Jose wrote:
Downwash occurs, as you describe in the paragraph
above. It is a consequence of lift, not the cause.

We perhaps disagree merely on the idea of which "causes" the other. How
do you figure that lift causes downwash? Lift doesn't happen unless the
air above is rarified. The air above is not rarified until some of the
molecules are gotten rid of somehow.

No.

The process of getting rid of
those molecules is just a newtonian process (which lends itself to
certain bulk equations).

They aren't 'gotten rid of' they are accelerated which causes them to
be spaced farther apart -- thus lowering the pressure.


They are different ways of looking at the same thing, depending on which
aspect you want to concentrate on.


The lift is a result of the pressure difference between the lower and
upper surfaces of the wing. The downwash is the result of the momentum
of the air above the rarefied region created by the wing moving
downward.

The downrushing air starts it s downwash above the wing and does
not pass the wing in the vertical direction until after he wing has
passed.
It does not contribute to lift.

It is not really caused by lift (my mistake), it is caused by the same
phenomenum that causes lift.

--

FF