Studies for the Design of an Ariane 5 Liquid Fly-Back Booster

The report describes aerodynamic studies for the design of an Ariane 5 Liquid Fly-Back Booster (LFBB). A winged LFBB is one of the partially reusable space transportation systems considered within the German future space launcher technology research program ASTRA. The regarded system consists of two booster stages, which are attached to the expendable Ariane 5 core stage at an upgraded future technology level. The main area of interest of the presented aerodynamic study is the return flight after the staging procedure which dominates the layout of the LFBB. The report focusses on the longitudinal stability and trim of the LFBB. Detailed aerodynamic parameter studies are performed based on Euler calculations and the application of surface inclination methods. They cover the complete return flight from hypersonic to subsonic flow conditions. Force measurements and selected Navier-Stokes simulations confirm that a LFBB configuration may be designed primarily based on Euler simulations. The discussion of the numerical results and their comparison with experimental results shows that proposed LFBB allows a nearly indifferent flight along the complete return trajectory and that it additionally enables a very robust trim behaviour