Unsteady Loads on a Descending Launcher First Stage Demonstrator in the Aerodynamic Phase

In the Horizon Europe Project SALTO, a demonstrator of a vertically landing first stage with three Prometheus engines, the so-called T3, was investigated. It is intended to be recovered using a downrange landing approach. In this paper, the aerodynamic phase of the descent trajectory was investigated through wind tunnel experiments of the full launcher configuration in the Trisonic Wind Tunnel Cologne (TMK). The unsteady pressure fluctuations measured with high-frequency pressure sensors are presented. Especially on the base area of the vehicle, high pressure fluctuations were measured, with values around 30% of the dynamic pressure and occasionally up to 40%. The pressure fluctuations around the grid fins were lower but still on the order of 10%. The measured fluctuations did not exhibit prominent frequencies and were mainly broadband in nature.