Combined aerodynamic and orbital trajectories for partial drag-free flight at super-low altitudes

This paper proposes a new type of super-low-altitude flight governed by aerodynamic lift and gravitational forces. A general trajectory generation algorithm is proposed to create combined aerodynamic and orbital (CAO) trajectories, including spaceship reentry and missile boost-glide trajectories. The relationship between the number of hops per day and the aerodynamic coefficients are then presented for them. Analytical and numerical simulations conducted reveal that the changing argument of perigee caused by the lift component can essentially characterize the hops. A control strategy that use the on-orbit time-dependent change in angle of attack is developed, yielding an extended CAO trajectory with time-dependent hops, which is more difficult to track and predict. The partial drag-free flight addressed in this paper has potential applications in some stealth military missions.