Stage 3 (S-IVB)

Saturn V S-IVB
S-IVB-206 which was used for the Skylab 2 flight
Country of originUSA
RocketsSaturn IB (stage 2)
Saturn V (stage 3)
Height17.8 m (58.4 ft)
Diameter6.6 m (21.7 ft)
Mass119,900 kg (253,000 lb)
Engine details
Engines1 J-2 engine
Thrust1,001 kN (225,000 lbf)
Burn time475 seconds

The S-IVB (sometimes S4b, always pronounced "ess four bee") was built by the Douglas Aircraft Company and served as the third stage on the Saturn V and second stage on the Saturn IB. It had one J-2 engine. For lunar missions it was fired twice: first for the orbit insertion after second stage cutoff, and then for translunar injection (TLI).


Cutaway drawing of the Saturn V S-IVB

The S-IVB evolved from the upper stage of the Saturn I rocket, the S-IV, and was the first stage of the Saturn V to be designed. The S-IV used a cluster of six engines but used the same fuels as the S-IVB liquid hydrogen and liquid oxygen. It was also originally meant to be the fourth stage of a planned rocket called the C-4, hence the name S-IV.

Eleven companies submitted proposals for being the lead contractor on the stage by the deadline of 29 February 1960. NASA administrator T. Keith Glennan decided on 19 April that Douglas Aircraft Company would be awarded the contract. Convair had come a close second but Glennan did not want to monopolize the liquid hydrogen fueled rocket market as Convair was already building the Centaur rocket stage.

In the end the Marshall Space Flight Center decided to use the C-5 rocket (later called the Saturn V), which had three stages and would be topped with an uprated S-IV called the S-IVB which instead of using a cluster of engines would have a single J-2 engine. Douglas was awarded the contract for the S-IVB because of the similarities between it and the S-IV. At the same time it was decided to create the C-IB rocket (Saturn IB) that would also use the S-IVB as its second stage and could be used for testing the Apollo spacecraft in Earth orbit.

Apollo 7 S-IVB in orbit over Cape Canaveral

Douglas built two distinct versions of the S-IVB, the 200 series and the 500 series. The 200 series was used by the Saturn IB and differed from the 500 in the fact that it did not have a flared interstage and had less helium pressurization on board as it would not be restarted. (On the 500 series, the interstage needed to flare out to match the larger diameter of the lower stages of the Saturn V.) The 200 series also had three solid rockets for separating the S-IVB stage from the S-IB stage during launch, rather than the two on the 500 series, and lacked the linear APS thrusters that the 500 series required for ullage operations prior to restarting the J2 engine.

The S-IVB carried 73,280 liters (19,359 U.S. gallons) of LOX, massing 87,200 kg (192,243 lbs). It carried 252,750 liters (66,770 U.S. gallons) of LH2, massing 18,000 kg (39,683 lbs).

Three versions of the SIV/SIVB

An S-IVB provided the hull for Skylab, the United States' first space station.

During Apollo 13, Apollo 14, Apollo 15, Apollo 16 and Apollo 17, the S-IVB was crashed into the Moon in order to perform seismic measurement used for characterizing the lunar core.

The proposed Earth Departure Stage (EDS) and the second stage of the Ares I rocket will bear some of the characteristics of the S-IVB stage, as both will have an uprated J-2 engine (J-2X series), with the former performing the same functions as that of the Series 500 version of the stage (placing the payload into orbit, and later firing the spacecraft into trans-lunar space).

200 Series
Serial numberUseLaunch dateCurrent location
S-IVB-S"Battleship" static test stage
S-IVB-FTest stage for the facilities
S-IVB-D"Dynamic" test stage delivered to Marshall Space Flight Center in 1965U.S. Space & Rocket Center, Huntsville, Alabama
S-IVB-TCancelled December 1964
S-IVB-201AS-201February 26, 1966
S-IVB-202AS-202August 25, 1966
S-IVB-203AS-203July 5, 1966
S-IVB-204Apollo 5January 22, 1968
S-IVB-205Apollo 7October 11, 1968
S-IVB-206Skylab 2May 25, 1973
S-IVB-207Skylab 3July 28, 1973
S-IVB-208Skylab 4November 16, 1973
S-IVB-209Skylab rescue vehicleKennedy Space Center
S-IVB-210Apollo Soyuz Test ProjectJuly 15, 1975
S-IVB-211UnusedU.S. Space & Rocket Center, Huntsville, Alabama
S-IVB-212Converted to SkylabMay 14, 1973
500 Series
Serial numberUseLaunch dateCurrent location
S-IVB-501Apollo 4November 9, 1967
S-IVB-502Apollo 6April 4, 1968
S-IVB-503Destroyed during testing
S-IVB-503NApollo 8December 21, 1968Solar orbit
S-IVB-504Apollo 9March 3, 1969Solar orbit
S-IVB-505Apollo 10May 18, 1969Solar orbit
S-IVB-506Apollo 11July 16, 1969Solar orbit
S-IVB-507Apollo 12November 14, 1969Solar orbit; Believed to have been discovered as an asteroid in 2002 and given the designation J002E3
S-IVB-508Apollo 13April 11, 1970Lunar surface
S-IVB-509Apollo 14January 31, 1971Lunar surface
S-IVB-510Apollo 15July 26, 1971Lunar surface
S-IVB-511Apollo 16April 16, 1972Lunar surface
S-IVB-512Apollo 17December 7, 1972Lunar surface
S-IVB-513Apollo 18 (cancelled)N/AJohnson Space Center
S-IVB-514UnusedKennedy Space Center
S-IVB-515Converted for use as backup SkylabNational Air and Space Museum