Yaw String in a Spin

At 17:00 19 January 2005, wrote:
Andy,

Remember my spin entry tests in the V2b a year and
a half ago. One of
the departures was so violent, I lost reference, and
even though I knew
which way I entered, I can see how a surprise stall
with the same sort
of departure could cause disorientation and application
of pro spin
rudder. At low altitudes (during a save, for instance),
the delay in
recovery could be very bad news.

As for spin dynamics, it might be interesting to look
at airfoil tufts
throughout to see what's going on. Anyone have a link?
I think most of
us envision a spin as a straight line down, the aircraft
rotating about
this axis.

This vision was the basis for my remarks about not
recognizing a spin on turn to final. We need to re-think
the teaching of spin recognition to include a better
vision of what the aircraft movement really is -- a
circular skid path, to point that out and impress it
on students and ourselves. Successive spins at lower
and lower altitudes will demonstrate that the lower
one is the more obvious the sidewise motion will be.
But no demonstrations in the pattern, please!




That seems too simple. At any rate, the yaw string
should
always be displaced into the direction of spin (or
average there if
oscillating). Staying in the spin requires that the
inside wing be
producing higher drag (as a result of AOA), and thus
the pro-rotation
displacement.

I won't be able to fly until April, but maybe one of
you southwestern
types could provide some video of the yaw string through
2 or three
full rotations. We can discuss this ad nauseum, but
a few pictures
would make the discussion much more interesting and
possibly fruitfull.
Andy, you up for it?