The Reusability Flight Experiment – ReFEx: From Design to Flight – Hardware

Abstract

The hypersonic flight experiment ReFEx has been under development at the German Aerospace Center (DLR) for a number of years and passed CDR in September of 2021. It will be launched on a VSB-30 sounding rocket in 2023 from Koonibba Test Range (KTR) in Southern Australia. The sounding rocket will inject ReFEx into a trajectory typical of aerodynamically controlled RLV-booster stages, where it will test several key technologies required for future reusable aerodynamically controlled first stages. A key feature of ReFEx is its sole reliance on aerodynamic means for the return leg of the flight, including a heading change of more than 30°, providing valuable flight data at the other end of the spectrum for RLVs (Reusable Launch Vehicle) from current propulsive return concepts [1]. With its length of 2.7 m, a wingspan of 1.1 m, a mass of approx. 400 kg, ReFEx features a densely packed fuselage, containing systems critical for flight as well as sophisticated sensors for flight analysis. With the passage of CDR, the project is progressing into the flight hardware production and verification phase [1]. The paper summarizes the latest status of ReFEx and shows how key challenges such as trajectory optimization, aerodynamic control with control reversals of the aero surfaces, thermal loading, folding wind systems as well as operational issues such as flight safety and campaign planning where tackled to be able to freeze the design and reach CDR status.