LE-9

The LE-9 is a liquid cryogenic rocket engine burning liquid hydrogen and liquid oxygen in an expander bleed cycle. Two or three will be used to power the core stage of the H3 launch vehicle.^[1][2][5]

LE-9

Country of origin	Japan
Designer	JAXA
Manufacturer	Mitsubishi Heavy Industries
Application	sustainer engine
Associated LV	H3 Launch Vehicle
Predecessor	LE-7A
Status	In production
Liquid-fuel engine
Propellant	Liquid oxygen / Liquid hydrogen
Mixture ratio	5.9
Cycle	Expander Bleed cycle
Configuration
Chamber	1
Nozzle ratio	37:1
Performance
Thrust, vacuum	1,471 kN (331,000 lbf)
Thrust-to-weight ratio	62.50
Chamber pressure	10.0 MPa (1,450 psi)
Specific impulse, vacuum	426 s (4.18 km/s)
Dimensions
Length	3.8 m
Dry mass	2.4 t (5,300 lb)
Used in
H3 Launch Vehicle core stage.
References
References	[1][2][3][4]

The newly developed LE-9 engine is the most important factor in achieving cost reduction, improved safety and increased thrust. The expander bleed cycle used in the LE-9 engine is a highly reliable combustion method that Japan has put into practical use for the LE-5A/B engine. However, it is physically difficult for an expander bleed cycle engine to generate large thrust, so the development of the LE-9 engine with a thrust of 1,471 kN (331,000 lb_f) is the most challenging and important development element.^[6]

Firing tests of the LE-9 first-stage engine began in April 2017.^[7]

On 21 January 2022, the launch of the first H3 was rescheduled to FY 2022 or later, citing technical problems regarding the first stage LE-9 engine.^[8]

The LE-9 was operated successfully for the first time, on March 7, 2023. The second stage of that rocket, did not ignite and the mission was a failure.^[9] On February 17, 2024, the second launch of H3 was successful and LE-9 operations were successful for the second consecutive time.^[10]

See also

• H3 Launch Vehicle
• LE-7
• LE-5