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M-1 (rocket engine)
Encyclopedia
Aerojet
's M-1 was the largest and most powerful liquid hydrogen
-fueled rocket engine
to be designed and built. The M-1 offered a baseline thrust of 6.67 million N (1.5 million lbf
) and 8 million N (1.8 million lbf) as its immediate growth target. The M-1 was larger and produced more thrust than the famed F-1
that powered the first stage of the Saturn V
rocket to the moon.
studies from the late 1950s for its launch needs in the 1960s. By 1961 these had evolved into the Space Launching System design. The SLS consisted of a series of four rocket designs, all built around a series of solid-fuel boosters and liquid hydrogen
powered upper stages.
The smallest model, intended to launch the Dynasoar, used two 100 inches (2,540 mm) solids and an "A" liquid core. To power the "A" booster, Aerojet was contracted to convert an LR-87
, used in the Titan II missile, to run on liquid hydrogen. A prototype was successfully tested between 1958 and 1960. Initial studies of the 100 inches (2,540 mm) solid were also handed to Aerojet, starting in 1959.
The SLS also envisioned a number of much larger designs intended to launch the Air Force's Lunex Project
manned lunar landing. Lunex was a "direct landing" mission, in which a single very large spacecraft would fly to the Moon, land, and return. In order to launch such a design to low earth orbit
(LEO), a very large booster with a 125000 lb (56,699 kg) payload would be required. These larger SLS designs followed the same basic outline as the smaller Dynasoar booster, but used much more powerful 180 inches (4,572 mm) solids and the "B" and "C" liquid stages. To provide the required power, the liquid stages mounted a cluster of twelve J-2s
. To reduce this complexity, the Air Force also had Aerojet start studies of a much larger hydrogen-fueled design that would replace the twelve J-2s with only two engines. These initial studies would eventually emerge as the M-1, with a thrust of 1.2 million pounds force.
When NASA
formed in 1958, they also started planning for a lunar landing. Like the Air Force, their Project Apollo
initially favoured a direct landing profile, requiring a large booster to launch the spacecraft into LEO. Prior to NASA taking over Wernher von Braun
's Saturn
work for the US Army, they had no large rocket designs of their own, and started a study program known as Nova
to study a range of options. Initially the payload requirements were fairly limited, and the favoured Nova designs used a first stage with four F-1 engines and a payload of about 50000 lb (22,679.6 kg). These designs were presented to President Dwight D. Eisenhower
on January 27, 1959.
However, the Apollo spacecraft requirements quickly grew, settling on a 10000 lb (4,535.9 kg) spacecraft (the CSM) with a three-man crew. To launch a 10000 lb (4,535.9 kg) craft to the moon required a massive 125000 lb (56,699 kg) payload to LEO. Nova designs of this capability were quickly presented with up to eight F-1 engines, along with much more powerful upper stages that demanded the M-1 engine. Thus, for a brief period, the M-1 was used on the baseline designs for both NASA's and the Air Force's lunar programs.
In 1961, President John F. Kennedy
announced his intentions of landing a man on the moon "before the decade was out". After a brief argument, NASA
won the mission over the Air Force. However, Nova would require massive manufacturing capability that did not currently exist, and it was not clear that booster construction could be started in time for a landing before 1970. By 1962 they had decided to use von Braun's Saturn design, which went through a process of re-design to produce a usable booster that could be built in the existing facilities at Michoud, Louisiana
.
With the selection of Saturn for the lunar missions, work on Nova turned to the post-Apollo era. The designs were re-targeted for "manned planetary expedition", namely a manned landing on Mars
. Even utilizing a "lightweight" mission profile like that selected for Apollo, a Mars mission required a truly massive payload of about one million pounds to low earth orbit. This led to a second series of design studies, also known as Nova although they were essentially unrelated to the earlier designs.
