General Electric J79

"J79" redirects here. For British Halcyon class minesweeper, see HMS Scott (J79).

J79

J79 on display at the National Museum of the United States Air Force
Type	Afterburning turbojet
National origin	United States
Manufacturer	General Electric Aircraft Engines
First run	20 May 1955 (first flight)
Major applications	Convair B-58 Hustler Lockheed F-104 Starfighter McDonnell Douglas F-4 Phantom II North American A-5 Vigilante
Number built	>17,000 ^[1]
Unit cost	$624,727 (J79-GE-3, 1960)^[2]
Developed from	General Electric J73
Variants	General Electric CJ805
Developed into	General Electric CJ805-23

The General Electric J79 is an axial-flow turbojet engine built for use in a variety of fighter and bomber aircraft and a supersonic cruise missile. The J79 was produced by General Electric Aircraft Engines in the United States, and under license by several other companies worldwide

A commercial version, designated the CJ805, powered the Convair 880, while an aft-turbofan derivative, the CJ805-23, powered the Convair 990 airliners and a single Sud Aviation Caravelle intended to demonstrate to the US market the benefits of a by-pass engine over the existing Avon turbojet.

In 1959 the gas generator of the J79 was developed as a stationary 10MW-class (13,000 bhp) free-turbine turboshaft engine for naval power, power generation, and industrial use, called the LM1500.^[3]^[4] Its first application was in the research hydrofoil USS Plainview.

Development

The J79 was developed in the 1950s for reliable Mach 2 performance. The U.S.A.F. had a requirement to power their next generation bomber which became the Convair B-58 and this application launched the J79.^[5]

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.^[6] The first flight after the 50-hour qualification test was on 8 December 1955, powering the second pre-production Douglas F4D Skyray, with the J79 in place of its original Westinghouse J40 engine as part of the General Electric development and qualification program. The YF-104 was the next airplane to fly with the J79 followed by a re-engined Grumman F11F Tiger in a Navy-sponsored program to gain experience with the engine before the first flight of the F4H (F-4).

The J79 was used on the F-104 Starfighter, B-58 Hustler, F-4 Phantom II, A-5 Vigilante, IAI Kfir and SSM-N-9 Regulus II supersonic cruise missile. It was produced for 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. A downgraded version of the F-16 Fighting Falcon with a J79 was proposed as a low-cost fighter for export, and though a prototype aircraft was flown, it found no customers.

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 Pratt & Whitney F100 used in the F-15 Eagle which give better cruise fuel efficiency by-passing air around the core of the engine.

For their part in designing the J79, Gerhard Neumann and Neil Burgess of 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).^[7]

Design

Sectioned compressor stage of a J79

The J79 is a single-spool turbojet with a seventeen-stage compressor with, what was at the time, 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.

Anyone new to variable stators had to overcome the complexity of the linkages and the difficulty of sealing the pivots and airfoil root/casing clearances. Two spools needed more knowledge about bearings and sealing. GE studied both options for nearly a year before deciding, in 1952, that they should pursue variable stators for the 12:1 pressure ratio(PR) compressor.^[8] Rolls-Royce had tested a rig compressor with four stages of variable stators in 1949 but did not pursue the idea at the time for the 6.5:1(PR) Avon.^[9] Connors^[10] tells us that Pratt and Whitney chose two spools for the 12:1(PR) J57 as they knew a lot more about bearings and sealing than about variable stators.

The J79 was originally known as the X-24A^[11] and was supported by a demonstrator engine, the GOL-1590.

The compressor blades are made of stainless steel and are mounted on disks (the first seven stage's disks being made of titanium) and spaced with corrosion-resistant (not stainless) steel spacers.^[12] The J79 makes a particular howling sound at certain throttle settings. This strange feature led to the NASA operated F-104B Starfighter, N819NA, being named Howling Howland.^[13] Early engines also produced noticeable quantities of smoke, especially at mid-throttle/cruise settings, a disadvantage in a combat aircraft making them easier to visually spot. Later models were redesigned to be "smokeless".

The turboshaft counterpart to the J79 is the General Electric 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.

The J79 has two commercial derivatives: CJ805-3 (a non-afterburning engine, fitted with thrust reverser and sound suppressor), and the CJ805-23 (with a free-wheeling aft fan and thrust reverser) fitted to the Convair CV-880 and the Convair CV-990 respectively.

