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Saturn IB S-IVB-206.jpg
S-IVB-206 which was used for the Skylab 2 flight
Manufacturer Douglas
Used on Saturn IB (stage 2)
Saturn V (stage 3)
General characteristics
Height 58 feet 5 inches (17.81 m)
Diameter 21 feet 8 inches (6.60 m)
Gross mass 253,000 pounds (115,000 kg)
Propellant mass 229,000 lb (104,000 kg)
Engine details
Engines 1 J-2 engine
Thrust 232,250 pounds-force (1,033,100 N)
Specific impulse 421 s (4.13 km/s)
Burn time 475 seconds
Fuel LOX/LH2

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).


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.


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 S-IC and S-II 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. On the 500 series this was reduced to two, and two small APS (auxiliary propulsion system) thruster modules were added as ullage motors for restarting the J-2 engine and to provide attitude control during coast phases of flight.

Cutaway drawing of the Saturn V S-IVB

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). Empty mass was 10,000 kg (23,000 lb)[1][2]

Attitude control was provided by J-2 engine gimballing during powered flight and by the two APS modules during coast. The APS modules each contained four thrusters providing 150 pounds of thrust (three for roll, pitch, and yaw; one for ullage) and were fueled by a hypergolic mixture of dinitrogen tetroxide and monomethyl hydrazine. They were used for three-axis control during coast phases, roll control during J-2 firings, and ullage for the second ignition of the J-2 engine and deorbit into the moon.[1][2]

A surplus S-IVB tank, serial number 212, was converted into the hull for Skylab, the United States' first space station. Skylab was launched on a Saturn V on May 14, 1973, and re-entered the atmosphere on July 11, 1979. A second S-IVB, serial number 515, was also converted into a backup Skylab, which never flew.

During Apollo 13, Apollo 14, Apollo 15, Apollo 16 and Apollo 17, the S-IVB stages were crashed into the Moon to perform seismic measurements used for characterizing the lunar interior.

Stages built[edit]

200 Series
Serial number Use Launch date Current location
S-IVB-S "Battleship" static test stage On display with the Saturn 1B SA-211 first stage stacked in a launch-ready condition at the Alabama Welcome Center on I-65 in Ardmore, Alabama. 34°57′16″N 86°53′31″W / 34.954548°N 86.89193°W / 34.954548; -86.89193
S-IVB-F Test stage for the facilities
S-IVB-D "Dynamic" test stage delivered to Marshall Space Flight Center in 1965 U.S. Space & Rocket Center, Huntsville, Alabama 34°42′38″N 86°39′27″W / 34.710456°N 86.657432°W / 34.710456; -86.657432
S-IVB-T Cancelled December 1964
S-IVB-201 AS-201 February 26, 1966 Suborbital test; impacted Atlantic Ocean at 9.6621S, 10.0783E[citation needed]
S-IVB-202 AS-202 August 25, 1966 Suborbital test; impacted Atlantic Ocean[3]
S-IVB-203 AS-203 July 5, 1966 Exploded in orbit during bulkhead test at end of mission; debris decayed
S-IVB-204 Apollo 5 (originally intended for Apollo 1) January 22, 1968 Launched LM-1 into low earth orbit for unmanned test; decayed
S-IVB-205 Apollo 7 October 11, 1968 Decayed from low earth orbit
S-IVB-206 Skylab 2 May 25, 1973 Decayed from low earth orbit
S-IVB-207 Skylab 3 July 28, 1973 Decayed from low earth orbit
S-IVB-208 Skylab 4 November 16, 1973 Decayed from low earth orbit
S-IVB-209 Skylab rescue vehicle Kennedy Space Center
S-IVB-210 Apollo Soyuz Test Project July 15, 1975 Decayed from low earth orbit
S-IVB-211 Unused U.S. Space & Rocket Center, Huntsville, Alabama
S-IVB-212 Converted to Skylab May 14, 1973
500 Series
Serial number Use Launch date Current location
S-IVB-501 Apollo 4 November 9, 1967 J-2 restart during first unmanned Saturn V flight test placed S-IVB and spacecraft on earth-intersecting trajectory; impacted Pacific Ocean at 23.435N, 161.207E.
S-IVB-502 Apollo 6 April 4, 1968 Second unmanned Saturn V flight test. J-2 restart failed due to damage from pogo oscillation of previous stages; decayed from low earth orbit
S-IVB-503 Destroyed during testing
S-IVB-503N Apollo 8 December 21, 1968 Heliocentric orbit
S-IVB-504 Apollo 9 March 3, 1969 Heliocentric orbit
S-IVB-505 Apollo 10 May 18, 1969 Heliocentric orbit
S-IVB-506 Apollo 11 July 16, 1969 Heliocentric orbit
S-IVB-507 Apollo 12 November 14, 1969 Heliocentric orbit; Believed to have been discovered as an asteroid in 2002 and given the designation J002E3
S-IVB-508 Apollo 13 April 11, 1970 Impacted lunar surface April 14, 1970*[4][5]
S-IVB-509 Apollo 14 January 31, 1971 Lunar surface*
S-IVB-510 Apollo 15 July 26, 1971 Lunar surface*
S-IVB-511 Apollo 16 April 16, 1972 Lunar surface*
S-IVB-512 Apollo 17 December 7, 1972 Lunar surface*
S-IVB-513 Apollo 18 (cancelled) N/A Johnson Space Center
S-IVB-514 Unused Kennedy Space Center
S-IVB-515 Converted to Skylab B N/A National Air and Space Museum

(* See List of artificial objects on the Moon for location.)


The second stage of the Ares I rocket and the proposed Earth Departure Stage (EDS) would have had some of the characteristics of the S-IVB stage, as both would have had an uprated J-2 engine, called the J-2X, with the latter 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).

See also[edit]


  1. ^ a b "SP-4206 Stages to Saturn". NASA. Archived from the original on 15 October 2012. 
  2. ^ a b "Saturn S-IVB". apollosaturn. Archived from the original on 19 August 2012. Retrieved 4 November 2011. 
  3. ^ AS-202 Press Kit
  4. ^ Satellite catalog
  5. ^ LROC page

External links[edit]