Analysis of Entry Footprint Based on Pseudospectral Method

Abstract

Entry footprint is an essential manifestation of vehicle maneuverability, which can provide the basis for trajectory planning and guidance, landing point selection, etc. A fast footprint-generation method based on the pseudospectral method is proposed. The influencing factors of footprint are simulated and analyzed. In this method, the attack and bank angles are simultaneously discretized as control quantities to form the nonlinear programming problem of the pseudospectral method, and the footprint is obtained by solving the maximum transverse range problem for several different longitudinal conditions. Moreover, the affecting factors of the footprint are studied. The simulation results show that the mass, reference area, atmospheric density, etc., do not cause the change of the footprint within a specific range. Beyond a certain range, the short longitudinal trajectory would be significantly affected. The left half of the footprint is affected, while the right half is not changed. The effect of the lift-to-resistance ratio on the footprint is significant, and its size is positively related to the footprint range.

Keywords

• entry footprint
• trajectory optimization
• pseudospectral method
• influence factors
• lift-to-resistance ratio