Recent improvements in the LUMEN test bed for oxygen-methane rocket engine technologies

Abstract

LUMEN (Liquid Upper Stage Demonstrator Engine) is a modular rocket engine designed to serve as a test bed for components and technologies for cryogenic propulsion systems. LUMEN is an expander-bleed cycle rocket engine that uses liquid oxygen (LOX) and liquefied natural gas (LNG) as propellants, operating in the 25-kN thrust class. Since the first LUMEN tests in 2024, a second campaign took place with a focus on operating the engine as a research test bed. Several sub-component improvements were implemented, which combined resulted in improved engine performance. Notably, a reduction in injector head pressure losses combined with the removal of two valves improved the overall system pressure balance. A further improvement on the system level was a reduction in chill-down time in order to save propellant. LUMEN was also used to perform a world-wide first demonstration of regulation of a cryogenic engine with a neural network controller