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RL10 Engine

Overview

For six decades, L3Harris' RL10 engine has played a vital role in placing hundreds of military, government and commercial spacecraft into Earth’s orbit and beyond. The engine has helped send spacecraft to explore every planet in our solar system, including Voyager 1 and Voyager 2, the first two spacecraft to reach interstellar space.

Today, multiple  RL10 variants carry the engine’s legacy forward as the launch industry’s “workhorse,” powering the upper stages of United Launch Alliance’s (ULA) Atlas V and Delta IV Heavy rockets. Two RL10 engines power the upper stage of ULA’s new Vulcan Centaur rocket.

RL10 engines also help power NASA’s Space Launch System (SLS) rocket, designed to carry astronauts to deep-space destinations aboard the Orion exploration spacecraft. A single RL10 powered the Interim Cryogenic Propulsion Stage on Artemis I, an uncrewed test flight of SLS and Orion. Four RL10 engines will support the more powerful Exploration Upper Stage that is being developed for future versions of SLS.

L3Harris has developed and is working to qualify a modern version of the engine known as the RL10C-X that includes major components built using 3D printing technology. Incorporating 3D printing into the manufacturing process will reduce lead times and cost while maintaining the outstanding performance and reliability customers have come to expect.

Key Features

  • 1959: First RL10 test
  • 1963: First successful Atlas Centaur flight (two RL10 engines powered upper stage)
  • 1964: Saturn S-4 Launch (six RL10 engines powered upper stage)
  • 1993: First DC-X "Delta Clipper" flight (four RL10A-5 engines powered vehicle)
  • 2002: First Atlas V flight (two RL10A-4-2 engines powered Centaur upper stage)
  • 2009: 400th RL10 engine flight
  • 2010: Demonstrated deep-throttling from 104 percent of rated power down to 5.9 percent (an unprecedented thrust range of 17.6:1)
  • 2013: RL10 marks 50 years of service
  • 2014: First flight of RL10C-1
  • 2020: 500th RL10 engine flight
  • 2021: First operational use of an RL10 engine equipped with 3D-printed components
  • 2022: A single RL10 powered the Interim Cryogenic Propulsion Stage on the first SLS mission

Models RL10B-2, RL10C-2-1

Models RL10B-2, RL10C-2-1Launch VehicleDelta IV
Models RL10B-2, RL10C-2-1Thrust24,750 lbf
Models RL10B-2, RL10C-2-1Weight664 lbs
Models RL10B-2, RL10C-2-1FuelLiquid hydrogen
Models RL10B-2, RL10C-2-1OxidizerLiquid oxygen
Models RL10B-2, RL10C-2-1Nominal Mixture Ratio5.88:1
Models RL10B-2, RL10C-2-1Specific Impulse465.5 sec
Models RL10B-2, RL10C-2-1Length86.5" (stowed), 163.5" (deployed)
Models RL10B-2, RL10C-2-1Nozzle Diameter84.5"

 

Model RL10A-4-2

Model RL10A-4-2Launch VehicleAtlas V
Model RL10A-4-2Thrust22,300 lbf
Model RL10A-4-2Weight370 lbs
Model RL10A-4-2FuelLiquid hydrogen
Model RL10A-4-2OxidizerLiquid oxygen
Model RL10A-4-2Nominal Mixture Ratio5.5:1
Model RL10A-4-2Specific Impulse451.0 sec
Model RL10A-4-2Length90"
Model RL10A-4-2Nozzle Diameter46"

 

Model RL10C-1

Model RL10C-1Launch VehicleAtlas V
Model RL10C-1Thrust22,890 lbf
Model RL10C-1Weight420 lbs
Model RL10C-1FuelLiquid hydrogen
Model RL10C-1OxidizerLiquid oxygen
Model RL10C-1Nominal Mixture Ratio5.5:1
Model RL10C-1Specific Impulse449.7 sec
Model RL10C-1Length86"
Model RL10C-1Nozzle Diameter57"

 

Model RL10C-1-1

Model RL10C-1-1Launch VehicleAtlas V, Vulcan Centaur
Model RL10C-1-1Thrust23,825 lbf
Model RL10C-1-1Weight415 lbs
Model RL10C-1-1FuelLiquid hydrogen
Model RL10C-1-1OxidizerLiquid oxygen
Model RL10C-1-1Nominal Mixture Ratio5.5:1
Model RL10C-1-1Specific Impulse453.8 sec
Model RL10C-1-1Length96.7"
Model RL10C-1-1Nozzle Diameter62"

 

Model RL10C-X

Model RL10C-XLaunch VehicleVulcan Centaur
Model RL10C-XThrust24,120 lbf
Model RL10C-XWeight510 lbs
Model RL10C-XFuelLiquid hydrogen
Model RL10C-XOxidizerLiquid oxygen
Model RL10C-XNominal Mixture Ratio5.5:1
Model RL10C-XSpecific Impulse460.9 sec
Model RL10C-XLength130.4"
Model RL10C-XNozzle Diameter73.7"

 

Model RL10C-3

Model RL10C-3Launch VehicleSLS Exploration Upper Stage
Model RL10C-3Thrust24,340 lbf
Model RL10C-3Weight508 lbs
Model RL10C-3FuelLiquid hydrogen
Model RL10C-3OxidizerLiquid oxygen
Model RL10C-3Nominal Mixture Ratio5.7:1
Model RL10C-3Specific Impulse460.1 sec
Model RL10C-3Length124.3"
Model RL10C-3Nozzle Diameter73"

Resources

  • RL10 Propulsion System Data Sheet

    RL10 Propulsion System Data Sheet

  • Premier Propulsion Provider for the U.S. Air Force Data Sheet

    Premier Propulsion Provider for the U.S. Air Force Data Sheet

Featured News

Two employees inspect an engine

Press release | 11. 21. 2024

L3Harris Delivers New Generation of RL10 Rocket Engines

L3Harris Technologies has delivered the first RL10 engine that features a 3D-printed copper thrust chamber to United Launch Alliance (ULA).

Two employees inspect an engine

Press release | 11. 21. 2024

L3Harris Delivers New Generation of RL10 Rocket Engines

The United Launch Alliance (ULA) Vulcan rocket lifts off Oct. 4, 2024 from Space Launch Complex-41 (SLC-41) at Cape Canaveral on the Cert-2 flight test. Photo Credit: United Launch Alliance

Press release | 10. 04. 2024

L3Harris Supports United Launch Alliance’s Second Vulcan Launch

Rocket motor test fires in a forest

Editorial | 08. 05. 2024

The L3Harris Difference - Delivering on Aerojet Rocketdyne

cyber computer room

Press release | 07. 29. 2024

L3Harris Highlights Performance Progress One Year After Acquiring Aerojet Rocketdyne

A United Launch Alliance (ULA) Atlas V rocket carrying NASA astronauts Barry “Butch” Wilmore and Sunita “Suni” Williams aboard the Boeing Starliner spacecraft lifts off from Space Launch Complex-41 at 10:52 a.m. EDT on June 5, 2024. Photos by United Launch Alliance

Editorial | 06. 05. 2024

RL10 Engine Makes Human Spaceflight Debut on ULA’s Atlas V Launch of Starliner Spacecraft

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