Lockheed J37
Encyclopedia
The Lockheed J37 (company designation L-1000) was one of the first turbojet engines designed in the United States
. It was not considered very important when it was first introduced in the 1930s and development was allowed to languish. By the time it was developed enough for production use, other engines, often British-derived, had surpassed it in performance. The design was later converted to a turboprop
, the T35 and still later sold to Wright Aeronautical
, where it saw some interest for use on what would become the B-52 Stratofortress
, before that design moved to jet power. The J37 and T35 were built to the extent of a number of testbed examples but never entered production.
, a manufacturer of steam engine
s for cars and other uses. Over the next few years he worked on a number of projects and starting in autumn 1933 began working on a steam turbine
for aircraft use. The engine featured a centrifugal compressor
that fed air to a combustion chamber, which in turn fed steam into a turbine
before exiting through a nozzle, powering the compressor and a propeller. The engine was fitted to a test aircraft in early 1934, where it demonstrated performance on par with existing piston engines but maintaining power to higher altitudes due to the compressor. Work on the design ended in 1936 after Doble found little interest in the design from aircraft manufacturers or the Army.
Price started work on his own turbojet design in 1938, although this initial design was far more complex than what eventually emerged as the J37. In an effort to keep the fuel efficiency
of the engine similar to existing piston engine, Price used a combination of low-compression axial compressor
stages feeding a high-compression reciprocating compressor
. In 1941 he was hired by Lockheed to evaluate the General Electric
supercharger
s being fit to the experimental XP-49
, a high-altitude version of their famous P-38. By this time Price had the basic design of his jet completed and was able to attract the interest of Lockheed's Chief Research Engineer, Kelly Johnson
, who would later found the company's famous Skunk Works
. Johnson had been thinking about a new high-speed design after running into various compressibility problems at high speed with the P-38 and the jet engine seemed like a natural fit in this project. During 1941 he ordered the development of a new aircraft to be powered by Price's engine, developing the engine as the L-1000 and the aircraft as the L-133.
Later that year the Tizard Mission
arrived in the US and presented many technological advances being worked on in England, including information on Frank Whittle
's jet engine designs. Rumors of similar work in Germany
and the well-publicized flights in Italy
suggested that practically everyone but the US was working on jets and getting a design of their own suddenly took on the utmost importance. Vannevar Bush
, Tizard's counterpart in the US, decided the best course of action was to simply license the British designs. A committee under the direction of William F. Durand
was set up to put the British designs into production and build an aircraft to test them. These projects emerged as the General Electric J31
powering the P-59 Airacomet
.
On 30 March 1942, Lockheed submitted proposals for the Lockheed L-133 and L-1000 to the US Army Air Force's development division at Wright Field
. By this point the original design proved too complex and had evolved into a new design replacing the pistons with a set of three centrifugal stages, with intercooling between each of the stages. The main combustor was a "canular" type with twelve flame cans in an annular container, feeding their exhaust to a five-stage axial turbine. For additional thrust, fuel could be sprayed between the turbine stages. To fine tune performance at different altitudes, the compressor and turbine stages were coupled using a variable-speed hydraulic clutch
. The design called for a weight of 1,700 lb (775 kg) and a sea level thrust of 5,100 lbf (22700 N). By November 1942 the design had been further refined, with the weight settling at 1,610 lb (735 kg) and the combustion area using chrome-steels. The Army remained uninterested and Lockheed apparently started getting cold feet.
Nevertheless, on 19 May 1943 Price agreed to start a more radical redesign at the urging of Wright Field. He produced a much simpler design consisting of two sixteen-stage axial compressors with a single stage of intercooling between them. The first four stages of the frontmost compressor remained clutched to allow them to operate at optimum speed. For testing purposes the compressor blades had no airfoil shaping and were attached to the central hub on rotating mounts to allow their angles to be changed between runs. The turbine was reduced to four stages. The low-pressure compressor was encased in a two-part cylindrical casing with stiffening ribs, which gave it an odd appearance similar to the bottom of an egg carton
. The shorter high-pressure compressor was similarly encased but with ribs running front-to-back only. Power was taken off between the two compressor stages to power accessories, with the gearbox placed on the top of the engine outside of the compressor casings.
In June 1943 the Army eventually demonstrated their interest in a Lockheed jet design but contracted for the P-80 Shooting Star
, to be powered by a licensed version of the Halford H.1. They remained interested in the L-1000 as well and sent out a long-term development contract under the name XJ37-1 in July 1943 with the first delivery on 1 August 1945. However, when the war ended the first example was only about two thirds complete. Some of the work had been contracted out to Menasco Manufacturing and at the end of the year the entire mechanical side of the project was turned over to them.