Many of the new designs used the M-1 as their second-stage engine, although demanding much higher payloads. In order to meet these goals, the M-1 project was uprated from 1.2 million pounds force to a nominal 1.5 million pounds force, and the designers deliberately added more turbopump
capability to allow it to expand to at least 1.8 million pounds force, and potentially as high as 2.0 million pounds force. Additionally, the M-1 was even considered for a number of first stage designs, in place of the F-1 or the 180 inches (4,572 mm) solids. For this role the specific impulse
was dramatically reduced, and it appears some consideration was given to various expanding nozzle
designs to address this.
M-1 development continued through this period, although as the Apollo program expanded, NASA started cutting funding to the M-1 project in order to complete Saturn-related developments first. In 1965, another NASA project studied advanced versions of the Saturn, replacing the cluster of five J-2's
on the S-II
second stage with one M-1, five J-2T's, (an improved version of the J-2 with an aerospike
nozzle), or a high pressure engine known as the HG-3.
By 1966 it was clear that present funding levels for NASA would not be maintained in the post-Apollo era. The Nova design studies ended that year, and the M-1 along with it. The last M-1 contract expired on August 24, 1965, although testing continued on existing funds until August 1966. Studies on the J-2T ended at the same time. Although the HG-3 was never built, its design formed the basis for the Space Shuttle Main Engine
.
, burning some of its liquid hydrogen and oxygen in a small combustor to provide hot gases for running the fuel pumps. In the case of the M-1, the hydrogen and oxygen turbopump
s were completely separate, each using their own turbine, rather than running both off a common power shaft. The hydrogen and oxygen pumps were some of the most powerful ever built at the time, producing 75,000 horsepower
for the former, and 27000 hp for the latter.
Normally a gas-generator engine would dump the exhaust from the turbines overboard. In the case of the M-1, the resulting exhaust was fairly cool, and was instead directed into cooling pipes on the lower portion of the engine skirt. This meant that liquid hydrogen was needed for cooling only on the high-heat areas of the engine —the combustion chamber, nozzle and upper part of the skirt— reducing plumbing complexity considerably. The gas entered the skirt area at about 700 °F (371.1 °C), heating to about 1000 °F (537.8 °C) before being dumped through a series of small nozzles at the end of the skirt. The exhaust added 28000 lbf (124.6 kN) of thrust.
The engine was started by driving the pumps to speed by helium
gas stored in a separate high-pressure container. This started the fuel flow into the main engine and gas generator. The main engine was ignited by a generator that sprayed sparks into the combustion area. Shutdown was achieved by simply turning off the fuel flow to the gas generator, allowing the pumps to slow down on their own.
The use of separate turbopumps and other components allowed the various parts of the M-1 to be built and tested individually. Over the three-year lifetime of the project, a total of eight combustion chambers were built (two of them uncooled test units), eleven gas generators, four oxygen pumps, as well as four hydrogen pumps that were in the process of being completed.
Aerojet
Aerojet is an American rocket and missile propulsion manufacturer based primarily in Rancho Cordova, California with divisions in Redmond, Washington, Orange, Gainesville and Camden, Arkansas. Aerojet is owned by GenCorp. They are the only US propulsion company that provides both solid rocket...
's M-1 was the largest and most powerful liquid hydrogen
Liquid hydrogen
Liquid hydrogen is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.To exist as a liquid, H2 must be pressurized above and cooled below hydrogen's Critical point. However, for hydrogen to be in a full liquid state without boiling off, it needs to be...
-fueled rocket engine
Rocket engine
A rocket engine, or simply "rocket", is a jet engineRocket Propulsion Elements; 7th edition- chapter 1 that uses only propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines and obtain thrust in accordance with Newton's third law...
to be designed and built. The M-1 offered a baseline thrust of 6.67 million N (1.5 million lbf
Pound-force
The pound force is a unit of force in some systems of measurement including English engineering units and British gravitational units.- Definitions :...
) and 8 million N (1.8 million lbf) as its immediate growth target. The M-1 was larger and produced more thrust than the famed F-1
F-1 (rocket engine)
The F-1 is a rocket engine developed by Rocketdyne and used in the Saturn V. Five F-1 engines were used in the S-IC first stage of each Saturn V, which served as the main launch vehicle in the Apollo program. The F-1 is still the most powerful single-chamber liquid-fueled rocket engine ever...
that powered the first stage of the Saturn V
Saturn V
The Saturn V was an American human-rated expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. A multistage liquid-fueled launch vehicle, NASA launched 13 Saturn Vs from the Kennedy Space Center, Florida with no loss of crew or payload...
rocket to the moon.
