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.
History 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 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 outside the combustion chamber, through a tangential tube 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.
Design The Rocketdyne-developed F-1 engine is
the most powerful single-nozzle liquid-fueled rocket engine ever flown.
The RD-170 produces 11% more and the RD-171 produces 20% greater thrust using
a cluster of four combustion chambers and four nozzles. The M-1 rocket engine
was designed to have more thrust, however it was only tested at the
component level. The F-1 was a liquid-fueled rocket motor, burning RP-1
as fuel, and using liquid oxygen as the oxidizer. A turbopump was used to inject
fuel and oxygen into the combustion chamber.
The heart of the engine was the thrust chamber, which mixed and burned the fuel
and oxidizer to produce thrust. A domed chamber at the top of the engine served
as a manifold supplying liquid oxygen to the injectors, and also served as a
mount for the gimbal bearing which transmitted the thrust to the body of
the rocket. Below this dome were the injectors, which directed fuel and
oxidizer into the thrust chamber in a way designed to promote mixing and
combustion. Fuel was supplied to the injectors from a separate manifold; some
of the fuel first travelled in 178 tubes down the length of the thrust
chamber—which formed approximately the upper half of the exhaust nozzle—and
back, to cool the nozzle. A gas-generator was used to drive a
turbine which in turn drove separate fuel and oxygen pumps, each feeding the
thrust chamber assembly. The turbine was driven at 5,500 RPM by the gas
generator, producing 55,000 brake horsepower. The fuel pump produced
15,471 US gallons of RP-1 per minute while the oxidizer pump delivered 24,811
US gal of liquid oxygen per minute. Environmentally, the turbopump was
required to withstand temperatures ranging from input gas at 1,500 °F to
liquid oxygen at −300 °F. Structurally, fuel was used to lubricate and cool the
turbine bearings. Below the thrust chamber was the nozzle
extension, roughly half the length of the engine. This extension increased the
expansion ratio of the engine from 10:1 to 16:1. The exhaust from the turbopump
was fed into the nozzle extension by a large, tapered manifold; this relatively
cool gas formed a film which protected the nozzle extension from the hot)
exhaust gas. Each second, a single F-1 burned 5,683
pounds of oxidizer and fuel: 3,945 lb of liquid oxygen and 1,738 lb of RP-1,
generating 1,500,000 lbf of thrust. This equated to a flow rate of 671.4 US gal
per second; 413.5 US gal of LOX and 257.9 US gal of RP-1. During their two
and a half minutes of operation, the five F-1s propelled the Saturn V vehicle
to a height of 42 miles and a speed of 6,164 mph. The combined flow rate of the
five F-1s in the Saturn V was 3,357 US gal per second, or 28,415 lb. Each F-1
engine had more thrust than three Space Shuttle Main Engines combined.
Designer of the pump for the E-1/F-1 for Rocketdyne was Ernest A. Lamont. His
hand-written original calculations are part of the family archives and
available for display. He stated that the design of the rocket engine hinged
on the question of whether the pump design was viable.
= Pre and post ignition procedures = During static test firing, the
kerosene-based RP-1 fuel left hydrocarbon deposits and vapors in the
engine post test firing. These had to be removed from the engine to avoid
problems during engine handling and future firing, and the solvent
trichloroethylene was used to clean the engine's fuel system immediately before
and after each test firing. The cleaning procedure involved pumping TCE through
the engine's fuel system and letting the solvent overflow for a period ranging
from several seconds to 30–35 minutes, depending upon the engine and the
severity of the deposits. For some engines, the engine's gas generator and
LOX dome were also flushed with TCE prior to test firing. The F-1 rocket
engine had its LOX dome, gas generator, and thrust chamber fuel jacket flushed
with TCE during launch preparations. = Specifications =
Sources: = F-1 improvements =
F-1 thrust and efficiency were improved between Apollo 8 and Apollo 17, which
was necessary to meet the increasing payload capacity demands of later Apollo
missions. There were small performance variations between engines on a given
mission, and variations in average thrust between missions. For Apollo 15,
F-1 performance was: Thrust: 1,553,200 lbf
Burn time: 159 seconds Specific impulse: 264.72 seconds
Mixture ratio: 2.2674 S-IC total sea level liftoff thrust:
7,766,000 lbf Measuring and making comparisons of
rocket engine thrust is more complicated than it first appears. Based on actual
measurement the liftoff thrust of Apollo 15 was 7,823,000 lbf, which equates to
an average F-1 thrust of 1,565,000 lbf – significantly more than the specified
value. = F-1A after Apollo =
During the 1960s, Rocketdyne undertook uprating development of the F-1
resulting in the new engine specification F-1A. While outwardly very
similar to the F-1, the F-1A produced a larger thrust of about 1,800,000 lbf in
tests, and would have been used on future Saturn V vehicles in the
post-Apollo era. However, the Saturn V production line was closed prior to the
end of Project Apollo and no F-1A engine flew on a launch vehicle.
There were proposals to use eight F-1 engines on the first stage of the Nova
rocket. Numerous proposals have been made from the 1970s on to develop new
expendable boosters based around the F-1 engine design. These include the
Saturn-Shuttle, and one in 2013. As of 2013, none has proceeded beyond the
initial study phase. The F-1 is the largest, highest thrust
single-chamber, single-nozzle liquid fuel engine flown. The RD-170 and RD-171
from the Soviet Union use a cluster of four separate combustion chambers and
nozzles, giving the appearance of four engines; however, the combustion
chambers are all driven by a single turbopump. The assembly produces around
20% more thrust than the F-1, the highest thrust liquid-fuel engines ever
flown. Larger solid-fuel engines exist, such as the Space Shuttle Solid Rocket
Booster with a sea-level liftoff thrust of 2,800,000 lbf apiece.
