Maximum terminal velocity turns at nearly constant altitude

Abstract

An optimal control problem is formulated for a maneuvering re-entry vehicle to execute a maximum terminal velocity turn at constant altitude to a fixed final position. A control solution technique is devised that uses a Newton scheme to repetitively solve a nonlinear algebraic system for two parameters to provide the on-line guidance. The turn control takes advantage of the high dynamic pressure at the beginning of the flight path; the lift solution acts to null deviations from the prescribed altitude. Control solutions are compared for an approximate physical model, for a simulation of the approximate optimal guidance in a true physical model, and for a parameter optimization solution for the true model. End constraint satisfaction is excellent and overall trajectory agreement is good, if the assumed atmospheric model is reasonably accurate.