THE 456th FIGHTER INTERCEPTOR SQUADRON

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Allison J-33 Turbojet Engine

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Allison J33 Turbojet

 If the Allison J-33 looks vaguely familiar, it is a direct descendant from the famous jet engine design of Frank Whittle. Whittle's first jet engine design, the WU, became the first production jet engine, the Whittle W-1. It's characteristic cluster of combustion chambers gave the Whittle its distinctive shape.

The General Electric Company developed the design for the J-33 out of its work with the Whittle during the Second World War. The first J-33 was tested in January 1944 and became the engine for the Lockheed P-80 Shooting Star. The Allison Division of General Motors took over production of the engine in late 1945.

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J33

Deployed in the late 1940s, the J-33 powered the redesignated F-80, the Lockheed T-33 trainer for the USAF and the TV-2 trainer for the U.S. Navy. It also was used in the F-94 Starfire, essentially a two-seat version of the F-80, and very similar to the two-seat T-33. From 1949 to 1955, the Allison works built almost 7,000 of the most popular design, the J-33-A-35, for the USAF alone. The engine on display at the Arkansas Air Museum is a J-33-A-35.

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J33

The J-33 was also used in various models of ground-to-ground guided missiles for the USAF including the Mace, Matador and Snark. The Allison jet powered the Convair XF-92, the first jet aircraft to use the radical delta-wing designs pioneered by Germany's Dr. Alexander Lippisch during the 1930s.

The J-33 employed a single-stage, double-entry centrifugal-flow compressor for its fourteen straight through combustion chambers. The single-stage axial-flow turbine behind the combustion chamber assembly drives the compressor. In this design, almost three-fourths of the power generated is consumed by the compressor and only a fourth is translated into thrust. This is the great limiting factor of the design, only 3,900 pounds of thrust for its 1,795 pound weight.

SPECIFICATIONS
Compressor: Single-stage centrifugal
Turbine: Single axial
Weight: 1,795 lbs.
Thrust: 4,600 lbs. (5,400 lbs. with water/alcohol injection)
Max RPM: 11,750
Max Altitude: 47,000 ft.

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 Originally developed by the General Electric Company for the Lockheed P-80 "Shooting Star", the J33 engine is a direct descendant of the British Whittle engine of the early 1940s. The first J33 underwent static testing on January 13, 1944, just 6 1/2 months after development began. Five months later, a J33 engine flew in the XP-80A replacing the De Havilland H-1A, a change that was to become permanent. In November 1945, the Allison Division of General Motors assumed complete responsibility for the development and production of J33 series engines. The J33s were used in various models of Air Force and Navy aircraft, and in the USAF's Mace, Matador, and Snark surface-to-surface guided missiles.

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J33

The engine on display, a J33-A-35, is of the series used exclusively on the F-80C fighter, T-33A trainer, and the Navy TV-2 trainer. Between 1949 and 1955, Allison produced over 6,600 J33-A-35s for the Air Force, more than any other J33 series engine.

SPECIFICATIONS
Compressor: Single-stage centrifugal
Turbine: Single axial
Weight: 1,795 lbs.
Cost: $20,000
Thrust: 4,600 lbs. (5,400 lbs. with water/alcohol injection)
Maximum RPM: 11,750
Maximum Operating Altitude: 47,000 ft.

Thrust-to-weight ratio: 2.56 (25.1 N/kg)

COURTESY OF THE AIR FORCE MUSEUM

 

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The J33 was a US-produced development of Frank Whittle's early Rolls-Royce Derwent, enlarged to produce dramatically more thrust, starting at 4,000 lbf (18 kN) and ending at 4,600 lbf (20,000 N) with an additional low-altitude boost to 5,400 lbf (24,000 N) with water-alcohol injection.

The J33 was originally developed by General Electric as part of their work with Whittle's designs during World War II. Their first engine was known as the I-A, but after minor changes to adapt it to US production, it started limited production as the I-16 in 1942, the 16 referring to its 1,600 lbf (7,100 N) thrust. Full production started as the J31 when the Army Air Force introduced common naming for all their engine projects.

Along with the I-16, GE also started work on an enlarged version, known as the I-40. As the name implied, the engine was designed to provide 4,000 lbf (18 kN). The development cycle was remarkably rapid. Design work started in mid-1943 and the first prototype underwent static testing on January 13, 1944. Stanley Hooker of Rolls was shown the I-40 in 1943 and was startled at how much progress they had made so quickly, and returned to England to quickly design an even larger design, the 5,000 lbf (22 kN) Rolls-Royce Nene.

Lockheed was in the midst of the XP-80 project at the time, originally intending to power their design with a US-produced version of the Halford H-1 of about 3,000 lbf (13 kN). Production of the H-1 ran into delays, and since the I-40 would dramatically improve performance, plans were made to fit the prototypes with the I-40 instead.

The I-40 became important to the USAAF's plans when the I-16 powered P-59 was skipped over in favor of the I-40 powered P-80 as the US's first production jet fighter. In 1945 the license to actually produce the engine was not given to General Electric, but Allison Engine instead. Allison, working largely from government-owned wartime factories, could produce the engine in quantity more quickly and cheaply. GE was upset about this and complained that in the future they would no longer turn over their work for production.

By the time the production lines were shut down Allison had built over 6,600 J33's, and General Electric another 300 (mostly the early runs). In addition to P-80 and its derivatives T-33/TV-2 and F-94A/B, J33 was used in XF-92, MGM-1 Matador, SM-62 Snark, and MGM-13 Mace surface-to-surface guided missiles.

 

 

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Last Updated

02/10/2014

 

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