General Electric J79
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| J79 | |
|---|---|
 J79 on display at the National Museum of the United States Air Force |
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| Type | Turbojet |
| Manufacturer | General Electric Aircraft Engines |
| Designed by | Gerhard Neumann |
| Maiden flight | 20 May 1955 |
| Introduction | 17 February 1956 |
| Number built | >17,000 [1] |
| Unit cost | $624,727 (J79-GE-3, 1960)[2] |
The General Electric J79 is an axial-flow turbojet engine built for use in a variety of fighter and bomber aircraft. Produced by General Electric Aircraft Engines and under license by other companies worldwide, it was one of the first US-designed engines to outperform designs from the United Kingdom[citation needed], which had previously led in the jet field.
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[edit] Development
The J79 was developed in the 1950s as an outgrowth of the General Electric J73 engine program, originally called J73-GE-X24A, intended for reliable Mach 2 performance.
The first flight of the engine was on 20 May 1955 where the engine was placed in the bomb bay of a J47-powered B-45C (48-009). The J79 was lowered from the bomb bay and the four J47s were shut down leaving the B-45 flying on the single J79.[3] The first flight after testing was on 17 February 1956, powering the first pre-production Lockheed YF-104A Starfighter. [4] While the engine proved highly successful from an operational standpoint, the Vietnam War experience showed the disadvantages of its highly visible, smoky exhaust when used to power military aircraft. It enjoyed a production run of more than 30 years. Over 17,000 J79s were built in the United States and under license in Belgium, Canada, Germany, Israel, Italy and Japan.
The second prototype XF4D-1 Skyray was loaned to General Electric in 1956 for further testing of the J79, with this engine fitted the Skyray could exceed Mach 1 in level flight where the standard aircraft remained subsonic. [5] Grumman's F-11F-1 was also fitted with the engine. The aircraft was designated F-11F-1F Super Tiger, but did not enter production.
The J79 was used on the F-104 Starfighter, B-58 Hustler, F-4 Phantom II, A-5 Vigilante and the IAI Kfir. A downgraded version of the F-16 with a J79 was proposed as a low-cost fighter for export, but found no customers although a prototype aircraft was flown. A simplified civilian version, designated the CJ-805, powered the Convair 880 and a single Sud Aviation Caravelle intended as a prototype for the US market, while a turbofan derivative, the CJ-805-23, powered the Convair 990 airliners.
The J79 was replaced by the late 1960s in new fighter designs by afterburning turbofans such as the Pratt & Whitney TF30 used in the F-111 and F-14, and newer generation turbofans with the P&W F100 used in the F-15 Eagle which offer better cruise fuel economy by moving unburned air.
For their part in designing the J79 Gerhard Neumann and General Electric Aircraft Engines were jointly awarded the Collier Trophy in 1958, also sharing the honor with Clarence Johnson (Lockheed F-104) and the U.S. Air Force (Flight Records).[6]
[edit] Design
The J79 is a single-spool turbojet with a 17-stage compressor with a novel arrangement of variable stator blades which allow the engine to develop pressure similar to a twin-spool engine at a much lower weight. Each blade is made largely of titanium which was not used for large aircraft structures until the 1960s, and each blade today costs several thousand dollars to replace.
In the F-104 and the F-4, the J79 makes a unique howling sound at certain throttle settings. The sound is thought to be due to airflow in the exhaust section of the engine being disturbed by the engine bypass flaps. This strange feature led to the NASA operated F-104B Starfighter, N819NA, being named Howling Howland.[7]
The turboshaft counterpart to the J79 is the LM1500, used for land and marine applications. Many J79 derived engines have found uses as gas turbine power generators in remote locations, in applications such as the powering of pipelines.
[edit] Variants and applications
- XJ79-GE-1
- Prototype. First ground static test run on 8 June 1954 produced 14,350 lbf with afterburner.[8]
- Flight test engines were designated YJ79-GE-1.
- J79-GE-2 and -2A
- Powered the F-4H-1 (F-4A) Phantom, 16,100 lbf (71.6 kN) of afterburner thrust.
- J79-GE-3
- Used in the YF-104A, F-104A and the F-11F-1F Super Tiger
- J79-GE3A
- YF-104A, F-104A and F-104B.
