Within the EU program Horizon 2020 the German Aerospace Center (DLR) and the five partners from industry teamed up in the project RETALT (RETro propulsion Assisted Landing Technologies) to enhance the know-how in reusable rockets in Europe, which start upright and land upright after a successful mission. For that, they commonly decided to investigate and develop key technologies to land rockets backwards. During the three years of the project lifetime the consortium will investigate the areas of aerodynamics, aerothermodynamics (i.e. the temperatures that evolve at the surface of the vehicle during flight), flight dynamics, guidance, navigation and control, and advanced structural parts, materials and mechanisms.
For this purpose, two types of rocket launchers will be investigated which both start and land in an upright position. One of them has two stages and is similar to conventional rockets like the Falcon 9 or the Ariane 5 launcher (RETALT1). For this launcher only the first stage will be landed again. The second launcher (RETALT2) has only a single stage. It is a more academic configuration and when returning it will break not only with retro propulsion but also with the aid of a large aerodynamic base surface at the bottom.
The RETALT-Team will investigate the aspects and physical foundations of retro propulsive landing based on the reference configurations and models and demonstrators of smaller scale. Thus, models of a scale of around 1:100 will be tested in the DLR wind tunnel facilities and demonstrators of structural components such as the landing legs will be built at a scale of around 1:3. In the course of the project, the technologies will be tested in representative environments in view of a demonstration in orbit in follow-up projects.
The DLR Institute of Aerodynamics and Flow Technology is involved in the project with the Supersonic and Hypersonic Technologies Department and the Spacecraft Department. The Supersonic and Hypersonic Technologies Department is responsible for the coordination of the project, the design of the reference configurations and the assessment of aerodynamics and aerothermodynamic behavior via wind tunnel tests. The Spacecraft Department characterizes the aerothermodynamic behavior of the configurations with the aid of Computational Fluid Dynamics (CFD) simulations and is responsible for the validation of the DLR flow solver TAU for such applications.