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RL10A-4-2

Pratt & Whitney RL10A-4-2 is a restartable liquid-hydrogen/liquid-oxygen upper-stage engine used on Atlas V Centaur. ULA’s March 2010 user’s guide documents single- and dual-engine Centaur configurations, with 99.2 kN thrust per engine and 450.5 s specific impulse. The engine is gimbaled, turbopump-fed and regeneratively cooled, with a secondary nozzle extension to increase its expansion ratio.

RL10A-4-2
NASA/Dimitri Gerondidakis (RL10 engine acceptance test, 12 August 2016) · Public domain: NASA-created U.S. Government work, documented on Wikimedia Commons as NASA imagery. Credit NASA and imply no endorsement. Context: https://images.nasa.gov/ · Source

Identity

Domains
spaceflight
Identity Level
variant
Kind
liquid-rocket-engine
Name
RL10A-4-2
Status
retired

Details

Description
Pratt & Whitney RL10A-4-2 is a restartable liquid-hydrogen/liquid-oxygen upper-stage engine used on Atlas V Centaur. ULA’s March 2010 user’s guide documents single- and dual-engine Centaur configurations, with 99.2 kN thrust per engine and 450.5 s specific impulse. The engine is gimbaled, turbopump-fed and regeneratively cooled, with a secondary nozzle extension to increase its expansion ratio.
Family
Propellants
liquid hydrogenliquid oxygen
Rocket Specs
Restartable
Yes
Vacuum Specific Impulse
…
Vacuum Thrust
…

Links

Official Url
https://www.ulalaunch.com/docs/default-source/rockets/atlasvusersguide2010.pdf

Assets & Meta

Creation Time
August 1, 2026 at 07:54:06 UTC
Updated Time
October 29, 2026 at 13:12:37 UTC
Image
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