S-IV rocket stage.jpg
Schematics of the S-IV
ManufacturerDouglas Aircraft Company
Country of originUnited States
Used onSaturn I (stage 2)
General characteristics
Height12.19 m (40.0 ft)
Diameter5.49 m (18.0 ft)
Gross mass50,576 kg (111,501 lb)
Propellant mass45,359 kg (100,000 lb)
Empty mass5,217 kg (11,500 lb)
Launch history
Total launches6
(stage only)
First flightJanuary 29, 1964
Last flightJuly 30, 1965
S-IV 100 series
Engines6 RL-10 engines
Thrust400 kN (90,000 lbf)
Specific impulse410 s (4.0 km/s)
Burn time482 s
PropellantLH2 / LOX

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.[1]

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 RL-10A-3 engines. Each one of the engines supplied 66.7 kilonewtons (15,000 lbf) of thrust for a total of about 400 kilonewtons (90,000 lbf). 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.[2][3]


  • Bilstein, Roger E. (1999). "6". Stages to Saturn: A Technological History of the Apollo/Saturn Launch. DIANE Publishing. Retrieved 2010-05-04.
  • NASA (April 1975). "Apollo Program Summary Report (Large file)" (PDF).