Variants

J79-GE-3 and Lockheed YF-104A Starfighter

XJ79-GE-1: Prototype. First ground static test run on 8 June 1954 produced 14,350 lbf (63.83 kN) with afterburner.^[14]
YJ79-GE-1: Flight test engines were designated YJ79-GE-1.
J79-GE-2: Powered the McDonnell F-4H-1 Phantom (F-4A), 16,100 lbf (71.62 kN) of afterburner thrust.
J79-GE-2A: essentially similar to the -2
J79-GE-3: Used in the YF-104A, F-104A and the Grumman F11F-1F Super Tiger
J79-GE3A: YF-104A, F-104A and F-104B.
J79-GE-3B: F-104A and F-104B.
J79-GE-5A: Convair B-58 Hustler 15,600 lbf (69.39 kN) with afterburner.
J79-GE-5B: Convair B-58 Hustler 15,600 lbf (69.39 kN) with afterburner.
J79-GE-7: F-104C, F-104D and F-104F.
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: North American A-5 Vigilante and F4H-1 (F-4B) with 16,950 lbf (75.4 kN) of afterburner thrust
J79-GE-8A: Sub-variant of the -8
J79-GE-8B: Sub-variant of the -8
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.

J79-15A at the USAF Museum.

J79-GE-15: F-4C, RF-4C, F-4D;with 17,000 lbf (75.6kN) of afterburner thrust.
J79-GE-17: F-4E, 17,900 lbf (80 kN) of afterburner thrust.
J79-GE-19: Aeritalia F-104S; also retrofitted to F-104A's of the 319th FIS.
J79-GE-J1E: License-built in Israel by Beit Shemesh Engines Ltd. (BSEL) with 18,750 lbf (83.40 kN) afterburning thrust for the IAI Kfir.
J79-GE-119: F-16/79

Applications

J79 powered Convair B-58 Hustler

Aircraft

Land speed record cars

Specifications (J79-GE-17)

J79 with components labeled

Cutaway view of an air-start motor of a General Electric J79 turbojet

With air-start systems gas turbine engine compressor spools are rotated by the action of a large volume of compressed air acting directly on the compressor blades or driving the engine through a small, geared turbine motor.

Data from

General characteristics

Type: Afterburning turbojet engine
Length: 17.4 ft (5.3 m)
Diameter: 3.2 ft (0.98 m)
Dry weight: 3,850 lb (1,750 kg)

Components

Compressor: 17-stage axial compressor with variable stator vanes
Combustors: cannular
Turbine: 3-stage

Performance

Maximum thrust: 11,905 lbf (52.96 kN) dry; 17,835 lbf (79.33 kN) with afterburner
Overall pressure ratio: 13.5:1
Air mass flow: 170 lb/s (77 kg/s)
Turbine inlet temperature: 1,710 °F (930 °C; 1,210 K)
Specific fuel consumption: 1.965 lb/(lbf·h) (200 kg/(kN·h)) with afterburner, 0.85 lb/(lbf·h) (87 kg/(kN·h)) at military thrust
Thrust-to-weight ratio: 4.6 lbf/lb (45.4 N/kg)

References

Notes

↑ General Electric - Aviation History Retrieved: 7 April 2008
↑ Pace 1992, p. 33.
↑ Stoeckly, E. E. (1 April 1966). "Development of the General Electric LM 1500 Gas Turbine as a Marine Power Plant". J. Eng. Power. 88 (2): 144–152. doi:10.1115/1.3678497.
↑ "Taking it back to 1959 when the J79 turbojet engine was reconfigured as the LM1500.". General Electric. 1959.
↑ "seven decades of progress" General Electric, Aero Publishers Inc. Fallbrook, ISBN 0-8168-8355-6, p.76
↑ Pace 1992 p. 67.
↑ Collier Trophy winners, 1950-1959, National Aeronautic Association. Retrieved: 7 April 2008
↑ "Starting Something Big" Robert V. Garvin, AIAA Inc. 1998, ISBN 1-56347289-9, p.13
↑ Rolls-Royce Aero Engines" Bill Gunston, Patrick Stephens Ltd. 1989, ISBN 1-85260-037-3, p.133
↑ The Engines of Pratt & Whitney A Technical History" Jack Connors, AIAA Inc. 2010, ISBN 978-1-60086-711-8, p.221
↑ "seven decades of progress" General Electric, Aero Publishers Inc. 1979, ISBN 0-8168-8355-6, p.89
↑ AgentJayZ (2010). "Compressor Rotor II - Turbine Engines: A Closer Look". Retrieved April 22, 2011.
↑ Bashow 1986, p. 16.
↑ Pace 1992, p. 69.

Bibliography

Neumann, Gerhard (June 1984). Herman the German. William Morrow & Co. p. 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. Osceola, 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 0-919195-12-1.
Gunston, Bill. Fighters of the Fifties. Cambridge, England. Patrick Stephens Limited, 1981. ISBN 0-85059-463-4.
Williams, Nick and Steve Ginter "Douglas F4D Skyray". Simi Valley, California: Ginter, 1986. ISBN 0-942612-13-2.

External links

Wikimedia Commons has media related to General Electric J79.

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 GE93 H80 T31 T58/CT58 T64/CT64 T407 T408 T700/CT7

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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