Many descriptions have been posted here in several threads on spinning
over the last couple of weeks and I have found all of them to be
fascinating. I've been prompted to think through again my own
understanding of the stall and the spin in gliders.

One description that has been strongly asserted in several threads is
that there is a difference in angle of attack on the two wings on an
aircraft in a descending turn AND that the difference in AOA is due to
the slower horizontal speed of the inside wing as it traverses a
shorter circle than does the outside wing in the descending turn.
The slower speed of the inside wing thus coinsides with a higher AOA
on the inside wing than is experienced by the outside wing. This of
course has implications for which wing may reach stall AOA first.

I am only a pilot and have no training in aerodynamics whatsoever.
For what it's worth (not much probably), I find the above explanation
of the cause of different AOA on the left and right wings of an
aircraft in a descending turn to be easily understandable and very
likely accurate, but incomplete.

Many years ago I read in Sammy Mason's book Stalls, Spins and Safety,
an additional description of the AOA on the wings of an aircraft in
ascending and descending turns. I find that his description is
persuasive and illunimating and contributes to a more complete
understanding of the stall and spin.

Here is a short quote from Sammy Mason's book:

"During a level, coordinated turn, once the bank is established,
the airplane will continue to turn about the yaw axis and pitch upward
about the pitch axis. It will not be rolling about the roll axis.
When a stall is encountered in a level turn, the reaction will
normally be very little different than during a wings-level stall.."
"During a descending turn, or spiral, in addition to pitch and
yaw, the airplane will be rolling about the roll axis in the direction
of the turn. As the airplane rolls, it induces an upflow of air into
the descending wing. This results in the descending wing having the
greatest angle of attack. If a stall is encountered, the airplane
will likely roll into the turn." pp.40-41.

Sammy Mason goes on to describe the opposite differences in AOA on the
two wings of an aircraft in an ascending turn.

In a descending turn are both wings going down? Of course they are,
relative to an outside frame of reference and assuming the rate of
aircraft descent is greater than the rate of roll (or however one
describes the rate at which wings are going around in a roll). From
the frame of reference of the aircraft are the two wings proceeding in
opposite rotational directions? Sammy Mason's description of the
aircraft rolling about its roll axis in a descending turn describes
just such a difference -- and its contribution to the differing AOA on
the two wings. This suggests that the difference in AOA on the two
wings is not due only to their differences in horizontal speed in
their differing size circles.

Your milage may vary, of course, and each pilot likely benefits from
some image of what is happening to an aircraft in a stall and spin.
In my view, Sammy Mason's descriptions add additional insights for me
to the nature of stalls and spins.

Sammy Mason's flying career is described in the book as having begun
in the 1930's, and included WWII, and then working with C.L."Kelly"
Johnson of the Lockheed "Skunkworks". He was a jet aircraft test
pilot for Lockheed and became Lockheed's authority on stall/spin
testing.