FUTURE EUROPEAN REUSABLE BOOSTER STAGES: EVALUATION OF VTHL AND VTVL RETURN METHODS

Kurzfassung

Reusability of launch systems will strongly impact the launch service market if certain characteristics, such as sufficient reliability and low refurbishment costs, can be achieved. The German Aerospace Center (DLR) is performing a systematic investigation of return methods for a reusable booster stage of a future European launch vehicle. This launcher shall be able to transport 7 t to a geostationary transfer orbit (GTO), launching from the European spaceport in Kourou. The final goal is the determination of the impact of the different return methods on a technical, operational and economical level and the assessment of their relevance for a future European launch system. Compared to previous work presented at the IAC 2017 [3], this paper includes winged vertical take-off and horizontal landing (VTHL) as well as non-winged vertical take-off and vertical landing (VTVL) configurations. The preliminary results of a first design phase employing structural indexes derived from existing stages were used to narrow down the field of potential designs, especially with regard to the rocket staging. The selected launchers were modelled in more detail, including the preliminary design of major subsystems such as propulsion, aerodynamics, structure, propellant management and the thermal protection system. The comparison of different potential propellants is made across the different return options in order to assess the suitability of the various possible combinations. The fuels investigated within this paper in combination with liquid oxygen are kerosene, liquid hydrogen and methane. Two different engine cycles, namely gas-generator and staged combustion, and their impact on the launcher systems are also evaluated.