An Advanced Hybrid Rocket Engine for an Alternative Upper Stage of the Brasilian VLM 1 LEO Launcher

Kurzfassung

The Institute of Aeronautics and Space (IAE), on behalf of the Brazilian Space Agency (AEB), is developing a new launch system called Microsatellite Launch Vehicle (VLM-1). The development is supported by German Aerospace Center (DLR) and some German industrial companies. Basically, the VLM-1 is planned as a three stage launcher with solid rocket engines, which could deliver up to 200 kg payload in Low Earth Orbit (LEO). To propel the 1st and 2nd stage the launcher will be equipped with solid rocket engines of the type S50, which have identical structure for both stages. The only exception is a different nozzle expansion ratio. As a 3rd stage the solid rocket engine S44 combined with attached RCS system, based on cold gas engines, is planned. To overcome the maneuverability limitations at injection phase of payload into LEO, an alternative hybrid rocket engine (HRE) for the 3rd stage is analyzed by the Institute of Aerodynamics and Flow Technology of DLR Braunschweig. As a suitable propellant mixture for this engine High Test Peroxide (HTP) is selected as oxidizer, with concentrations higher than 87.5 wt%, and polymeric hydrocarbon fuels with different ingredients, which improves the regression rate and combustion efficiency. One of the analyzed propellant mixtures is verified in experiments carried out within the DLR AHRES program (Advanced Hybrid Rocket Engine Simulation) on the test facility Trauen, Germany. In this paper the predesign of the HRE concept possesses the ability of multi-ignition, due to a catalyst for the decomposition of hydrogen peroxide (HTP), throttle-ability in the range 1:3 of maximum thrust and also thrust vector control. For the design and optimization of the HRE the DLR software tool AHRES is applied. Within this paper, results of interior ballistic computations, heat transfer and temperature distribution inside the combustion chamber, as well as the properties of pressure feed system are shown and analyzed. The solid fuel grain geometry is designed using the burn-back module STAR (part of DLR AHRES software tool), which is coupled with optimizer NOMAD (based on direct search optimization algorithm). For the moveable nozzle with ablation, gas flow properties, temperature distribution within multilayer structure, radial and tangential stresses as well as structure dilatations for each CAD plane in longitudinal axis direction are presented.