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Old Nov 14, 2011, 10:14 AM
Tim Green is offline
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Launch the drones ...
Ashtabula, OH USA
Joined May 1999
3,723 Posts
Originally Posted by DPATE View Post
Okay sounds good. Can you explain the "Bernoulli" theory of lift as you see it so we can all be on the same page?
Text book theory ...

That the air over the top has farther to travel due to top surface being longer than bottom surface, so it speeds up before meeting at trailing edge, creating less pressure on top - voila - lift.

Issues with this theory ...

The idea here is that it speeds up because the air streams meet at the trailing edge - which is wrong. They don't meet at the trailing edge - the top air stream gets to the trailing edge first, in spite of the longer distance it travels - this theory ignores reality in this key way.

So, this leaves us wondering what speeds up the air on the top surface of the wing - well - less pressure speeds up air, therefore - the air speeds up because of the vacuum created on the top surface when either a board or a wing is given a positive AOA. The vacuum comes first. Then the air speeds up.

But this is hard to prove at home - so I like the chopper experiment, as a way to get to the essentials.
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Last edited by Tim Green; Nov 14, 2011 at 10:24 AM.
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