Optimal Truncated-Power-Series Approach for Different Reentry Phases.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING
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The optimal reentry problem is formulated for a phase by phase planar trajectory. The reentry portion of the trajectory for a shuttle type vehicle is divided into two phases and each phase is treated as an individual optimal control problem. Optimization is with respect to 1 peak heat rate for the entry phase, 2 a combination of total control energy, total heat absorbed, and satisfactory end conditions for the glide phase, and 3 a total surface distance. The control for each phase consists of a truncated power series as a function of the system states and the independent variable range. The entry phase ends at pullup and has a single constant for control. The glide phase ends at conditions desired for a transition from a high to a low angle of attack, the transition phase is left for a later study. By process of elimination the glide phase control form is reduced to a constant plus two terms. Searching for the coefficients which optimize the power series is accomplished using Davidons minimization routine. Results indicated that a constant adaptive controller is a reasonable sub-optimal solution for both phases. Modified author abstract
- Spacecraft Trajectories and Reentry