A stall occurs when the wing's critical angle of attack is exceeded.

• A. True
• B. False
• C. Not sure
• D. Only with flaps

Answer: (A)

Stall happens when the wing’s angle of attack reaches and then exceeds its critical angle of attack. The airfoil can produce lift as the flow stays attached to the upper surface, and the lift increases with AoA up to a maximum. At the critical AoA, the flow begins to separate, the boundary layer detaches, lift falls off sharply, and drag rises—this is the stall. This concept is tied to the wing configuration: factors like flaps alter the lift-curve and can lower the critical AoA, so stall can occur at different speeds or with different settings, but the underlying cause remains exceeding the critical angle of attack.