On Thu, 24 Nov 2005 at 08:56:56 in message
, Ron Garret
wrote:

That's actually what keeps the plane in the air.

See http://www.av8n.com/how/htm/airfoils...ation-vortices

rg

That is a good article. I would partially disagree in that he minimises
viscosity of the air as a factor. True it is small, however if the air
had no viscosity then there would be no circulation and hence no lift.
He actually shows diagrams without circulation which produce no lift.

The necessity of viscosity was demonstrated by Jean le Rond d'Alembert.
In fact he did painstaking mathematics, without recognising viscosity,
and failed to be able to show why there should be any forces on a body
in an airflow at all. He went to his grave a puzzled and dissatisfied
man.

That is d'Alembert's Paradox.
--
David CL Francis