There is a *net* downward momentum of air.

I have several aerodynamics books that say differently.

Otherwise there is no lift.

If there is a pressure difference between the top and bottom, you will
have lift. Your airfoil is blisssfully unaware of the air with which
it has no contact.

No. wingtip vortices are caused by downwash. Infinite wings don't
have wingtip vortices because they don't have ends, not because they
don't have downwash.

Again, I have many aerodynamics books that say differently. Even
Aerodynamics for Naval Aviators.


On Fri, 24 Feb 2006 01:22:36 -0600, "Highflyer" wrote:

Disagree. There is a *net* downward momentum of air. Otherwise there is no
lift. However the downward momentum for any finite section of the infinite
wing is infinitesimal. Note, however, that even though in Calculus 100 we
assume that an infinitesimal is approximately equal to zero and can be
ignored, it is only approximately to zero and only very very near zero.

While zero times any number is still zero, almost zero times infinity is
NOT zero. Ergo, the downwash is not zero either.