Mitsubishi Heavy Industries, Ltd. is currently developing the LE-9 booster stage engine for the H3 launch vehicle in cooperation with the Japan Aerospace Exploration Agency (JAXA). Since the combustor of the LE-9 is larger than those found on conventional engines, it is necessary to suppress the significant pressure fluctuation (combustion instability) caused by unstable combustion. For this reason, we have newly developed a technology to disperse flow fluctuation using a combination of various injection element lengths and a technology to absorb pressure fluctuation using a resonator. This brought about significant improvement of combustion stability. With these key technologies, we have gained the prospective of the practical application of the LE-9, which is the world's first large-thrust engine that adopts the expander bleed cycle. The development of the LE-9 is proceeding smoothly toward the launch of the first vehicle in 2020.
