Optimization design of approach and landing trajectory for variable configuration RLV with multi-control surfaces

To solve approach and landing problem of variable configuration reusable launch vehicle( RLV) with multi-control surfaces,a design method of approach and landing trajectory was proposed. The landing trajectory was divided into steep glide landing trajectory and flare landing trajectory. The controllable deflection limit of the aerodynamic surfaces and deep downturn quasi equilibrium equation constraints were considered and the steep glide landing trajectory optimization design was carried out. The RLV aerodynamic surface adjusting redundancy and variable configuration processes were considered,with constraint conditions of the gear down time,the flare normal overload and the grounding state,by the trajectory propagation based on the RLV dynamics equation,the optimal flare landing trajectory was designed and optimized. The steep glide landing trajectory and flare landing trajectory composed a complete approach and landing trajectory.Therefore,the designed approach and landing trajectory considered multi constraint conditions and improved the stability and safety of the landing process.