Welcome, from sunny Australia!
Anti-Aircraft Missile System
Cheap & nasty, but maybe effective ...

Whilst I haven't had any real combat experience (luckily!), I have flown the excellent simulation by SSi / Mindscape, Su-27 Flanker. One thing that I've noticed is that given a little warning even I can evade an inbound missile ... and that's the key - ONE missile. If I have two inbounds, I'm in serious trouble, and although I never quit, it is often tempting to cut out the inevitable and simply eject. ;) There is, however, a few guys I've seen flying sims that are really switched on, with situational awareness and so on, and they can deal with a couple of missiles at the same time.
So, all that got me thinking as to how to make an anti-aircraft missile system where instead of having just the one of two missiles chasing the target aircraft, why not ten? Obviously the cost of doing this with the current crop of missiles would be terribly expensive and so out of the question.
So there has to be an easier way!
The system that I have in mind has no radar, and so incoming aircraft would get no 'electro-magnetic paints' from the system. The only way that the system has of tracking aircraft is by a manually steered laser, focused on the enemy aircraft by the system operator through a stabilised sight. This sighting operator wouldn't have a missile launcher of his/her own, but instead transmit the firing solution and information to outlying launchers - at least ten of them as far away as, say, five miles - but they must be in the line of sight, as the information would be passed by laser as well. So, if the launch area is tree covered then this would be a problem. (raised masts, perhaps?) The other problem is that on a cloudy day the system wouldn't be very good either ... or at night or that matter. One way to get around these two problems is to simply use radar in both the sighting operator's position and the missle seeker heads, but this would attract the unwanted attention of enemy anti-radar missile. Well, no-one said war was easy! Still on a clear day I think the system would be a very good deterrent defence, especially for the price. Also, the sighting operator would be best up as high as possible, on a hill - This is so he/she can look down at low flying aircraft and still track them.
Note that there could easily be more than one sighting operator, as the missiles would be looking for a specific frequency reflected from the target aircraft, and so it doesn't matter where that laser paint comes from. (see below for more details)
Once the targeting operator gets a 'go' signal from enough launchers, he/she would then command the system to fire on the incoming enemy aircraft. This is where the fun starts. ;)
Simultaneously, a number (ten or so) launchers would fire a solid rocket booster stage for the missile. Immediately, the seeker head on the top of the missile would start tracking the target by means of infra-red sensors in the nose, based on information received from the tracking operator.
The booster stage would take the missile through Mach 1, where the cruise stage of the missile would start to ignite. It's important to get the missile past the speed of sound, as the rear of the body of the missile would act as an ramjet.

A ramjet is about the simplest engine that's possible. It's a little like a rocket, but uses the air outside to mix with the fuel instead of carrying it along internally. The outside bodywork acts as the nozzle, providing thrust. Using common jet fuel, a ramjet only works well above Mach 3 or so, but by using a different type of fuel (methane, alcohol ??) I believe that the small ramjet used in this missile could be made to work just above Mach 1. The ramjet inlet/exhaust would also be designed so as to limit the speed to below Mach 2, to limit airframe heating and make designing the aerodynamics a bit easier. (Almost no aircraft fly above ~M1.8 these days)

To reduce costs, the missile would not have any explosives, but instead rely on the detonation of the remaining fuel to fragment the missile when it's close to the target aircraft, or, preferably direct impact.

The seeker head at the front of the missile would look for the laser signature that's being held on the target aircraft by the sighting operator. The laser would have a distinct frequency signature, with modulation, and so that's what the seeker head would look for, allowing for a bit of doppler shift from the target aircraft moving around. The distinct frequency would be needed, as once the pilot of an aircraft knows they're being chased by a missile, he/she starts dropping flares & chaff to distract the incoming missile's IR seeker. Since a flare burns chemically and hence emits on many IR frequencies, it would lack the distinct modulated signal that the aircraft is reflecting from the ground laser.

The pilot of the target aircraft would suddenly find up to ten or so missile inbound at him/her, and so the chance of evading them is very remote. There's also a good chance that the pilot would not realise that there was so many missiles inbound, and perhaps only try to avoid the first one or two. There's also a chance that the aircraft's detection systems would not pick being both detected and launched apon, as there would be no radar to detect, and only a brief IR signature to pick up as the multiple missiles approach. I'm not sure if current fighter/attck aircraft detection systems can pick up the aircraft being painted by a laser, but I also don't think it would matter ... ;)

(pictures of the various systems to come, as I have time to make them)
 
 

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