Abstract: Aerospace vehicle with combination power is an important development direction for future space transportation systems. Using electromagnetic propulsion for aerospace vehicle takeoff is a new emerging technological ap-proach to solving the problem of aerospace flight. In response to the risks associated with electromagnetic propul-sion separation in ground effect, the Stargazer, a two-stage-to-orbit vehicle with abdominal intake, was taken as the research object. Numerical methods were used to firstly study its basic aerodynamic characteristics and typical separation flow field structure under Ma1.6. Subsequently, the study focused on the impact of ground clearances and electromagnetic braking accelerations on separation safety. The results show that the uniqueness of separa-tion flow is reflected in the choked flow stage, where the choked air inlet is further congested by the ground reflect-ed shock waves and shock waves of electromagnetic assisted stage. There are also separation bubbles and the generation and dissipation of shock waves during the separation process, and the aircraft quickly pitches up due to this influence; In the stages of multi-body interference and only ground effects, the aircraft gradually pitches down due to the impact of the electromagnetic assisted stage bow shock wave and ground reflected shock waves. There-fore, there is a serious separation risk throughout the entire separation process. The height above ground affects the separation safety by changing the positions of the reflected shock waves on the aircraft, and the shock wave structures at a relative height of 0.3 can restrain the speed of pitching up in early stage and the speed of pitching down in later stage. The braking acceleration mainly affects the separation safety by changing the interference time of the electromagnetic assisted stage and the beginning time of only ground effect stage. Choosing 200m/s2 for braking is not only beneficial for increasing relative displacement, but also for suppressing the risk of pitching down.

Key words: electromagnetic propulsion system, aerospace vehicle, supersonic ground effect, separation, air inlet, ground clearance, braking acceleration