RS-27A
RS-27A is Rocketdyne's improved liquid-oxygen/RP-1 main engine for Delta II 7000-series first stages, distinct from the earlier RS-27 model. NASA data reports 200,000 lbf (889.6 kN) sea-level thrust, 237,000 lbf (1,054.2 kN) vacuum thrust, and 255/302 s sea-level/vacuum specific impulse.
Identity
- Domains
- spaceflight
- Identity Level
- variant
- Kind
- liquid-rocket-engine
- Name
- RS-27A
- Status
- retired
Details
- Description
- RS-27A is Rocketdyne's improved liquid-oxygen/RP-1 main engine for Delta II 7000-series first stages, distinct from the earlier RS-27 model. NASA data reports 200,000 lbf (889.6 kN) sea-level thrust, 237,000 lbf (1,054.2 kN) vacuum thrust, and 255/302 s sea-level/vacuum specific impulse.
- Developers
- Family
- Lineage
- Note
- NASA and ULA identify RS-27A as the Delta II 7000-series development of the RS-27 engine.
- Related Propulsion System
- Relationship
- direct-derivative-of
- Sources
- Accessed Date
- 2026-08-01
- Publisher
- NASA
- Title
- Delta II Data Sheet
- Accessed Date
- 2026-08-01
- Publisher
- United Launch Alliance
- Title
- ULA Marks Delta II 20 Year Anniversary with Successful NASA Kepler Launch
- Manufacturers
- Propellants
- RP-1liquid oxygen
- Rocket Specs
- Chamber Count
- 1
- Cycle
- gas-generator
- Sea Level Specific Impulse S
- 255
- Sea Level Thrust Kn
- 889.6
- Vacuum Specific Impulse S
- 302
- Vacuum Thrust Kn
- 1054.2
Links
Assets & Meta
- Creation Time
- August 1, 2026 at 10:27:27 UTC
- Updated Time
- August 22, 2026 at 07:03:21 UTC
Other
- Sources
- Accessed Date
- 2026-08-01
- Note
- Names RS-27A as the Delta II main engine.
- Publisher
- NASA
- Title
- Delta II Data Sheet
- Accessed Date
- 2026-08-01
- Note
- Confirms the RS-27A first-stage installation and RP-1/LOX propellants.
- Publisher
- NASA
- Title
- Delta II, Industry Workhorse, Ready for Final Flight
- Accessed Date
- 2026-08-01
- Note
- Identifies the RS-27A on the Delta II 7925-10L first stage.
- Publisher
- United Launch Alliance
- Title
- ULA Marks Delta II 20 Year Anniversary with Successful NASA Kepler Launch
- Accessed Date
- 2026-08-22
- Note
- NASA's propulsion table identifies RS-27A as a production Rocketdyne gas-generator engine using LOX/RP-1.
- Publisher
- NASA Technical Reports Server
- Title
- Propulsion Needs for 2001-2010 Engines (Continued)
- Accessed Date
- 2026-08-22
- Note
- NASA's engine comparison table reports RS-27A performance of 200,000 lbf sea-level thrust, 237,000 lbf vacuum thrust, 255 s sea-level specific impulse, and 302 s vacuum specific impulse; values are normalized to kN in rocketSpecs.
- Publisher
- NASA Technical Reports Server
- Title
- From Earth to Orbit: An assessment of transportation options