Comparative analyses of European horizontal-landing reusable first stage concepts

Abstract Partially reusable two-stage-to-orbit (TSTO) launch configurations have been investigated on system level by DLR in the ENTRAIN study which encompasses an examination of both vertical takeoff horizontal landing (VTHL) and vertical takeoff vertical landing (VTVL) reusable first stages. A target payload performance of 7.5 Mg into GTO is selected as the common mission requirement of all concepts. In this paper, the preliminary designs of TSTO configurations consisting of a winged reusable first stage and an expendable upper stage are presented and discussed. The considered propellant combinations include LOX/LH2, LOX/LCH4 and LOX/RP-1. Configurations based on staged combustion and gas generator cycle engines are analyzed. The focus of the presented preliminary analyses is on the overall performance of the space transportation system, the design and architecture of the winged reusable first stage and the comparison and evaluation of different VTHL configurations.