Hi Brendan,

I must preface this by saying that I'm not an aerodynamics expert, only a
model aircraft enthusiast who also does research in controlling small aircraft.

At 08:54 AM 6/28/2002 -0700, you wrote:
>The definition of stall: "A condition in which an aircraft or airfoil
>experiences an interruption of airflow resulting in loss of lift and a
>tendency to drop"
>
>If you ask me, being at a dead standstill seems to indicate an interruption
>of airflow, and a tendency to drop.

There is no such thing as angle of attack when you are at a dead
standstill, so I don't think we can argue one way or another there.
However, I have always heard that stall was a very specific condition which
occurs when the airflow over the wing separates from the surface and
becomes very turbulent. If you look at a graph of wing lift vs. angle of
attack at a constant airspeed, you usually see lift increasing with AOA up
to a point, and then a sharp drop-off in lift. The region beyond this point
is called stall, AFAIK. If you make a graph of lift vs. airspeed at a
constant AOA, you simply see a monotonically increasing roughly quadratic
curve (at least in the subsonic region), there is no precipitous drop at
any airspeed, simply a gentle decrease toward 0 lift at 0 airspeed. There
are many reasons why a wing could be generating inadequate lift to
counteract gravity, but only one specific such cause is called stall.


>I think it is actually possible to stall an older aircraft by going too
>fast.  The air rides down the front of the wings, so that you lose the
>airfoil effect, but you're moving very fast.  Like you said, the angle of
>attack has a large effect.

I don't know about this effect of airflow being deflected at very high
speeds but you may well be correct.

Sean

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