intercept bombers at a distance. It’s size and weight make it a very poor weapon to take into a closer-in fight against fighters.
Another reason nobody has mentioned yet is that no operational fighter has rear radar (though it is a proposed feature for the Su-35 Super Flanker). The radar antenna is located in the aircraft’s nose, and generally only covers approximately a 120 degree cone in front of the aircraft. You would be unable to track a target that is behind you.
where its own mini AWG-9 radar can leave it totally independant of the launch aircraft. The AIM-54 doesn’t reaquire the launch aircraft to have a continuous lock on the target. A search sweep where the target is painted briefly for short intervals will suffice at long ranges. The missle’s computer extrapolates where the target is most likely to be the next time it is painted by the launch aircraft. When it is close enough to go fully active it has a traditional lock on the target but by then it’s hopefully too late for the target to evade.