Design and Development Status of LE-9 Engine for H3 Launch Vehicle

摘要

Japanese new booster engine LE-9 has been under development since 2015 as one of the key components of the H3 Launch Vehicle. The expander bleed cycle is adopted as its engine cycle to embody three key concepts of H3: reliability, affordability, and high performance. This engine cycle has fewer components than other cycles like the gas generator cycle and the staged combustion cycle. In addition to simplifying engine cycle, electro-mechanically actuated (EMA) valves have removed pneumatic lines, contributing to the reduction of the components. This design concept directly contributes to increasing reliability and lowering cost. The expander cycle has never been adopted to booster engines due to its weaker turbine driving power than other cycles, but the expander bleed cycle, Japanese unique open expander cycle, makes it possible. In addition, several new manufacturing technologies are also being developed to realize lower engine cost. To confirm the performance of the high-thrust expander cycle engine and the feasibility of new technologies, full-scale firing test including turbopumps tests have been conducted in JAXA's facilities since the beginning of 2017. In this paper, the key features of LE-9 engine system, the latest status of development activities, and the future plan are summarized and discussed.