RS-27
Rocketdyne RS-27 is a single-start, fixed-thrust, pump-fed, regeneratively cooled liquid bipropellant engine derived from H-1 and Thor hardware for Delta launch vehicles. NASA reports 205,000 lbf (911.9 kN) sea-level thrust and 262.7 s sea-level specific impulse for the engine, with a 2.24:1 oxidizer/fuel mixture ratio; its gas-generator-driven turbopump burns liquid oxygen and RP-1. The RS-27 is also documented in the Atlas II MA-5A booster system.
Identity
- Aliases
- RS-27 (two-chamber booster)
- Domains
- spaceflight
- Identity Level
- model
- Kind
- liquid-rocket-engine
- Name
- RS-27
- Status
- retired
Details
- Description
- Rocketdyne RS-27 is a single-start, fixed-thrust, pump-fed, regeneratively cooled liquid bipropellant engine derived from H-1 and Thor hardware for Delta launch vehicles. NASA reports 205,000 lbf (911.9 kN) sea-level thrust and 262.7 s sea-level specific impulse for the engine, with a 2.24:1 oxidizer/fuel mixture ratio; its gas-generator-driven turbopump burns liquid oxygen and RP-1. The RS-27 is also documented in the Atlas II MA-5A booster system.
- Developers
- Lineage
- Note
- NASA identifies RS-27 as developed from H-1 and Thor engine hardware for Delta.
- Related Propulsion System
- Relationship
- direct-derivative-of
- Sources
- Accessed Date
- 2026-07-29
- Publisher
- NASA
- Title
- Santa Susana Field Laboratory program history: Thor and RS-27
- Manufacturers
- Propellants
- RP-1liquid oxygen
- Rocket Specs
- Chamber Count
- 1
- Cycle
- gas-generator
- Sea Level Specific Impulse S
- 262.7
- Sea Level Thrust Kn
- 911.9
Links
- Official Url
- https://ssfl.msfc.nasa.gov/history/programs
Assets & Meta
- Creation Time
- July 29, 2026 at 11:09:02 UTC
- Updated Time
- August 22, 2026 at 06:57:17 UTC
Other
- Sources
- Accessed Date
- 2026-07-29
- Publisher
- NASA
- Title
- Santa Susana Field Laboratory program history: Thor and RS-27
- Accessed Date
- 2026-07-29
- Publisher
- Lockheed Martin
- Title
- Atlas Launch System Mission Planner's Guide, Revision 7
- Accessed Date
- 2026-07-29
- Note
- Supports the legacy vehicle installation and the narrow canonical identity used for migration.
- Publisher
- Official vehicle or program source
- Title
- Atlas IIAS official vehicle reference
- Accessed Date
- 2026-08-21
- Note
- Describes RS-27 as a single-start, fixed-thrust, pump-fed, regeneratively cooled LOX/RP-1 engine with a gas-generator-driven turbopump, 205,000 lbf sea-level thrust, 262.7 s sea-level specific impulse, and a 2.24:1 oxidizer/fuel mixture ratio.
- Publisher
- NASA Technical Reports Server
- Title
- Reusable Rocket Engine Maintenance Study