David M. wrote:

> I'm getting seriously out of my depth here, since I didn't even take high
> school physics, but as far as I understand the most important part of lift
> is the suction created by the partial vacuum *above* the wings -- that means
> that wings are pulling air down more than pushing it down, effectively, and
> the hstab will be in downwash even if it is level with or slightly above the
> wings.  Only a very high hstab, like the one on a t-tail, will be clear of it.
> Now Jon, Tony, or Andy can step in and explain how I've totally
> misunderstood the aerodynamics.

I've heard it described several ways (lift); I think you're pretty close. I don't know 
I'd say "partial vacuum", though, which might give an exaggerated impression. Thinking 
Bernoulli's nozzle example from elementary physics, the flow over the top, curved 
of a wing sees faster airflow, and lower pressure. Integrating the pressure over the 
and upper surfaces of the wing results in a net upward force (assuming steady-state
flight). Probably there is a bit of both pushing _and_ pulling going on. If the lower
surface of the wing is at a positive alpha, it's not too difficult to think that there 
some "pushing" going on.

Well, it would be interesting to get Tony's impression, and of course a physicist will
describe this in his own way, too.


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