On 2/2/2016 7:46 PM, Jonathan St. Cloud wrote:
The 2-32 is not very slippery, no need to look inside when spin recovery
did not work, I recovered from the spiral. Point being, if you had not
considered this possibility and are in a slippery glider you might keep
this in mind. This is the only aircraft I had intentional spun that would
spiral out of the spin.



On Tuesday, February 2, 2016 at 3:05:29 PM UTC-8, Andrzej Kobus wrote:

You should be able to tell the difference. Look at your airspeed
indicator. In the spin the air speed will be low or at least stable and
in the spiral it will be high and quickly increasing. That was the case
on all gliders I spanned. Turn and bank indicator ball in the spin will
be all the way to the outside of the turn.

Having never spun anything more slippery than a 2-32 (at least four of which
have been spun into the ground from well aloft), but having many times
incipiently-spun a 15-meter glass bird, and having thoroughly spun a 1-26 (in
both directions) for up to 17 turns (in one direction only), and having gained
a modicum of knowledge concerning aeronautical industry practices and war
stories related to spinning, I long ago concluded several things about spins:
1) they were then (and remain) beyond mankind's computational skills regarding
"absolutely-predictable behavior," and (along with flutter testing) rightfully
are one of the reasons within industry that test-piloting remains a
well-respected, and reasonably well-paying occupation; 2) anyone who treats
them complacently is either seriously ignorant or willfully blind; and 3) just
because a bird is certified is no reason to complacently bet your life on the
*next* spin behaving identically to past spins. I'm not trying to be dramatic
here, just trying to convey the very real complexity of spinning aerodynamics.

My present working conclusion is big, heavy, clean sailplanes (e.g. ASH-25,
Nimbus 4DM) may well (likely do, for cleanliness & inertial reasons) have less
"ham-fisted margin" between the time of stopping rotation and returning to
level flight than "the rest of the glider fleet." Thoughtful pilots will fly
them accordionly...

As to "looking inside at ASI/needle-ball" to verify whether one is in a spin
or spiral dive, I'd hesitate to make a sweeping claim one does or does not
have to, but - assuming for the sake of discussion that ground clearance isn't
an issue - if you choose wrongly as to which methodology to apply first in the
face of "WTF is the ship doing?" I know I'd rather apply spiral dive
corrective action *before* anti-spin corrective action, simply because being
late on the former includes dire structural implications. Best, of course, to
have confirmed what the ship is doing before attempting corrective action, and
instruments are (used to be, anyway) a part of every instructors' teaching
toolkit.

I could never get that (still in the flying fleet) 1-26 I spent so much time
with investigating its spinning behavior, to remain in a spin in one direction
(I've forgotten which) for more than 5 (sometimes less than 3) turns;
throughout it "hunted up/down in pitch" in phase with decreasing/increasing
spin rate until on one of its downward-pitching excursions, it always exited
in a skidding diving turn which showed every indication was about to become a
spiral dive if left unaddressed. It spun rock-steadily in the other direction,
but required ailerons to be strictly neutralized to avoid more or less
instantly exiting in either a nose-low slipping turn (aileron out of the spin)
or a nose-low skidding spiral dive (aileron into the spin). The transition
from spinning flight to non-spinning flight was attention grabbing in that
aerodynamically dirty bird. Quite audible and accompanied by obvious lateral
accelerations. I never could convince myself to permit the skidding spiral
dive entry aft-stick recovery to continue to nose level without quickly
neutralizing the ailerons so cautious was I of spiral dive possibilities,
though I think it would have safely recovered at that early stage of things.
My "spin-now-stopped" recoveries involved rapidly neutralizing ailerons and
maintaining full aft stick. I never managed to induce a secondary stall under
those circumstances in that docile, forgiving, ship.

The transition from spinning to non-spinning flight may well *not* be obvious
in some other ship. You pays your money and takes your chances with spin
behavior, ideally treading thoughtfully, cautiously and preparedly...

Bob - so call me overcautious - W.