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Old 19th Oct 2012, 09:10
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This is one that he mentioned: Incorrect Lift Theory
Of course that theory is completely incorrect, it assumes that if the airsteam ahead of the airfoil is parallel to the airstream aft of the airfoil, then lift is produced. Of course bernoulli fails to explain a wrong assumption...

As energy is not conserved the Bernoulli relation cannot be applied to airflow round a wing in flight
Interesting aspect. However, as long as we ignore friction (which we usually do in all those theories), the force generated ("Lift") is perpendicular to the direction of movement, hence there is no work done, a force perpendicular to a movement does not produce work, hence energy is conserved. The same applies to any element of the wing surface, pressure (hence force) is produced perpendicular to the local surface, and therefore perpendicular to the streamlines, so along the streamlines energy is conserved.
But interesting to think about, how a Rat can then extract energy... Or how a propeller can inject energy with bernoulli (constand energy along a streamline) still being valid...
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