"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
>
>

"john smith" wrote:
> I ran into quite a few guys who flew P-39's. The all said the same
> thing. It had dangerous flat spin characteristics. .

> Somewhere in my library I have a book which mentions that Bob
> Hoover was sent to North Africa to disprove this.

My father served with the 111th Observation Group(?) in N. Africa. He told
me all the pilots believed that the P-39 could unpredictably tumble
nose-over-tail and was unrecoverable if it did. No amount of demonstrations
by Bell factory pilots could convince them otherwise, and their distrust of
the aircraft was so profound that its combat effectiveness in that theater
was nil. It was quickly replaced by the P-40 which the pilots also disliked
because they perceived it to be inferior to the BF-109. The arrival of
P-51Bs, my father said, was an occasion for great rejoicing.
--
Dan
C172RG at BFM