Overview of Research and Development Status of Reusable Rocket Engine

Abstract

This paper reports the status of research and development of a reusable rocket engine in Japan. In the case of an expendable engine, in system selection, much weight must be put on performance, whereas in the case of a reusable engine, in addition to satisfactory performance required by the mission, reusability must be considered. In the system study, total design management (TDM) was employed for the LOx/ethanol engine, and the relation between performance and reusability was quantitatively evaluated. In the research on key components, the combustion chamber, bearings, and seals for turbopumps were selected as key components. To extend the lifetime of the combustion chamber, lowering the wall temperature is important, and thermal barrier coating (TBC) or film cooling (FC) becomes necessary. Turbopumps with a port for installation of a fiberscope on the bearing’s inner ring and on the shaft seal’s nose for direct observation were developed, and the feasibility of 100 reuses was established. A demonstration engine of the reusable sounding rocket was manufactured, and more than 100 operation cycle tests were carried out to confirm the feasibility of 100 reuses. Durability was confirmed by lifetime audit testing.