Development and Performance of the 10 kN Hybrid Rocket Motor for the Stratos II Sounding Rocket

This paper presents the development work of the 10 kN hybrid rocket motor DHX-200 Aurora. The DHX-200 Aurora was developed by Delft Aerospace Rocket Engineering (DARE) to power the Stratos II and Stratos II+ sounding rocket, with the later one being launched in October 2015. Stratos II and Stratos II+ are the flagship projects of DARE, a student group working on rocketry at Delft University of Technology. Successors of Stratos II have the eventual goal of reaching space. During the development process two major revisions of the motor have been designed with smaller changes between tests. The second major design revision was made after a first test series showed low combustion efficiency, through the usage of a CFD model to improve mixing. Both revisions have been tested statically in total for 14 times both at facilities of ’Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek’ (TNO) and ’Deutsches Zentrum f ¨ ur Luft- und Raumfahrt’ (DLR). All tests were conducted in a full-scale, flight-ready configuration with the primary goal of demonstrating the required performance for the Stratos II and Stratos II+ sounding rocket. It was found out that the motor suffered from combustion instabilities at around 450 Hz, when operated at its design oxidizer mass flux level of 600 kg=m2=s, that caused low combustion efficiency and elevated heat flux levels in the pre-combustion chamber. Through design changes the instabilities could be lowered and both problems removed. The design goal of total impulse could not be met, but the specific impulse measured was higher than expected. Still, the overall performance proofed to be sufficient enough for the system to be used as the propulsion system for Stratos II+.