The LE-9 engine is a new hydrolox engine developed by Mitsubishi Heavy Industries for the first-stage of the more powerful H-III launcher. The LE-9 engine uses an expander bleed cycle.
Development of the LE-9 began in the 2010s, with the first hot-fire of a complete engine in 2017.
First flown in 2001 on the first H-III launcher's flight, it continues in service today. The launch failure on the first flight of the H-III launcher was due to the second-stage, not the first-stage and its LE-9 engine.
