"Greg Esres" wrote in message
oups.com...
An infinitely wide wing has no wingtips. You suggest it could not
provide lift.

Heck no. It just does so with no *net* downward momentum of air. In
other words, the upward momentum ahead of the wing is equal to the
downward momentum at the rear of the wing.


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.



I've read the "wingtip vortices provide lift" papers,

I'm not proposing that.

the wing causes downwash which provides lift (action-reaction) and
=that= creates vortices.

Infinite wings have no downwash, yet provide lift. By *definition*,
downwash is caused by wingtip vortices.

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.

Highflyer
Highflight Aviation Services
Pinckneyville Airport ( PJY )