The S-I was the first stage of the Saturn I rocket used by NASA for the Apollo program.
Design
The S-I stage was powered by eight H-1 rocket engines burning RP-1 fuel with liquid oxygen (LOX) as oxidizer. The design of the S-I was based on Jupiter and Redstone tanks to leverage existing chains. A central Jupiter tank was surrounded by a cluster of eight Redstone tanks. Four of these Redstone tanks contained LOX and four contained RP-1. The outer tanks were painted to alter thermal conditions inside the tanks and to provide a "roll pattern" used to estimate radial motion during flight. The engines were arranged in two clusters, a group of four fixed central engines and a group of four outer gimbaled engines. The gimbals allowed the stage to be controlled with thrust vectoring. On launches after SA-5, eight fins were added to enhance control during atmospheric flight.
History The S-I stage was developed by Chrysler and consisted of 9 tanks that were previously used on existing rockets. The central tank was a Jupiter tank that held liquid oxygen. This Jupiter tank was sounded by eight Redstone tanks, four for liquid oxygen and four for RP-1. The first four launches had no fins on the S-I, but the remaining six added them to improve stability during atmospheric flight. The initial launch of the Saturn I consisted of an active S-I, an inactive S-IV and inactive S-V stage. Tensions were high as a launch vehicle of this size had never flown before. The S-I was partially loaded with propellant to lessen the destruction if an anomaly occurred near or on the pad. In the end, the launch was successful and the subsequent SA-5 launch was identified by John F. Kennedy as the launch that put the U.S. above the USSR in terms of lift capability.
Flight history +Mission serial numberLaunch date (UTC)Launch notesSA-1October 27, 1961 15:06:04First test flight. Block I. Suborbital. Range: 398 km. Apogee: 136.5 km. Apogee Mass: 115,700 lb (52,500 kg). Dummy S-IV and S-V stages.SA-2April 25, 1962 14:00:34Second test flight. Block I. Suborbital. 86,000 kg water released at apogee of 145 km as part of Project Highwater. Dummy S-IV and S-V stages.SA-3November 16, 1962 17:45:02Third test flight. Block I. Suborbital. 86,000 kg water released at apogee of 167 km. Dummy S-IV and S-V stages. Second and last Project Highwater flight.SA-4March 28, 1963 20:11:55Fourth test flight. Block I. Suborbital. Dummy S-IV second stage and S-V third stage. Apogee: 129 km. Range: 400 km.SA-5January 29, 1964 16:25:01First live S-IV second stage. First Block II. First to orbit: 760 x 264 km. Mass: 38,700 lb (17,550 kg). Decayed 30 April 1966.SA-6May 28, 1964 17:07:00First Apollo boilerplate CSM launch. Block II. Orbit: 204 x 179 km. Mass: 38,900 lb (17,650 kg). Apollo BP-13 decayed 1 June 1964.SA-7September 18, 1964 16:22:43Second Apollo boilerplate CSM launch. Block II. Orbit: 203 x 178 km. Mass: 36,800 lb (16,700 kg). Apollo BP-15 decayed 22 September 1964.SA-9February 16, 1965 14:37:03Third Apollo boilerplate CSM. First Pegasus micrometeoroid satellite. Orbit: 523 x 430 km. Mass: 3,200 lb (1,450 kg). Pegasus 1 decayed 17 September 1978. Apollo BP-26 decayed 10 July 1985.SA-8May 25, 1965 07:35:01Fourth Apollo boilerplate CSM. Only night launch. Second Pegasus micrometeoroid satellite. Orbit: 594 x 467 km. Mass: 3,200 lb (1,450 kg). Pegasus 2 decayed 3 November 1979. Apollo BP-16 decayed 8 July 1989.SA-10July 30, 1965 13:00:00Third Pegasus micrometeoroid satellite. Orbit: 567 x 535 km. Mass: 3,200 lb (1,450 kg). Pegasus 3 decayed 4 August 1969. Apollo BP-9A decayed 22 November 1975.
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