General Electric J31

type	Turbojet
national origin	United States
manufacturers	{M
first run	1940s
major applications	P-59 Airacomet FR Fireball
developed from	Power Jets W.1
developed into	General Electric I-40/Allison J33

J31
General Electric J31 turbojet engine

The General Electric J31 was the first working jet engine produced in the United States and also the first jet engine to be produced in quantity there.

Design and development

The J31 was essentially a production version of the prototype Whittle W.1 that had been sent to the US after the Tizard Mission successes. General Electric's extensive experience in turbocharger production made them the natural choice for producing the engine, which they initially referred to as the I-16, I-A referring to the original prototype. The United States Army Air Forces later decided to standardize all their jet engine naming, at which point the I-16 became the J31.

Like the W.1, the I-16 produced 1,650 pounds force (7.3 kN) of thrust and weighed about 850 lb. Production started for the P-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 to Allison as the J33, much to GE's chagrin and another derivative of the J31, the General Electric I-20, given the military designation J39, was ordered but later cancelled.

Applications

• Bell P-59 Airacomet
• Ryan FR Fireball
• Ryan XF2R Dark Shark

Survivors

• There is a J31 on display at the New England Air Museum, Bradley International Airport, Windsor Locks, CT

Specifications (J31)

Data from

General characteristics

• Type: Centrifugal compressor turbojet
• Length: 72 in (1,829 mm)
• Diameter: 41.5 in (1,054 mm)
• Dry weight: 850 lb (386 kg)

Components

• Compressor: Single-stage double-sided centrifugal
• Combustors: 10 reverse-flow can
• Turbine: Single-stage axial
• Fuel type: Kerosene (AN-F32) or 100/130 gasoline
• Oil system: Pressure spray, wet sump with scavenge cooling and filtration

Performance

• Maximum thrust: 1,650 lbf (7.33 kN)
• Overall pressure ratio: 3.8:1
• Air mass flow: 33 lb (15.0 kg)/second at 16,000 rpm
• Turbine inlet temperature: 1,220 °F (660 °C)
• Specific fuel consumption: 1.2 lb/lbf/hr (0.1223 kg/kN/hr)
• Thrust-to-weight ratio: 1.94:1

See also

• Whittle W.1
• Rolls-Royce Welland
• General Electric I-40/J33

References

• Gunston, Bill (2006). World Encyclopedia of Aero Engines, 5th Edition. Phoenix Mill, Gloucestershire, England, UK: Sutton Publishing Limited. ISBN 0-7509-4479-X. 
• Kay, Anthony L. (2007). Turbojet History and Development 1930-1960 Volume 2:USSR, USA, Japan, France, Canada, Sweden, Switzerland, Italy and Hungary (1st ed.). Ramsbury: The Crowood Press. ISBN 978-1861269393.