Genghis,
It was only the very last marks - Griffon engined marks 21 and above - that were affected.
The torsional stiffness of the wings on the mark 21, 22 & 24 was increased by 47% over previous marks, raising the theoretical aileron reversal limit from 580 to 825 mph IAS.
Up to this point, aileron reversal had not been considered a problem, as the vne was lower than the theoretical AR speed for other reasons. But with the advent of ever more powerful engines, the designers felt that the margin was decreasing too rapidly between the attainable speed in normal operating conditions and the AR limit.
Apparently the Bristol Bagshot experienced the phenomenon in 1927, also the Lockheed C141 (somewhat later, obviously). The Mig. 29 had small vortex generators added each side of the nose to overcome an early tendency to aileron reversal at angles of attack above 25 degrees.
Last edited by Saab Dastard; 20th Mar 2006 at 23:59.