The S-IVB stage (200 series)

The Saturn IB S-IVB (second) stages in storage at the Douglas Aircraft Company's Sacramento Test Operations Facility (SACTO)in Sacramento, California.

credit to NASA

General information

The S-IVB stage was an uprated version of the S-IV. The designation S-IV has its roots in an initial design for a four stage moon rocket. Its first role of the S-IV, was to act as a second stage for the Saturn I booster. This S-IV stage had six cryogenic RL-10 engines with a combined thrust of 37 Tons. At some point NASA settled down on a three stage design of the moon rocket, which became known as the Saturn V. As soon as the requirements for the third stage of the Saturn V stack came into view it became clear that the S-IV with some modification would meet those requirements.

The slightly larger S-IVB had a single cryogenic J-2 engine which would deliver about 100 Ton of thrust, more than twice the thrust of the S-IV with its six RL-10 engines. The S-IVB was produced in two versions: the 200 series which was used as a second stage for the Saturn IB booster and the 500 series which was used as a third stage for the Saturn V booster. This S-IVB 500 would have the important ability to restart the J-2 engine in space to leave the Earth parking orbit into a trajectory to the Moon. (Trans Lunar Injection)


S-IVB stage main parts

From bottom up:
  1. One J-2 engine
  2. A conical shaped thrust structure
  3. The aft skirt
  4. The fuel tank and the liquid oxygen tank with their common bulkhead
  5. The forward skirt
  6. The interstage, a cylindrical shaped connecting ring between the S-IVB and the S-IB stage


Characteristics

  1. Height      : 14.49 meter
    Diameter  : 6.51 meter
    Mass empty stage           : 11.28 Ton
    Mass of propellants        : 106.61 Ton
    Mass of loaded stage      : 117.89 Ton
    Amount of fuel:
    Liquid Oxygen   : 86.88 Ton, 76 569 litres (Mass dens. LOx: 1.137 kg/ltr)
    Liquid Hydrogen : 19.73 Ton, 242 808 litres (Mass dens. LH2: 0.070 kg/ltr).
  2. Typical flight profile
    Ignition at an altitude of 61 km for 7 min and 49 sec., orbit insertion at an altitude of 227 km; downrange distance of 1887 km; velocity: 7 768 m/sec (27 964 km/hr, 26.1 Mach)
  3. J-2 engine:
    J-2 engine thrust : 104 Tons (metric)
    Height of J-2 engine : 3.38 meter
    Diameter of J-2 engine : 2.07 meter
    Mass of J-2 engine : 1.58 Ton
    Combustion pressure inside an J-2 chamber : 53 bar
    Combustion chamber diameter probably around 0.47 meter.
    Fuel consumption rate per J-2 engine : 0.23 Ton/sec.
    Specific Impulse at ground level : 440 sec.
  4. Manufacturer of the J-2 engines: Pratt & Whitney (initially)
    North American Aviation, Rocket dyne Division (eventually)
    Manufacturer of the S-IVB stage: Douglas Airplane Co.

This picture shows the flight path of the SA-205 (Apollo 7) during ascent. The J-2 engine of the S-IVB stage was ignited 2½ minutes after lift-off at an alititude of 61 km. It deliverd thrust for about 8 minutes and was then disposed of at an altitude of 227 km.

Apollo 7 ground track during ascent

This picture shows the ground track of the SA-205 (Apollo 7) during ascent. The S-IVB provided thrust for about 8 minutes and was then separated. The orbit decay of the S-IVB took about 7 days, the stage went down in the middle of the Indian Ocean.

Plan View S-IVB stage Forward section, Looking down

 
The S-IVB 200 stage

From top to bottom: the forward skirt, the combined oxygen & hydrogen tank, the aft skirt, the conical shaped thrust structure and the J-2 engine

Plan View S-IVB stage Aft section, Looking up

 



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Copyright 2005 by   Sander Panhuyzen
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