Aerodynamic Design and Analysis of an ARIANE 5 Liquid Fly-Back Booster

Within the German future space launcher technology research program ASTRA two reusable first stage designs are under investigation. The one dedicated for near term application with an existing expendable core stage is called a winged liquid fly-back booster (LFBB). The main goal of the present study is the refinement of an existing LFBB design. The regarded partially reusable space transportation system consists of two booster stages, which are attached to the expendable Ariane 5 core stage at an upgraded future technology level. The two main areas of interest of the study are the descent after the staging procedure and the ascent in the phase with maximum dynamic pressure. The descent dominates the aerodynamic design of the LFBB and the ascent limits the mission with view to aerodynamic and structural loads under changing atmospheric conditions. The aerodynamic parameter studies pointed out that an LFBB may not be trimmed or stabilised without the introduction of canards as control surface. A detailed analysis of the flow field for the considered ascent condition points to some regions which have to be considered in more detail during the structural layout of core stage and booster