3 ms·

This idea would unfortunately negate one of the top benefits of a high-bypass turbofan. Noise reduction.

• mschip 11y ago
  And noise reduction is actually a really important benefit of this engine as some airports have restrictions on noise.
• mhandley 11y ago
  Yes, but why is a high bypass turbofan quieter? If I understood correctly, it's because most of the thrust comes from the large slow moving fan, so you don't need to blast nearly so much air through the turbine as a turbojet to get the same thrust. The whole purpose of decoupling the fans is to give you an even higher bypass ratio - two or three large electric fans driven from one turbine can have a larger swept area than a single large geared turbofan, so can run slower for the same thrust, and hence be quieter.
  • WalterBright 11y ago
    > Yes, but why is a high bypass turbofan quieter? The noise comes from high speed air alongside slow moving air. A high bypass fan moves more air at slower speed to get the same push. The slower speed means less noise.
• Gibbon1 11y ago
  Actually would be a lot quieter, since the turbine wouldn't have a high velocity exhaust output. And the fans are fairly quiet. One real advantage would be quick throttle response. Gas turbines are slow to ramp up output power which is a real problem when dealing with wind shear on takeoff and landing. A 30 knot wind shear turns your 140 knots air speed turns into 110 knots airspeed. An electric fan's response would be very fast, probably faster than a prop plane.