Moritz Ertl, Yannik Feldner, Tobias Ecker
DOI Number XXX-YYY-ZZZ
Conference Number HiSST-2022-35
Several actors in the space trasport sector are moving towards reusable launch vehicles (RLV) for the
first stages of launchers, among them SpaceX with the Falcon 9 [1] and Rocket Lab with the Neutron [2].
Also the current European long term strategy [3] is aiming towards reusability with plans for THEMIS [4]
and Ariane Next [5]. In accordance with this strategy the German Aerospace Center (DLR) has entered
into a collaboration with the Japan Aerospace Exploration Agency (JAXA) and the French Space Agency
(CNES) for the development of RLV relevant technologies in the frame of a vertical takeoff and vertical
landing (VTVL) reusable subscale launcher first stage demonstrator the “Cooperative Action Leading
to Launcher Innovation in Stage Toss back Operations” (CALLISTO) [6, 7].
Generally a VTVL first stage will return to the launch pad utilising retropropulsion and an Approach and
Landing System (ALS) [8] with deployable landing legs. The landing leads to new additional aerothermal
design questions compared to traditional launchers. It has been observed, that part of the critical heat
loads are happening after touch down and engine shut off. These are caused by heat radiation from the
launch pad to the vehicle structure. This can affect an ALS built from carbon fibre, which is prevented
from cooling down. The heat fluxes, therefore, influence the structural design and the thermal protection
system (TPS) of the ALS. The impact is even more relevant to experimental vehicles if hopper flights
are part of the program.
To aid the development of reusable launch vehicles in the VTVL configuration we analyse the heat fluxes
onto the ground for an impinging supersonic jet from a liquid hydrogen and oxygen engine. The analysis
is based on Reynolds averaged NavierStokes computational fluid dynamics. We look at some modelling
choices and we investigate the influence of the ground distance on the heat flux distribution.