In my first reply to Chris, I should've said "as Bruce Hoult points out"
instead of Mark Boyd.

Chris OCallaghan wrote:

Eric,

Point of interest: did you let the spin fully develop after the
coordinated turning stall? There is an aerodynamic tipping point --
that is the self-righting tendency of the tail that would typically
favor a spiral over a spin assuming that the only deflected control
surface was the elevator. Of course a wing drops when in a turning
stall, but without aileron deflection generating drag my guess would
be that designed yaw stability would prevent spin development.