Thanks for all the info guys.
Nick, Your induced flow explanation of the effect of ground effect is great - thanks.
I have not yet fully understood the speed of sound bit yet though - although Dave J's third paragraph seems to pick up on the chord/camber question I asked before. Is this part of fluid dynamics, or gas properties? What I gather is that you are saying that any wing producing lift will cause a reaction with the ground that will manifest itself with the speed of sound. Why then is the downwash seen on the ground behind a forward flying aircraft? Or is the direction of reaction due to the relative airflow over the wing?
and for PPF#1: you say:
"any lift that is generated is actually being produced on one side of the aircraft"
I disagree. This would cause the aircraft to roll. Again, you cannot think of the disc as a big wing. This flows into your comments that:
"But we know that we can reduce our rate of descent to zero if we like, even with the collective at flat pitch..... How is this possible? What causes this tremendous increase in lift?"
You are not reducing your rate of descent to zero in an auto unless you are consuming your potential energy. You have not caused any such tremendous increase in lift - you have simply traded inertial energy for the increase in drag that you have incurred by pulling pitch and asking for more lift.
edited due to confusing myself - (again!!)
Last edited by helmet fire; 9th November 2002 at 00:44.