Menu
Home Explore People Places Arts History Plants & Animals Science Life & Culture Technology
On this page
RL10
Liquid fuel cryogenic rocket engine, typically used on rocket upper stages

The RL10 is a liquid-fuel cryogenic rocket engine built in the United States by Aerojet Rocketdyne that burns cryogenic liquid hydrogen and liquid oxygen propellants. Modern versions produce up to 110 kN (24,729 lbf) of thrust per engine in vacuum. RL10 versions were produced for the Centaur upper stage of the Atlas V and the DCSS of the Delta IV. More versions are in development or in use for the Exploration Upper Stage of the Space Launch System and the Centaur V of the Vulcan rocket.

The expander cycle that the engine uses drives the turbopump with waste heat absorbed by the engine combustion chamber, throat, and nozzle. This, combined with the hydrogen fuel, leads to very high specific impulses (Isp) in the range of 373 to 470 s (3.66–4.61 km/s) in a vacuum. Mass ranges from 131 to 317 kg (289–699 lb) depending on the version of the engine.

Related Image Collections Add Image
Profiles
1 Image
We don't have any YouTube videos related to RL10 yet.
We don't have any PDF documents related to RL10 yet.
We don't have any Books related to RL10 yet.
We don't have any archived web articles related to RL10 yet.

History

The RL10 was the first liquid hydrogen rocket engine to be built in the United States, with development of the engine by Marshall Space Flight Center and Pratt & Whitney beginning in the 1950s. The RL10 was originally developed as a throttleable engine for the USAF Lunex lunar lander.4

The RL10 was first tested on the ground in 1959, at Pratt & Whitney's Florida Research and Development Center in West Palm Beach, Florida.56 The first successful flight took place on November 27, 1963.78 For that launch, two RL10A-3 engines powered the Centaur upper stage of an Atlas launch vehicle. The launch was used to conduct a heavily instrumented performance and structural integrity test of the vehicle.9

Multiple versions of this engine have been flown. The S-IV of the Saturn I used a cluster of six RL10A-3S, a version which was modified for installation on the Saturn10 and the Titan program included Centaur D-1T upper stages powered by two RL10A-3-3 Engines.1112

Four modified RL10A-5 engines were used in the McDonnell Douglas DC-X.13

A flaw in the brazing of an RL10B-2 combustion chamber was identified as the cause of failure for the 4 May 1999 Delta III launch carrying the Orion-3 communications satellite.14

The DIRECT version 3.0 proposal to replace Ares I and Ares V with a family of rockets sharing a common core stage recommended the RL10 for the second stage of the J-246 and J-247 launch vehicles.15 Up to seven RL10 engines would have been used in the proposed Jupiter Upper Stage, serving an equivalent role to the Space Launch System Exploration Upper Stage.

Common Extensible Cryogenic Engine

In the early 2000s, NASA contracted with Pratt & Whitney Rocketdyne to develop the Common Extensible Cryogenic Engine (CECE) demonstrator. CECE was intended to lead to RL10 engines capable of deep throttling.16 In 2007, its operability (with some "chugging") was demonstrated at 11:1 throttle ratios.17 In 2009, NASA reported successfully throttling from 104 percent thrust to eight percent thrust, a record for an expander cycle engine of this type. Chugging was eliminated by injector and propellant feed system modifications that control the pressure, temperature and flow of propellants.18 In 2010, the throttling range was expanded further to a 17.6:1 ratio, throttling from 104% to 5.9% power.19

Early 2010s possible successor

In 2012 NASA joined with the US Air Force (USAF) to study next-generation upper stage propulsion, formalizing the agencies' joint interests in a new upper stage engine to replace the Aerojet Rocketdyne RL10.

"We know the list price on an RL10. If you look at cost over time, a very large portion of the unit cost of the EELVs is attributable to the propulsion systems, and the RL10 is a very old engine, and there's a lot of craftwork associated with its manufacture. ... That's what this study will figure out, is it worthwhile to build an RL10 replacement?"

— Dale Thomas, Associated Director Technical, Marshall Space Flight Center20

From the study, NASA hoped to find a less expensive RL10-class engine for the upper stage of the Space Launch System (SLS).2122

USAF hoped to replace the Rocketdyne RL10 engines used on the upper stages of the Lockheed Martin Atlas V and the Boeing Delta IV Evolved Expendable Launch Vehicles (EELV) that were the primary methods of putting US government satellites into space.23 A related requirements study was conducted at the same time under the Affordable Upper Stage Engine Program (AUSEP).24

Improvements

The RL10 has evolved over the years. The RL10B-2 that was used on the DCSS had improved performance, an extendable carbon-carbon nozzle, electro-mechanical gimbaling for reduced weight and increased reliability, and a specific impulse of 465.5 seconds (4.565 km/s).2526

As of 2016, Aerojet Rocketdyne was working toward incorporating additive manufacturing into the RL10 construction process. The company conducted full-scale, hot-fire tests on an engine that had a printed main injector in March 2016.27 Another project by Aerojet Rocketdyne was an engine with a printed thrust chamber assembly in April 2017.28

