A CGI artist's impression of a J-2X.Spa
|Country of origin||United States|
|Manufacturer||Pratt & Whitney Rocketdyne|
|Application||Upper stage engine|
|Associated L/V||Block II Space Launch System (EDS)|
|Propellant||Liquid oxygen / Liquid hydrogen|
|Thrust (vac.)||1,307 kN (294,000 lbf)|
|Isp (vac.)||448 seconds|
|Length||185 inches (4,700 mm)|
|Diameter||120 inches (3,000 mm)|
|Dry weight||5,450 pounds (2,470 kg)|
The J-2X is a liquid-fuel cryogenic rocket engine planned for use on NASA's Space Launch System. Built in the United States of America by Rocketdyne, the J-2X will burn cryogenic liquid hydrogen & liquid oxygen propellants, with each engine producing 1,307 kN (294,000 lbf) of thrust in vacuum at a specific impulse (Isp) of 448 seconds. The engine will have a mass of approximately 5,450 pounds (2,470 kg), significantly heavier than its predecessors.
The J-2X was originally intended to be based on the J-2 used on the S-II and S-IVB stages of the Saturn rockets used during the Apollo program, but as required thrust for the Ares I increased due to weight problems it became a clean sheet design. It entered development in 2007 as part of the now-cancelled Constellation program. Originally planned for use on the upper stages of the Ares I and Ares V rockets, the J-2X is now intended for use in the 2030s and beyond on the Earth Departure Stage of the Block II Space Launch System, the successor to the Constellation program. The engine is intended to be more efficient and simpler to build than its J-2 ancestor, and cost less than the RS-25 Space Shuttle Main Engine. Differences in the new engine include the removal of beryllium, a centrifugal turbo pump versus the axial turbo pump of the J-2, different chamber and nozzle expansion ratios, a channel-walled combustion chamber versus the tube-welded chamber of the J-2, a redesign of all the electronics, a gas generator and supersonic main injector based on the RS-68, and the use of 21st-century joining techniques.
On 16 July 2007 NASA officially announced the award to Pratt & Whitney Rocketdyne (PWR) of a $1.2 billion contract "for design, development, testing and evaluation of the J-2X engine", and began construction of a new test stand for altitude testing of J-2X engines at Stennis Space Center on 23 August 2007.
Component testing was undertaken between December 2007 and May 2008, with nine tests of heritage J-2 engine components at SSC in preparation for the design of the J-2X engine. and on 8 September 2008 PWR announced successful testing of the initial J-2X gas generator design. The completion of a second round of successful gas generator tests was announced on 21 September 2010.
Starting in 2011, the full J-2X engine, derived from heritage and new designs, has undergone hot-fire tests.
- June 2011: The first hot-fire test.
- November 2011: A test-firing lasting 499.97 seconds.
- June 2012: A test-firing lasting 1,150 seconds, during which the J-2X was throttled up and down.
- July 2012: A test-firing for 1,350 seconds (22½ minutes)
- December 2012: Final test-firing
In October 2013, it was reported that work on the J-2X would stop following development testing in 2014, due to funding limitations, an expected delayed need for the engine's capabilities for piloted missions to Mars, and plans to use clusters of RL-10 engines for nearer-term SLS missions.
|Wikimedia Commons has media related to J-2X (rocket engine).|
- "J-2X Engine". Pratt & Whitney. Retrieved 26 February 2012.
- Mark Wade (17 November 2011). "J-2X". Encyclopedia Astronautica.
- "The J-2X Upper Stage Engine: From Design to Hardware. Thomas Byrd, Deputy Manager, J-2X Upper Stage Engine Element Ares Projects Office Marshall Space Flight Center Huntsville, AL 35812".
- William D Greene (4 June 2012). "J-2X Extra: What's in a Name?". NASA.
- "NASA Awards Upper Stage Engine Contract for Ares Rockets". NASA. 16 July 2007. Retrieved 17 July 2007.
- "NASA's Stennis Space Center Marks New Chapter in Space Exploration". NASA. 23 August 2007.
- "NASA Successfully Completes First Series of Ares Engine Tests". NASA. 8 May 2008.
- "Pratt & Whitney Rocketdyne Completes Successful Test of J-2X Gas Generator". Pratt & Whitney Rocketdyne. 8 September 2008.
- "Pratt & Whitney Rocketdyne Completes Latest Round of Tests on J-2X Gas Generator" (Press release). Pratt & Whitney Rocketdyne. September 21, 2010.
- Morring, Frank. "First J-2X Hot-Fire Test Could Come Next Week". Aviation Week. Retrieved 19 June 2011.
- "NASA Test Fires Engine for Giant New Rocket". Space.com. 9 November 2011. Retrieved 26 February 2012.
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- "A Summer of Records for Engine Testing". National Aeronautics and Space Administration. 26 June 2012. Retrieved 26 June 2012.
- "Beating Heart of J-2X Engine Finishes Year of Successful Testing". National Aeronautics and Space Administration. 13 Dec 2012. Retrieved 14 Dec 2012.
- "NASA’s J-2X Engine To Be Mothballed After Testing". Aviation Week and Space Technology magazine. 4 Oct 2013. Retrieved 29 Oct 2013.