General Electric J31

J31

General Electric J31 turbojet engine
Type	Turbojet
National origin	United States
Manufacturer	General Electric
First run	April 1943^[1]
Major applications	P-59 Airacomet Ryan FR Fireball
Developed from	Power Jets W.2B/23
Developed into	General Electric I-40/Allison J33

The General Electric J31 was the first jet engine to be mass-produced in the United States.

Design and development

After a visit to England mid-1941, General Henry H. Arnold was so impressed by flight demonstrations of the Gloster E.28/39 jet aircraft he had witnessed that he arranged for the Power Jets W.1X turbojet engine to be shipped by air to the U.S, along with drawings for the more powerful W.2B/23 engine, so that the US could develop its own jet engine.

General Electric's extensive experience in turbocharger production made them the natural choice for producing such an engine. The initial prototype, the General Electric I-A, was essentially based on the Power Jets W.2B/23. It first ran on 18 April 1942 and developed a static thrust 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.

Using their turbocharger expertise, General Electric were able to, in a short space of time, develop a 1400lf thrust version, known as the I-14. Later they increased the thrust to 1610lbf. This version was referred to internally as the I-16^[2] However, the United States Army Air Forces later decided to standardise all their jet engine naming, at which point the I-16 became the J31.

Production of the J31 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. 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 Power Jets W.2B/23 turbojet entered production as the 1600lbf thrust Rolls-Royce Welland 1 in October, 1943. The Gloster Meteor I fighter, which entered RAF service in July, 1944, was powered by the Welland I.

Applications

Cutaway version of the J31 engine at the National Air and Space Museum

Survivors

There is a J31 on display at the New England Air Museum, Bradley International Airport, Windsor Locks, CT ^[3]
There is a J31 on display at Aerospace Discovery at Florida Air Museum in Lakeland, FL. Home of the SUN 'n FUN Fly-In.
There is a cutaway version of a J31 on display at the Smithsonian National Air and Space Museum Steven F. Udvar-Hazy Center in Chantilly, VA.

Specifications (J31)

Data from ^[4]

General characteristics

Type: Centrifugal compressor turbojet
Length: 72 in (183 cm)
Diameter: 41.5 in (105 cm)
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

References

Wikimedia Commons has media related to General Electric J31.

↑ http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19520085000
↑ https://books.google.co.uk/books?id=GqhnBwAAQBAJ&pg=PA26&lpg=PA26&dq=General+Electric+I-A+engine+performance&source=bl&ots=KCmoSFrft5&sig=mgxqgWceDStX0_vbHXnyYIg-VFc&hl=en&sa=X&ved=0ahUKEwiC88zDv__LAhUB1xoKHb54BAcQ6AEISjAJ#v=onepage&q=General%20Electric%20I-A%20engine%20performance&f=false
↑ http://neam.org/index.php?option=com_content&view=article&id=1049
↑ Wilkinson, Paul H. (1945). Aircraft Engines of the world 1945. New York: Paul H. Wilkinson. pp. 270–271.

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.

General Electric aircraft engines

Turbojets	CJ610 CJ805 GE1 GE4/J5P J31 J33 J35 J47 J73 J79 J85 J87 YJ93 J97 YJ101

Turbofans	CF6 CF34 CF700 CFE738† CFM56/F108† CJ805-23 F101 F110 F118 YF120 F136† F404/F412/RM12 F414 GE90 GEnx GP7000† HF120† LEAP† Passport TF34 TF39 RM12

Turboprops/Turboshafts	GE27 GE36 GE38-1B H80 T31 T58/CT58 T64/CT64 T407 T408 T700/CT7 Advanced Turboprop

Aeroderivative gas turbine engines	LM500 LM1500 LM1600 LM2500 LM6000 LMS100 LV100†

† Joint development aeroengines

United States military gas turbine aircraft engine designation system

Turbojets	J30 J31 J32 J33 J34 J35 J36 J37 XJ38 J39 J40 XJ41 J42 J43 J44 J45 J46 J47 J48 XJ49 J51 J52 J53 J54 J55 J56 J57 J58 J59 J60 J61 J63 J65 J67 J69 J71 J73 J75 J79 J81 J83 J85 J87 J89 J91 YJ93 J95 J97 J99 J100 YJ101 J102 J400 J401 J402 J403 J700

Turboprops/ Turboshafts	T30 T31 T33 T34 T35 T36 T37 T38 T39 T40 T41 T42 T43 T44 T45 T46 T47 T48 T49 T50 T51 T52 T53 T54 T55 T56 T57 T58 T60 T61 T62 T63 T64 T65 T66 T67 T68 T69 T70 T71 T72 T73 T74 T76 T78 T80 T100 T101 T400 T405 T406 T407 T408 T700 T701 T702 T703 T706 T708 T800

Turbofans	TF30 TF31 TF32 TF33 TF34 TF35 TF37 TF39 TF41 F100 F101 F102 F103 F104 F105 F106 F107 F108 F109 F110 F112 F113 F117 F118 F119 YF120 F121 F122 F124 F125 F126 F127 F128 F129 F135 F136 F137 F138 F400 F401 F402 F404 F405 F408 F412 F414 F415

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