History
The M-1 traces its history to US Air ForceUnited States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...
studies from the late 1950s for its launch needs in the 1960s. By 1961 these had evolved into the Space Launching System design. The SLS consisted of a series of four rocket designs, all built around a series of solid-fuel boosters and liquid hydrogen
Liquid hydrogen
Liquid hydrogen is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form.To exist as a liquid, H2 must be pressurized above and cooled below hydrogen's Critical point. However, for hydrogen to be in a full liquid state without boiling off, it needs to be...
powered upper stages.
The smallest model, intended to launch the Dynasoar, used two 100 inches (2,540 mm) solids and an "A" liquid core. To power the "A" booster, Aerojet was contracted to convert an LR-87
LR-87
The LR-87 was a liquid-propellent rocket engine, which was used to propel the first stages of Titan intercontinental ballistic missiles and launch vehicles. Though this powerful engine used two discrete combustion chambers, it is considered a single unit owing to both chambers using common...
, used in the Titan II missile, to run on liquid hydrogen. A prototype was successfully tested between 1958 and 1960. Initial studies of the 100 inches (2,540 mm) solid were also handed to Aerojet, starting in 1959.
The SLS also envisioned a number of much larger designs intended to launch the Air Force's Lunex Project
Lunex Project
The Lunex Project was a US Air Force 1958 plan for a manned lunar landing prior to the Apollo Program. The final lunar expedition plan in 1961 was for a 21-airman underground Air Force base on the Moon by 1968 at a total cost of $ 7.5 billion....
manned lunar landing. Lunex was a "direct landing" mission, in which a single very large spacecraft would fly to the Moon, land, and return. In order to launch such a design to low earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
(LEO), a very large booster with a 125000 lb (56,699 kg) payload would be required. These larger SLS designs followed the same basic outline as the smaller Dynasoar booster, but used much more powerful 180 inches (4,572 mm) solids and the "B" and "C" liquid stages. To provide the required power, the liquid stages mounted a cluster of twelve J-2s
J-2 (rocket engine)
Rocketdyne's J-2 rocket engine was a major component of the Saturn V rocket used in the Apollo program to send men to the Moon. Five J-2 engines were used on the S-II second stage, and one J-2 was used on the S-IVB third stage. The S-IVB was also used as the second stage of the smaller Saturn IB...
. To reduce this complexity, the Air Force also had Aerojet start studies of a much larger hydrogen-fueled design that would replace the twelve J-2s with only two engines. These initial studies would eventually emerge as the M-1, with a thrust of 1.2 million pounds force.
When NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
formed in 1958, they also started planning for a lunar landing. Like the Air Force, their Project Apollo
Project Apollo
The Apollo program was the spaceflight effort carried out by the United States' National Aeronautics and Space Administration , that landed the first humans on Earth's Moon. Conceived during the Presidency of Dwight D. Eisenhower, Apollo began in earnest after President John F...
initially favoured a direct landing profile, requiring a large booster to launch the spacecraft into LEO. Prior to NASA taking over Wernher von Braun
Wernher von Braun
Wernher Magnus Maximilian, Freiherr von Braun was a German rocket scientist, aerospace engineer, space architect, and one of the leading figures in the development of rocket technology in Nazi Germany during World War II and in the United States after that.A former member of the Nazi party,...
