Comparison of Return Options for Reusable First Stages

Abstract

DLR's Space Launcher Systems Analysis division analyzes generic Reusable Launch Vehicles for missions to Geostationary Transfer Orbit. The launcher configurations consist of a reusable first stage and two expendable upper stages. For the reusable first stage different separation Mach numbers are considered. The return options considered are stage fly-back and stage in-air capturing. Based on mass estimation, analysis of ascent and descent aerodynamics as well as ascent and reentry trajectory optimization first results for the return options stage fly-back and in-air capturing are presented.

Guidance command generation and nonlinear dynamic inversion control for reusable launch vehicles

“…Several studies on future launch vehicle configurations and technologies for expendable and reusable launch vehicles have been extensively conducted in the past at DLR [1,2,3,4,5,6,7,8]. Currently, partly or fully reusable launch vehicles using different return methods are investigated at DLR in the context of the research projects Akira and X-tras [9,10,11].…”

“…In particular, the winged Liquid Fly-back Booster concept Lfbb, studied extensively during the early 2000's [13,14] and more recently in [9], based on an LOX/LH2 propellant combination for vertical takeoff and vertical landing (VTVL), as well as the more recent study of the delta-winged horizontal takeoff and horizontal landing (HTHL) concept Aurora [10,11] based on an LOX/Kerosene propellant combination have been considered.…”

UAV Pre-Study for In-Air-Capturing Maneuver

“…The main motivation for reusable booster stages or complete spaceships for several missions is reduction of costs [1], [2]. A safe and nondestructive retrieval of the stage from high altitudes to a specified landing position is the key challenge to be solved for reusability.…”

“…Another approach, which is the focus of this paper, is to capture the returning stage with an aircraft which tows it to the landing destination. While this method has yet to be demonstrated, its main advantage would be the reduction of mission fuel and thus an increase of mission payload compared to a retrieval with fuel reserves using the booster's own propulsion [2].…”

“…The racetracks were performed in altitudes between 70 and 100 m above ground level. The leg length is approximately 500 m, and the distance between the legs is 150 m. The available time for a2 Micro Air Lab straight leg of the course without wind influence is between 13 and 15 s.…”