IR missile protection

[Force_Feedback]

Because of the doppler shift of the emissions the seekers get different 'highs' from different directions, making the missile go from side to side, eventually losing the lock, it does not blind them, that would require too much power.

[Sundowner.pl]

Yeah I might be wrong on that one, have to read about it more. I'm more basing on what the earlier generation systems were doing in the 60/70's.

[159th_Viper]

Article I ran across that simplifies things a wee bit - Informative nonetheless......

 

 

 

"IR Guided Missiles

 

 

Now lets take a look at IR guided missiles. These missiles track the heat sources of an aircraft, which usually means the hot engines. There are several countermeasures that can be used against IR guided missiles, the three most common being infrared signature suppression, infrared flares (decoys), and infrared jamming.

 

 

 

 

Common aircraft "hot spots" seen by an infrared missile seeker

 

 

Infrared signature suppression is simply what it sounds like. If the infrared signature of an aircraft is low enough, a missile can have trouble finding the aircraft and tracking it. Here is an entertaining way to think of an IR missile versus an aircraft. Picture yourself as the IR missile...be the missile. Humans can't see in infrared naturally, so we will use the visible spectrum in our example. Picture the aircraft you are after as a flashlight, which is a pretty good approximation of what a missile seeker would actually see. It is dusk, not very sunny but not yet dark. Just as in the visible spectrum, there is ambient infrared light in the atmosphere too. Let's pretend you are hunting a MiG, which has big, hot jet engines. These engines would be comparable to the headlights of a car and are pretty easy to see against the background. In comparison, let's pretend you are now hunting a helicopter, one with a new infrared suppressor. Instead of a bright light, it looks more like a cheap flashlight with rundown batteries. It's a bit harder to see, isn't it? When you consider that a missile doesn't have quite the brain power you do, it gets even harder to see.

Now let's look at infrared flares. IR flares are nothing more than fancy road flares designed to emit IR radiation that mimics that of an aircraft. They are used as decoys. When an aircraft is being threatened by an IR missile, it ejects flares in the hopes that the missile will go after the flare, and not the aircraft. Be the missile again...picture a bright flashlight traveling across your field of view. Suddenly, several other light sources "break off" from the flashlight, and they look quite a bit like the flashlight you were following, and maybe even brighter. If you are a "dumb" missile, which light source do you go after?

 

 

 

Flares ejected by a C-130 Hercules military transport

 

 

Infrared jamming is a technique that confuses a missile. Jammers are usually mounted on the aircraft they protect, and a common system is the ALQ-144 (often called the "Disco Ball"). To understand how these systems work, picture yourself in a disco hall (like you didn't see that one coming). All of the lights are out. Picture John Travolta holding a small flashlight, right in front of the disco ball. As long as the disco ball is turned off, you can pick out the flashlight just fine. As soon as someone turns on the disco ball, though, you'd be hard pressed to tell what was the flashlight, and what was the disco ball.

 

 

 

ALQ-144 infrared jammer on a helicopter

 

 

Other jamming systems have the ability to "saturate" a seeker. Imagine yourself in the same dark room, with the same small flashlight. You can pinpoint the flashlight just fine, until someone turns on a World War II searchlight in your face. Now you can't see much of anything, let alone the small flashlight. Do these CM techniques work against incoming missiles? Of course they do! Otherwise, military forces all over the world wouldn't spend the money, or use up the space and weight on their aircraft to carry them. Which method is most effective? As usual, it depends. Jamming can be very effective, but it is usually expensive, and sometimes specific to a particular missile. Flares work rather well, but can also be missile specific. Infrared suppression is the most "universal" solution, but it is also the most difficult since reducing an aircraft's IR signature low enough to completely evade a missile is challenging. As a result, it is wise to consider a mix of all of these solutions if you are designing an aircraft that might someday be in harm's way."

 

 

 

 

http://www.aerospaceweb.org/question/electronics/q0191.shtml

[Mugatu]

In the first picture it looks like the SA-7 went straight for the engine, smack bang in the middle of the fuselage. Is there any deflection/cooling of the exhaust in the Apache?

 

There seems to be a common thread with the new generation of helo's (Tiger, ROOIVALK, Mi-28 ) with much reduced IR signatures, lessons from Russia's involvement if Afghanistan with the Mi-24.

 

http://img148.imageshack.us/img148/9439/15333tp4.jpg