General Electric J85
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|A General Electric J85-5|
|National origin||United States|
|Major applications||Cessna A-37 Dragonfly |
Canadair CT-114 Tutor
Northrop T-38 Talon
|Variants||General Electric CJ610|
|Developed into||General Electric CF700|
The General Electric J85 is a small single-shaft turbojet engine. Military versions produce up to 2,950 lbf (13.1 kN) of thrust dry; afterburning variants can reach up to 5,000 lbf (22 kN). The engine, depending upon additional equipment and specific model, weighs from 300 to 500 pounds (140 to 230 kg). It is one of GE's most successful and longest in service military jet engines, with the civilian versions having logged over 16.5 million hours of operation. The United States Air Force plans to continue using the J85 in aircraft through 2040. Civilian models, known as the CJ610, are similar but supplied without an afterburner, while the CF700 adds a rear-mounted fan for improved fuel economy.
Design and development
The J85 was originally designed to power a large decoy missile, the McDonnell ADM-20 Quail. The Quail was designed to be released from a B-52 Stratofortress in-flight and fly for long distances in formation with the launch aircraft, multiplying the number of targets facing the SA-2 surface-to-air missile operators on the ground. This mission demanded a small engine that could nevertheless provide enough power to keep up with the jet bomber. Like the similar Armstrong Siddeley Viper being built in England, the engine on a Quail drone had no need to last for extended periods of time, so therefore could be built of low-quality materials.
The fit was a success on the Quail, but again like the Viper it was later built with normal grade materials and subsequently used to power small jet aircraft, including the Northrop T-38 Talon, Northrop F-5, Canadair CT-114 Tutor, and Cessna A-37 Dragonfly light attack aircraft. More recently, J85s have powered the Scaled Composites White Knight aircraft, the carrier for the Scaled Composites SpaceShipOne spacecraft, and the Me 262 Project.
The basic engine design is quite small, about 18 inches (46 cm) in diameter, and 45 inches (110 cm) long. It features an eight-stage axial-flow compressor powered by two turbine stages, and is capable of generating up to 2,950 lbf (13.1 kN) of dry thrust, or more with an afterburner. At full throttle at sea level, this engine, without afterburner, consumes approximately 400 US gallons (1,500 L) of fuel per hour. At cruise altitude and power, it consumes approximately 100 US gal (380 L) per hour.
Several variants were produced. The J85-21 variant added a stage ahead of the base 8-stage compressor for a total of 9 stages, improving thrust.
More than 12,000 J85 engines had been built by the time production ended in 1988.
Iranian reverse engineering
The Iranian Ministry of Defense constructed a new engine based on the General Electric J85 named "OWJ". The engine was presented at a defense exhibition on 22 August 2016. the owj engine has a dry thrust of 3,500 lbf (16 kN).
- 2,600 lbf (12 kN) thrust
- 2,850 lbf (12.7 kN) thrust
- 2,450 lbf (10.9 kN) thrust
- 2,950 lbf (13.1 kN) thrust
- 2,400 lbf (11 kN) thrust, 3,600 lbf (16 kN) afterburning thrust
- 3,850 lbf (17.1 kN) afterburning thrust
- 2,450 lbf (10.9 kN) thrust
- 4,080 lbf (18.1 kN), 4,850 lbf (21.6 kN) thrust
- 4,300 lbf (19 kN) thrust
- Orenda manufactured J85-GE-15 for the Canadair CF-116 4,300 lbf (19 kN) thrust
- 2,850 lbf (12.7 kN) thrust
- 3,500 lbf (16 kN) military thrust; 5,000 lbf (22 kN) afterburning thrust.
- 5,000 lbf (22 kN) thrust
- military version of the CJ610, similar to the GE-7, 2,850 lbf (12.7 kN) thrust.
- Manufactured by Orenda for the Canadair CT-114 Tutor, 2,650 lbf (11.8 kN) thrust
- Boom Technology XB-1 "Baby Boom" demonstrator
- Canadair CL-41 Tutor
- Canadair CF-5
- Cessna A-37 Dragonfly
- Fairchild C-123 Provider
- Fairchild AC-119K
- Fiat G.91Y
- Lockheed Have Blue
- McDonnell ADM-20 Quail decoy missile
- Ryan MQM-34D Mod II target drone
- North American OV-10B(Z) Bronco
- North American T-2 Buckeye
- Northrop F-5
- Northrop T-38 Talon
- Ryan XV-5 Vertifan
- Saab 105Ö
- Scaled Composites White Knight
- Viper Aircraft Viperjet MKII
Data from
- Type: turbojet engine (with or without afterburner)
- Length: 45.4–51.1 in (115–130 cm) without afterburner (depending on accessory equipment installed)
- Diameter: 17.7 in (45 cm)
- Dry weight: 396–421 lb (180–191 kg) (depending on accessory equipment installed)
- Maximum thrust: 2,850–3,100 lbf (12.7–13.8 kN) (dry)
- Overall pressure ratio: 8.3
- Air mass flow: 45 lb (20 kg) per second
- Turbine inlet temperature: 1,470 °F (800 °C)
- Specific fuel consumption: 0.96–0.97 lb/(lbf⋅h) or 27–27 g/(kN⋅s)
- Thrust-to-weight ratio: 7.5 (-21), 6.6 (-5), 6.8 (-13), 7 (-15)
- 2001-04-17T00:00:00+01:00. "T-38 engine upgrades set to extend trainer's life to 2040". Flight Global. Retrieved 2020-05-20.
- "Archived copy". Archived from the original on 2014-02-03. Retrieved 2014-01-28.CS1 maint: archived copy as title (link)
- "Iran unveil indigenous turbojet engine". Aviationanalysis.net. Retrieved 26 August 2018.
- Norris, Guy (18 June 2017). ""Baby Boom" Demonstrator Passes Design Review". Aviation Week. Retrieved 21 March 2018.
- 400 Mph On Water - Popular Mechanics Archived 2007-09-30 at the Wayback Machine
- Gunston, Bill (2006). World Encyclopedia of Aero Engines, 5th Edition. Phoenix Mill, Gloucestershire, England, UK: Sutton Publishing Limited. ISBN 0-7509-4479-X.
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