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Old 19th October 2012 | 21:14
  #171 (permalink)  
italia458
 
Joined: Jun 2010
Posts: 381
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From: Canada
I take it you are a 'Newtonian'
I wouldn't call myself a scientist but I have essentially the same 'beliefs' as they do. I'm not on any one side, I'm all about exploring what the real answer is, regardless of what it is.

http://cdn4.explainthatstuff.com/air...ind-tunnel.jpg

Disregard the arrows in that picture. It might help to visualize the airfoil like in the picture above, except start with the airfoil pointing vertical (perpendicular to the air flow). With the airfoil stationary to the air, you'll measure that the static pressure around the whole airfoil is exactly the same as the ambient static pressure. As soon as you start moving that airfoil in one direction (not the band ) you'll see that a low pressure area develops on the side opposite to the direction of movement. The faster you move the more pronounced is this area of low pressure. You'll notice that the air wants to rush in and fill that void. That is exactly what's happening when air is flowing over the wing in normal flight - there is a slight void created (not as dramatic as the one you're visualizing) and the surrounding air expands to fill it, which decreases pressure and accelerates the flow.

Now that you're experimenting with that concept I should point out that at these extreme angles of attack the explanation of the origin of the force which pushes the airfoil upwards is different. At very high angles of attack there is a noticeable amount of lift that is generated by the deflection of air off the bottom of the airfoil. However, in normal flight, these extremes are not reached and therefore it is not really a valid explanation of lift of an airfoil in flight.

Last edited by italia458; 21st October 2012 at 20:23. Reason: Correction.
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