Applications

Current

  • Centaur III: The single engine centaur (SEC) version uses the RL10C-1,29 while the dual engine centaur (DEC) version retains the smaller RL10A-4-2.30 An Atlas V mission (SBIRS-5) marked the first use of the RL10C-1-1 version. The mission was successful but observed unexpected vibration, and further use of the RL10C-1-1 model is on hold until the problem is better understood.31 The engine was used again successfully on SBIRS-6.
  • Centaur V stage: On May 11, 2018, United Launch Alliance (ULA) announced that the RL10 upper stage engine had been selected for its Vulcan Centaur rocket following a competitive procurement process.32 Early versions of the Centaur V will use the RL10C-1-1,33 but later versions will transition to the RL10C-X.34 Vulcan flew its successful maiden flight on January 8, 2024.35
  • Interim Cryogenic Propulsion Stage: The Interim Cryogenic Propulsion Stage or ICPS is used for the SLS and is similar to the DCSS, except that the engine is an RL10B-2 and it is adapted to fit on top of the 8.4 meter diameter core stage with four RS-25 Space Shuttle Main Engines.

In development

Cancelled

Table of versions

VersionStatusFirst flightDry massThrustIsp (ve), vac.LengthNozzle diameterT:WO:FExpansion ratioChamber pressureBurn timeAssociated stageNotes
RL10A-1Retired1962131 kg (289 lb)67 kN (15,000 lbf)425 s (4.17 km/s)1.73 m (5 ft 8 in)1.53 m (5 ft 0 in)52:15:140:120.7 bar (2,070 kPa)430 sCentaur APrototype41424344
RL10A-3CRetired1963131 kg (289 lb)65.6 kN (14,700 lbf)444 s (4.35 km/s)2.49 m (8 ft 2 in)1.53 m (5 ft 0 in)51:15:157:132.75 bar (3,275 kPa)470 sCentaur B/C/D/E45
RL10A-3SRetired1964134 kg (296 lb)67 kN (15,000 lbf)427 s (4.19 km/s)1.73 m (5 ft 8 in)51:15:140:120.7 bar (2,070 kPa)S-IV4647
RL10A-4Retired1992168 kg (370 lb)92.5 kN (20,800 lbf)449 s (4.40 km/s)2.29 m (7 ft 6 in)1.17 m (3 ft 10 in)56:15.5:184:139.8 bar (3,980 kPa)392 sCentaur IIA4849
RL10A-5Retired1993143 kg (315 lb)64.7 kN (14,500 lbf)373 s (3.66 km/s)1.07 m (3 ft 6 in)1.02 m (3 ft 4 in)46:16:14:139.8 bar (3,980 kPa)127 sDC-X5051
RL10B-2Retired1998301 kg (664 lb)110.1 kN (24,750 lbf)465.5 s (4.565 km/s)Stowed: 2.2 m (7 ft 2.5 in)Deployed: 4.15 m (13 ft 7.5 in)2.15 m (7 ft 0.5 in)40:15.88:1280:144.12 bar (4,412 kPa)5m: 1,125 s4m: 700 sDCSSICPSSucceeded by RL10C-2.5253
RL10A-4-1Retired2000167 kg (368 lb)99.1 kN (22,300 lbf)451 s (4.42 km/s)1.78 m (5 ft 10 in)1.53 m (5 ft 0 in)61:184:142 bar (4,200 kPa)740 sCentaur IIIA5455
RL10A-4-2Active2002170 kg (370 lb)99 kN (22,300 lbf)451 s (4.42 km/s)2.29 m (7 ft 6 in)1.17 m (3 ft 10 in)61:184:142 bar (4,200 kPa)740 sCentaur IIIBCentaur SECCentaur DECUsed for Starliner launches.565758
RL10B-XCancelled—317 kg (699 lb)93.4 kN (21,000 lbf)470 s (4.6 km/s)1.53 m (5 ft 0 in)30:1250:1408 sCentaur B-X59
CECEDemonstrator project—160 kg (350 lb)67 kN (15,000 lbf), throttle to 5–10%>445 s (4.36 km/s)1.53 m (5 ft 0 in)43:1N/A6061
RL10C-1Retired2014190 kg (420 lb)101.5 kN (22,820 lbf)449.7 s (4.410 km/s)2.18 m (7 ft 2 in)1.45 m (4 ft 9 in)57:15.5:1130:1Centaur SECCentaur DECSucceeded by RL-10C-1-1.62636465
RL10C-1-1Active2021188 kg (415 lb)105.98 kN (23,825 lbf)453.8 s (4.450 km/s)2.46 m (8 ft 0.7 in)1.57 m (5 ft 2 in)57:15.5:1155:1Atlas: 842 sVulcan: 1,077 sCentaur SECCentaur VCurrent standard engine for Atlas V and Vulcan Centaur.6667
RL10C-2-1Retired2022301 kg (664 lb)110.1 kN (24,750 lbf)465.5 s (4.565 km/s)Stowed: 2.2 m (7 ft 2.5 in)Deployed: 4.15 m (13 ft 7.5 in)2.15 m (7 ft 0.5 in)37:15.88:1280:1DCSS6869
RL10C-2Delivered, not yet flown2026 (expected)110.1 kN (24,750 lbf)465.5 s (4.565 km/s)Stowed: 2.2 m (7 ft 2.5 in)Deployed: 4.15 m (13 ft 7.5 in)2.15 m (7 ft 1 in)37:15.88:1280:1ICPSConversion of C-370
RL10C-3Delivered, not yet flown2028 (expected)230 kg (508 lb)108.3 kN (24,340 lbf)460.1 s (4.512 km/s)3.16 m (10 ft 4.3 in)1.85 m (6 ft 1 in)48:15.7:1215:1EUS717273
RL10C-5-1Cancelled—188 kg (414 lb)106 kN (23,825 lbF)453.8 s (4.450 km/s)2.46 m (8 ft 0.7 in)1.57 m (4 ft 9 in)57:15.5:1OmegA7475
RL10C-XIn development2025 (expected)231 kg (509 lb)107.29 kN (24,120 lbF)460.9 s (4.520 km/s)3.31 m (130.4 in)1.87 m (73.7 in)47.29:15.5:1Centaur VAdditive manufacturing 7677

