In 1964, the U.S. Air Force had opened competition for engines to power an enormous new strategic cargo plane. Boeing, Douglas, and Lockheed each had a competing entry. The engines to power any version would have to be more powerful and more efficient than anything the world had seen to date. In addition, the Air Force was tired of being burned with cost overruns. The winner of this competition was to receive one lump sum to design, develop, produce, and support the engine for 10 years into the future. The intent of the Department of Defense was to shift the responsibility for bad decisions or poor productivity from the tax-payer to the manufacturer.

GE saw this as an opportunity to establish a benchmark for engine technology that might last into the next century. Taking a massive gamble, GE proposed a radically new concept, a high-bypass turbofan.

Early jet engines were turbojets. A rotating compressor compressed the outside air; a combustor injected fuel into the compressed air and ignited the mixture; and the hot exhaust, before it escaped to push the plane, used some of its energy to turn a turbine that kept the compressor going. A turbofan engine put another turbine in the hot gas flow. GE's first turbofans, the CF700 and the CJ805-23, were aft-fan designs. A second turbine was placed in the hot gas flow, and it turned a fan behind it at the very back of the engine that helped push...