A leading-edge slat will delay stall, allowing a higher angle of attack before stall.

• A. Only at high speed
• B. Only with flaps
• C. True
• D. False

Answer: (C)

A leading-edge slat increases the wing’s maximum lift capability by shaping the airflow at high angles of attack. It creates a gap (slot) that lets high-energy air flow from below the wing to the upper surface, energizing the boundary layer and delaying flow separation. Because the airflow remains attached longer, the wing can reach a higher angle of attack before stalling, raising the stall angle. This effect is valuable during takeoff and landing when the wing operates near stall speed, and it isn’t limited to high speed or only when flaps are used. So the statement is true.