The S-IV was the second stage of the Saturn I rocket used by NASA for early flights in the Apollo program.
The S-IV was manufactured by the Douglas Aircraft Company and later modified by them to the S-IVB, a similar but distinct stage used on the Saturn IB and Saturn V rockets.
The S-IV stage was a large LOX/LH2-fueled rocket stage used for the early test flights of the Saturn I rocket. It formed the second stage of the Saturn I and was powered by a cluster of six RL10A-3 engines. Each one of the engines supplied of thrust for a total of about . The cryogenic LH2 (liquid hydrogen) and LOX (liquid oxygen) tanks were separated by a common bulkhead. The forward bulkhead of the LOX tank formed the aft bulkhead of the LH2 tank. This saved up to 20% of structural weight. Flight history
+Mission serial numberLaunch date (UTC)ImageLaunch notesSA-1October 27, 196115:06:04SA-2April 25, 196214:00:34SA-3November 16, 196217:45:02SA-4March 28, 196320:11:55SA-5January 29, 196416:25:01SA-6May 28, 196417:07:00SA-7September 18, 196416:22:43SA-9February 16, 196514:37:03SA-8May 25, 196507:35:01SA-10July 30, 196513:00:00
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