Flight test results of investigation of acceleration effects on a gun launched rocket engine

Nowadays a lot of research is 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 a Lorentz Rail Accelerator. The structure of the hybrid rocket engine 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 a hybrid rocket engine is mounted on a 155 mm howitzer shell. The experimental setup is then launched from a 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. Following the data are transmitted to a ground station, during free flight, by a telemetry device, which is mounted on the howitzer shell instead of an igniter. 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 hybrid rocket engine structure can withstand the mechanical loads that are caused by high acceleration that would occur during a launch from a LRA. Therefore a hybrid rocket engine is suitable for high acceleration launch. The sampled data are compared with FEM-calculations. Differences in simulation and measurement are observed.