Design and Simulation of Range Enhancement of Reentry Vehicle

Abstract

Trajectory dispersion for the reusable launch vehicle during the entry interface and after entering in the Earth atmosphere is needed to be corrected. Normally the Terminal Area Energy Management phase of the reentry is the appropriate phase to accomplish the above mentioned task. To do these corrections, range maximization is required during this phase so that guidance and control have enough time to adjust these dispersions. For the winged body reusable launch vehicle with sufficient lift to drag ratio, the range may be enhanced after the entry by exploiting its lift to drag ratio. Various optimization algorithms are proposed to achieve the stated maximization objective. Quasi equilibrium glide solution for equation of motion at constant dynamic pressure is proposed in this research. A reference trajectory based on the mentioned solution is generated includes reference values of angle of attack and flight path angle against given velocity and altitude. Angle of attack is used as a regulating variable. For tracking, an error signal based on the negative feedback is generated. This error signal used as a correction factor which is in fact difference in reference value of quasi equilibrium glide solution and actual value of the flight path angle. Variable gains are used for the trajectory tracking via a feedback controller. Simulations results using optimization technique and maximum lift to drag ratio are also generated for the purpose of comparison. Simulated results exhibited that the proposed scheme is a good candidate in achieving the desired objective of range maximization with added benefit of smooth control signal and flight vehicle safety.