LE-9
LE-9 is the liquid-hydrogen/liquid-oxygen first-stage engine for H3, installed in groups of two or three according to launch-vehicle configuration. It scales expander-bleed technology to a high-thrust booster engine: hydrogen heated during chamber and nozzle cooling powers the pumps without a preburner. JAXA’s detailed LE-9 table lists 1,471 kN vacuum thrust, 422 s specific impulse, 3.75 m overall length and approximately 2.4 tonnes mass. Its separate H3 brochure rounds vacuum thrust to 1,472 kN. LE-X research supplied development data for LE-9.
Identity
- Domains
- spaceflight
- Identity Level
- model
- Kind
- liquid-rocket-engine
- Name
- LE-9
- Status
- active
Details
- Description
- LE-9 is the liquid-hydrogen/liquid-oxygen first-stage engine for H3, installed in groups of two or three according to launch-vehicle configuration. It scales expander-bleed technology to a high-thrust booster engine: hydrogen heated during chamber and nozzle cooling powers the pumps without a preburner. JAXA’s detailed LE-9 table lists 1,471 kN vacuum thrust, 422 s specific impulse, 3.75 m overall length and approximately 2.4 tonnes mass. Its separate H3 brochure rounds vacuum thrust to 1,472 kN. LE-X research supplied development data for LE-9.
- Dry Mass
- …
- Length
- …
- Lineage
- Note
- JAXA identifies LE-9 as a scaled-up application of the expander-bleed cycle used by the LE-5B series.
- Related Propulsion System
- Relationship
- technology-derived-from
- Sources
- Accessed Date
- 2026-07-29
- Publisher
- Japan Aerospace Exploration Agency
- Title
- LE-5B-3
- Propellants
- liquid hydrogenliquid oxygen
- Rocket Specs
- Cycle
- expander-bleed
- Vacuum Specific Impulse
- …
- Vacuum Thrust
- …
Links
- Official Url
- https://www.rocket.jaxa.jp/rocket/h3/
Assets & Meta
- Creation Time
- July 29, 2026 at 08:49:33 UTC
- Updated Time
- October 29, 2026 at 15:30:59 UTC
Other
- Sources
- Accessed Date
- 2026-07-29
- Note
- Supports the legacy vehicle installation and the narrow canonical identity used during migration.
- Publisher
- Official vehicle or program source
- Title
- H3-30S official vehicle reference
- Accessed Date
- 2026-07-29
- Publisher
- Japan Aerospace Exploration Agency
- Title
- H3 Launch Vehicle: LE-5B-3 and LE-9
- Accessed Date
- 2026-07-29
- Publisher
- Japan Aerospace Exploration Agency
- Title
- LE-5B-3
- Accessed Date
- 2026-08-22
- Note
- JAXA identifies LE-9 as the H3 main engine, documents its expander-bleed cycle and LE-5-series heritage, and describes the two- or three-engine first-stage configurations.
- Publisher
- Japan Aerospace Exploration Agency
- Title
- H3 Launch Vehicle
- Accessed Date
- 2026-08-22
- Note
- JAXA's H3 brochure lists two- or three-unit LE-9 first-stage configurations and 1,472 kN thrust per engine.
- Publisher
- Japan Aerospace Exploration Agency
- Title
- H3 Launch Vehicle
- Accessed Date
- 2026-10-29
- Note
- Detailed table explicitly labels 1471 kN as vacuum thrust; lists 422 s Isp, 3.75 m length and approximately 2.4 t mass. Development section identifies LE-X research heritage.
- Publisher
- Japan Aerospace Exploration Agency
- Title
- LE-9 engine