Re-entry and Flight Dynamics of a Winged Reusable First Stage

Abstract

Reusing launch vehicle stages has the potential to reduce launch costs and is hence of high interest in the context of defining the next generation of European launch vehicles. Winged reusable first stages have been a focus of the system launcher analysis group at DLR in the past years. Using wings and other aerodynamic surfaces, the aerodynamic forces during re-entry are used to safely decelerate the vehicle, thus rendering the reignition of any engines and the use of propellants unnecessary. Nevertheless, the design of a winged first rocket stage capable of fulfilling its main objective, accelerating the launch vehicle from ground up to stage separation, while also being able to do an autonomous and controlled atmospheric re-entry offers its challenges. Traversing from hypersonic to subsonic velocities, the vehicle has to be controllable at a vast range of flight conditions. Understanding the flight dynamics behind the re-entry of a winged vehicle in an early design stage is necessary to identify challenges with regards to controlling and actively steering such a high-performance vehicle in order arrive at a feasible and robust design that does not fail to converge in later design iterations. This work focuses on the analysis of the vehicle dynamics using linearized dynamic equations with 6 degrees of freedom. The controllability using aerodynamic surfaces and RCS shall be investigated and, possibly, proven by simulation.