Any aircraft spins, only tendency differs.
Two ingredients for spin: Stall and skid. Why?
Imagine the right side of CL vs. AOA curve which represents the stall part after CLmax. At this side, curve steeply drops down, this means any different AOA between right and left wing will cause quite differnt CLvalues between the wings. The result is quite different Lift creation over the wings causing an endless autoratation. This autorotation cannot be stopped with ailerons because they re already stalled and ineffective. What causes to different AOAs between left and right wings? Answer: Skiding or slipping. i.e improper rudder use or rudder trim.
Deep Stall is another term used for -usually- high mounted horizontal tail planes (like MD 80s). The phenomena is: when the wings are heavily stalled, the turbulent flow leaving the trailing edge, may pass over horizontal stabilizer as stalling it as well. So, now no pitch down moment can be commanded through elevator. So airplane remains at this endless stall.
Last edited by JABBARA; 20th June 2009 at 00:06.