The first engine was finally ready for operation in 1946. The Army contracted for another four examples. Around this time a turboprop
version was proposed, the XT35 Typhoon. This was a fairly simple adaptation of the J37, adding a fifth turbine stage at the rear of the engine, containing a radial turbine that drove the pusher propeller and exited the exhaust around the outer rim of the engine. An alternate arrangement would send the exhaust through an opening in the propeller boss. In September 1947 Lockheed finally threw in the towel and sold the design to Wright Aeronautical
.
At the time the Army (soon to be US Air Force) was in the process of developing a new truly intercontinental bomber. Given engine and airframe technology at that time it appeared that the only way to build such an aircraft would be to use turboprops and Wright was interested in capturing that market. In June 1946 Boeing
proposed their Model 462 to fill the requirement, featuring six T35 engines, later reduced to four in a series of redesigns. However, by 1948 advances in airframe design, particularly the introduction of the swept wing
, allowed the bomber to move to jet power, eventually leading to the B-52 Stratofortress
.
Work on the J37/T35 continued until July 1953, by which point three engines had been delivered to the USAF. The Air Force turned over the engines and all collected data to the industry as a whole. No further interest was forthcoming and the project ended after an estimated $4.5 million (~30 million year 2000 dollars) had been spent.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. It was not considered very important when it was first introduced in the 1930s and development was allowed to languish. By the time it was developed enough for production use, other engines, often British-derived, had surpassed it in performance. The design was later converted to a turboprop
Turboprop
A turboprop engine is a type of turbine engine which drives an aircraft propeller using a reduction gear.The gas turbine is designed specifically for this application, with almost all of its output being used to drive the propeller...
, the T35 and still later sold to Wright Aeronautical
Wright Aeronautical
Wright Aeronautical was an aircraft and aircraft engine manufacturer located in New Jersey.-History:This American company evolved from the 1909-1916 Wright Company, which merged with the Glenn L. Martin Company in 1916 to form the Wright-Martin Aircraft Corporation. Glenn Martin resigned from...
, where it saw some interest for use on what would become the B-52 Stratofortress
B-52 Stratofortress
The Boeing B-52 Stratofortress is a long-range, subsonic, jet-powered strategic bomber operated by the United States Air Force since the 1950s. The B-52 was designed and built by Boeing, who have continued to provide maintainence and upgrades to the aircraft in service...
, before that design moved to jet power. The J37 and T35 were built to the extent of a number of testbed examples but never entered production.
Design and development
In 1930 Nathan C. Price joined Doble Steam MotorsAbner Doble
Abner Doble , was an American mechanical engineer who built and sold steam-powered automobiles. His father was William Ashton Doble, inventor of the Doble water wheel, and his grandfather and namesake was the founder of the Abner Doble Company.Abner Doble began apprenticing at his family's factory...
, a manufacturer of steam engine
Steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines are external combustion engines, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power, nuclear power or geothermal energy may be...
s for cars and other uses. Over the next few years he worked on a number of projects and starting in autumn 1933 began working on a steam turbine
Steam turbine
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....
for aircraft use. The engine featured a centrifugal compressor
Centrifugal compressor
Centrifugal compressors, sometimes termed radial compressors, are a sub-class of dynamic axisymmetric work-absorbing turbomachinery.The idealized compressive dynamic turbo-machine achieves a pressure rise by adding kinetic energy/velocity to a continuous flow of fluid through the rotor or impeller...
that fed air to a combustion chamber, which in turn fed steam into a turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid 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 move and...
before exiting through a nozzle, powering the compressor and a propeller. The engine was fitted to a test aircraft in early 1934, where it demonstrated performance on par with existing piston engines but maintaining power to higher altitudes due to the compressor. Work on the design ended in 1936 after Doble found little interest in the design from aircraft manufacturers or the Army.
Price started work on his own turbojet design in 1938, although this initial design was far more complex than what eventually emerged as the J37. In an effort to keep the fuel efficiency
Fuel efficiency
Fuel efficiency is a form of thermal efficiency, meaning the efficiency of a process that converts chemical potential energy contained in a carrier fuel into kinetic energy or work. Overall fuel efficiency may vary per device, which in turn may vary per application, and this spectrum of variance is...
of the engine similar to existing piston engine, Price used a combination of low-compression axial compressor
Axial compressor
Axial compressors are rotating, airfoil-based compressors in which the working fluid principally flows parallel to the axis of rotation. This is in contrast with other rotating compressors such as centrifugal, axi-centrifugal and mixed-flow compressors where the air may enter axially but will have...
stages feeding a high-compression reciprocating compressor
Reciprocating compressor
A reciprocating compressor or piston compressor is a positive-displacement compressor that uses pistons driven by a crankshaft to deliver gases at high pressure....
