S-IV

S-IV

Schematics of the S-IV
Manufacturer	Douglas Aircraft Company
Country of origin	United States
Used on	Saturn I (stage 2)
General characteristics
Height	12.19 m (40.0 ft)
Diameter	5.49 m (18.0 ft)
Gross mass	50,576 kg (111,501 lb)
Propellant mass	45,359 kg (100,000 lb)
Empty mass	5,217 kg (11,500 lb)
Launch history
Status	Retired
Total launches	6
Successes (stage only)	6
Failed	0
First flight	January 29, 1964
Last flight	July 30, 1965
S-IV 100 series
Powered by	6 RL-10 engines
Maximum thrust	400 kN (90,000 lbf)
Specific impulse	410 s (4.0 km/s)
Burn time	482 s
Propellant	LH2 / 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 lb_f) of thrust for a total of about 400 kilonewtons (90,000 lb_f). 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]