Rocketdyne F-1

F-1

F-1 rocket engine specifications
Country of origin	United States
Manufacturer	Rocketdyne
Liquid-fuel engine
Propellant	LOX / RP-1
Cycle	Gas-generator
Performance
Thrust (vac.)	1,746,000 lbf (7,770 kN)
Thrust (SL)	1,522,000 lbf (6,770 kN)
Thrust-to-weight ratio	94.1
Chamber pressure	70 bars (1,015 psi; 7 MPa)
Isp (vac.)	304 seconds (2.98 km/s)
Isp (SL)	263 seconds (2.58 km/s)

The F-1 is a gas-generator cycle rocket engine developed in the United States by Rocketdyne in the late 1950s and used in the Saturn V rocket in the 1960s and early 1970s. Five F-1 engines were used in the S-IC first stage of each Saturn V, which served as the main launch vehicle of the Apollo program. The F-1 remains the most powerful single-combustion chamber liquid-propellant rocket engine ever developed.

The F-1 was originally developed by Rocketdyne to meet a 1955 U.S. Air Force requirement for a very large rocket engine. The eventual result of that requirement was two engines, the E-1 and the much larger F-1. The E-1, although successfully tested in static firing, was quickly seen as a technological dead-end, and was abandoned for the larger, more powerful F-1. The Air Force eventually halted development of the F-1 because of a lack of requirement for such a large engine. However, the recently created National Aeronautics and Space Administration (NASA) appreciated the usefulness of an engine with so much power, and contracted Rocketdyne to complete its development. Test firings of F-1 components had been performed as early as 1957. The first static firing of a full-stage developmental F-1 was performed in March 1959. The first F-1 was delivered to NASA MSFC in October 1963. In December 1964, the F-1 completed flight-rating tests. Testing continued at least through 1965.

Early development tests revealed serious combustion instability problems which sometimes caused catastrophic failure. Initially, progress on this problem was slow, as it was intermittent and unpredictable. Oscillations of 4 kHz with harmonics to 24 kHz were observed. Eventually, engineers developed a diagnostic technique of detonating small explosive charges (which they called "bombs") outside the combustion chamber, through a tangential tube (RDX, C4 or black powder were used) while the engine was firing. This allowed them to determine exactly how the running chamber responded to variations in pressure, and to determine how to nullify these oscillations. The designers could then quickly experiment with different co-axial fuel-injector designs to obtain the one most resistant to instability. These problems were addressed from 1959 through 1961. Eventually, engine combustion was so stable, it would self-damp artificially induced instability within 1/10 of a second.