THERMO-MECHANICAL DESIGN OF THE EXPERT NOSE AND TESTING OF THE LOAD INTRODUCTIONS

Kurzfassung

EXPERT is a mission to gather precise in-flight data of the re-entry aerothermodynamic environment [1]. That led to the selection of a ceramic matrix composite heat shield as the Thermal Protection System (TPS) for the nose of the vehicle. The Instrumented Nose Assembly (NAP) is a sub-system of the EXPERT vehicle, consisting of the ceramic matrix composite (CMC) nose and embedded payloads to measure temperature, heat flux and spectroscopic data. Since EXPERT is a vehicle with a high ballistic coefficient the aerodynamic pressure in the stagnation area reaches a value of 1.5 bar. During re-entry the peak heat flux will reach up to 1.8 MW/m² and the predicted temperatures will reach up to 2050°C in the capsule front. Due to the very large temperature gradients between hot surface and internal cold structures the problem of mismatching thermal expansion has to be solved. At the same time the nose has to withstand the high pressure loads. The paper describes the design of the nose and the load introductions attaching the nose to the vehicle. The thermo-mechanical analyses as well as mechanical tests of the load introduction are presented.