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A wing helping to improve aircraft fuel economy

RE: A wing helping to improve aircraft fuel economy

Scroll down to "Fighter Jets go green"

And the world has gone mad.

RE: A wing helping to improve aircraft fuel economy

One more time a wing tip device is supposed to bring astonishing fuel savings...
A couple of observations :
* The guy started from the worst case of a rectangular wing without any tip fairing (first picture). This kind of wing tip dissipates more energy because of non-optimal distribution of lift along span and because of viscous dissipation in the air flowing over the sharp edges.
* 6% savings under which conditions ? (might be 6% at stall speed and -3% at cruise speed)
* The induced drag is related to the kinetic energy you left behind the airplane and that makes up the trailing vortices. If you dissipate this energy, this won't necessarily translate into gain for the aircraft : instead of releasing kinetic energy in wake, you dissipate it in the immediate wake
* and concerning wing tip devices in general, think that you can always improve aerodynamic efficiency by increasing the span, but then the guys from wing structural design will make you pay the bill in terms of mass : wing design is always a compromise.


 

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