I do not wish to enter this discussion directly, but I do wish to insert
a report on an personal experiment done by Don Young who was an
aeronautical engineer and who, at one time, was in charge of the wind
tunnel at Write Patterson Air Force Base.
Mr. Young did some of the original tests on the Custer Channel Wing for
the military in the 1940's
The channel wing was supposed to get lift by placing the prop at the
trailing edge of the wing and drawing high velocity air across the upper
surface. Supposedly the high velocity air would reduce the pressure and
the wing would create lift.
Mr. Young built a very elaborate and expensive test bed with a four foot
wing, three point load cell support and motorcycle engine. My field is
electronics and instrumentation, but my real interest stemmed from a
1940's article on the Custer Channel Wing that was in Popular Mechanics
and which forever captured my imagination. When an opportunity to work
on such a project presented itself, I volunteered to help implement his
instrumentation concepts and assist in running many of the tests.
The heart of this tale is that even though a series of manometers
mounted flush with the top surface of the wing indicated that it should
be tugging at its moorings, the load cells showed only ten percent (or
less) of the lift expected from the calculations. In his first
experiments the channel was mounted horizontally, about five feet off of
the ground. The air flow entered the channel from a high angle and the
exit air from the channel was deflected downward at nearly a forty five
degree angle. It was easy to see the exit air pattern because of the
impact on the grass a couple of yards beyond the wing. Considering the
huge air flow taking place through the channel, the flow under the
channel was surprisingly, nearly stagnant.
I suspect the vertical, vector component of the deflected air flow was
the only source of measurable lift, but Mr Young would never speculate
as to why his wing would not do as expected. He died last year and his
family disassembled his apparatus and sold it off piecemeal.
I have duplicated much of his experiment on a much smaller scale and
have had the same results.
Bill
Anatole France:
"The whole art of teaching is only the art of awakening the natural
curiosity of young minds for the purpose of satisfying it afterwards."