45 years ago today, June 25, 1969, the first stage of the Apollo 11 Saturn V was loaded with fuel.
The first stage of the Saturn V burned RP-1 (kerosene) as fuel with liquid oxygen as the oxidizer. Since this stage was the only launch vehicle stage with non-cryogenic fuel, it could be loaded in advance, even prior to the countdown demonstration test. The second and third stages used liquid hydrogen as fuel and liquid oxygen as oxidizer, and were loaded the day of launch.
The first stage fuel tank was overfilled, on purpose. On launch day, when the liquid oxygen was loaded into the stage, the RP-1 would cool, becoming more dense. After the fuel had cooled the final quantity needed could be determined and the extra RP-1 drained from the vehicle. By always having only a drain to perform on launch day, the RP-1 fueling system didn’t require use, allowing the elimination of a volatile system from pad use. On Apollo 11, the first stage was loaded with 1,424,889 pounds (646,319 kg) of RP-1 at liftoff.
Today’s video explains this process, along with the location of the pad facilities, as the preparation for the launch of Apollo 11 continues.