A dumb doubt on stalls
Jim Macklin wrote:
Feel free to look me up on the FAA web. Certificated
airplanes are designed to not fully stall the wing or the
tail for that matter. But within the limits of what does
happen, and without discussing wash-in, wash-out, twist,
airfoil section changes, control stops, stick shaker and
pullers, gust loading, accelerated stalls, mushing, getting
a useable idea of what happens when the controls are applied
smoothly, violently or the airplane breaks apart in flight.
If the nose would always go down from a stall, spin chutes
would not be required. If the airplane is abused in flight,
it will do some pretty remarkable things. I know a Beech
test pilot who wondered about what would happen in an E90 at
cruise if you put the props into reverse. The airplane did
not break, but they were reported to have changed their
clothes after the flight. Same pilot tried the same thing
in an F90 with the T-tail and nothing really uncontrollable
happened.
It is possible to design a wing that will stall, 100% across
the entire span, but it won't be certified for civil use.
If the tail surface reaches max lift (down-force) and you
try to go slower, it will begin the stall as air flow
reaches the critical angle of attack on the tail
PROGRESSIVELY and the nose will drop because the moment
between the CP and CG will not be countered by the tail
forces. Do it slowly and the nose pitches down slowly.
Pull a few Gs and the reaction is faster and the degree to
which the stall progresses on the tail and wing is much
faster because inertia will carry the aircraft past the
critical angles at a higher kinetic energy level.
I've never seen this discussed in any book on aerodynamics that I've
ever read. Do you have even one credible reference to support your claims?
Matt
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