Research on entry guidance and test methods for reusable launch vehicle

The purpose of the re-entry phase is to reduce excessive speed and altitude to meet the initialisation conditions of the Terminal Area Energy Management (TAEM) phase for a reusable launch vehicle (RLV). The key to re-entry guidance research lies in designing the lateral bank angle profile and the longitudinal angle-of-attack profile. The bank angle profile must be designed to ensure achievement of the total re-entry range, while the angle-of-attack profile should primarily minimise the aerodynamic heating load of the vehicle. In this paper, a guidance law design method based on the drag-energy profile is presented, and the profile is obtained using an optimisation method. A linear control law is derived to track the drag reference; the angle-of-attack and bank angle profiles are developed, and a re-entry flight guidance and control system is established based on a specific vehicle model. Flight simulation results show that the control system works effectively: the RLV can fly to the start of the TAEM phase with a range error of less than 0.2 km, a maximum overload of 1.6 g (meeting the constraint requirement of 2.5 g) and a maximum dynamic pressure of 13 kPa (below the allowable limit of 17 kPa); the trajectory azimuth angle error is limited to within ±18°, which fully verifies the accuracy, safety and feasibility of the proposed guidance method.