ABOUT LE-7A
The LE-7A is a cryogenic staged combustion cycle engine developed by Mitsubishi Heavy Industries for the first stage of Japan’s H-IIA and H-IIB launch vehicles. It is an improved version of the LE-7, with simplified manufacturing and higher reliability. The LE-7A burns liquid hydrogen and liquid oxygen, delivering 1,098 kN of vacuum thrust as Japan’s most powerful indigenous engine.
Image: JAXA
PERFORMANCE
| Thrust (Sea Level) | 870 kN (195,600 lbf) kN |
| Thrust (Vacuum) | 1,098 kN (246,800 lbf) kN |
| ISP (Sea Level) | 338 s s |
| ISP (Vacuum) | 440 s s |
| Chamber Pressure | 12.0 MPa (1,740 psi) bar |
| Mass | 1 kg |
| Thrust-to-Weight | 62 |
| Throttle Range | 72–100% |
| Restart Capable | No |
THRUST CONVERSIONS (VACUUM)
| Kilonewtons | 1.0 kN |
| Pounds-force | 225 lbf |
ENGINE CYCLE
Staged Combustion
In staged combustion, one propellant is burned with the turbopump exhaust, then all products are injected into the main chamber for complete combustion. This achieves higher chamber pressures and efficiency. Used by the RS-25 (SSME) and RD-180.
PROPULSION
| Propellant | Liquid Hydrogen (LH₂) |
| Oxidizer | LOX |
| Engine Cycle | Staged Combustion |
| Mixture Ratio | 5.9:1 |
| Flow Rate | ~255 kg/s kg/s |
PHYSICAL
| Dimensions | 1.82 m diameter × 3.6 m length |
| Combustion Chambers | 1 |
| Nozzle Expansion Ratio | 51.9:1:1 |
GENERAL
| Manufacturer | Mitsubishi Heavy Industries (MHI) |
| Country | Japan |
| Status | Active |
| First Flight | April 16, 2026 |
VARIANTS (2)
- LE-7
- LE-7A
ENGINE LINEAGE
LE-7→LE-7A→LE-9 (H3 rocket)
⚖ PROPELLANTS