- J79-GE-3B
- F-104A and F-104B.
- J79-GE-5A
- B-58 Hustler 15,600 lbf (69.3 kN) with afterburner.
- J79-GE-7A
- F-104C, F-104D and F-104F.
- J79-OEL-7
- Licensed production GE-7 manufactured by Orenda Engines to power the Canadair CF-104.
- J79-GE-8, -8A and -8B
- A-5 Vigilante and F4H-1 (F-4B) with 16,950 lbf (75.4 kN) of afterburner thrust
- J79-GE-10
- F-4J, 17,900 lbf (79.379 kN) of afterburner thrust.
- J79-GE-11A
- F-104G and TF-104G. 15,600 lbf (69 kN) with afterburner. Many -11 engines were licensed manufactured in Europe as part of the large F-104 consortium production programme, Alfa Romeo, Fiat and Fabrique Nationale being the main suppliers for the project.
- J79-IHI-11A
- Licensed production GE-11A, built in Japan by Ishikawajima-Harima Heavy Industries Co., Ltd to power their similarly licensed built F-104J and F-104DJ Starfighters.
- J79-MTU-J1K
- Licensed built and improved version of the GE-11A manufactured by MTU Aero Engines in Germany.
- J79-GE-15
- F-4C, RF-4C, F-4D.
- J79-GE-17
- F-4E, 17,900 lbf (79.379 kN) of afterburner thrust.
- J79-GE-19
- J79-GE-J1E
- A licensed built J79 with 18,750 lbf (83.4 kN) afterburning thrust for the IAI Kfir.
- CJ-805-3
- Civil variant used on the Convair 880 series of airliners.
- CJ-805-23
- Civil turbofan variant for the Convair 990.
[edit] Specifications (J79-GE-17)
General characteristics
- Type: Afterburning turbojet engine
- Length: 17.4 ft (5.3 m)
- Diameter: 3.2 ft (1.0 m)
- Dry weight: 3,850 lb (1,750 kg)
Components
- Compressor: 17-stage axial compressor with variable stator vanes
Performance
- Thrust: 11,905 lbf (52.9 kN) dry; 17,835 lbf (79.3 kN) with afterburner
- Overall pressure ratio: 13.5:1
- Turbine inlet temperature: 1,210 °F (655 °C)
- Specific fuel consumption: 1.965 lb/(h·lbf) (200 kg/(h·kN)) with afterburner, 0.85 lb/(h·lbf) (87 kg/(h·kN)) at military thrust
- Thrust-to-weight ratio: 4.6:1 (45.4 N/kg)
[edit] Gallery
 Perhaps the most famous aircraft to use the J79 was the F-4 Phantom II. |
 A simplified civilian version of the J79, the turbofan derivative CJ-805-23, powered the Convair 990 airliners. |
 North American Eagle supersonic car display engine shows compressor blades smaller at each stage. |
 Sectioned compressor stage of a J79. |
 Turbine stage of a J79. |
[edit] See also
[edit] References
[edit] Notes
- ^ General Electric - Aviation History Retrieved: 7 April 2008
- ^ Pace 1992, p. 33.
- ^ Pace 1992 p. 67.
- ^ Pace 1992, p. 23.
- ^ Gunston 1981, p.71.
- ^ Collier Trophy winners, 1950-1959, National Aeronautic Association. Retrieved: 7 April 2008
- ^ Bashow 1986, p. 16.
- ^ Pace 1992, p. 69.
[edit] Bibliography
- Neumann, Gerhard (June 1984). Herman the German (in English). William Morrow & Co, 269. ISBN 0-688-01682-0. “The former enemy alien and Air Corps G.I. whose inventive skills and maverick management techniques made jet engine history”
- Pace, Steve. Lockheed F-104 Starfighter. Oscela, Wisconsin: Motorbooks International, 1992. ISBN 0-87938-608-8.
- Bashow, David L. Starfighter: A Loving Retrospective of the CF-104 Era in Canadian Fighter Aviation, 1961-1986. Stoney Creek, Ontario: Fortress Publications Inc., 1990. ISBN 0-91919-512-1.
- Gunston, Bill. Fighters of the Fifties. Cambridge, England. Patrick Stephens Limited, 1981. ISBN 0-85059-463-4.
[edit] External links
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