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S-IC First Stage

S-IC finishes using the fuel filled with the huge body for only two and a half minutes, and his mission is terminated. Then, it reaches the altitude of about six times of the aircraft cruising.
  • Diameter : 33ft (10.06m)
  • Height : 138ft (42.06m)
  • Weight(dry) : 303000lb (137.44ton)
  • Weight(loaded) : 4881000lb(2213.97ton)
  • Manufacturer : The Boeing Co. New Orleans
  • Burn time : 2.5min approx.
  • Velocity at burnout : 6000mph(9654km/h)
  • Altitude at burnout : 38miles(61.14km)


S69-34675 May 7, 1969 Apollo 12 Erection in VAB research: J.L. Pickering
S-IC structure consists of five units of Forward Skirt, LOX Tank, Intertank, FUEL Tank, Thrust Structure from the top. And, five F1 engines, eight Ullage Rockets in fairings are carried on this.

Forward Skirt Assembly

Saturn V S-IC stage structure
The independent two DC28V batteries, the electric power source to manipulate variety units of the S-IC are carried here. No.1 battery is called the main power battery, has 640 ampere-minute rating, and is 22 pounds. This is used to control various solenoids. No.2 battery is called the instrumentation battery, has 1,250 ampere-minute rating, and is 55 pounds. This is used for flight measurement and redundant systems.
MSFC-6870792 October 1, 1968 Saturn V first stages S-1C-10, S-1C-11, and S-1C-9 at Michoud Assembly Facility NASA
And, here is telemetry transmitter by six kinds of frequency. Most of telemetry systems units are mounted on Thrust Structure, RF transmitter and tape recorder are mounted on this Forward Skirt Assembly. At the time of ullagerocket, retrorocket jetting, telemetry transmission is disturbed. So, at that time, data will be recorded by tape recorder, and will be transmitted later. The control of this tape recorder is performed by the digital computer carried on IU.
Furthermore, ODOP (Offset Doppler Tracking) system to tracking movement of the rocket is carried here. High frequency signal from the ground is received with this ODOP system, then sent back again to the ground. The ground can know the movement of the rocket from doppler shift of the frequency.
With APOLLO 4 and 6, four color film cameras are carried here, make a film of the inside of LOX tank during the flight. The capsule that camera and film are stored is separated 25 seconds after the S-IC separation, parachute is opened and splash down, collected with the help of the signal of radio beacon.

Saturn V S-IC Stage

LOX Tank Assembly

331000 gallons (about 1426ton) of LOX (Liquid Oxygen) of -297 degree Fahrenheit are carried here. Through five LOX suction lines, 2000 gallons (about 19ton) of LOXs are supplied to the F1 engine per 1 second in flight. Cut-off sensor is being installed in the top end part of this LOX suction line. When it is detected that LOX disappeared by this, engines are stopped.
LOX is injected from two Fill & Drains located at the bottom of the tank with 1500 gallons per minute until they become 6.5% of the tanks. It is poured at 10000 gallons per minute until it meets 95% when it exceeds 6.5%. Then, it is poured until it is 100% at 1500 gallons per minute at the end.
70-H-1087 July 7, 1970 Apollo 15's S-IC booster stage is trucked from the turning basin to the VAB

When temperature of LOX rose, cooling is done by sending the bubble of the helium to the inside of LOX suction line. And, this helium and oxygen, nitrogen are used for pressurize of LOX. 45 seconds before launch, Helium is poured until pressure becomes 26psia through GOX (Gaseous Oxygen) distributor located at the top of the LOX tank from ground equipment. Then, pressurize is done during the flight as a part of LOX is heated by the heat of the engine and returning it to the LOX tank.

Intertank Assembly

This ring-shaped structure is located between LOX Tank and FUEL Tank, and connect those modules. Here is the access door for the maintenance and various connectors called umbilical opening. A LOX outlet for the emergency, pressurize port, electric connector and so on is contained in this umbilical opening.

KSC-68C-7912 December 3, 1968 The Apollo 10 S-IC stage is hoisted in the VAB for stacking

FUEL Tank Assembly

The fuel used by S-IC is a kind of kerosene called RP-1. 203000 gallons (about 630ton) of RP-1s are carried on this fuel tank. Through 10 Fuel suction lines, 1350 gallons (about 4ton) of RP-1 are supplied to the F1 engine per 1 second in flight. The pipe which makes the bubble of nitrogen is installed in Fuel suction line. Temperature of the fuel is prevented from rising before launch using this pipe. And five LOX suction lines are passing in this tank for supply LOX to F1 engines.
Fuel is injectioned at 200 gallons per minute from Fill & Drain located at the bottom of the tank until they become 10% of the tanks. It is poured at 2000 gallons per minute until it meets 102% when it exceeds 10%.
Pressurize of fuel is done by the helium supplied by four high pressure bottles located in the LOX tank. This helium is sent to the F1 engine once and heated. Then, it is returned to the fuel tank again, and used for pressurize.
And, fuel is used as the fluid power to change the direction of the engines during the flight. Fuel is sent to servo actuator from high pressure fuel duct during the flight.

Thrust Structure Assembly

Saturn V S-IC Thrust Structure Assembly
Thrust Structure which F1 engine is installed is heavy (24ton) parts in S-IC. These parts support the whole weight of the rocket, and all the thrust of the engine is transmitted to the body. Four holddownposts are being installed here. These are used for pressing down a rocket on the launch pad until get enough thrust after F1 engine ignite. Fuel supply, LOX outlet, and so on are being installed here. And four fins and fairings are installed surround F1 engines. In each fairings, two Retro (reverse jetting) Rocket are built in respectively. These fins are installed to give a vertical rocket stability, and heated in 200 degree Fahrenheit during the flight due to the air friction. Fins are covered with titanium to hold out this heat. A fair ring is blown off when Retro (reverse jetting) Rocket ignited.

72-H-1060 July 1972 Skylab S-IC booster is seen during Boeing/NASA handover ceremonies at Michoud

Range Safety System

This system stops an engine with the command from the ground, burst fuel tank, throw fuel away in the air, in the emergency. When a proper command is received from the ground, redundant Safety Command Receiver stops an engine, fire Shaped Charge, and tank is exploded.