Partial specifications

All versions

  • Contractor: Pratt & Whitney
  • Propellants: liquid oxygen, liquid hydrogen78
  • Design: expander cycle79
  • Ignition: electric spark.80

RL10A

  • Thrust (altitude): 15,000 lb-f (66.7 kN)81
  • Specific impulse: 433 seconds (4.25 km/s)
  • Engine weight, dry: 298 lb (135 kg)
  • Height: 68 in (1.73 m)
  • Diameter: 39 in (0.99 m)
  • Nozzle expansion ratio: 40 to 1
  • Propellant flow: 35 lb/s (16 kg/s)
  • Vehicle application: Saturn I, S-IV 2nd stage, 6 engines
  • Vehicle application: Centaur upper stage, 2 engines

RL10B-2

  • Thrust (altitude): 24,750 lbf (110.1 kN)82
  • Specific impulse: 465.5 seconds (4.565 km/s)83
  • Engine weight, dry: 664 lb (301.2 kg)84
  • Height: 163.5 in (4.14 m)85
  • Diameter: 84.5 in (2.21 m)86
  • Expansion ratio: 280 to 1
  • Mixture ratio: 5.88 to 1 oxygen:hydrogen mass ratio87
  • Propellant flow: fuel, 7.72 lb/s (3.5 kg/s); oxidizer 45.42 lb/s (20.6 kg/s)88
  • Vehicle application: Delta III, Delta IV second stage (1 engine)

Engines on display

See also

Bibliography

Wikimedia Commons has media related to RL10.

References

  1. "Aerojet Rocketdyne RL10 Propulsion System" (PDF). Aerojet Rocketdyne. Archived from the original (PDF) on January 30, 2022. https://web.archive.org/web/20220130111530/https://rocket.com/sites/default/files/documents/Capabilities/PDFs/RL10_data_sheet.pdf ↩

  2. "RL-10C". www.astronautix.com. Archived from the original on December 28, 2016. Retrieved April 6, 2020. https://web.archive.org/web/20161228011427/http://astronautix.com/r/rl-10c.html ↩

  3. "RL-10A-1". www.astronautix.com. Archived from the original on December 28, 2016. Retrieved April 6, 2020. https://web.archive.org/web/20161228075543/http://astronautix.com/r/rl-10a-1.html ↩

  4. Wade, Mark. "Encyclopedia Astronautica—Lunex Project page". Encyclopedia Astronautica. Archived from the original on August 31, 2006. https://web.archive.org/web/20060831191541/http://www.astronautix.com/articles/lunex.htm ↩

  5. Connors, p 319 ↩

  6. "Centaur". Gunter's Space Pages. http://space.skyrocket.de/doc_stage/centaur.htm ↩

  7. Sutton, George (2005). History of liquid propellant rocket engines. American Institute of Aeronautics and Astronautics. ISBN 1-56347-649-5. 1-56347-649-5 ↩

  8. "Renowned Rocket Engine Celebrates 40 Years of Flight". Pratt & Whitney. November 24, 2003. Archived from the original on June 14, 2011. https://web.archive.org/web/20110614033822/http://www.pratt-whitney.com/vgn-ext-templating/v/index.jsp?vgnextoid=cabbe002c2f3c010VgnVCM1000000881000aRCRD&vgnextchannel=7dfc34890cb06110VgnVCM1000004601000aRCRD&vgnextfmt=default ↩

  9. "Atlas Centaur 2". National Space Science Data Center. NASA. https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1963-047A ↩

