wright1902glider wrote:

Now here's a simple 19th Century way to prove the point. Attach a
length of yarn to the "lower" surface of a slow-flying plane. Watch the
yarn and see what direction it takes in flight. Is it straight back? Or
is it down? If air is indeed being forced downward by the wing,
shouldn't we be able to see the results in the yarn?

Harry


Thank you, Harry!