F-1B booster As part of the Space Launch System
program, NASA had been running the Advanced Booster Competition, which was
scheduled to end with the selection of a winning booster configuration in 2015.
In 2012, Pratt & Whitney Rocketdyne(PWR) proposed using a derivative of the F-1
engine in the competition as a Liquid rocket booster. In 2013, engineers at
the Marshall Space Flight Center began tests with an original F-1, serial
number F-6049, which was removed from Apollo 11 due to a glitch. The engine
was never used, and for many years it was at the Smithsonian Institution. The
tests are designed to refamiliarize NASA with the design and propellants of the
F-1 in anticipation of using an evolved version of the engine in future deep
space flight applications. Pratt and Whitney, Rocketdyne, and
Dynetics, Inc. presented a competitor known as Pyrios in NASA's Advanced
Booster Program, which aims to find a more powerful successor to the
five-segment Space Shuttle Solid Rocket Boosters intended for early versions of
the Space Launch System, using two increased-thrust and heavily modified
F-1B engines per booster. Due to the engine's potential advantage in specific
impulse, if this F-1B configuration were integrated with the SLS Block II, the
vehicle could deliver 150 metric tons to low earth orbit, while 113 metric tons
is what is regarded as achievable with the currently planned solid boosters
combined with a 4 engine RS-25 core stage.
The F-1B engine has a design goal to be at least as powerful as the
un-flight-tested F-1A, while also being more cost effective. The design
incorporates a greatly simplified combustion chamber, a reduced number of
engine parts, and the removal of the F-1 exhaust recycling system, including the
turbopump exhaust mid-nozzle and the "curtain" cooling manifold. The
reduction in parts costs is aided by using selective laser melting in the 3-D
printing of metallic parts. The resulting F-1B engine is intended to
produce 1,800,000 lbf of thrust at sea level, a 15% increase over the
approximate 1,550,000 lbf of thrust that the mature Apollo 15 F-1 engines
produced. Locations of F-1 engines
Sixty-five F-1 engines were launched aboard thirteen Saturn Vs, and each
first stage landed in the Atlantic Ocean after about two and a half minutes of
flight. Ten of these followed approximately the same flight azimuth of
72 degrees, but Apollo 15 and Apollo 17 followed significantly more southerly
azimuths. The Skylab launch vehicle flew at a more northerly azimuth to reach a
higher inclination orbit. Ten F-1 engines were installed on two
Saturn Vs that never flew. The first stage from SA-514 is on display at the
Johnson Space Center in Houston and the first stage from SA-515 is on display at
the Michoud Assembly Facility in New Orleans.
A test engine is on display at the Powerhouse Museum in Sydney, Australia.
It was the 25th out of 114 research and development engines built by Rocketdyne
and it was fired 35 times. The engine is on loan to the museum from the
Smithsonian's National Air and Space Museum. It is the only F-1 on display
outside the United States. = Recovery =
On March 28, 2012, a team funded by Jeff Bezos, founder of Amazon.com, reported
that they had located the F-1 rocket engines from an Apollo mission using
sonar equipment. Bezos stated he planned to raise at least one of the engines,
which rest at a depth of 14,000 feet, about 400 miles east of Cape Canaveral,
Florida; however, the condition of the engines, which have been submerged for
more than 40 years, was unknown. NASA Administrator Charles Bolden released a
statement congratulating Bezos and his team for their find and wished them
success. He also affirmed NASA's position that any recovered artifacts
would remain property of the agency, but that they would likely be offered to the
Smithsonian Institution and other museums, depending on the number
recovered. On March 20, 2013, Bezos announced he
had succeeded in bringing parts of an F-1 engine to the surface, and released
photographs. Bezos noted, "Many of the original serial numbers are missing or
partially missing, which is going to make mission identification difficult.
We might see more during restoration." The recovery ship was Seaboard Worker,
and had on board a team of specialists organized by Bezos for the recovery
effort. On July 19, 2013, Bezos revealed that the serial number of one of the
recovered engine is Rocketdyne serial number 2044, the #5 engine that helped
Neil Armstrong, Buzz Aldrin, and Michael Collins to reach the Moon with the
Apollo 11 mission. The recovered parts are at the Kansas Cosmosphere and Space
Center in Hutchinson for the process of conservation.
In August 2014, it was revealed that parts of two different F-1 engines were
recovered, one from Apollo 11 and one from another Apollo flight, while a
photograph of a cleaned-up engine was released. Bezos plans to put the engines
on display at various places, including the National Air and Space Museum in
Washington, DC. See also
Comparison of orbital rocket engines References
Notes Bibliography
Apollo 15 Press Kit Saturn V Launch Vehicle, Flight
Evaluation Report, AS-510, MPR-SAT-FE-71-2, October 28, 1971.
External links E-1 at the Encyclopedia Astronautica
F-1 at the Encyclopedia Astronautica F-1A at the Encyclopedia Astronautica
NASA SP-4206 Stages to Saturn - the official NASA history of the Saturn
launch vehicle F-1 Engine Operating Instructions
The Saturn V F-1 Engine: Powering Apollo into History at Springer.com
Remembering The Giants: Apollo Rocket Propulsion Development, 2009, John C.
Stennis Space Center. Monograph in Aerospace History No. 45 NASA
How NASA brought the monstrous F-1 “moon rocket” engine back to life
New F-1B rocket engine upgrades Apollo-era design with 1.8M lbs of
thrust MSFC History office F-1 Fact sheet