boertjie wrote:
What actually happen is the seeker head of the missile follows the target and the missile tries to zero the off boresight angle of the seeker head versus that of the missile body, thereby steering the missile to the target...
I hope i have that right
Hmmm. Vague memories tell me it isn't that simple except for a target flying straight towards or directly away from the launch aircraft. If you follow this method (continuously pointing the missile at the target), the missile typically follows a curved flight path which requires constant direction changes and is inefficient.
Assuming the missile is fired with the target straight ahead of the launch aircraft but moving from Left to Right, initially the missile flies straight ahead, but as the target moves to the right, the missile corrects to fly slightly right of aircraft boresight. As the missile gets closer to the aircraft, the corrections get more and more drastic, eventually in the worst case the missile is close to doing a tail-chase on the target which is a good way to run out of energy.
The preferred algorithm is predictive - make an estimate of where the target will be by the time the missile gets to the target range assuming the target keeps on moving the way it is moving at the time of firing. Direct the missile to this theoretical intercept point so it makes one turn after launch to point at intercept point then flies straight. Once "close" to the target, intercept it - the algorithm can be as simple as "if the angle between missile and target starts increasing, steer towards the target". I guess that this fully optimised algorithm is only be available for the newer (V4 and later) missiles since it needs information on target motion (which V4 radar can supply once it is within about 10km of the target) as well as a good guidance system, but I guess even V3S and V3C have some element of "aim ahead of the target" built into their steering computers.