Generation of Landing Footprints for Re-entry Vehicles Based on Lateral Profile Priority

This study proposes a method for calculating the landing footprints of re-entry vehicles based on the three-dimensional acceleration profile. Unlike the traditional case in which the reference angle-of-attack profile is given in advance, here, the manoeuvrability of the vehicle is enhanced owing to the release of the constraints of the angle-of-attack profile. Compared with the traditional methods of generating landing footprints, this method is more challenging because it is necessary to adjust the angle-of-attack and the bank angle simultaneously to obtain all feasible trajectories. With the enhancement of manoeuvrability, the traditional landing footprints solving strategy with a fixed bank direction under the premise of a given angle-of-attack is expected to make the footprints of the result locally smaller. Therefore, a layered design based on a three-dimensional profile and lateral priority strategy is proposed to solve the problem. First, a lateral flight corridor considering various path constraints is constructed. Then, the boundary interpolation of the flight corridor is used to generate an initial lateral profile. The longitudinal profile corresponding to the lateral profile is analysed according to the coupling relationship between the longitudinal and lateral profiles, and the corresponding trajectory is then obtained by numerical integration. The tentative landing footprints can be obtained by traversing all feasible profiles in the lateral corridor. Finally, to solve the problem of inaccuracy in the solution of landing footprints, the core innovation of this study is the generation of multiple groups of different lateral flight corridors by adjusting the initial and terminal bank directions. By solving the tentative landing footprints under different flight corridors and merging them, highly accurate landing footprints were obtained. The proposed method is tested with the CAV-H model of Lockheed Martin, and the results are compared with those of traditional methods to verify its effectiveness and feasibility.