  10. Brügge, Norbert. "Evolution of Pratt & Whitney's cryogenic rocket engine RL-10". Retrieved September 16, 2022. https://www.b14643.de/Spacerockets/Specials/P&W_RL10_engine/index.htm ↩

  11. Brügge, Norbert. "Evolution of Pratt & Whitney's cryogenic rocket engine RL-10". Retrieved September 16, 2022. https://www.b14643.de/Spacerockets/Specials/P&W_RL10_engine/index.htm ↩

  12. "Titan 3E/Centaur D-1T Systems Summary REPORT NO. CASD·LVP73-007" (PDF). Convair & Martin Marietta Aerospace. September 1, 1973. pp. 2–4. Retrieved September 16, 2022. https://ntrs.nasa.gov/api/citations/19750004937/downloads/19750004937.pdf ↩

  13. Wade, Mark. "DCX". Encyclopedia Astronautica. Archived from the original on December 28, 2012. Retrieved January 4, 2013. https://web.archive.org/web/20121228125150/http://www.astronautix.com/lvs/dcx.htm ↩

  14. "Delta 269 (Delta III) Investigation Report" (PDF). Boeing. August 16, 2000. MDC 99H0047A. Archived from the original (PDF) on June 16, 2001. https://web.archive.org/web/20010616012841/http://www.boeing.com/defense-space/space/delta/delta3/d3_report.pdf ↩

  15. "Jupiter Launch Vehicle – Technical Performance Summaries". Archived from the original on January 29, 2009. Retrieved July 18, 2009.{{cite web}}: CS1 maint: bot: original URL status unknown (link) https://web.archive.org/web/20090129072105/http://launchcomplexmodels.com/Direct/media.htm ↩

  16. "Common Extensible Cryogenic Engine (CECE)". United Technologies Corporation. Archived from the original on March 4, 2012. https://web.archive.org/web/20120304081145/http://www.pw.utc.com/products/pwr/propulsion_solutions/cece.asp ↩

  17. "Throttling Back to the Moon". NASA. July 16, 2007. Archived from the original on April 2, 2010. https://web.archive.org/web/20100402064331/http://science.nasa.gov/headlines/y2007/16jul_cece.htm ↩

  18. "NASA Tests Engine Technology for Landing Astronauts on the Moon". NASA. January 14, 2009. https://www.nasa.gov/home/hqnews/2009/jan/HQ_09-005_Cryo_engine_test.html ↩

  19. Giuliano, Victor (July 25, 2010). "CECE: Expanding the Envelope of Deep Throttling Technology in Liquid Oxygen/Liquid Hydrogen Rocket Engines for NASA Exploration Missions" (PDF). NASA Technical Reports Server. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100032918.pdf ↩

  20. Roseberg, Zach (April 12, 2012). "NASA, US Air Force to study joint rocket engine". Flight Global. Retrieved June 1, 2012. http://www.flightglobal.com/news/articles/nasa-us-air-force-to-study-joint-rocket-engine-370660/ ↩

  21. Roseberg, Zach (April 12, 2012). "NASA, US Air Force to study joint rocket engine". Flight Global. Retrieved June 1, 2012. http://www.flightglobal.com/news/articles/nasa-us-air-force-to-study-joint-rocket-engine-370660/ ↩

  22. Newton, Kimberly (April 12, 2012). "NASA Partners With U.S. Air Force to Study Common Rocket Propulsion Challenges". NASA. Archived from the original on June 24, 2017. Retrieved January 10, 2018. https://web.archive.org/web/20170624235440/https://www.nasa.gov/centers/marshall/news/news/releases/2012/12-040.html ↩

  23. Roseberg, Zach (April 12, 2012). "NASA, US Air Force to study joint rocket engine". Flight Global. Retrieved June 1, 2012. http://www.flightglobal.com/news/articles/nasa-us-air-force-to-study-joint-rocket-engine-370660/ ↩

  24. Newton, Kimberly (April 12, 2012). "NASA Partners With U.S. Air Force to Study Common Rocket Propulsion Challenges". NASA. Archived from the original on June 24, 2017. Retrieved January 10, 2018. https://web.archive.org/web/20170624235440/https://www.nasa.gov/centers/marshall/news/news/releases/2012/12-040.html ↩

  25. "RL-10B-2". astronautix.com. Retrieved September 16, 2022. http://www.astronautix.com/r/rl-10b-2.html ↩

  26. "RL10B-2" (PDF). Pratt & Whitney Rocketdyne. 2009. Archived from the original (PDF) on March 26, 2012. Retrieved January 29, 2012. https://web.archive.org/web/20120326211303/http://www.pw.utc.com/products/pwr/assets/pwr_rl10b-2.pdf ↩

  27. "Aerojet Rocketdyne Successfully Tests Complex 3-D Printed Injector in World's Most Reliable Upper Stage Rocket Engine" (Press release). Aerojet Rocketdyne. March 7, 2016. Retrieved April 20, 2017. http://www.rocket.com/article/aerojet-rocketdyne-successfully-tests-complex-3-d-printed-injector-worlds-most-reliable ↩

