The
Allison Engine Company was a U.S.
aircraft engineAn aircraft engine is a propulsion system for an aircraft. Aircraft engines are almost always either lightweight piston engines or gas turbines. This article is an overview of the basic types of aircraft engines and the design concepts employed in engine development for aircraft.- Engine design...
manufacturer which was acquired by
Rolls-Royce plcRolls-Royce plc is a British aircraft engine maker, and the second-largest in the world, behind GE Aviation. The company has related businesses in the defence aerospace, marine and energy markets....
in 1995 to become a subsidiary,
Rolls-Royce Corporation. With the acquisition of Allison, Rolls-Royce expanded its product line to the point where it can now offer engines in virtually all market segments, from helicopters (e.g.
AE 1107C-LibertyThe Rolls-Royce T406 is a turboshaft engine which powers the Bell-Boeing V-22 Osprey tiltrotor. The Osprey is in service with the United States Marine Corps and United States Air Force...
), to the largest
wide-body aircraftA wide-body aircraft is a large airliner with two passenger aisles, also known as a twin-aisle aircraft. The typical fuselage diameter is . In the typical widebody economy cabin, passengers are seated seven to ten abreast, allowing a total capacity of 200 to 600 passengers...
(e.g.
Rolls-Royce TrentRolls-Royce Trent is the name given to a family of high bypass turbofan engines manufactured by Rolls-Royce. All are developments of the RB211 with thrust ratings of . Versions of the Trent are in service on the Airbus A330, A340, A380 and Boeing 777, and variants are in development for the...
).
Early work
Allison started as an engine and car "hot rodding" company servicing the
Indianapolis Motor SpeedwayThe Indianapolis Motor Speedway, located in Speedway, Indiana in the United States, is the home of the Indianapolis 500-Mile Race....
in Indianapolis. Its only regular production line item was steel-backed lead bushings, used as bearings in various aircraft engines. It also built various drive shafts, extensions and gear chains for high power engines, on demand. Another, smaller, business was the conversion of older Liberty engines to more powerful models, both for aircraft and marine use.
In the late 1920s the
U.S. ArmyThe United States Army is the branch of the United States Military responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military and is one of seven uniformed services...
funded the development of a series of high-power engines, as part of its
hyper engineThe hyper engine was a 1930s study project of the United States Army Air Corps, an effort to develop an aircraft engine capable of delivering 1 horsepower per cubic inch of engine displacement...
series, which it intended to produce on
Continental MotorsContinental Motors Company was an American engine and automobile manufacturer. The company produced engines for various independent manufacturers of automobiles, tractors, and stationary equipment from the 1900s through the 1960s. Continental Motors also produced Continental-branded automobiles in...
' production lines. Allison's manager, N.H. Gilman, decided to experiment with its own high-power cylinder design. The result was presented to the Army in 1928, which turned down the development proposal.
In 1929, shortly after the death of
James AllisonJames Ashbury Allison , born in Marcellus, Michigan, was an American entrepreneur and businessman. He was the inventor of the Allison Perfection Fountain Pen and with Carl G. Fisher a founder of Prest-O-Lite, a manufacturer of automobile headlights. With Carl G. Fisher, Frank H. Wheeler, and Arthur C...
, the company was purchased by the
Fisher brothersFisher Body is an automobile coachbuilder founded by the Fisher brothers in 1908 in Detroit, Michigan, which is now an operating division of General Motors Corporation.- Fisher Brothers :...
, who instructed it to use the cylinder design for a six cylinder engine for a "family aircraft". Before work on this design had progressed very far, Fisher sold the company to General Motors, which ended development due to financial pressures of the
Great DepressionThe Great Depression was a severe worldwide economic depression in the decade preceding World War II. The timing of the Great Depression varied across nations, but in most countries it started in about 1929 and lasted until the late 1930s or early 1940s...
. Nevertheless Gilman pressed ahead with the cylinder design, building a "paper project" V-12 engine. The Army was once again uninterested, but instead suggested Allison try selling it to the
U.S. NavyThe United States Navy is the sea branch of the U.S. Armed Forces. It is one of the seven uniformed services of the United States. As of 31 December 2008, the U.S. Navy had about 331,682 personnel on active duty and 124,000 in the Navy Reserve. It operates 283 ships in active service and more than...
