S-I

The S-I was the first stage of the Saturn I rocket used by NASA for the Apollo program.

S-I

S-I diagram
Manufacturer	Chrysler
Country of origin	United States
Used on	Saturn I
General characteristics
Height	24.5 m (80.3 feet)
Diameter	6.5 m (21.4 feet)
Gross mass	432,681 kg (953,898 lb)
Propellant mass	397,414 kg (854,101 lb)
Empty mass	45,267 kg (99,796 lb)
Associated stages
Family	Saturn
Launch history
Status	Retired
Total launches	10
Successes (stage only)	10
First flight	October 27, 1961
Last flight	July 30, 1965
S-I engine details
Powered by	8 H-1 engines
Maximum thrust	(vac) 7,582.1 KN (1,704,524 lbf)
Specific impulse	289 sec
Propellant	RP-1 / LOX

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 number	Launch date (UTC)	Launch notes
SA-1	October 27, 1961 15:06:04	First 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-2	April 25, 1962 14:00:34	Second 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-3	November 16, 1962 17:45:02	Third 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-4	March 28, 1963 20:11:55	Fourth test flight. Block I. Suborbital. Dummy S-IV second stage and S-V third stage. Apogee: 129 km. Range: 400 km.
SA-5	January 29, 1964 16:25:01	First 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-6	May 28, 1964 17:07:00	First 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-7	September 18, 1964 16:22:43	Second 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-9	February 16, 1965 14:37:03	Third 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-8	May 25, 1965 07:35:01	Fourth 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-10	July 30, 1965 13:00:00	Third 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.