  28. "Aerojet Rocketdyne Achieves 3-D Printing Milestone with Successful Testing of Full-Scale RL10 Copper Thrust Chamber Assembly" (Press release). Aerojet Rocketdyne. April 3, 2017. Retrieved April 11, 2017. http://www.rocket.com/article/aerojet-rocketdyne-achieves-3-d-printing-milestone-successful-testing-full-scale-rl10-copper ↩

  29. "Aerojet Rocketdyne RL10 Propulsion System" (PDF). Aerojet Rocketdyne. Archived from the original (PDF) on January 30, 2022. https://web.archive.org/web/20220130111530/https://rocket.com/sites/default/files/documents/Capabilities/PDFs/RL10_data_sheet.pdf ↩

  30. Wade, Mark (November 17, 2011). "RL-10A-1". Encyclopedia Astronautica. Archived from the original on November 15, 2011. Retrieved February 27, 2012. https://web.archive.org/web/20111115155200/http://www.astronautix.com/engines/rl10a1.htm ↩

  31. "ULA delays further use of enhanced upper-stage engine pending studies". June 23, 2021. https://spacenews.com/ula-delays-further-use-of-enhanced-upper-stage-engine-pending-studies/ ↩

  32. "United Launch Alliance Selects Aerojet Rocketdyne's RL10 Engine". ULA. May 11, 2018. Retrieved May 13, 2018. https://www.ulalaunch.com/about/news/2018/05/11/united-launch-alliance-selects-aerojet-rocketdyne-s-rl10-engine-for-next-generation-vulcan-centaur-upper-stage ↩

  33. "Aerojet Rocketdyne RL10 Propulsion System" (PDF). Aerojet Rocketdyne. Archived from the original (PDF) on January 30, 2022. https://web.archive.org/web/20220130111530/https://rocket.com/sites/default/files/documents/Capabilities/PDFs/RL10_data_sheet.pdf ↩

  34. "Vulcan Cutaway Poster" (PDF). United Launch Alliance. Retrieved October 15, 2021. https://www.ulalaunch.com/docs/default-source/rockets/vulcancentaur.pdf?sfvrsn=10d7f58f_2 ↩

  35. Belam, Martin (January 8, 2024). "Nasa Peregrine 1 launch: Vulcan Centaur rocket carrying Nasa moon lander lifts off in Florida – live updates". the Guardian. ISSN 0261-3077. Retrieved January 8, 2024. https://www.theguardian.com/science/live/2024/jan/08/nasa-peregrine-1-launch-rocket-moon-latest-news-updates-live ↩

  36. Sloss, Philip (March 4, 2021). "NASA, Boeing looking to begin SLS Exploration Upper Stage manufacturing in 2021". NASASpaceflight. Retrieved October 15, 2021. https://www.nasaspaceflight.com/2021/03/nasa-boeing-begin-sls-eus-2021/ ↩

  37. "RL-10 Selected for OmegA Rocket". Aerojet Rocketdyne. April 16, 2018. Retrieved May 14, 2018. http://www.rocket.com/article/rl10-selected-omega%E2%84%A2-rocket ↩

  38. "Northrop Grumman to terminate OmegA rocket program". SpaceNews. September 9, 2020. Retrieved November 23, 2020. https://dev.spacenews.com/northrop-grumman-to-terminate-omega-rocket-program/ ↩

  39. Kutter, Bernard F.; Zegler, Frank; Barr, Jon; Bulk, Tim; Pitchford, Brian (2009). "Robust Lunar Exploration Using an Efficient Lunar Lander Derived from Existing Upper Stages" (PDF). AIAA. Archived from the original (PDF) on July 24, 2011. Retrieved March 9, 2011. https://web.archive.org/web/20110724230154/https://info.aiaa.org/tac/SMG/STTC/White%20Papers/DualThrustAxisLander%28DTAL%292009.pdf ↩

  40. Zegler, Frank; Bernard Kutter (September 2, 2010). "Evolving to a Depot-Based Space Transportation Architecture" (PDF). AIAA SPACE 2010 Conference & Exposition. AIAA. Archived from the original (PDF) on October 20, 2011. Retrieved January 25, 2011. ACES design conceptualization has been underway at ULA for many years. It leverages design features of both the Centaur and Delta Cryogenic Second Stage (DCSS) upper stages and intends to supplement and perhaps replace these stages in the future. ... https://web.archive.org/web/20111020010301/http://www.ulalaunch.com/site/docs/publications/DepotBasedTransportationArchitecture2010.pdf ↩

  41. Brügge, Norbert. "Evolution of Pratt & Whitney's cryogenic rocket engine RL-10". Retrieved September 16, 2022. https://www.b14643.de/Spacerockets/Specials/P&W_RL10_engine/index.htm ↩

