S-IVB

S-IVB

S-IVB-206 which was used for the Skylab 2 flight
Manufacturer	Douglas
Country of origin	USA
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)
S-IVB
Powered by	1 J-2 engine
Maximum thrust	232,250 pounds-force (1,033,100 N)
Specific impulse	421 s (4.13 km/s)
Burn time	475 seconds
Propellant	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).

History

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.

Configuration

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 additional linear APS thrusters were added for ullage operations prior to restarting the J-2 engine.

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)

Attitude control was provided by 2 Auxiliary Propulsion System pods, and by engine gimballing. The APS modules provided 150 pounds of thrust each, and were fuelled 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 (on the 500 series) ullage for the second ignition of the J-2 engine and deorbit into the moon.

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.

• 
  Apollo 7 S-IVB in orbit over Cape Canaveral, likened to a four-jawed "angry alligator"
• 
  Distant view of Apollo 7 S-IVB stage
• 
  Apollo 8 S-IVB, shortly after separation
• The three versions of the S-IV/S-IVB
  The three versions of the S-IV/S-IVB

Stages built

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. 34.954548°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
S-IVB-T	Cancelled December 1964
S-IVB-201	AS-201	February 26, 1966	Suborbital test; impacted Atlantic Ocean at 9.6621S, 10.0783E
S-IVB-202	AS-202	August 25, 1966	Suborbital test; impacted Atlantic Ocean
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*
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.)

Future

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

• S-IC
• S-II
• Apollo (spacecraft)

References

• Marshall Space Flight Center, Apollo Systems Description Volume II - Saturn Launch Vehicles, 1 February 1964