RS-68A
Overview
Generating 705,000 pounds of thrust at sea level, the Aerojet Rocketdyne RS-68A is the world’s most powerful hydrogen-fueled rocket engine.
The engine provides main propulsion on United Launch Alliance’s Delta IV rocket, which is used primarily by the U.S. Department of Defense. The Delta IV Heavy, featuring three vehicle cores in a side-by-side configuration, is capable of launching the Defense Department’s heaviest payloads.
The original variant of the engine, the RS-68, was developed with private company funds. The RS-68A represents an improvement over the RS-68 and provides 42,000 pounds of additional thrust. The upgraded RS-68A completed its first test firing in September 2008, was certified in April 2011 and made its inaugural flight in June 2012.
Key Features
- World’s largest and highest thrust hydrogen-fueled engine
- Commercially-developed
- Produces more than 17 million horsepower
Program Milestones
- November 2002: First flight – RS-68
- September 2008: First test firing – RS-68A
- November 2010: RS-68A certification testing complete
- April 2011: RS-68A design certification complete
- June 2012: First flight – RS-68A
Engine Specifications
|
Engine |
Full Power |
Minimum Power |
| Thrust (Vacuum): | 800K lbf | 412K lbf |
|
Thrust (Sea Level): |
705K lbf |
318K lbf |
|
Chamber Pressure: |
1,580 psia |
820 psia |
|
Engine Mixture Ratio: |
5.97 |
5.99 |
|
Isp, Vacuum: |
411 sec |
411 sec |
|
Isp, Sea Level: |
362 sec |
317 sec |
|
Height: |
17.1 ft | 17.1 ft |
|
Weight: |
14,740 lbs | 14,740 lbs |
|
Diameter: |
8 ft | 8 ft |
| Expansion Ratio: | 21.5 | 21.5 |
Resources
Press Releases
- April 26, 2021 - Aerojet Rocketdyne Powers Launch of ULA’s Delta IV Heavy to Orbit
- April 12, 2021 - World’s Most Powerful Hydrogen-Fueled Rocket Engine Completes Final Acceptance Test for ULA Delta IV Heavy Launch Vehicle
- Dec. 11, 2020 - Aerojet Rocketdyne Powers ULA Launch of National Reconnaissance Office Payload
- Mar. 3, 2020 - Aerojet Rocketdyne Provides World’s Most Powerful Hydrogen-Fueled Rocket Engine for Display at INFINITY Science Center
- Aug. 22, 2019 - Aerojet Rocketdyne Helping to Propel Modernization of GPS Satellite Constellation
- March 15, 2019 - Aerojet Rocketdyne Powers WGS-10 Military Communications Satellite from Launch Pad to Orbit
- Dec. 6, 2018 - Aerojet Rocketdyne Gears Up for Next ULA Delta IV Heavy Mission
- Aug. 12, 2018 - On Parker Solar Probe, NASA Leaves the Driving to Aerojet Rocketdyne
- Jan. 12, 2018 - Aerojet Rocketdyne Supports ULA Launch in Support of National Security
- March 18, 2017 - Aerojet Rocketdyne Supports ULA Launch of Wideband Global SATCOM Spacecraft for the U.S. Military