  42. Wade, Mark (November 17, 2011). "RL-10A-1". Encyclopedia Astronautica. Archived from the original on November 15, 2011. Retrieved February 27, 2012. https://web.archive.org/web/20111115155200/http://www.astronautix.com/engines/rl10a1.htm ↩

  43. Bilstein, Roger E. (1996). "Unconventional Cryogenics: RL-10 and J-2". Stages to Saturn; A Technological History of the Apollo/Saturn Launch Vehicles. Washington, D.C.: NASA History Office. Retrieved December 2, 2011. https://history.nasa.gov/SP-4206/ch5.htm ↩

  44. "Atlas Centaur". Gunter's Space Page. Retrieved February 29, 2012. http://space.skyrocket.de/doc_lau/atlas_centaur.htm ↩

  45. Wade, Mark (November 17, 2011). "RL-10A-3". Encyclopedia Astronautica. Archived from the original on December 6, 2011. Retrieved February 27, 2012. https://web.archive.org/web/20111206225154/http://www.astronautix.com/engines/rl10a3.htm ↩

  46. Brügge, Norbert. "Evolution of Pratt & Whitney's cryogenic rocket engine RL-10". Retrieved September 16, 2022. https://www.b14643.de/Spacerockets/Specials/P&W_RL10_engine/index.htm ↩

  47. Sutton, George (2005). History of liquid propellant rocket engines. American Institute of Aeronautics and Astronautics. ISBN 1-56347-649-5. 1-56347-649-5 ↩

  48. Brügge, Norbert. "Evolution of Pratt & Whitney's cryogenic rocket engine RL-10". Retrieved September 16, 2022. https://www.b14643.de/Spacerockets/Specials/P&W_RL10_engine/index.htm ↩

  49. Wade, Mark (November 17, 2011). "RL-10A-4". Encyclopedia Astronautica. Archived from the original on November 15, 2011. Retrieved February 27, 2012. https://web.archive.org/web/20111115172045/http://www.astronautix.com/engines/rl10a4.htm ↩

  50. Brügge, Norbert. "Evolution of Pratt & Whitney's cryogenic rocket engine RL-10". Retrieved September 16, 2022. https://www.b14643.de/Spacerockets/Specials/P&W_RL10_engine/index.htm ↩

  51. Wade, Mark (November 17, 2011). "RL-10A-5". Encyclopedia Astronautica. Archived from the original on November 15, 2011. Retrieved February 27, 2012. https://web.archive.org/web/20111115141830/http://www.astronautix.com/engines/rl10a5.htm ↩

  52. Wade, Mark (November 17, 2011). "RL-10B-2". Encyclopedia Astronautica. Archived from the original on February 4, 2012. Retrieved February 27, 2012. https://web.archive.org/web/20120204144940/http://www.astronautix.com/engines/rl10b2.htm ↩

  53. "Delta IV Launch Services User's Guide, June 2013" (PDF). ULA Launch. Retrieved March 15, 2018. https://www.ulalaunch.com/docs/default-source/rockets/delta-iv-user's-guide.pdf ↩

  54. Brügge, Norbert. "Evolution of Pratt & Whitney's cryogenic rocket engine RL-10". Retrieved September 16, 2022. https://www.b14643.de/Spacerockets/Specials/P&W_RL10_engine/index.htm ↩

  55. Wade, Mark (November 17, 2011). "RL-10A-4-1". Encyclopedia Astronautica. Archived from the original on November 17, 2011. Retrieved February 27, 2012. https://web.archive.org/web/20111117134046/http://www.astronautix.com/engines/rl10a41.htm ↩

  56. Brügge, Norbert. "Evolution of Pratt & Whitney's cryogenic rocket engine RL-10". Retrieved September 16, 2022. https://www.b14643.de/Spacerockets/Specials/P&W_RL10_engine/index.htm ↩

  57. Wade, Mark (November 17, 2011). "RL-10A-4-2". Encyclopedia Astronautica. Archived from the original on January 30, 2012. Retrieved February 27, 2012. https://web.archive.org/web/20120130143126/http://www.astronautix.com/engines/rl10a42.htm ↩

  58. "RL10 Engine". Aerojet Rocketdyne. Archived from the original on April 30, 2017. Retrieved March 13, 2016. https://web.archive.org/web/20170430183058/http://www.rocket.com/rl10-engine ↩

  59. Wade, Mark (November 17, 2011). "RL-10B-X". Encyclopedia Astronautica. Archived from the original on November 15, 2011. Retrieved February 27, 2012. https://web.archive.org/web/20111115150728/http://www.astronautix.com/engines/rl10bx.htm ↩

  60. "Commons Extensible Cryogenic Engine". Pratt & Whitney Rocketdyne. Archived from the original on March 4, 2012. Retrieved February 28, 2012. https://web.archive.org/web/20120304081145/http://www.pw.utc.com/products/pwr/propulsion_solutions/cece.asp ↩

