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General Electric J79

 

  GE-J79

 

An axial-flow turbojet engine, 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 J79 is a single-spool turbojet with a seventeen-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 stainless steel. Each blade today costs several thousand dollars to replace. The compressor blades are mounted on disks (the first seven stages being made of titanium) and spaced with corrosion-resistant (not stainless) steel spacers.

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. 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, and the IAI Kfir. 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 unit cost of the J79-GE-3 in 1960 was US$624,727. 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.

In the F-104 and the F-4, the J79 makes a particular 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.

A simplified civilian 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 as a prototype for the US market.

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 offer better cruise fuel efficiency by moving unburned 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).

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) Most fitted to the Convair CV-880 and the Convair CV-990.

 

Variants and applications:

XJ79-GE-1
Prototype. First ground static test run on 8 June 1954 produced 14,350 lbf (63.83 kN) with afterburner.
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-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
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.
CJ805
A non-afterburning civilianised engine, fitted with thrust reverser and sound suppressor, including the aft-fan CJ805-23.

 

Applications:
Convair 880
Convair 990 Coronado
Convair B-58 Hustler
General Dynamics F-16/79
Grumman F-11F-1F Super Tiger
IAI Kfir
Lockheed F-104 Starfighter
McDonnell Douglas F-4 Phantom II
North American A-5 Vigilante
SSM-N-9/RGM-15 Regulus II

Land speed record cars
Art Arfons' "Green Monster"
Craig Breedlove's "Spirit of America - Sonic 1"

 

Specifications:

J79-GE-17
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)
Compressor: 17-stage axial compressor with variable stator vanes
Combustors: cannular
Turbine: 3-stage
Maximum 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: 1,710 °F (932 °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)

 

 


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