Date: 31 Mar 2001 16:43:09
From: John Naus <jnaus@fn3.freenet.tlh.fl.us>
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BBarksdl <bbarksdl@aol.com> wrote:
> In the April issue of Discover magazine, Robert Kunzig challanges the textbook
> explanation of the principles of flight. I have always felt the books were
> wrong on this when they say that the shape of the wing invokes Bernoulli's
> Principle to provide the lift required. Kunzig refutes the role of Bernoulli's
> Principle. He says that planes fly by pushing air down, getting lift from the
> equal and opposite reaction that pushes the plane up. I'm trying to reconcile
> that with my own thoughts on the subject - that the forces that cause an
> airplane to fly are essentially the same as those that cause a kite to fly.
> Either way you look at it, the shape of the wing is not the main element.
> Otherwise, how could a plane fly upside-down? As an old barnstormer was
> reported to have said, "Give me enough power, and I'll fly a barn door."
The answer is that lift is a combination of both Bernoulli and opposite
reaction forces. A good example of opposite recation playing a significant
role is when the aircraft is in "ground effect". I have not seen the
article myself but would be interested in hearing Kunzig's description of
how a wing top vortex generator or stall gate works. If lift was
only provided by air pushing down from a wing the top of the wing would
be flat. Obviously, a flat wing would be cheaper to produce then a
curved wing!
To answer your question about flying upside-down you are correct in saying
that power can be used to overcome loss of lift. If you remove the wings and
add a big enough engine anything will fly (ie. a rocket).
John