's Saturn
Saturn V
The Saturn V was an American human-rated expendable rocket used by NASA's Apollo and Skylab programs from 1967 until 1973. A multistage liquid-fueled launch vehicle, NASA launched 13 Saturn Vs from the Kennedy Space Center, Florida with no loss of crew or payload...
work for the US Army, they had no large rocket designs of their own, and started a study program known as Nova
Nova rocket
Nova was a series of proposed rocket designs, originally as NASA's first large launchers for missions similar to the production-level Saturn V, and later as larger follow-ons to the Saturn V intended for missions to Mars. The two series of designs were essentially separate, but shared their name...
to study a range of options. Initially the payload requirements were fairly limited, and the favoured Nova designs used a first stage with four F-1 engines and a payload of about 50000 lb (22,679.6 kg). These designs were presented to President Dwight D. Eisenhower
Dwight D. Eisenhower
Dwight David "Ike" Eisenhower was the 34th President of the United States, from 1953 until 1961. He was a five-star general in the United States Army...
on January 27, 1959.
However, the Apollo spacecraft requirements quickly grew, settling on a 10000 lb (4,535.9 kg) spacecraft (the CSM) with a three-man crew. To launch a 10000 lb (4,535.9 kg) craft to the moon required a massive 125000 lb (56,699 kg) payload to LEO. Nova designs of this capability were quickly presented with up to eight F-1 engines, along with much more powerful upper stages that demanded the M-1 engine. Thus, for a brief period, the M-1 was used on the baseline designs for both NASA's and the Air Force's lunar programs.
In 1961, President John F. Kennedy
John F. Kennedy
John Fitzgerald "Jack" Kennedy , often referred to by his initials JFK, was the 35th President of the United States, serving from 1961 until his assassination in 1963....
announced his intentions of landing a man on the moon "before the decade was out". After a brief argument, NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
won the mission over the Air Force. However, Nova would require massive manufacturing capability that did not currently exist, and it was not clear that booster construction could be started in time for a landing before 1970. By 1962 they had decided to use von Braun's Saturn design, which went through a process of re-design to produce a usable booster that could be built in the existing facilities at Michoud, Louisiana
Michoud, Louisiana
Michoud [MĒĒ-shū] is an area in Eastern New Orleans, part of the Ninth Ward of New Orleans, Louisiana, located at latitude 30.03N, longitude -89.925W....
.
With the selection of Saturn for the lunar missions, work on Nova turned to the post-Apollo era. The designs were re-targeted for "manned planetary expedition", namely a manned landing on Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
. Even utilizing a "lightweight" mission profile like that selected for Apollo, a Mars mission required a truly massive payload of about one million pounds to low earth orbit. This led to a second series of design studies, also known as Nova although they were essentially unrelated to the earlier designs.
Many of the new designs used the M-1 as their second-stage engine, although demanding much higher payloads. In order to meet these goals, the M-1 project was uprated from 1.2 million pounds force to a nominal 1.5 million pounds force, and the designers deliberately added more turbopump
Turbopump
A turbopump is a gas turbine that comprises basically two main components: a rotodynamic pump and a driving turbine, usually both mounted on the same shaft, or sometimes geared together...
capability to allow it to expand to at least 1.8 million pounds force, and potentially as high as 2.0 million pounds force. Additionally, the M-1 was even considered for a number of first stage designs, in place of the F-1 or the 180 inches (4,572 mm) solids. For this role the specific impulse
Specific impulse
Specific impulse is a way to describe the efficiency of rocket and jet engines. It represents the derivative of the impulse with respect to amount of propellant used, i.e., the thrust divided by the amount of propellant used per unit time. If the "amount" of propellant is given in terms of mass ,...
was dramatically reduced, and it appears some consideration was given to various expanding nozzle
Expanding nozzle
The expanding nozzle is a type of rocket nozzle that, unlike traditional designs, maintains its efficiency at a wide range of altitudes. It is a member of the class of altitude compensating nozzles, a class that also includes the plug nozzle and aerospike...
designs to address this.