. In 1941 he was hired by Lockheed to evaluate the General Electric
General Electric
General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...
supercharger
Supercharger
A 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 burned and more work to be done per cycle,...
s being fit to the experimental XP-49
Lockheed XP-49
|-See also:-Bibliography:* Green, William. War Planes of the Second World War, Volume Four: Fighters. London: MacDonald & Co. Ltd., 1961 . ISBN 0-356-01448-7....
, a high-altitude version of their famous P-38. By this time Price had the basic design of his jet completed and was able to attract the interest of Lockheed's Chief Research Engineer, Kelly Johnson
Clarence Johnson
Clarence Leonard "Kelly" Johnson was an aircraft engineer and aeronautical innovator. As a member and first team leader of the Lockheed Skunk Works, Johnson worked for more than four decades and is said to have been an "organizing genius"...
, who would later found the company's famous Skunk Works
Skunk works
Skunk Works is an official alias for Lockheed Martin’s Advanced Development Programs , formerly called Lockheed Advanced Development Projects. Skunk Works is responsible for a number of famous aircraft designs, including the U-2, the SR-71 Blackbird, the F-117 Nighthawk, and the F-22 Raptor...
. Johnson had been thinking about a new high-speed design after running into various compressibility problems at high speed with the P-38 and the jet engine seemed like a natural fit in this project. During 1941 he ordered the development of a new aircraft to be powered by Price's engine, developing the engine as the L-1000 and the aircraft as the L-133.
Later that year the Tizard Mission
Tizard Mission
The Tizard Mission officially the British Technical and Scientific Mission was a British delegation that visited the United States during the Second World War in order to obtain the industrial resources to exploit the military potential of the research and development work completed by the UK up...
arrived in the US and presented many technological advances being worked on in England, including information on Frank Whittle
Frank Whittle
Air Commodore Sir Frank Whittle, OM, KBE, CB, FRS, Hon FRAeS was a British Royal Air Force engineer officer. He is credited with independently inventing the turbojet engine Air Commodore Sir Frank Whittle, OM, KBE, CB, FRS, Hon FRAeS (1 June 1907 – 9 August 1996) was a British Royal Air...
's jet engine designs. Rumors of similar work in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
and the well-publicized flights in Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
suggested that practically everyone but the US was working on jets and getting a design of their own suddenly took on the utmost importance. Vannevar Bush
Vannevar Bush
Vannevar Bush was an American engineer and science administrator known for his work on analog computing, his political role in the development of the atomic bomb as a primary organizer of the Manhattan Project, the founding of Raytheon, and the idea of the memex, an adjustable microfilm viewer...
, Tizard's counterpart in the US, decided the best course of action was to simply license the British designs. A committee under the direction of William F. Durand
William F. Durand
William F. Durand was a United States naval officer and pioneer mechanical engineer. He contributed significantly to the development of aircraft propellers...
was set up to put the British designs into production and build an aircraft to test them. These projects emerged as the General Electric J31
General Electric J31
|-See also:...
powering the P-59 Airacomet
P-59 Airacomet
The Bell P-59 Airacomet was the first American jet fighter aircraft, designed and built during World War II. The United States Army Air Forces was not impressed by its performance and cancelled the contract when fewer than half of the aircraft ordered had been produced. Although no P-59s went...
.
On 30 March 1942, Lockheed submitted proposals for the Lockheed L-133 and L-1000 to the US Army Air Force's development division at Wright Field
Wright Field
Wright Field was an airfield of the United States Army Air Corps and Air Forces near Riverside, Ohio. From 1927 to 1947 it was the research and development center for the Air Corps, and during World War II a flight test center....
. By this point the original design proved too complex and had evolved into a new design replacing the pistons with a set of three centrifugal stages, with intercooling between each of the stages. The main combustor was a "canular" type with twelve flame cans in an annular container, feeding their exhaust to a five-stage axial turbine. For additional thrust, fuel could be sprayed between the turbine stages. To fine tune performance at different altitudes, the compressor and turbine stages were coupled using a variable-speed hydraulic clutch
Fluid coupling
A fluid coupling is a hydrodynamic device used to transmit rotating mechanical power. It has been used in automobile transmissions as an alternative to a mechanical clutch...
