is the tendency of the airplane to roll into a progressively steeper bank angle during high performance turning flight. ### Wing Speed Differential During a turn, the outer wing travels a greater distance than the inner wing. This results in a higher airspeed on the outer wing, and more lift being generated. At some point, this will overcome the airplane's natural lateral stability, and cause overbanking. This also results in more drag being produced by the outer wing, and the airplane will have a tendency to slip in association with the wing speed differential. ### Cause of Wing Speed Differential The wings will have a maximum speed difference when a turn is at a minimum radius, and a minimum bank angle. - Steeper bank angles decrease turn radius, however, at very steep bank angles, the wingtips travel at almost the same speed. At 90 degrees of bank, the wingtips would have an identical speed. ![[Bill Palmer wing radius vs bank.jpeg]] - radius of turn is related to both bank angle and airspeed. The radius of turn decreases as bank angle is increased, and as airspeed is decreased. The airplane will begin to experience the overbanking tendency at a higher bank angle when flown at higher speeds, and a lower bank angle when flown at lower speeds.