Practical uses of liquid methane in rocket engine applications

Abstract

Liquid methane has been considered an attractive rocket propellant for several decades. However, most rocket engine development efforts in the last 30 years have focused on using more traditional fuels such as hydrogen, kerosene, and earth storables, without any serious development or application of methane to propulsion systems. This paper presents a summary of recent 870 lbf thrust LOX / LCH 4 (liquid oxygen/liquid methane) engine test results and recent LOX / LCH 4 torch igniter testing. Multiple test series were conducted using both radiation cooled and ablative chamber hardware. This engine testing yielded measured minimum C * efficiencies of 97% using non-optimized engine hardware, with expectations that better than 99% efficiency can readily be achieved with minor hardware optimization. The combustion process was shown to be stable in all tests and the operating transition from poor quality methane (two-phase fluid) at startup to liquid–liquid, sub-cooled, steady state operation was demonstrated. Engine test results showed chamber wall compatibility with high propellant mixture ratios and excellent boundary layer performance of methane as a chamber film coolant. The Aerojet work on methane propulsion and energy applications is also briefly summarized.