. The design called for a weight of 1,700 lb (775 kg) and a sea level thrust of 5,100 lbf (22700 N). By November 1942 the design had been further refined, with the weight settling at 1,610 lb (735 kg) and the combustion area using chrome-steels. The Army remained uninterested and Lockheed apparently started getting cold feet.
Nevertheless, on 19 May 1943 Price agreed to start a more radical redesign at the urging of Wright Field. He produced a much simpler design consisting of two sixteen-stage axial compressors with a single stage of intercooling between them. The first four stages of the frontmost compressor remained clutched to allow them to operate at optimum speed. For testing purposes the compressor blades had no airfoil shaping and were attached to the central hub on rotating mounts to allow their angles to be changed between runs. The turbine was reduced to four stages. The low-pressure compressor was encased in a two-part cylindrical casing with stiffening ribs, which gave it an odd appearance similar to the bottom of an egg carton
Egg carton
An egg carton is a carton designed for carrying and transporting whole eggs. These cartons have a dimpled form in which each dimple accommodates an individual egg and isolates that egg from eggs in adjacent dimples...
. The shorter high-pressure compressor was similarly encased but with ribs running front-to-back only. Power was taken off between the two compressor stages to power accessories, with the gearbox placed on the top of the engine outside of the compressor casings.
In June 1943 the Army eventually demonstrated their interest in a Lockheed jet design but contracted for the P-80 Shooting Star
P-80 Shooting Star
The Lockheed P-80 Shooting Star was the first jet fighter used operationally by the United States Army Air Forces. Designed in 1943 as a response to the German Messerschmitt Me-262 jet fighter, and delivered in just 143 days from the start of the design process, production models were flying but...
, to be powered by a licensed version of the Halford H.1. They remained interested in the L-1000 as well and sent out a long-term development contract under the name XJ37-1 in July 1943 with the first delivery on 1 August 1945. However, when the war ended the first example was only about two thirds complete. Some of the work had been contracted out to Menasco Manufacturing and at the end of the year the entire mechanical side of the project was turned over to them.
The first engine was finally ready for operation in 1946. The Army contracted for another four examples. Around this time a turboprop
Turboprop
A turboprop engine is a type of turbine engine which drives an aircraft propeller using a reduction gear.The gas turbine is designed specifically for this application, with almost all of its output being used to drive the propeller...
version was proposed, the XT35 Typhoon. This was a fairly simple adaptation of the J37, adding a fifth turbine stage at the rear of the engine, containing a radial turbine that drove the pusher propeller and exited the exhaust around the outer rim of the engine. An alternate arrangement would send the exhaust through an opening in the propeller boss. In September 1947 Lockheed finally threw in the towel and sold the design to Wright Aeronautical
Wright Aeronautical
Wright Aeronautical was an aircraft and aircraft engine manufacturer located in New Jersey.-History:This American company evolved from the 1909-1916 Wright Company, which merged with the Glenn L. Martin Company in 1916 to form the Wright-Martin Aircraft Corporation. Glenn Martin resigned from...
.
At the time the Army (soon to be US Air Force) was in the process of developing a new truly intercontinental bomber. Given engine and airframe technology at that time it appeared that the only way to build such an aircraft would be to use turboprops and Wright was interested in capturing that market. In June 1946 Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
proposed their Model 462 to fill the requirement, featuring six T35 engines, later reduced to four in a series of redesigns. However, by 1948 advances in airframe design, particularly the introduction of the swept wing
Swept wing
A swept wing is a wing planform favored for high subsonic jet speeds first investigated by Germany during the Second World War. Since the introduction of the MiG-15 and North American F-86 which demonstrated a decisive superiority over the slower first generation of straight-wing jet fighters...
, allowed the bomber to move to jet power, eventually leading to the B-52 Stratofortress
B-52 Stratofortress
The Boeing B-52 Stratofortress is a long-range, subsonic, jet-powered strategic bomber operated by the United States Air Force since the 1950s. The B-52 was designed and built by Boeing, who have continued to provide maintainence and upgrades to the aircraft in service...
.
Work on the J37/T35 continued until July 1953, by which point three engines had been delivered to the USAF. The Air Force turned over the engines and all collected data to the industry as a whole. No further interest was forthcoming and the project ended after an estimated $4.5 million (~30 million year 2000 dollars) had been spent.