Effects of the lift-to-drag ratio on climbing characteristics of reusable launch vehicles

Abstract

This study aims at climbing characteristics investigation of the first-stage reusable launch vehicle in small Two-Stage-To-Orbit (TSTO) systems adopting ground boosting, horizontal take-off strategy. On the basis of the two-dimensional, three degree of freedom ballistic equations, the impact of the lift-to-drag ratio of the vehicle on some key performance parameters, which include the velocity gain, the height gain, the trajectory inclination angle, the dynamic pressure, and the maximal overload, etc are systematically analyzed under different thrust-weight ratios. In addition, a comparison study by taking a vertical launch trajectory as a reference is carried out. The results clearly show that the velocity gain in the lift-assistance climbing trajectory is larger than that in vertical trajectory. Moreover, a high lift-to-drag ratio is not only propitious to elevate the height of separation, but also conducive to reduce the dynamic pressure as well as the maximal overload, especially in small thrust-weight ratio conditions. The adjustment range of the trajectory inclination angle is significantly extended due to a high lift-to-drag value simultaneously. Finally, both the advantage of the ground boosting launch strategy for vehicles using rocket engines and a rational ballistic are discussed based on the results. Furthermore, some critical requirements of aerodynamic configuration design are proposed.