Pratt & Whitney Pure Power Geared Turbofan Engine

In most jet engines (more properly called turbofans), the fan that pulls air into the engine is directly linked to the compressor that squeezes that air down for combustion, so they have to turn at the same rate. By placing gears between the compressor and the fan, decoupling the two, the Pure Power engine allows for a more efficient arrangement: a big, slow fan shoving air into a small, fast turbine. The result is a shorter, lighter engine that can produce the same amount of power as a larger conventional turbofan, while burning 12 to 15 percent less fuel and emitting 35 percent less carbon dioxide. Pratt & Whitney finished ground- and air-testing of the engine this year, and the first of them will go on the Bombardier C-Series jet starting in 2013.
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