  61. "Common Extensible Cryogenic Engine – Aerojet Rocketdyne". www.rocket.com. Archived from the original on November 12, 2014. Retrieved April 8, 2018. https://web.archive.org/web/20141112144157/http://www.rocket.com/common-extensible-cryogenic-engine ↩

  62. "Cryogenic Propulsion Stage" (PDF). NASA. August 5, 2011. Retrieved October 11, 2014. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110015783.pdf ↩

  63. "Atlas-V with RL10C powered Centaur". forum.nasaspaceflight.com. Retrieved April 8, 2018. http://forum.nasaspaceflight.com/index.php?topic=34891.0 ↩

  64. "Evolution of Pratt & Whitney's cryogenic rocket engine RL-10". Archived from the original on March 3, 2016. Retrieved February 20, 2016. https://web.archive.org/web/20160303141931/http://b14643.de/Spacerockets/Diverse/P%26W_RL10_engine/index.htm ↩

  65. "RL10 Engine". Aerojet Rocketdyne. Archived from the original on April 30, 2017. Retrieved March 13, 2016. https://web.archive.org/web/20170430183058/http://www.rocket.com/rl10-engine ↩

  66. Brügge, Norbert. "Evolution of Pratt & Whitney's cryogenic rocket engine RL-10". Retrieved September 16, 2022. https://www.b14643.de/Spacerockets/Specials/P&W_RL10_engine/index.htm ↩

  67. "Aerojet Rocketdyne RL10 Propulsion System" (PDF). Aerojet Rocketdyne. Archived from the original (PDF) on January 30, 2022. https://web.archive.org/web/20220130111530/https://rocket.com/sites/default/files/documents/Capabilities/PDFs/RL10_data_sheet.pdf ↩

  68. "RL10 Engine | Aerojet Rocketdyne". www.rocket.com. Retrieved June 19, 2020. https://www.rocket.com/space/liquid-engines/rl10-engine ↩

  69. Graham, William (September 24, 2022). "Last West Coast Delta IV Heavy launches with NROL-91". NASASpaceFlight.com. Retrieved August 29, 2023. https://www.nasaspaceflight.com/2022/09/delta-iv-nrol-91/ ↩

  70. "NASA'S SPACE LAUNCH SYSTEM BEGINS MOVING TO THE LAUNCH SITE" (PDF). NASA. April 15, 2020. Archived (PDF) from the original on October 13, 2021. Retrieved May 24, 2023. https://ntrs.nasa.gov/api/citations/20205000944/downloads/Askins%20JANNAF%202020%20PAPER%2004152020.docx.pdf ↩

  71. Brügge, Norbert. "Evolution of Pratt & Whitney's cryogenic rocket engine RL-10". Retrieved September 16, 2022. https://www.b14643.de/Spacerockets/Specials/P&W_RL10_engine/index.htm ↩

  72. "Aerojet Rocketdyne RL10 Propulsion System" (PDF). Aerojet Rocketdyne. Archived from the original (PDF) on January 30, 2022. https://web.archive.org/web/20220130111530/https://rocket.com/sites/default/files/documents/Capabilities/PDFs/RL10_data_sheet.pdf ↩

  73. "NASA'S SPACE LAUNCH SYSTEM BEGINS MOVING TO THE LAUNCH SITE" (PDF). NASA. April 15, 2020. Archived (PDF) from the original on October 13, 2021. Retrieved May 24, 2023. https://ntrs.nasa.gov/api/citations/20205000944/downloads/Askins%20JANNAF%202020%20PAPER%2004152020.docx.pdf ↩

  74. "Aerojet Rocketdyne RL10 Propulsion System" (PDF). Aerojet Rocketdyne. Archived from the original (PDF) on January 30, 2022. https://web.archive.org/web/20220130111530/https://rocket.com/sites/default/files/documents/Capabilities/PDFs/RL10_data_sheet.pdf ↩

  75. "Northrop Grumman to terminate OmegA rocket program". SpaceNews. September 9, 2020. Retrieved November 23, 2020. https://dev.spacenews.com/northrop-grumman-to-terminate-omega-rocket-program/ ↩

  76. "Aerojet Rocketdyne Secures Its Largest RL10 Engine Contract From ULA". www.aerojetrocketdyne.com. Retrieved April 16, 2022. https://ir.aerojetrocketdyne.com/news-releases/news-release-details/aerojet-rocketdyne-secures-its-largest-rl10-engine-contract ↩

  77. "RL10 Engine | Aerojet Rocketdyne". Rocket.com. Retrieved May 7, 2022. https://www.rocket.com/space/liquid-engines/rl10-engine ↩

  78. "RL10B-2" (PDF). Pratt & Whitney Rocketdyne. 2009. Archived from the original (PDF) on March 26, 2012. Retrieved January 29, 2012. https://web.archive.org/web/20120326211303/http://www.pw.utc.com/products/pwr/assets/pwr_rl10b-2.pdf ↩

