What can large downward aileron deflections lead to at very high angles of attack?

Large downward aileron deflections at very high angles of attack can indeed lead to air separation over that portion of the wing. When the ailerons are deflected downward, they effectively increase the angle of attack of the wing segments where they are applied. If the angle of attack exceeds a certain critical point, airflow can become turbulent and separate from the wing surface, causing a breakdown of lift in that area. This phenomenon is particularly critical at high angles of attack, as the aircraft is more vulnerable to stalling.

In this situation, the mechanisms of lift and control become less effective due to the disrupted airflow, leading to potential loss of control. Understanding this behavior is essential for pilots, particularly during maneuvers that demand precise control at high angles of attack, as improper use of ailerons can contribute to an uncommanded roll or stall. Thus, recognizing how large downward aileron deflections can result in air separation helps pilots avoid dangerous configurations of flight and maintain better control.