The Design of the CMC-Tip Connection to the ATHEAt Hypersonic Vehicle Forebody

Abstract

Controlled hypersonic flight is a demanding technology and it is crucial for the development of fully reusable launch vehicles. The ATHEAt hypersonic flight experiment aimed at the development and testing of new technologies for reusable launch vehicles and at the collection of flight data for the validation and calibration of numerical design tools employed in their design processes. The goal of the ATHEAt flight was to achieve a speed of up to Mach 10 with sustained Mach 8 for approximately 3 minutes. Hypersonic flight at these conditions leads to severe aerothermal loads with high heat flux and a large integral heat load. Therefore, the forebody of the scientific payload of the ATHEAt vehicle featured a thermal protection system (TPS) made from ceramic matrix composites (CMC). The TPS mostly consisted of individual ceramic matrix composite shell structures of different types. However, the tip structure in the front of the vehicle was designed as a solid body of CMC material. The design of the tip connection to the adjacent vehicle structure required particular attention, as it encounters the highest heat flux acting on the vehicle but also attaches directly to the metallic structure of the vehicle. The design had to consider different thermal-mechanical sizing aspects, that are presented and discussed in this work.