Tina wrote:
In fact, if there is a downward component of the air's velocity that
had come from its passage over the upper surface of the airfoil, then
there had been an acceleration provided to that air -- acceleration in
this case being conventionally defined as the second time derivative
of position.

Now, if the air is accelerated downward, and it has mass, it means
there had been a force applied. The local prime mover is of course the
wing, so it must experience an upward force. Maybe you have a
different idea as to on what that equal and opposite force is
operating on -- I'd be interested in hearing about that.

There are a number of basic principles in operation here, be careful
not to paint yourself into too tight a corner unless you are quite
expert.

I am not claiming skill in this area -- physics was a minor a long
time ago -- but I remember some of the basics.


The main thing about all this is that both Bernoulli and Newton are
complete explanations of lift and will stand alone. In fact they are
both explanations of the same thing really as they occur simultainously
as lift is being created.
The big rub about Bernoulli is that for years Ole' Daniel was raped by
text books stating several totally false applications of Bernoulli as
fact. The equal transit theory for example, often stated as an
explanation for Bernoulli is totally incorrect.
The real truth of it is that neither Newton or Bernoulli were dealing
with lift at all in their respective work that explains lift.
My fondest hope is that someday, pilots will collectively get it
together enough to realize that Bernoulli and Newton are not in
competition with each other and never have been.
Personally though.....I like my old friend Mary Shafer's explanation for
lift that blames it on the "lift demons". :-)
DH

--
Dudley Henriques