Missile Guidance

I was just reading a very cool book called The Fundamentals of Aircraft Combat and Survivability Analysis and Design from my university library.  Apparently there are four main ways of directing a missile on a collision course with a target aircraft.

1. Pursuit - The missile tries to turn and point itself at the target for the duration of it's flight.  This usually ends up putting the missile behind the aircraft.  There are some big problems with this system.  First, the missile must execute extremely hard turns in the terminal phase of it's flight when it might be just meters away from the target aircraft.  Second, it must be considerably faster than the target aircraft if it is chasing the aircraft.  This usually occurs when the missile is cruising and has neither great speed, and little ability to turn.

2. Lead Angle Computation - The missile computes what angle between it's line-of-sight and the aircraft is needed to collide with the aircraft, and for maneuvering targets, this angle is computed and adjusted as fast as possible.

3. Three Point Guidance - The missile's course and maneuvers are based on trying to force it to rest on the line between the target and the launch aircraft.  This is computed on board the launch aircraft and relayed by wire or radio.  Beam-riding missiles work this way, to the best of my knowledge.

4. Proportional navigation - Based on the fact that if two moving objects maintain a constant line-of-sight angle between them, they are on a collision course.  Essentially the missile tries to keep a constant angle between it's longitudinal axis and the line between itself and the target.  This is the most common system.

Edited by Genghis

i find the missiles itself more interesting...from the V-1s and V-2s that i'm now building in Hearts of Irons 2 for use against the poms...to the scuds the iraqi's throw at israel, which wasn't much more accurate than the primative V-2s...

I've seen Behind Enemy Lines....I think that was the name of the film...anywho....when the bad guys fired a Russian made SAM at the F-15(????) as the missile got closer it fired from the tip first, seemd like a cannon in the tip of the missile....the shot damaged the tail section of the fighter...the missile then blew up the jet.  I can't remember but it was something like that.....so I am just wondering whether these SAMs have 1 or 2 or 3 or even 4 cannon shots in tip of the missile which fires first when the target is in range just to damage it or slow it the target first......Am I making sense???? 

Originally posted by Genghis I take it no one finds missile guidance as interesting as I do?

I find it very interesting mate .... i always wondered how in da f**k do they guide em ... and i never actually got down to doing some research on it .... but now u've explained, thx

actaually does sensor fusing which im hearing about quite allot  out of the USA change the way it gets guided? is there a strict rule between the sensor used and the guidance methodolgy?

Originally posted by Leonidas actaually does sensor fusing which im hearing about quite allot  out of the USA change the way it gets guided? is there a strict rule between the sensor used and the guidance methodolgy?

The fuze is just what detonates the warhead when it hits or comes close to the traget, and is to a large extent an autonomous subsystem of the missile, which although similar to is not the same as the guidance system.  The guidance system gets the missile to within lethal range of the target, the fuze then detonates it when it comes within lethal range.

The early Sidewinders used optical fuzes, and others used infrared fuzes to detect distance to target.  Sparrows used radio frequency fuzes.  The Soviet R-60/AA-8 Aphid AAM had infrared guidance with a radar proximity fuze.  Most missiles also have a back up contact fuze. 

 

Edited by Genghis

Originally posted by Erdene So the missile doesn't actually hit its target...it explodes in a proximity to the target??? The force from the explosion damages and downs the target????

Correct.  Counting on a direct hit is too risky when you have two objects moving above or close to the speed of sound.  Often the missile will hit the aircraft, but a proximity fuze increases your chances so much more of killing the target.

Which system does stinger and other small shoulder-held missiles use???

all passive guidance ones are fire forget, but too easy to be fool unless fit with imaging array or cooperated by other guidance model. while it's impossible to jam semi-active tracked missiles such as RBS 70.

IR guidance missiles are easy to operate due to their fire forget function. but you can't launch several  IR missiles to deal with several targets at the same time. coz all these missiles will just go for the target with most obvious IR signals.

current most advanced shoulder-held missiles such as chinese QW-4, all use IR imaging seeker. it can't be fool since it's terminal informations are targets imagines. one can simulate signals power and frequency, but can't simulate targets imagines.