Rocketdyne J-2S
Historical Rocketdyne J-2S (J-2 Simplified) tap-off-cycle LOX/LH2 upper-stage engine developed as a higher-performance follow-on to J-2. NASA records a nominal 265,000 lbf (1,178.4 kN) vacuum thrust, 436 s specific impulse, and full-scale validation of six flight-configuration engines in 273 tests; the program ended before a flight installation, so no vehicle relationship is asserted.
Identity
- Aliases
- J-2SRocketdyne J-2SJ2S
- Domains
- spaceflight
- Identity Level
- model
- Kind
- liquid-rocket-engine
- Name
- Rocketdyne J-2S
- Status
- historical
Details
- Description
- Historical Rocketdyne J-2S (J-2 Simplified) tap-off-cycle LOX/LH2 upper-stage engine developed as a higher-performance follow-on to J-2. NASA records a nominal 265,000 lbf (1,178.4 kN) vacuum thrust, 436 s specific impulse, and full-scale validation of six flight-configuration engines in 273 tests; the program ended before a flight installation, so no vehicle relationship is asserted.
- Developers
- Lineage
- Note
- NASA describes J-2S as the J-2 Simplified follow-on configuration, changing the cycle to tap-off while increasing performance and simplifying production and operation.
- Related Propulsion System
- Relationship
- direct-derivative-of
- Sources
- Accessed Date
- 2026-08-14
- Publisher
- NASA Technical Reports Server
- Title
- J-2S background information
- Accessed Date
- 2026-08-14
- Publisher
- NASA Technical Reports Server
- Title
- J-2S restart study
- Manufacturers
- Propellants
- liquid oxygenliquid hydrogen
- Rocket Specs
- Cycle
- tap-off
- Vacuum Specific Impulse S
- 436
- Vacuum Thrust Kn
- 1178.4
Links
- Official Url
- https://ntrs.nasa.gov/citations/19940016798
Assets & Meta
- Creation Time
- August 6, 2026 at 19:06:15 UTC
- Updated Time
- August 15, 2026 at 06:09:04 UTC
Other
- Sources
- Accessed Date
- 2026-08-14
- Note
- Identifies J-2S as a simplified, higher-performance J-2 follow-on with LOX/LH2 propellants, 265,000 lbf nominal vacuum thrust, and 436 s specific impulse.
- Publisher
- NASA Technical Reports Server
- Title
- J-2S background information
- Accessed Date
- 2026-08-14
- Note
- Documents the tap-off cycle and the high-energy upper-stage development boundary without asserting a flown vehicle installation.
- Publisher
- NASA Technical Reports Server
- Title
- J-2S restart study
- Accessed Date
- 2026-08-14
- Note
- Records six flight-configuration engines validated in 273 tests for 30,858 seconds and the 265,000-pound-thrust J-2S model boundary.
- Publisher
- NASA Technical Reports Server
- Title
- Advanced transportation system studies: J-2S restart study
- Accessed Date
- 2026-08-14
- Note
- Identifies J-2S heritage as a technical basis for later J-2X development.
- Publisher
- NASA Technical Reports Server
- Title
- The J-2X fuel turbopump: Design, development, and test