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Walk-around of upper portion of F-1 engine.

Picture 3 of 9.

Also indicative of early engines, the fuel high-pressure duct (the second horizontal pipe near the forward end of the engine) is straight. On later models of the engine, it is a "U"-shaped duct (e.g., as on F-107-1 at the Omniplex). Vince Wheelock tells me that S-IC-1 had the straight fuel high-pressure ducts, while the engines on S-IC-2 and subsequent sported the "U"-shaped ducts.