Optimal conceptual design of two-stage reusable rocket vehicles including trajectory optimization

Many candidate concepts of reusable space transportation vehicles have been proposed around the world. This paper applies an optimization method for conceptual designs of winged fully reusable rocket two-stage-to-orbit (TSTO) vehicles in both horizontal takeoff and vertical launch styles. We first describe our methods for analyzing vehicle design. Then we integrate those methods into the optimization problem, the solution of which yields the minimized parameter, defined as the total gross weight of the first-stage booster and the second-stage orbiter. This information allows us to determine the optimal vehicle configuration and flight trajectory for a highly feasible TSTO vehicle. The optimal solutions show the necessity of lightening and miniaturizing components. Vertical launch vehicles are lighter in total gross weight than horizontal takeoff vehicles. In addition to optimizing vehicle configuration, this study also optimizes ascent and return trajectories. These optimizations enable the booster to glide back to the launch site without propellant, despite the long downrange path from the staging point of the ascent trajectory.