Optimization of ascent trajectory for RBCC-powered RLV

Since the multi-phase and multi-control-variable trajectory of the reusable launch vehicle (RLV) which is coupled with the thrust powered by rocket based combined cycle (RBCC) is difficult to solve, the numerical optimization model and method based on Gauss Pseudospectral Method (GPM) were proposed, and the optimal-fuel ascent trajectory was obtained. The trajectory is divided into three phases powered by rocket, ramjet and scramjet in sequence. The angle of attack and fuel flow are control variables, and according to the trajectory mission, the ignition and work condition of the each mode, the optimization model was built, the terminal and path constraints were imposed. The optimal trajectory was solved by using GPM and the boundary control variables were solved by a special method. Compared with the result by traditional method, the optimization model and GPM can solve trajectory optimization problems effectively, and the optimal result accords with the characteristic of the RBCC-powered RLV and satisfies all the constraints.