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| J31 | |
|---|---|
 General Electric J31 turbojet engine | |
| Type | Turbojet |
| National origin | United States |
| Manufacturer | General Electric |
| First run | April 1943[1] |
| Major applications | |
| Number built | 241[2] |
| Developed from | General Electric I-A |
| Developed into | General Electric I-40/Allison J33 |
TheGeneral Electric J31 was the firstjet engine to be mass-produced in theUnited States.
After a visit to England mid-1941, GeneralHenry H. Arnold was so impressed by flight demonstrations of theGloster E.28/39 jet aircraft he had witnessed that he arranged for thePower Jets W.1X turbojet engine to be shipped by air to the U.S., along with drawings for the more powerfulW.2B/23 engine, so that the US could develop its own jet engine.
General Electric's extensive experience inturbocharger production made that firm the natural choice for producing such an engine. The initial prototype, theGeneral Electric I-A, was essentially based on the W.2B/23. It first ran on 18 April 1942 and developed a staticthrust of 1250lbf.
The I-A air intake consisted of two peripheral slots which led to a double-sided, centrifugal compressor. A series of vanes guided the air into the impeller eyes. After radial compression, the air was diffused and turned 90 degrees rearwards, before entering a set of ten reverse-flow combustion chambers (i.e. cans). A relatively short shaft connected the compression system to the single stage axial turbine. After expansion through the turbine, the combustion products exhausted the engine through the simple conical propelling nozzle, via the jet-pipe. For the turbine section, GE used aproprietary metal developed for their turbochargers,Hastelloy B.[3]
Using their turbocharger expertise, General Electric were able, in a short space of time, to develop a 1,400 lbf (6.2 kN)-thrust version, known as the I-14. Later they increased the thrust to 1,600 lbf (7.1 kN). This version was referred to internally as the I-16[4] However, theUnited States Army Air Forces later decided to standardize all their jet engine naming, at which point the I-16 became the J31.
Production of the J31 started for theP-59 Airacomet in 1943, and by the time the lines shut down in 1945, a total of 241 had been built. GE also used the basic design to produce the much larger I-40 with 4,000 lbf, but this design was passed on toAllison as theJ33. Another derivative of the J31, the General Electric I-20, given the military designation J39, was ordered but later cancelled.
Meanwhile, the British version of the W.2B/23 turbojet entered production as the 1,600lbf thrustRolls-Royce Welland 1 in October, 1943. TheGloster Meteor I fighter, which entered RAF service in July 1944, was powered by the Welland I.
Data from[10]
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