Simulation of an Ablative Thermal Protection System for the Hypersonic Ascend of an Electromagnetically Launched Payload Carrier

Abstract

The German Aerospace Center is carrying out a study to develop a small payload carrier for the ascent to low earth orbit. The vehicle shall be electromagnetically launched by a Lorentz Rail Accelerator. Additionally, it will be propelled by a two stage hybrid rocket engine system to reach the desired orbit. Due to the high initial velocity of about 3.3 km/s at sea level, the vehicle needs a thermal protection system to withstand the aerothermodynamic loads on its forebody. An ablative carbon phenolic heat shield is chosen for this application. There are many investigations regarding carbon phenolic ablators, but usually these investigations are carried out for re-entry missions, where the high velocities are given at high altitude and low atmospheric density, in contrast to this application. A material response model is developed and coupled to a 6 degree of freedom trajectory simulation tool, which incorporates an aerodynamic and atmospheric model. The results show that despite the high convective heat loads, an ablator of 15 mm thickness at the stagnation region is sufficient to protect the vehicle against the harsh conditions.