CAUTION: Angle of Attack is conducive to conditions which initiate stall! Increasing angle of attack eventually results in a complete stall. As everything else, the zone theory explanation of stall is simple and straight forward. Zone theory explains stall in simplest of terms i.e. of pressure leakage. Needlessly complicated reasoning is employed by the wind tunnel enthusiasts focusing on the fallacy of “separation of flow” at increased angle of attack (AoA). Whereas in fact stall is the result of dislocation of the subduction and induction zones of the airfoil when nose of aircraft is pitched up at high AoA. The mechanism by which increasing AoA disturbs the position and pressures around the airfoil are described in full detail in the following discussion.

The figure below graphically explains the sequence of events leading to stall as the angle of attack is increased: The airfoil wing can be considered as a pneumatic battery producing pressure difference as it moves in air. This battery produces the subduction and induction zones or regions as shown below. In normal flight i.e., when the AoA is negligible, the two pressure zones maintain their locations around the airfoil. As long as the velocity is parallel to the wing, the zones are intact and produce lift normally. But at greater AoA, the position of zones shift due to transformation of the airfoil surfaces, particularly the deflector, which replaces the lifter. Thereafter at increasing AoA, air from the subduction zone leaks around the trailing edge B, over to the top interfering with the vacuum, that generates lift. This is analogous to shorting the positive and negative terminals of any electrical battery, which reduces the potential difference between the battery terminals. Consequently, If sufficient air bleeds around the trailing edge into the top induction zone, pressure difference neutralizes, and lift is reduced drastically resulting in a complete stall.

Thus once again, zone theory explains stall in simplest of terms without resorting to inapplicable concept of flow separation, and confusing wind tunnel experimentation. What others still don’t understand.