This paper describes the current developments regarding cryogenic rocket engine technology at Delft Aerospace Rocket Engineering (DARE). DARE is a student society based at Delft University of Technology with the goal of being the first student group in the world to launch a rocket into space. After the launch of the hybrid engine powered Stratos II+ sounding rocket in October 2015, DARE decided to investigate highly efficient liquid rocket engine technology . In this context DARE initiated the cryogenic project with the goal of developing a liquid rocket engine using liquid oxygen and liquid methane as propellants with a nominal thrust in the order of 10kN. Eventually this engine shall power a future sounding rocket into space. As an intermediate step, a 3 kN class engine is being developed. Subsystem development tests and possibly a hot-fire test campaign on this engine are planned for 2016 and its development intends to provide DARE with the required experience and knowledge to develop large scale liquid rocket engines. The engine is developed in cooperation with Heliaq Advanced Engineering and is designed to meet the requirements of the second stage engine of the ALV reusable launch vehicle. The design is a pressure-fed engine, regeneratively cooled using the liquid methane fuel. After passing the coolant channels, the methane is injected into the combustion chamber in gaseous state together with the liquid oxygen in a co-axial manner. The engine is ignited by means of a pyrotechnic igniter using an ammonium perchlorate based propellant. During a test sequence, the propellants are stored in insulated run-tanks and are pressurized using helium. This paper describes the project objective, the current progress on the design and production, and finally four proposed research topics that are indented to be conducted at the faculty of Aerospace Engineering of Delft University of Technology. @en

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+. @en