Development of 200 N-class throttleable hybrid rocket motor for lunar module application

In this study, ground tests of a lab-scale hybrid rocket motor were conducted to verify the feasibility of the hybrid propulsion system for lunar lander application. The primary goal is to assess the realizability of hybrid rocket by testing its throttleability and soft landing capability with a scale-down lunar module. A design thrust of 200 N was achieved by clustering four identical 50 N-class gaseous oxygen (GOX)/high-density polyethylene (HDPE) hybrid rocket motors with multi-port solid fuels. Ground tests were carried out via two main experiments: static test and drop test. Static test was focused on the overall performance of the clustering module such as cold injection, uniform oxidizer distribution, throttleability and simultaneous ignition of the four motors, while the drop test was performed to investigate the planned throttle behavior using a 1-D vertical drop test stand. The clustering module was controlled in an open-loop setup with a simple ballistic flight simulation input. The landing velocity of 1.01 m/s was achievable, confirming the possibility of soft landing missions on lunar surface using hybrid rocket motors.