Talk:J-2X (Engine)
Engine cycle[edit]
The sources diverge a bit - NASAs MSFC pages say that the J-2X will be developed from the baseline gas-generator cycle J-2 engines, while PWRs publications say that it is based on the tap-off cycle J-2S. The powerhead of the XRS-2000 engines, which had also been based on the J-2S, relied on a gas generator, but thats understandable when you use many small chambers.
The NASA fact sheet is also not really helpful for solving that mystery: The rendering of the J-2X is from the opposite side of the gas generators location in the J-2, but the objects visible on it are different to a J-2. Also it mentions the gas generator only indirectly: "In this rocket engine system, the turbopumps supply liquid hydrogen fuel and liquid oxygen to the main combustion chamber, where the fuel and oxidizer mix. They burn at very high pressures and temperatures to produce gas, which exits from the nozzle to produce thrust. The gas generator drives the fuel and oxidizer turbopumps." --Urwumpe 11:40, 5 November 2007 (MSK)