STERN

The Static Test Expansion-deflection Rocket Nozzle (Stern) engine was a 5kN gaseous hydrogen-air rocket engine with an expansion-deflection nozzle and a copper heat-sink chamber. It was tested in both cold and hot flow conditions. The experiments were designed to test the altitude-compensating performance of a nozzle with this geometry, which required high-speed wall-pressure measurements using tappings in the side of the nozzle to compare flow expansion with theoretical results. It demonstrated excellent flow stability on the nozzle walls with no flow separation at any operating condition, but also lower than desired wake pressures leading to higher base drag. The experimental data allowed Reaction Engines to optimise their designs for follow on test programs.