RBCC constant dynamic pressure booster trajectory design and propellant mass flowrate analysis for TSTO transportation system

Due to the coupling of rocket based combined cycle (RBCC) engine performance with flight vehicles, the design and the development of RBCC engines should be done for different flight trajectory. Based on the equations of dynamics and kinematics, the constant dynamic path design methodology of boost trajectory for vehicles powered by RBCC engines was studied and the altitude-step walking method was established. The simulation of the trajectory of the first stage flight vehicle powered by RBCC engine in a Two-Stage-To-Orbit (TSTO) hypersonic space transportation for Ma=0~8 was made by the program designed in C++ language. According to the baseline trajectory, with the coupling optimization strategy of Genetic Algorithm/ Sequential Quadratic Programming, a propellant flowrate control history that minimizes the propellant consumption for the non constant dynamic pressure flight path was calculated. The results show that considering the coupling between RBCC engines and flight path, the computation model can be used for the RBCC boost trajectory design and analysis; The whole boost process can consume as high as 55% takeoff mass propellant, in which the mass ratio of non-constant-dynamic-pressure segment to constant-dynamic-pressure segment is 2.3; Through optimization, the efficiency of propellant consumption can be enhanced by 3.5%; In ejector mode(Ma=0~2.5), the optimum mass flowrate regulative ratio of primary rockets is 4.3. The mass flowrate of primary rockets should be throttled when RBCC engines transit from inject to ramjet mode operation and the minimum mass flowrate is needed during the mode transition process.