Phugoid oscillations in optimal reentry trajectories

Abstract

Ahstraet--A major problem with operations of lifting reentry vehicle having an aft center-of-gravity location due to large engine mass at the rear is the required hypersonic trim to fight the desired trajectory. This condition is most severe for lifting maneuvers. As a first step toward analyzing this problem, this paper considers the lift requirement for some basic maneuvers in the plane of a great circle. Considerations are given to optimal lift control for achieving the maximization of either the final altitude, speed or range. For the maximum-range problem, phugoid oscillation along an optimal trajectory is less severe as compared to a glide with maximum lift-to-drag ratio. An explicit formula for the number of oscillations for an entry from orbital speed is proposed.

Phugoid dynamic characteristic of hypersonic gliding vehicles

“…Vinh [9,10] studied the dynamic stability of shuttle vehicle systematically. He analyzed the phugoid oscillations during planar reentry maneuvers of single-stage-to-orbit vehicles and obtained an explicit formula for the number of phugoid oscillations [11].…”