INVESTIGATION OF FEASIBLE FLIGHT TRAJECTORIES AND RE-ENTRY ATMOSPHERIC GUIDANCE FOR SPACELINER 7

Kurzfassung

Preliminary trajectory modellings of the SpaceLiner for the reference mission Australia – Europe, Australia – North America, Europe – North America have been performed. The SpaceLiner 7-3 50 passenger concept has been selected as the reference vehicle for the mission, which consists of three phases namely Ascent phase, Descent Phase and Booster Fly back Phase. Trajectory simulations have been made according to structural and thermal constraints. The reference mission has been defined and trajectories are analyzed in both flight directions with particular attention in the vehicle constraints. Further, off nominal conditions of the SpaceLiner mission have been analyzed and trajectory trade-offs have been considered under degraded vehicle performances. In the presented study three different cases are taken into account: Reduction in performance of engine Isp, reduction in available ascent propellant and the failure of one booster engine at take-off. A simple and innovative control guidance law has been proposed to compute the active controls that govern the descent phase of aerodynamic gliding, which allowed the reduction of trajectories computations and delivers a bank angle profile that should respect the heat constraint. The guidance provides the steering commands for trajectory control from the final condition of the ascent until the TAEM conditions. This design is based on a semi analytic solution of the equations of motion defining the drag acceleration profile referred to specific energy that meets the landing position of the re-entry flight while maintaining the flight within system and operational constraints. Guidance commands are based on a control law that ensures bank angle modulation while the angle-of-attack remains constant.