S-IC

Manufacturing

MSFC built two test stages (S-IC-S, the structural test "stage" which actually consisted of the various stage subassemblies but which was never fully assembled into a complete stage, and S-IC-T, the static test stage) and the first two flight models (S-IC-1 and -2).

It took roughly seven to nine months to build the tanks and 14 months to complete a stage. The first stage built by Boeing was S-IC-D, a test model. Boeing also built an additional test stage, designated S-IC-F.

In addition to the four test stages, NASA ordered 15 flight stages (S-IC-1 through -15) to support the initial Apollo program. S-IC-16 to -25 would have been utilized for follow-on Apollo missions, including those from the Apollo Applications Program.

Design

The S-IC was composed of five major subsections.

The largest and heaviest single component of the S-IC was the thrust structure, with a mass of 48000 lb. It was designed to support the thrust of the five engines and redistribute it evenly across the base of the rocket. There were four anchors which held down the rocket as it built thrust. These were among the largest aluminum forgings produced in the U.S. at the time, measuring 15 ft long and weighing in at 1800 lb. The four stabilizing fins withstood a temperature of 2000 F.

The five F-1 engines were ignited in 3 staggered events, where the center engine was first ignited, followed by a diagonal pair of outer engines, and then the remaining two outer engines. These three ignition events were separated by just 300 milliseconds. This staggered ignition approach lessened the loads on the thrust structure, as an instantaneous ignition of all five engines would impart immense stress on the stage.

Above the thrust structure was the fuel tank, containing 209000 USgal of RP-1 fuel. The tank itself had a mass of over 12 ST dry and could release 1300 USgal/s. Nitrogen was bubbled through the tank before launch to keep the fuel mixed. During the flight the fuel was pressurized using helium, which was stored in tanks in the liquid oxygen tank above. Both the thrust structure and fuel tank had alternating black and white paint, in order to monitor the vehicle's roll during flight.

Between the fuel and liquid oxygen tanks was the intertank. This contained propellant fill and drain lines for the liquid oxygen tank as well as a portion of the five liquid oxygen feed lines for the engines.

The liquid oxygen (LOX) tank held 334500 USgal. It raised special issues for the designer. The lines through which the LOX ran to the engine had to be straight (as any bend would slow the flow of LOX, which would necessitate even larger and heavier piping) and therefore had to pass through the fuel tank. This meant insulating these lines inside a tunnel to stop fuel freezing to the outside and also meant adding five extra holes in the top of the fuel tank.

Atop the liquid oxygen tank sat the forward skirt, which connected the S-IC to the S-II stage and contained telemetry equipment and LOX tank vent lines.

Two solid motor retrorockets were located inside each of the four conical engine fairings. At separation of the S-IC from the flight vehicle, the eight retrorockets fired, blowing off removable sections of the fairings forward of the fins, and backing the S-IC away from the flight vehicle as the engines on the S-II stage were ignited.

The propellant tanks of the S-IC were manufactured from 2219-series aluminum panels, while the interstage, forward skirt, and thrust structure were built from 7075-series aluminum. The latter three sections also were corrugated with external stringers, providing additional structural support. The propellant tanks did not feature external stringers, as the tank pressurization provided sufficient rigidity.

The S-IC also carried the ODOP transponder to track the flight after takeoff.

Image:SaturnV S-IC.jpg|Cutaway diagram of the S-IC. Image:apmisc-MSFC-6870792.jpg|Saturn V first stages S-1C-10, S-1C-11, and S-1C-9 at Michoud Assembly Facility. File:Apollo 11 first stage separation.jpg|Apollo 11 S-IC separation.

Stages built

Proposed variants

Besides the version flown as the Saturn S-IC stage, other versions were proposed for several vehicle concepts:

Saturn S-IC-8

A 1960 study with eight F-1 engines, intended for the Saturn C-8.

Saturn IC C-3B

A 1961 study with five F-1 engines, intended for the Saturn C-3B and Saturn C-3BN.

Saturn IC C-4B

A 1961 study with five F-1 engines, intended for the Saturn C-4B.

Saturn IC C-5A

A 1961 study with five F-1 engines, intended for the Saturn C-5 and Saturn C-5N.

Saturn IC-Flat Bulkhead

A 1965 study, featuring reduced length and structural weight.

Saturn S-IC-TLB stage

A 1967 study with two F-1 engines for a reusable booster, intended for the Saturn S-IC-TLB.

Saturn S-ID Sustainer-1

A 1967 study with a single F-1 engine for a "stage and a half" booster/sustainer stage configuration.

Saturn S-ID Booster

A 1968 study with a four F-1 engine for a "stage and a half" recoverable booster, intended for the Saturn V-B, Saturn V-C, and Saturn V-D.

Saturn S-ID Sustainer

A 1968 study with a single F-1 engine for a "stage and a half" booster/sustainer stage configuration, intended for the Saturn V-B, Saturn V-C, and Saturn V-D.

References

References

1. (May 1983). "NASA, The First 25 Years: 1958-1983". National Aeronautics and Space Administration.
2. (Jul 1989). "Apollo, the race to the moon". Simon and Schuster.
3. Woods, W. David. (2011-08-08). "How Apollo Flew to the Moon". Springer Science & Business Media.
4. "History of the George C. Marshall Space Flight Center from January 1 - June 30, 1964, Volume 1".
5. "Michoud Assembly Facility January 1, 1967 - December 31, 1967".
6. (15 May 1965). "Saturn Illustrated Chronology Part 8".
7. "Saturn V News Reference".
8. "chapter 7".
9. Casebolt, Barry J.. (March 18, 1974). "Headed for Florida Museum — Veteran Moon Rocket Booster Leaves MSFC". The Huntsville Times.
10. "Saturn Vehicle History".
11. "Saturn IC".
12. "Saturn S-IC-8".
13. "Saturn IC C-3B".
14. "Saturn IC C-4B".
15. "Saturn IC C-5A".
16. "Saturn IC-Flat Bulkhead".
17. "Saturn S-IC-TLB stage".
18. "Saturn S-ID Sustainer-1".
19. "Saturn S-ID Booster".
20. "Saturn S-ID Sustainer".