If I
may, comparatively briefly:
We all know the word 'stall' refers the wing's airflow breaking away at a
certain angle.
You, the pilot, controls the angle at which the airflow approaches
the wing. Hands off the pitch control that angle stays where you trimmed
it, regardless of attitude. You probably don't really believe that. but it's
true -- unless -- you are too far aft CG, or the total airplane has a pitching
moment that increases 'nose-up' as the AOA increases.
Many (military) aircraft with artificial stabilization are designed to
use all lifting surfaces to get the best L/D, for more performance -- at the
cost of stability.
GenAv planes don't. Some Experimentals are marginally stable or even
unstable when at high AOAs. Add to that, all the fatal GenAv accidents
are caused by unintentional stalls, a quarter to a third of all
fatals.
Because the pilot pulled his wing past its stall AOA ..
unintentionally.
Unintentionally, because he can not SEE the air-to-wing angle.
Because he does not habitually reference how he is 'planing' his wing.
He uses airspeed, a very vague, inaccurate reference to the wing-wing
angle.
For GenAv planes, the FAA persistently, ignorantly, does not require all
airplanes to have an AOA indicating vane right in the pilot's field of vision,
and require him to demonstrate using it, to get his license.
The great majority of pilots are not aerodynamics guys who have designed
an airplane, built their own design, and then got in it and risked their life
on their own design knowledge. Most know about AOA, but don't
understand it -- or use it.
I was ignorant too, in spite of my Navy wings and five more year of GenAv
flying. Until 1960 when I bought Waco's last prototype Experimental and
restored and flew it, and then conducted a FAA Type Certification program for
my own similar design, a 6-seater ... then I realized I needed to really
understand what was going on at high AOAs, and started making my own AOA
vanes, so I could see the angles, down to one degree, and watch them as I
maneuvered the plane, stalled and unstalled the wing, watched the vane move as
I moved the wheel in and out, like there was a string attached to the AOA
vane.
It makes me so sad, every time I see a stall-related crash ... friends
and compatriots, year after year, hundreds of great aircraft and wonderful
people, die unnecessarily.
Why?
The GenAv survivors should blame the FAA and manufacturers' marketing
departments.
We Experimenters have only ourselves to blame. We don't believe in AOAs.
We don't want to take the time or spend the money. We don't want
to make our beautiful planes ugly. We don't want to degrade performance
one mph. We don't want to learn new tricks. We're great pilots,
and we'll never make that mistake. But a few of us do.
Please excuse my continued harping on this. It's just 'tough
love'.
Terrence
L235/320 N211AL
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