  79. Sutton, A. M.; Peery, S. D.; Minick, A. B. (January 1998). "50K expander cycle engine demonstration" (PDF). AIP Conference Proceedings. 420: 1062–1065. Bibcode:1998AIPC..420.1062S. doi:10.1063/1.54719. Archived from the original on April 8, 2013. https://apps.dtic.mil/sti/pdfs/ADA397948.pdf ↩

  80. McCutcheon, Kimble D. "U.S. Manned Rocket Propulsion Evolution, Part 8.21: The Pratt & Whitney RL10 Engine". Aircraft Engine Historical Society. Retrieved August 28, 2024. https://enginehistory.org/Rockets/RPE08.21/RPE08.21.shtml ↩

  81. Bilstein, Roger E. (1996). "Unconventional Cryogenics: RL-10 and J-2". Stages to Saturn; A Technological History of the Apollo/Saturn Launch Vehicles. Washington, D.C.: NASA History Office. Retrieved December 2, 2011. https://history.nasa.gov/SP-4206/ch5.htm ↩

  82. "RL10B-2" (PDF). Pratt & Whitney Rocketdyne. 2009. Archived from the original (PDF) on March 26, 2012. Retrieved January 29, 2012. https://web.archive.org/web/20120326211303/http://www.pw.utc.com/products/pwr/assets/pwr_rl10b-2.pdf ↩

  83. "RL10B-2" (PDF). Pratt & Whitney Rocketdyne. 2009. Archived from the original (PDF) on March 26, 2012. Retrieved January 29, 2012. https://web.archive.org/web/20120326211303/http://www.pw.utc.com/products/pwr/assets/pwr_rl10b-2.pdf ↩

  84. "RL10B-2" (PDF). Pratt & Whitney Rocketdyne. 2009. Archived from the original (PDF) on March 26, 2012. Retrieved January 29, 2012. https://web.archive.org/web/20120326211303/http://www.pw.utc.com/products/pwr/assets/pwr_rl10b-2.pdf ↩

  85. "RL10B-2" (PDF). Pratt & Whitney Rocketdyne. 2009. Archived from the original (PDF) on March 26, 2012. Retrieved January 29, 2012. https://web.archive.org/web/20120326211303/http://www.pw.utc.com/products/pwr/assets/pwr_rl10b-2.pdf ↩

  86. "RL10B-2" (PDF). Pratt & Whitney Rocketdyne. 2009. Archived from the original (PDF) on March 26, 2012. Retrieved January 29, 2012. https://web.archive.org/web/20120326211303/http://www.pw.utc.com/products/pwr/assets/pwr_rl10b-2.pdf ↩

  87. "RL10B-2" (PDF). Pratt & Whitney Rocketdyne. 2009. Archived from the original (PDF) on March 26, 2012. Retrieved January 29, 2012. https://web.archive.org/web/20120326211303/http://www.pw.utc.com/products/pwr/assets/pwr_rl10b-2.pdf ↩

  88. "RL10B-2" (PDF). Pratt & Whitney Rocketdyne. 2009. Archived from the original (PDF) on March 26, 2012. Retrieved January 29, 2012. https://web.archive.org/web/20120326211303/http://www.pw.utc.com/products/pwr/assets/pwr_rl10b-2.pdf ↩

  89. "Pratt & Whitney RL10A-1 Rocket Engine". New England Air Museum. Archived from the original on April 27, 2014. https://web.archive.org/web/20140427060823/http://neam.org/index.php?option=com_content&view=article&id=1112 ↩

  90. "Photos of Rocket Engines". Historic Spacecraft. Retrieved April 26, 2014. http://historicspacecraft.com/rocket_engines.html ↩

  91. "Photos of Rocket Engines". Historic Spacecraft. Retrieved April 26, 2014. http://historicspacecraft.com/rocket_engines.html ↩

  92. Colaguori, Nancy; Kidder, Bryan (November 3, 2006). "Pratt & Whitney Rocketdyne Donates Model of Legendary Rl10 Rocket Engine to Southern University" (Press release). Pratt & Whitney Rocketdyne. PR Newswire. Archived from the original on April 27, 2014. https://web.archive.org/web/20140427115735/http://www.prnewswire.com/news-releases/pratt--whitney-rocketdyne-donates-model-of-legendary-rl10-rocket-engine-to-southern-university-55982567.html ↩

  93. "American Space Museum & Space Walk of Fame". www.facebook.com. Archived from the original on February 26, 2022. Retrieved April 8, 2018. https://ghostarchive.org/iarchive/facebook/175507880819/10152534320660820 ↩

  94. "RL-10 engine | Science Museum Group Collection". collection.sciencemuseumgroup.org.uk. Retrieved April 12, 2024. https://collection.sciencemuseumgroup.org.uk/objects/co40018/rl-10-engine-engine-power-producing-equipment ↩

  95. "San Diego Air & Space Museum - Historical Balboa Park, San Diego". sandiegoairandspace.org. Retrieved April 12, 2024. https://sandiegoairandspace.org/collection/item/aerojet-rocketdyne-rl10-engine ↩