Chris OCallaghan wrote:

Your original post suggested a coordinated turn. See my response
regarding crossed controls. It sounds like the Blanik has an odd
tendency to want to overbank from a shallow turn, leading to an
aileron/rudder deflection that establishes the drag profile needed to
enter a fully developed spin.

It is not an oddity of the Blanik (in fact, it is an excellent trainer
for spins, because it does them so normally), but a consequence of a
coordinated turn. Because the inner wing is traveling more slowly than
the outer wing, it must have a higher lift coefficent to develop the
same lift as the outer wing. It achieves this with a downward deflected
aileron (and flap in many flapped gliders). This downward deflected
aileron produces a wing tip that stalls at a lower angle of attack than
the outer wingtip, which has an upward deflected wing tip.


In a turning stall, there is a tendency to rotate at stall break due
to assymetric drag.

The asymetric drag is due to a partially stalled inner wing, and
generally in the aileron area.

However, if there is no aileron input to aggrevate
the situation, the glider will typically drop its nose (lowering angle
of attack) and gain speed.

This is true, and is the reason the spin recovery includes centralizing
the ailerons. On some gliders, this is enough to unstall the inner wing
tip, and stop the incipient spin.

This lowers the drag on the low wing and
envigorates the self-righting tendency of the vertical stabilizer.

I don't think "lowers the drag" is the best way to think of this, but
instead, think of it as unstalling the wing tip (of course, a stalled
wing tip does have higher drag than the unstalled one). No stall, no spin.

This is why the first second or two after stall break scream SPIN, but
in fact the glider has self recovered and is now in a spiral.

The situation Bruce and I describe has no discernible stall "break". THe
inner wing begins to drop, and it can't be held up with the aileron. If
the pilot doesn't recognize this is a spin entry, he will continue
adding top aileron, which deepens the stall on the inner wing tip, and
very quickly has a fully developed spin. There never is a "break", as
you get with a straight ahead stall, but a smooth entry into a spin.