Flying Qualities and Controllability of Hypersonic Spaceplanes

The growing interest in hypersonic spaceplanes, as a new promising concept for space flight, requires that their flying qualities and controllability characteristics are well understood. These properties are investigated along the spaceplane’s ascent and re-entry trajectory. The analyses of the stability, trim capabilities and flying qualities of the open-loop system should prove whether the spaceplane is dynamically stable. If not, a control system is required. A simple adaptive controller can be designed, focusing on the compromise between optimality and robustness. The current paper addresses the flying-quality and controllability analyses, together with the design of such a control system. The responses for both longitudinal and lateral control in nominal and off-nominal conditions are simulated and evaluated. This robust and advanced control system cannot only stabilise the vehicle with relatively low control effort, but also minimise the effect of disturbances on the overall performance, guaranteeing safety of flight and mission success.