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Lift; Bernoulli or Newton

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Old 10th Nov 2011, 21:15
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Lift; Bernoulli or Newton

I am doing some reearch into lift and how it is taught and understood in general.

Does anyone have any thoughts on the debate (Newton or Bernoulli) or able to point me in the right direction where I could find some fairly basic information in order to give a brief presentation on the subject.

Thanks very much in advance.
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Old 10th Nov 2011, 21:23
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answer

Lift = Pressur diffrence caused by a velocity gradient----Bernouilli
DP is propotional to DV
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Old 10th Nov 2011, 21:29
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Old 10th Nov 2011, 21:47
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Its both and depending on the wing design it can favour one or the other.

Pilots will always say it Bernouilli because thats what they have been taught. Engineers will say its both.

If it was only Bernouilli paper aircraft wouldn't fly.
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Old 10th Nov 2011, 21:49
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The equal transit time fallacy is pretty common.

This link is pretty good: How Airplanes Fly
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Old 11th Nov 2011, 06:23
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There are probably 4 or 5 good reasons why an aerofoil produces lift - all of them working together. For the exam, the pressure differential across the top does all the work, which is just nonsense, but there you are.

A good place to start would be a book called Stick & Rudder. Full of common sense.

Phil
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Old 11th Nov 2011, 16:29
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And coanda- effect, to explain the downwash bending at the trailing edge?
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Old 11th Nov 2011, 17:16
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Last I time I passed a degree in aeronautics, Bernoulli's equation was derived starting with Newton's laws. It is utter cobblers to separate the two.

Try "Introduction to Flight" by Anderson,which is probably the best book readily available at the moment.

Stick and Rudder is about flying, not aerodynamics. There is a subtle difference!

Most aerodynamics textbooks start at Glauert's "Aerofoil and airscrew theory" published in 1926, they're pretty much all derivative after that, but Anderson, to be fair, is a bit more readable with better pictures. Glauert (and most later books) do go somewhat beyond Bernoulli however.

Coanda on the other hand is pure black magic, barely understood by anybody - but jolly useful, unless trying to pour tea.

G
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