"Tarver Engineering" wrote in message
...

"Dudley Henriques" wrote in message
rthlink.net...

"ArtKramr" wrote in message
...
I ran into quite a few guys who flew P-39's. The all said the same
thing. It
had dangerous flat spin characteristics. . Benig bombardier I asked,
"what the
hell is .that?" They explained. I don't remember what they said so I
can't
explain it here. But I am sure guys like Ed and Dudley can.

Flat spins are an aft cg scenario for the P39. Generally, in an airplane
with positive stability , a flat spin has to be entered deliberately and
HELD with power and aileron; the exact amounts of each differ with each
type
spun flat. The P39, had a problem with aft cg movement along a very
narrow
in range parameter with ammunition expenditure. If the airplane exceeded
critical angle of attack when the ammo cans were at a certain level, the
departure could easily cause an out of envelope spin mode that could go
flatter as autorational velocities and moments of inertia changed as the
spin progressed into ever increasing yaw rates.

Dudley, do you mean to say that the center of gravity is usually designed
such that the airplane avoids a tail slide in a stall? In other words,
the
nose rolls over and airspeed increases?

Departure in a P39 while in this configuration was a very difficult
thing
to
handle. Pilots like Tex Johnston had little trouble with recoveries
under
controlled conditions, but a low time pilot on operational flying could
find
himself in a world of hurt if getting caught this way. It usually
happened
if the airplane went defensive and turning after an initial extended
firing
run air to air. If engaged and going defensive, as the speed bled due to
radial g and the angle of attack increased, a departure was imminent if
you
went deep enough into the turn, especially if the turn was being forced
down
by an aircraft with a lighter WS and lower corner. You could easily be
pulled into departure city in a situation like that, and this is indeed
what
nailed a lot of 39 drivers. If you departed and went flat in this
airplane,
recovery was NOT where the amateurs should be!!!

Like being sucked into a black hole?

I should say also that most of the 39 pilots I have talked to through
the
years liked the airplane after flying it for a protracted period...and
that
includes Yeager! The trick was to fly it right the first time through to
the
last time....and I could say THAT about every airplane I've ever flown
at
least!! :-)))

All the thrills of your own airplane out to kill you and people shooting
at
you too!

jpt