Thanks for the reply. Perhaps I should explain my interest...
In WW1 Aero magazine a writer is proposing a theory that early/vintage aircraft had a 'diving tendency' that resulted in many crashes. I believe he blames several accidents on the then practice of diving with power on during approach.
I'm reasonably familiar with early aircraft and some did indeed have...
a) lots of camber
b) A rearward CoG
c) small tailplanes
A combination that doesn't exactly make for excess stability.
Assuming these aircraft were just on the right side of neutrally stable... could an increase in speed cause them to become unstable by increasing the pitching moment so much that the small tail could no longer cope?
I've seen one reference to pitching moment being proportional to the square of speed. However I have an airfoil analysis program (Javafoil from Martin Hepperle) and I don't see anything like this magnitude of change I increase the Reynolds number.
Perhaps many of these aircraft just needed the pilot to have a heavy lunch for them to be unstable and didn't need to be dived to push them over the edge.
Later edit: Now that I read your post again I think what you are saying is that the pitching moment is proportional to lift which in turn is proportional to the square of speed.
Last edited by cwatters; 24th May 2002 at 18:10.