Trajectory Optimization for an Apollo-type Vehicle Under Entry Conditions Encountered During Lunar Return

John W. Young

Jan 1967 · National Aeronautics and Space Administration

About this ebook

This report describes a numerical optimization study conducted to investigate optimal performance boundaries, from considerations of maneuver capability and entry heating, for an Apollo-type vehicle under entry conditions encountered during lunar return. Results presented show the effects on these performance boundaries of variations in initial entry conditions and vehicle characteristics and of constraints on such trajectory variables as altitude and acceleration. The effect of the earth's rotation on optimal performance is also included. Typical trajectories are presented to illustrate and contrast the basic nature of various optimal entry missions. The results of the study show that there are numerous trade-offs possible between maximum maneuver capability and optimal entry heating. The determining factors for these trade-offs are the initial entry conditions, the trajectory constraints, and the physical characteristics of the entry vehicle. The results also show that, although radiative effects can account for a significant portion of total entry heating, the trajectories for optimal heat entries are largely determined by convective inputs.