M-1 development continued through this period, although as the Apollo program expanded, NASA started cutting funding to the M-1 project in order to complete Saturn-related developments first. In 1965, another NASA project studied advanced versions of the Saturn, replacing the cluster of five J-2's
J-2 (rocket engine)
Rocketdyne's J-2 rocket engine was a major component of the Saturn V rocket used in the Apollo program to send men to the Moon. Five J-2 engines were used on the S-II second stage, and one J-2 was used on the S-IVB third stage. The S-IVB was also used as the second stage of the smaller Saturn IB...
on the S-II
S-II
The S-II was the second stage of the Saturn V rocket. It was built by North American Aviation. Using liquid hydrogen and liquid oxygen it had five J-2 engines in a cross pattern...
second stage with one M-1, five J-2T's, (an improved version of the J-2 with an aerospike
Aerospike engine
The aerospike engine is a type of rocket engine that maintains its aerodynamic efficiency across a wide range of altitudes through the use of an aerospike nozzle. It is a member of the class of altitude compensating nozzle engines. A vehicle with an aerospike engine uses 25–30% less fuel at low...
nozzle), or a high pressure engine known as the HG-3.
By 1966 it was clear that present funding levels for NASA would not be maintained in the post-Apollo era. The Nova design studies ended that year, and the M-1 along with it. The last M-1 contract expired on August 24, 1965, although testing continued on existing funds until August 1966. Studies on the J-2T ended at the same time. Although the HG-3 was never built, its design formed the basis for the Space Shuttle Main Engine
Space Shuttle main engine
The RS-25, otherwise known as the Space Shuttle Main Engine , is a reusable liquid-fuel rocket engine built by Pratt & Whitney Rocketdyne for the Space Shuttle, running on liquid hydrogen and oxygen. Each Space Shuttle was propelled by three SSMEs mated to one powerhead...
.
Description
The M-1 used the gas-generator cycleGas-generator cycle (rocket)
The gas generator cycle is a power cycle of a bipropellant rocket engine. Some of the propellant is burned in a gas-generator and the resulting hot gas is used to power the engine's pumps. The gas is then exhausted...
, burning some of its liquid hydrogen and oxygen in a small combustor to provide hot gases for running the fuel pumps. In the case of the M-1, the hydrogen and oxygen turbopump
Turbopump
A turbopump is a gas turbine that comprises basically two main components: a rotodynamic pump and a driving turbine, usually both mounted on the same shaft, or sometimes geared together...
s were completely separate, each using their own turbine, rather than running both off a common power shaft. The hydrogen and oxygen pumps were some of the most powerful ever built at the time, producing 75,000 horsepower
Horsepower
Horsepower is the name of several units of measurement of power. The most common definitions equal between 735.5 and 750 watts.Horsepower was originally defined to compare the output of steam engines with the power of draft horses in continuous operation. The unit was widely adopted to measure the...
for the former, and 27000 hp for the latter.
The engine was started by driving the pumps to speed by helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
gas stored in a separate high-pressure container. This started the fuel flow into the main engine and gas generator. The main engine was ignited by a generator that sprayed sparks into the combustion area. Shutdown was achieved by simply turning off the fuel flow to the gas generator, allowing the pumps to slow down on their own.
The use of separate turbopumps and other components allowed the various parts of the M-1 to be built and tested individually. Over the three-year lifetime of the project, a total of eight combustion chambers were built (two of them uncooled test units), eleven gas generators, four oxygen pumps, as well as four hydrogen pumps that were in the process of being completed.
External Links
- The M-1 Rocket Engine Project – early NASA document outlining the project.
- Development of a 1,500,000-lb-thrust /nominal vacuum/ liquid hydrogen/liquid oxygen engine Final report, 30 Apr. 1962 - 4 Aug. 1966 NASA document covering the M-1 Project from inception to completion.
- Activation and initial test operations, large rocket engine - Turbopump test facilities Technology report Aerojet General report on the development of the test facilities for the M-1 Turbopump
- Activation and Initial Test Operations, Large Rocket Engine - Thrust Chamber Test Facilities Technology Report Aerojet General report on the development of the test facilities for the M-1 Thrust Chamber
- Development of LO2/LH2 Gas Generators for the M-1 Engine NASA document covering the development of the gas generators for the M-1 engine
- Development of liquid oxygen/liquid hydrogen thrust chamber for the M-1 engine NASA document covering the development of the M-1 thrust chamber
- Design study of modification of m-1 liquid hydrogen turbopump for use in nuclear reactor test facility