Re-entry Dynamics and Control of Pivot Wing Fly Back Boosters

Abstract

Reusable first stage boosters have received much attention in recent years due to their potential to decrease the cost of space access. Studies have shown that the economic feasibility of reusable launch systems are driven primarily by their mission turnaround time, which is significantly reduced by horizontal landing at the launch site. Pivot wing fly back boosters have the potential to support routine, fast turnaround missions due to their horizontal landing capability. The success of these boosters hinges on their ability to execute an autonomous re-entry using only tail-based control surfaces. In this paper, we examine the effects of v-tail and conventional tail configurations on the re-entry closed-loop dynamics of this booster type using 6DOF trajectory simulation. Results show that a v-tail configuration is not a feasible choice when using traditional linearised autopilots due to a lack of dedicated yaw damper. Using identical control laws, the conventional tail vehicle was able to provide lateral stability due to its dedicated yaw damper. The conventional tail configuration also exhibited superior longitudinal tracking performance to the v-tail, and proved to be more robust to aerodynamic modelling errors and degraded elevator control authority. A rapid wing deployment strategy was investigated to eliminate the need for control mixing during wing deployment.