Allison J33

The J33 was a US-produced development of Frank Whittle's early Rolls-Royce Derwent, enlarged to produce dramatically more thrust, starting at convert|4000|lbf|kN|abbr=on and ending at convert|4600|lbf|kN|abbr=on with an additional low-altitude boost to convert|5400|lbf|abbr=on 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 convert|1600|lbf|abbr=on 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 convert|4000|lbf|kN|abbr=on. 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 convert|5000|lbf|kN|abbr=on 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 convert|3000|lbf|kN|abbr=on. 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 favour 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.

pecifications (J33-A-35)

jetspecs

type=Nonafterburning turbojet
length=
diameter=
weight=1,795 lb (815 kg)
compressor=Single-stage centrifugal compressor
combustion=
turbine=
fueltype=
oilsystem=
power=
thrust=
*4,600 lbf (20.4 kN) at 11,750 rpm
*5,400 lbf (24.0 kN) with water-alcohol injection
compression=
fuelcon=
specfuelcon=
power/weight=
thrust/weight=2.56 (25.1 N/kg)