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Old 28th Sep 2006, 07:38
  #32 (permalink)  
bookworm
 
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That's what the NASA website set out to prove; their java lift simulator available at that site indicates that, yes, there is an increase in the velocity of air flow over the top of the aerofoil, and a slowing down of the airflow beneath the aerofoil, and yes, this does result in a lowering of air pressure over the aerofoil compared with beneath .. BUT, the pressure differential is too low to generate the amount of lift that you'd expect from such an aerofoil.
Nope, that's not what the NASA site says.

There is an increase in velocity above the aerofoil and the velocity differential between upper and lower surface is related through Bernoulli's principle to the pressure difference. The pressure difference exactly accounts for the lift.

The piece of the "equal transit time" explanation that is incorrect is the association of the velocity differential with the difference in "path lengths" above and below the aerofoil. The velocity differential is much higher than would be anticipated from "equal transit times".
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