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  • Birds fly by pushing air.

  • Mankind has made many things that push air.

  • One of the greatest machines that push air is the jet engine.

  • Jet engines suck air in the front and push a jet of air out the back.

  • That force is called thrust, and it moves an airplane through the sky.

  • Let's see how it works.

  • A big fan at the front of the engine pulls air around the engine and sucks air into the core.

  • We'll come back to that outside air in a moment.

  • For now, let's follow the air in the core.

  • It goes into a compressor, something like many household fans joined together.

  • Each fan gets smaller and smaller as the blades squeeze the air into a tighter and tighter space, compressing the air like you would squeeze a balloon, until that squeezed air is mixed with jet fuel, a kind of super gasoline.

  • In the combustor, that air and fuel mixture meets a flame and shoots out the back of the engine.

  • The rush of hot air spins a turbine.

  • The turbine is like a windmill that scoops up energy from the heated air and spins the shaft connected to the fan at the front of the engine.

  • The excess hot air from the combustor blows out the back of the engine, producing thrust.

  • Remember that air rushing outside the engine core?

  • Together, the turbine and fan push a larger mass of air than the core ever can, for much more thrust.

  • But that extra air passing around the engine core works more efficiently if it moves more slowly than the hot air rushing out the combustor and the back of the engine.

  • One of the first engine makers, Pratt & Whitney, recently designed a new jet engine that lets the fan push air more slowly than the turbine by putting an amazing gear between them.

  • Pratt & Whitney calls this the Pure Power Engine because it uses less fuel and makes more thrust at the same time.

  • Less fuel saves money and cuts back on pollution, which is better for the environment and all living things.

  • And when the fan moves slowly, the noise drops so much you can barely hear the airplane in the sky.

  • It's a new design for jet engines and a new era for jet airplanes that we all can enjoy.

Birds fly by pushing air.

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