. The Navy agreed to fund development of A and B models to a very limited degree for its
airshipAn airship or dirigible is a lighter-than-air aircraft that can be steered and propelled through the air using rudders and propellers or other thrust...
s, until the crash of the
USS MaconUSS Macon was a rigid airship built and operated by the United States Navy for scouting. It served as a flying aircraft carrier, launching Sparrowhawk biplanes. In service for less than two years, in 1935 Macon was damaged in a storm and lost off California's Big Sur coast, though most of her crew...
in 1935, when the Navy's need for a 1,000 hp engine disappeared.
V-1710
By this point the Army had become more interested in the design, and asked Allison to continue with a new "C" model. They had few funds of their own to invest, and Allison supported much of the development out of their own pocket. The
V-1710-CThe Allison V-1710 aircraft engine was the only indigenous US-developed V-12 liquid-cooled engine to see service during WWII. A sturdy and trustworthy design, it unfortunately lacked an advanced and efficient mechanical centrifugal supercharger...
first flew on 14 December, 1936 in the Consolidated A-11A testbed. The V-1710-C6 successfully completed the Army 150 hour Type Test on 23 April, 1937, at 1,000 hp (750 kW), the first engine of any type to do so. By this point all of the other Army engine projects had been cancelled or withdrawn, leaving the V-1710 as the only modern design available. It was soon found as the primary powerplant of the new generation of USAAC fighters, the
P-38 LightningThe Lockheed P-38 Lightning was a World War II American fighter aircraft built by Lockheed. Developed to a United States Army Air Corps requirement, the P-38 had distinctive twin booms and a single, central nacelle containing the cockpit and armament...
,
P-39 Airacobra and P-40 Warhawk.
The Army had been leaning heavily towards exhaust-driven
turbochargerA turbocharger, or turbo, is a gas compressor that is used for forced-induction of an internal combustion engine. A form of supercharger, the purpose of a turbocharger is to increase the density of air entering the engine to create more power...
s instead of the more common mechanically-driven
superchargerA supercharger is an air compressor used for forced induction of an internal combustion engine. The greater mass flow-rate provides more oxygen to support combustion than would be available in a naturally-aspirated engine, which allows more fuel to be provided and more work to be done per cycle,...
s, feeling that their added performance more than made up for the added complexity. Thus little effort was invested in equipping the V-1710 with a reasonable supercharger, and when placed in aircraft designs like the P-39 or P-40 which lacked the room for a turbo the engine suffered tremendously at higher altitudes. It was this reason in particular that the V-1710 was later removed from the
P-51 MustangThe North American Aviation P-51 Mustang was a long-range single-seat World War II fighter aircraft. Designed, built and airborne in just 117 days, the Mustang first flew in RAF service as a fighter-bomber and reconnaissance aircraft before conversion to a bomber escort, employed in raids over...
and replaced with the
Rolls-Royce MerlinThe Rolls-Royce Merlin is a British, liquid-cooled, 27-litre capacity, V-12 piston aero engine, designed and built by Rolls-Royce Limited...
instead.
Post-war
With the need for the V-1710 winding down at the end of the war, Allison found itself with a massive production infrastructure that was no longer needed. For this reason in 1947 the Army decided to take
General Electric'sThe General Electric Company, or GE , is a multinational American technology and services conglomerate incorporated in the State of New York. In 2009, Forbes ranked GE as the world's largest company...
versions of
Frank Whittle'sAir Commodore Sir Frank Whittle, OM, KBE, CB, FRS, Hon FRAeS was a British Royal Air Force officer. Sharing credit with Germany's Dr. Hans von Ohain for independently inventing the jet engine, he is hailed as a father of jet propulsion.From an early age Whittle demonstrated an aptitude for...
jet engineA jet engine is a reaction engine that discharges a fast moving jet of fluid to generate thrust in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets and pump-jets...
s and give them to Allison to produce instead. The main production model was GE's 4,000 lbf I-40, produced as the
Allison J33The General Electric/Allison J33 was a US-produced development of Frank Whittle's early Rolls-Royce Derwent, enlarged to produce dramatically more thrust, starting at and ending at with an additional low-altitude boost to with water-alcohol injection....
. By the time production ended in 1955, Allison had produced over 7,000 J33s.
Allison also took over GE's axial flow engine design, becoming the
Allison J35The General Electric/Allison J35 was originally developed by the General Electric in parallel with the Whittle-based centrifugal-flow J33, and was the United States Air Force's first axial-flow compressor engine. The J35 was fairly simple, consisting of an eleven-stage axial-flow compressor and a...
