Preliminary aerodynamic design of a reusable booster flight experiment

Abstract

The Reusable Flight Experiment (ReFEx) is an experimental vehicle currently in development by the German Aerospace Center (DLR), which simulates the reentry of a winged reusable booster stage. The topic covered in this paper is the aerodynamic design through the Mach number range from 5.0 to 0.8, including the transonic regime, by CFD simulations using the DLR TAU-Code. For steering and lift generation, the vehicle is equipped with multiple aerodynamic surfaces: canards, wings and a vertical fin. A VSB30 was chosen as the carrier rocket, leading to numerous limiting conditions that had to be fulfilled. The resulting tradeoffs are discussed. Also the process to achieve a configuration that meets all needs regarding stability during ascent and descent, controllability and energy management to autonomously follow a desired trajectory is explained. Since this vehicle is under development, the presented geometry is not necessarily the final shape. However, the completed design iterations strongly indicate that only details will differ between the presented state to the final and flyable ReFEx, scheduled to fly in 2022. Keywords Reusable flight experiment (ReFEx) • CFD • Aerodynamic design • Reusable booster Abbreviations Latin C Aerodynamic coefficient Ma Mach number d Diameter x, y, z Force in x-, y-, z-axes direction Greek α Angle of attack β Sideslip angle Subscripts CG Center of gravity NP Neutral point l, m, n Moment around x-, y-, z-axes p Pressure x, y, z Body-fixed x-,y-, z-axes Abbreviations CFD Computational fluid dynamics DLR German Aerospace Center MRP Moment reference point ReFEx Reusable flight experiment SM Static margin TAU Triangular adaptive upwind * C. Merrem

Comparison of a closed-loop control by means of high-fidelity and low-fidelity coupled CFD/RBD computations

“…This procedure is very computational intensive, in terms of time as well as cost, because these tables can exceed hundreds of entries in the most and even thousands in some cases. 1 Especially during the preliminary design phase of flight vehicles, these tables needs to be calculated from scratch when the design parameter change, e.g. during geometry variations.…”