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Detail of the taped cover over the fuel manifold inlet visible at the 12:00 position of dsc59800.jpg.

Picture 1 of 2.

Liquid hydrogen from the fuel turbopump is routed through this manifold to the regenerative cooling tubes comprising the thrust chamber walls. Like the RL10, the J-2 employs a "pass and a half" construction, with the "down" tubes being introduced at this manifold and the "up" tubes running the full length of the thrust chamber.

See the USSRC's RL10 thrust chamber section to see an example of this "pass and a half" construction.