Optimal propuslsion/guidance analysis of ramjet powered air-to-air missiles

This paper presents an optimal component integration and effectiveness analysis of ramjet powered air-to-air missiles. The approach is based on the simultaneous optimization of the propulsion and guidance, where classically these have been treated separately. To accomplish this, an optimal control approach is required that can determine the optimal propulsion/guidance control algorithm which is in feedback form for the nonlinear ramjet problem, and which can be mechanized on board the missile. Optimal control solutions using singular perturbation techniques (SPT) are derived for ramjet controlled missies which incorporate optimal aerodynamic control of turn rate and optimal thrust magnitude control of velocity. Maximum lift coefficient, maximum load factor, minimum and maximum velocity and thrust, and instrumentation related constraints are enforced. The control solutions are nonlinear and in a feedback form suitable for on-board implementation. Simulation studies have been conducted to measure total system performance when alternative mission/ propulsion/guidance related parameters are varied. Results are presented which both demonstrate the impact on trajectory shaping and the improvement in engagement performance which may be achieved over conventional (maximum thrust and conventional proportional navigation guidance) flight trajectories through use of optimal control techniques. As a consequence of the analytical techniques developed in this paper, a powerful new design evaluation tool is available to the designer of ramjet propelled vehicles.