On Feb 20, 12:11*pm, Andy wrote:

Let me reduce my original question to a specific situation. Suppose
you're flying in 60 degree weather, so no surface is contaminated with
ice. Suddenly, the nose pitches down and the stick stays where it
was.

If you are flying within the CG limits and at a reasonable speed (i.e.
within the envelope), then the main wing will stall before the tail.
Any modern aircraft will be designed to have good stability when
loaded within the CG limits and flown at reasonable speeds.

A propensity for the tail to stall in these conditions would be
similar to what would happen when an aircraft is loaded aft of the CG
limits and stalls (look up "deep stall"; and once you understand it
you will never load an aircraft aft of the recommended CG limit
_ever_). I've seen this happen with experimental R/C aircraft that I
was testing (as a hobbyist, not as a professional).

Of course, flying outside of the CG limits and/or pulling high-G
aerobatics (wherein you might induce sudden and extreme AOA changes in
the flying surfaces) are another situation entirely...

The beauty is if you're not fying an aircraft with contaminated flying
surfaces, both a tail tall and a main wing stall should have roughly
the same recovery procedu Allow the aircraft to regain flying
speed and reduce the angle-of-attack (once air is flowing normally
over the aircraft, you're fine), and then return to a normal pitch-and-
bank attitude. The only difference is in recognizing what you need to
do in order to regain flying speed. If you're holding the stick back
and the airspeed needle is down around zero, stop holding the stick
back! If you're holding the stick forward and the ASI is resting on
its stop, relax the forward pressure!

The vast majority of the time, bringing the controls closer to neutral
is the right thing to do - mostly because of the built-in stability of
nearly all aircraft produced in the last 60 years. But again, this is
true only when the aircraft is loaded within the CG limits.

Kirk - I really lament the fact that so few pilots truly understand
what the air is doing as it flows over their aircraft. Seeing the
diagram in a pilot handbook and memorizing answers for the FAA test is
just not good enough. SO MANY "pilot-error" accidents could be
avoided, if only people had a better grasp of the cause-and-effect
relationship between the cockpit controls, the flying surfaces (as the
controls are moved), and the airflow over the aircraft. Being able to
understand "if I do X, then Y will happen" (in terms of the airflow
and the aerodynamics) goes a long way towards knowing how to get out
of trouble, or avoid it altogether! Without this understanding, I
think a lot of pilots don't really know what risks they're taking as
they blithely fly along, and they don't understand how their safety-
margin is changing as they take different actions in the cockpit.

*sigh* OK, rant over... :-P

--Noel