S-IVB (Saturn V) Overview
The S-IVB, the third stage of the Saturn V rocket, was the one of the largest liquid hydrogen stages produced in the 1960s. Equipped with one J-2 rocket engine, it produced about 225,000 pounds of thrust. It was 21 feet 8 inches in diameter and 58 feet 8 inches high.
Structurally, the S-IVB stage consisted of
- An aft interstage, which mated the stage to the S-II second stage. Although I tend to associate the interstages with the lower stage, the interstage was properly part of the S-IVB.
- A cylindrical aft skirt, to which was connected the conical thrust structure. The engine was mounted to the thrust structure, which transmitted the thrust to the aft skirt, which in turn transmitted the thrust to the propellant tank walls.
- A liquid oxygen tank and a liquid hydrogen tank. Rather than each tank having customary hemispherical bulkheads at both ends (and separated by an intertank structure, as with the S-IC), the forward end of the LOX tank and the aft end of the LH2 tank were separated by a common bulkhead. The common bulkhead consisted of two aluminum domes forming the ends of the respective propellant containers separated by honeycomb insulation; the honeycomb insulation was necessary to prevent the LH2's -423° temperature from freezing the liquid oxygen.
- A cylindrical forward skirt, attached to the forward end of the LH2 tank, which transmitted the thrust loads to the Apollo payload. Range safety and telemetry antennas were mounted on the exterior of the forward skirt, and the interior of the forward skirt had cold plates to provide environmental conditioning for various electronic equipment also located on the walls of the forward skirt.
Having exploded the S-IVB stage in the diagram above, here we will put it back together here in this manufacturing flow sequence diagram.
You might consider this a do-it-yourself guide, perhaps "how to build an S-IVB stage in 31 easy steps."
- Fabricate dome segments
- Weld dome segments
Repeat for each of
- Forward dome
- Forward common bulkhead
- Aft common bulkhead
- Aft dome
- Assemble common bulkhead
- Assemble LOX tank
- Fabricate LH2 tank skins
- Weld LH2 tank
- Assemble tank
- Hydrostatic test; degrease
- Fabricate insulation tiles
- Insulate tank
- Internal installation
- Electrical fabrication & installation
- Fabricate & assemble forward skirt
- Fabricate & assemble aft skirt
- Fabricate & assemble thrust structure
- Join skirt assemblies & thrust structure
- Receive Rocketdyne engine
- Install engine
- Paint; weigh
- Load on transporter
- Fabricate & assemble auxilliary propulsion system
- Load on barge; ship to Sacramento
- Test fire at SACTO
- Fabricate & assemble aft interstage
- Barge to Seal Beach; load aft interstage; ship to KSC
- Assemble at KSC
This cut-away diagram shows the major structural elements assembled into the final stage.
Another cut-away diagram showing the major structural elements assembled into the final stage, while at the same time showing the interior of stage subassemblies:
Note the ambient helium spheres, used by the propellant pressurization system.