. The J35 was the primary powerplant for the
F-84 ThunderjetThe Republic F-84 Thunderjet was an American-built turbojet fighter-bomber aircraft. Originating as a 1944 United States Army Air Force proposal for a "day fighter", the F-84 flew in 1946...
and
F-89 ScorpionThe Northrop F-89 Scorpion was an early American jet-powered fighter designed from the outset as an all-weather interceptor. Though its straight wings limited its performance, it was among the first USAF jet fighters equipped to fire guided missiles, including the distinction of being the first...
, as well as appearing on numerous prototype designs. The J35 also finished production in 1955, by which point over 14,000 had been delivered.
Allison also started the development of a series of
turbopropTurboprop engines are a type of aircraft powerplant that use a gas turbine to drive a propeller. The gas turbine is designed specifically for this application, with almost all of its output being used to drive the propeller...
engines for the
U.S. NavyThe United States Navy is the sea branch of the U.S. Armed Forces. It is one of the seven uniformed services of the United States. As of 31 December 2008, the U.S. Navy had about 331,682 personnel on active duty and 124,000 in the Navy Reserve. It operates 283 ships in active service and more than...
, starting with the
T38The Allison T40 was an early turboprop engine, composed of two Allison T38 power sections driving a common gearbox.-Design and development:...
and a "twinned" version as the T40. The Navy was interested only in the T40, but the complexities of the driveshaft arrangement doomed the engine and the project was eventually cancelled. Allison tried again with the T56, basically an enlarged T38 with the power of the T40, and was eventually rewarded when this engine was selected to power the
C-130 HerculesThe Lockheed C-130 Hercules is a four-engine turboprop military transport aircraft built by Lockheed. Capable of takeoffs and landings from unprepared runways, the C-130 was originally designed as a troop, medical evacuation, and cargo transport aircraft...
.
Over the years a family of engines, based on the T56 basic configuration has been developed, culminating in the T406/Allison AE1107 turboshaft for the
V-22 OspreyThe Bell-Boeing V-22 Osprey is a multi-mission, military, tiltrotor aircraft with both a vertical takeoff and landing and short takeoff and landing capability. It is designed to perform missions like a conventional helicopter with the long-range, high-speed cruise performance of a turboprop...
, the Allison AE2100 turboprop, used on newer models of the C-130 and the Allison/
Rolls-Royce AE 3007The AE 3007 is a turbofan engine produced by Rolls-Royce. In military service it is designated F137.-Design and development:The engine provides up to 8,917 lbf of thrust. It consists of a fan, 14-stage high pressure compressor, 2-stage high pressure turbine and 3-stage low pressure turbine...
turbofan which propels many commuter aircraft, such as the
EmbraerEmbraer , is a Brazilian aerospace conglomerate. The company produces commercial, military, and corporate aircraft, and provides related aerospace services...
ERJ 135 family.
One of Allison's most successful projects is the
Model 250The Allison Model 250 is a highly successful turboshaft engine family, originally developed by the Allison Engine Company in the early 1960s...
turboshaft/turboprop engine family, which was started by the Company in the early 60s, when helicopters started to be powered by turbine, rather than reciprocating, engines.
Experiments
In the mid-1970s the Allison Division of General Motors Corporation in Detroit designed ceramic components into the Allison GT 404-4 truck engine. Allison continued to work with General Motors on development of
CeramicA ceramic is an inorganic, non-metallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
-
TurbineA turbine is a rotary engine that extracts energy from a fluid or air flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum, with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they...
powered engines until the early 1990s. During their work they were able to engineer fairly stable automobile engines that were capable of burning a variety of fuels including (but not limited to) gasoline, diesel, kerosene, alcohol, vegetable oil, and coal powder.
In the 1980s Allison collaborated with
Pratt & WhitneyPratt & Whitney is an American aircraft engine manufacturer of products widely used in both civil and military aircraft. As one of the "big three" aero-engine manufacturers, it competes with General Electric and Rolls-Royce, although it has also formed joint ventures with both of these companies...
on demonstrating the 578-DX
propfanAn unducted fan or propfan is a modified turbofan engine, with the fan placed outside of the engine nacelle on the same axis as the compressor blades. Propfans are also known as ultra-high bypass engines and, most recently, open rotor jet engines...
. Unlike the competing
General Electric GE-36 UDFThe General Electric GE36 was an experimental aircraft engine, a hybrid between a turbofan and a turboprop, known as an Unducted Fan or propfan. The GE36 was developed by General Electric Aircraft Engines....
, the 578-DX was fairly conventional, having a reduction gearbox between the LP turbine and the propfan blades. Noise considerations, plus a significant reduction in the real cost of aviation fuel, brought the NASA funded program to a halt.
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