| TF39 | |
|---|---|
 | |
| A TF39 on a C-5 Galaxy at ILA (Internationale LuftfahrtAusstellung) in Berlin, 2008 | |
| Type | High-bypassturbofan |
| National origin | United States |
| Manufacturer | GE Aviation |
| First run | 1964 |
| Major applications | Lockheed C-5 Galaxy |
| Number built | 463 |
| Developed into | General Electric CF6 General Electric LM2500 |
TheGeneral Electric TF39 is ahigh-bypass turbofan engine that was developed to power theLockheed C-5 Galaxy. The TF39 was the first high-power, high-bypass jet engine developed. The TF39 was further developed into theCF6 series of engines, and formed the basis of theLM2500 andLM6000 marine and industrial gas turbine. On September 7, 2017, the last active C-5A powered with TF39 engines made its final flight to Davis-Monthan Air Force Base for retirement.[1][2] The TF39 was effectively retired, and all remaining active C-5 Galaxies are Rebuilt C-5M Super Galaxies, powered by F138-GE-102 (derivative ofGeneral Electric CF6-80C2, specifically for C-5M upgrade) engines.
TheUnited States Air Force opened the "CX-X Program" in 1964, intending to produce a next-generation strategicairlifter. Of the several airframe and engine proposals returned for consideration, Lockheed's aircraft and General Electric's engine were selected for the new design in 1965.
The high-bypass turbofan was a huge leap in engine performance, offering a thrust of 43,000 pounds, while improvingfuel efficiency by about 25%.[3] The TF39 had an 8:1 bypass ratio, a 25:1 compressor pressure ratio, and a 2,500 °F (1,370 °C) turbine temperature made possible by advanced forced-air cooling. The first engine went for testing in 1965. Between 1968 and 1971, 463 TF39-1 and -1A engines were produced and delivered to power the C-5A fleet.
The TF39 was a revolutionary 1960s engine rated from 41,000 to 43,000lbf (191 to 205kN) of thrust. It introduced use of a large by-pass ratio which, together with advances in core technology, contributed to a significant improvement in fuel efficiency over engines available at the time.
The engine included features developed from previous GE engines:
The high-bypass ratio of 8:1 for the TF-39 had its origins in the lift-fan technology demonstrated by GE in theXV-5 Vertifan aircraft.[4] This aircraft had two X353-5 engines, each consisting of a 62.5-inch-diameter[6] lift-fan driven by a gas generator (J85). The bpr in VTOL operation was 12.3.[7] This tip-turbine driven lift-fan concept was turned 90 degrees and developed as an 80-inch-diameter "cruise fan" demonstrator, driven by a J79 gas generator.[4] For the CX-X program GE demonstrated a half-scale engine, the GE1/6, with 15,830 lb thrust and an sfc of 0.336.[8] This was developed into the TF39 with a 97 in diameter fan.
By modern standards the Low Pressure Compressor on the TF-39 is fairly unique as a single T-stage is mounted upstream of the fan rotor, rather than behind it. Although this T-stage supercharges the inner section of the fan rotor, not all of this airstream enters the High Pressure Compressor as a fair proportion also enters the bypass duct to supplement the air discharging from the outer section of the fan. In other words there are three streams leaving the fan, two of which enter the bypass duct.[9]
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Data from[10]
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