THE DOWNRANGE CAPABILITY WITH THE INFLUENCE OF REENTRY INITIAL CONDITIONS OF REUSABLE LAUNCH VEHICLE DURING THE PRIMARY ENTRY PHASE

摘要

Downrange capability is defined as difference of the maximum and minimum downrange to evaluate the flexibility of Reusable Launch Vehicle (RLV) in the Primary Entry Phase. In this paper, the Primary Entry Phase is divided into two phases, the constant bank angle glide phase at high altitude and the normal control phase in the entry corridor, to estimate the downrange by direct integration and by range prediction method based on a reference trajectory generation, respectively. Based on the maximum and minimum downrange optimized by synthesizing the two phases, the investigation indicates that the essential influence parameters of reentry initial conditions are the flight-path angle and the velocity at atmospheric penetration. They have corresponding initial altitude of the normal control phase to make the downrange capability maximum. An example of hypothetic RLV shows that the curves of the downrange capability vs. the reentry initial conditions are not monotonic. The maximum downrange capability can be achieved by the optimization of the initial flight-path angle and the initial entry velocity with their corresponding optimal initial altitude of the normal control phase.