In article ,
Alan Baker wrote:
But without that reduction of the pressure across the top curve of the
wing,
the pressure below it can't do much at all, can it?
Which I never disagreed with.
But anyone who thinks the upper surface of the wing is experiencing
anything but a downward force is just sadly misinformed.
Unfortunately for you, Alan, I have some actual observations of a
fabric-covered wing in flight. My Jodel, being a fabric-covered low-
wing aircraft, has a top surface easily observed during flight. The
fabric actually pulls up between the ribs in flight. It actually does.
And near the trailing edge, it's pushed down just a little between the
ribs. Which agrees perfectly with the distribution of lift on airfoil
diagrams.
And it is only deflected upward by the fact that the air *pushing* on
the bottom of the fabric's surface is doing so with greater force than
the air *pushing* down from above.
And don't give me any baloney about pressure inside the wing bulging
the fabric.If that was the case, it would all bulge, not just the 90%
aft of the leading edge.
I would only bulge where the air is at lower pressure than the air
inside the wing.
http://www.cartage.org.lb/en/themes/...mics/FlyingDyn
am
ics/Aerodynamics/SelectedTopics/Velocity/Velocity/Velocity.htm
I have a picture here of a biplane that had a poor fabric job. The
fabric hadn't been tensioned properly during application, and the view
from above of the wing in flight showed the fabric bulging upward
between the ribs quite amazingly. Positive pressure on the top surface
sure isn't going to do that.
Not on it's own, no. But greater positive pressure on the bottom surface
than on the top surface sure is and does.
There really isn't much substitute for actual observation. Flights of
imagination are usually way out to lunch. We have a few guys of in
homebuiltairplanes.com who are similarly convinced that all the
experts are wrong and have been for 150 years.
Observation can lead you astray: and that is clearly the case here if
you actually think that air can *pull* on a surface.
BTW, Brian:
This is precisely why I bother with "minutiae". The PP clearly believes
that the air is actually pulling...
--
Alan Baker
Vancouver, British Columbia
http://gallery.me.com/alangbaker/100008/DSCF0162/web.jpg