The Allison J33 Centrifugal Jet Engine
The General Electric J31 was the first quantity produced jet engine in the United States. It was based on the General Electric I-A, an American version of the original British Whittle W.1 prototype that had been sent to the US in 1941. The GE J31 was adopted for use in production P-59As and P-59Bs.
U.S. Air Force photo
Allison J33 on display in the Modern Flight Gallery at the National Museum of the United States Air Force
However, it was clear from the start that there was a requirement for greater thrust then the J31 could provide. Alongside production of the J31 General Electric started work on the J33 design, which was effectively an enlarged version of the British Rolls-Royce "Derwent" engine. Known initially by the GE designation I-40, the intention was to produce an engine with around 4000lbs of thrust.
U.S. Air Force Museum
The Allison J33-A-35, a US development of the early Roll-Royce "Derwent"
Development of the J33 proceeded quickly, with the first prototype undergoing static testing on January 13, 1944. The J33 was selected to power the first American production Jet fighter, the P-80. To GE's chagrin, the license for the production of the J33 was given to Allison, who were able to produce the engine more cheaply. Ultimately, Allison would produce around 6,600 J33 engines, and GE would complete around 300 early run engines.
Allison J33 Specifications
| Allison J33-A-35 | ||
|---|---|---|
| Country | United States |  |
| Introduction | 1949 | |
| Production end | 1955 | |
| Number built | around 7,000 | |
| Type | Centrifugal-Flow Turbo Jet | |
| Compressor | single stage Centrifugal | |
| Turbine | single stage axial | |
| After-burner | Water / Alcohol injection | |
| Maximum RPM | 11,800 rpm | |
| Weight | 814 kilograms | 1,800 pounds |
| Thrust | 2,450 kilograms | 5,400 pounds |
| Dry Thrust | 2,090 kilograms | 4,600 pounds |
| Thrust to weight ratio | 2.56 | |
| Max operating altitude | 14,300 meters | 47,000 feet |
USAF Museum
