Wschertz@aol.com wrote:

In a message dated 3/20/99 6:40:13, Paul Lamar wrote:

The outlets are right under the leading edge of the
stab to take advantage of the low pressure area
there. The inlets of course are under the wing
to take advantage of the high pressure area there.

Paul,
You keep refering to the "low pressure area" under the stab. I know that
conventional wisdom is that in most certified planes the stab is "flying
down", creating a low pressure area there, but it is not always the case.

If you are at the forward part of the CG envelope, it is true, but if you are
near the rearward part of the CG envelope, the stab may be having to provide
lift rather than a down force.

I refer you to
http://www.monmouth.com/~jsd/how/htm/aoastab.html

As a second instance, a fellow gave a slide presentation of taking his RV-4 to
Alaska with his wife. with all the gear that they had, they were right at the
back of the CG envelope (but still within it), and the photo out the canopy
showed the elevator horns sticking UP from the stab, indicating that the
elevator was down, and the empennage was creating lift (low pressure on top,
high pressure on bottom)

You might get some unusual overheating problems with exiting under the stab
when you load up the plane and need to operate near the rear CG.

Bill schertz

If that is the situation you are asking for trouble. By definition
downforce
on the stab is REQUIRED for a stable airplane without a pilot or
computer
in there :-) ( I know Canards. Hold those cards and letters.)

Think about this. If the nose goes down with stick fixed
and lift on the tail causing a negative over-all pitching moment 
(including the wing pitching moment Jeff :-)) the aircraft
will continue to build up speed and pitch down! Unstable
by definition. That is not to say a pilot or auto pilot
cannot control it.

There is probably a wing airfoil out there that the pitching moment
changes with speed or angle of attack.

I went to Alaska myself with a too aft CG in my 182 and I was wondering
for
awhile why all my landings were two or three bounce landings :-)
I then made the big guy ride in the front.

The stab suction is not required. It just means opening the flaps a wee
bit more. It is primarely a trick to reduce drag.

Paul

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