| J79 | |
|---|---|
| J79 on display at the National Museum of the United States Air Force | |
| Type | Turbojet |
| National origin | United States |
| Manufacturer | General Electric Aircraft Engines |
| First run | 20 May 1955 (first flight) |
| Major applications | F-104 Starfighter F-4 Phantom II A-5 Vigilante B-58 Hustler |
| 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. The J79 was produced by General Electric Aircraft Engines in the United States, and under license by several other companies worldwide
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.
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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 the 50-hr 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. 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 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).[4]
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 7 being made of titanium) and spaced with corrosion-resistant (not stainless) steel spacers.[5]
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.[6]
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.
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.
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