Flight Test Results of the Investigation of Acceleration Effects on a Gun-Launched Rocket Engine

Nowadays, much research has been done in the field of electromagnetic-driven Lorentz rail accelerators (LRA). To apply this technology to launch a sophisticated payload carrying vehicle, mechanical loads due to high acceleration have to be taken into account. The German Aerospace Center (DLR) is doing research in the field of a hybrid rocket propelled payload carrier which shall be launched from an LRA. The structure of the hybrid rocket engine (HRE) is the most critical component, regarding mechanical stress. To investigate the effects of high acceleration during the launch from an LRA, an experimental setup is created. An 80% scale model of an HRE is mounted on a 155-mm howitzer shell. The experimental setup is then launched from the Panzerhaubitze 2000 with an acceleration of 3300 g. The model is equipped with strain gauge sensors to determine deformation during the acceleration phase. An acceleration sensor is integrated to measure the acceleration during launch. Data of the strain gauge bridges and the accelerometer are sampled by an electronic device mounted on the projectile, and buffered in the internal RAM. The data are transmitted to a ground station during free flight by a telemetry device, which is mounted on the howitzer shell instead of a fuse. The flight path of the projectile is tracked by different radar stations to determine the impact point, so that the experiment can be recovered. The test shows that the HRE structure can withstand the mechanical loads that are caused by high acceleration that would occur during a launch from an LRA. Therefore, an HRE is suitable for high-acceleration launch. The sampled data are compared with finite element method calculations. Differences in simulation and measurement are observed.