Conference paper Open Access
The RETALT project, funded by the European Horizon 2020 program, has the objective to study critical technologies for Vertical Take-off Vertical Landing (VTVL) Reusable Launch Vehicles (RLVs) applying retro propulsion, combined with aerodynamic control surfaces and landing gear components. Two reference launch vehicle configurations are defined:
RETALT1, which is a Two Stage To Orbit (TSTO) RLV similar to the SpaceX rocket ”Falcon 9” and RETALT2, which is a Single Stage To Orbit (SSTO) RLV similar to the DC-X vehicle.
This paper describes a scaled drop test procedure for a scaled landing leg 1:5 (LL) of the reusable launcher configuration RETALT1 and summarizes the recorded data of the performed short time dynamic impact test.
The performed drop test simulates a dynamic shock loading (landing manoeuvre) on the 1:5 scaled landing structure to proof the strength resistance of the frames during landing. Additionally, the functionality of the kinematic system and the resistance and damping behaviour of the absorber is tested. The test results are used to correlate the mathematical strength and kinetic models for future works and provide an upscale methodology to the 1:1 launcher configuration for the landing gear.
The drop test consists of a large mass, which is mounted on a drop tower to store high potential energy, which is then transformed into kinetic energy after the release of the mass. After touching the foot pad of the LL, the impact energy leads to high forces in the landing leg and absorber. To withstand the applied kinetic energy, the compression and tension forces in the lightweight carbon fibre reinforced polymer (CFRP) LL were simulated via FEM. The applied kinetic energy quantity matches the optimal efficiency range of the non-linear damper system.
During the drop test the landing gear is equipped with high sampling accelerometers, strain gauges and an optical measurement system for the detection of the deformation and strains at critical positions such as interfaces, hinges, rivets and highly stressed CFRP components.
Furthermore, a short description of the control fins is represented in this paper, which were built by MT- Aerospace (MTA) and used for the development of kinematic mechanisms by MTA’s partner Almatech.