General Electric TF39 / CTF39
The General Electric TF39 is a high-bypass turbofan engine. Developed to power the Lockheed C-5 Galaxy and first run in 1964, it was the first high-power, high-bypass jet engine available. The TF39 was developed into the CF6 series of engines, and formed the basis of the General Electric LM2500 marine and industrial gas turbine.
The United States Air Force opened the "CX-X Program" in 1964, intending to produce a next-generation strategic airlifter. 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 TF39 is rated from 41,000 to 43,000 lbf (191 to 205 kN) of thrust. It employed a great deal of then-new technological features such as:
Mechanically, the TF39 is rather unusual for a high bypass ratio turbofan; the single stage is snubbered ('Snubbers' are protuberances that stick-out at right angles to the fan aerofoil somewhere between mid-span and blade tip). The snubbers on adjacent fan blades butt-up against each other, in a peripheral sense and improve the vibration characteristics of the blade to the fan rotor which has a set of inlet guide vanes for the outer bypass section and the core booster stage located in front of the fan rotor, rather than behind. This unique design is clearly seen from the front.
The only application was the Lockheed C-5A/B/C Galaxy.