page_title: RL10
section_title: Common Extensible Cryogenic Engine
hierarchical_section_title: RL10 / History / Common Extensible Cryogenic Engine
caption_attribution_description: English: The Common Extensible Cryogenic Engine, also known as CECE, completes the fourth and final series of hot-fire tests on a 15,000-pound thrust class cryogenic technology demonstrator rocket engine, increasing the throttling capability by 35 percent over previous tests. This test series demonstrated this engine could go from a thrust range of 104 percent power down to 5.9 percent. This equates to an unprecedented 17.6:1 deep-throttling capability, which means this cryogenic engine can quickly throttle up and down. This rocket engine is fuelled by a mixture of -182.8 Celsius liquid oxygen and -252.8 Celsius liquid hydrogen. The engine components are super-cooled to similar low temperatures. As CECE burns its frigid fuels, gas composed of hot steam is produced and propelled out the nozzle creating thrust. The steam is cooled by the cold engine nozzle, condensing and eventually freezing at the nozzle exit to form icicles.
context_page_description: 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 of thrust per engine in vacuum. Three RL10 versions are in production for the Centaur upper stage of the Atlas V and the DCSS of the Delta IV. Three more versions are in development for the Exploration Upper Stage of the Space Launch System, the upper stage of the OmegA rocket, 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 in the range of 373 to 470 s in a vacuum. Mass ranges from 131 to 317 kg depending on the version of the engine.
context_section_description: 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. In 2007, its operability (with some "chugging") was demonstrated at 11:1 throttle ratios. 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. In 2010, the throttling range was expanded further to a 17.6:1 ratio, throttling from 104% to 5.9% power.
caption: The CECE at partial throttle
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