Which surface, when deployed, increases maximum lift at high angles of attack by energizing the airflow over the leading edge?

Which surface, when deployed, increases maximum lift at high angles of attack by energizing the airflow over the leading edge?

• A. Flaps
• B. Ailerons
• C. Rudder
• D. Slats

Answer: (D)

Slats are leading-edge devices. When deployed, they extend a small surface from the wing’s front edge and create a slot. This slot lets high-pressure air from below the wing flow to the upper surface, energizing the boundary layer over the leading edge. That extra energy keeps the airflow attached at higher angles of attack, increasing the maximum lift the wing can produce before it stalls. Slats are used to boost takeoff and landing performance and are retracted at cruise to reduce drag. Flaps also increase lift but do so by increasing wing camber behind the leading edge (a trailing-edge device), not by energizing the leading-edge flow. Ailerons control roll on the trailing edge, and the rudder controls yaw.

Slats are leading-edge devices. When deployed, they extend a small surface from the wing’s front edge and create a slot. This slot lets high-pressure air from below the wing flow to the upper surface, energizing the boundary layer over the leading edge. That extra energy keeps the airflow attached at higher angles of attack, increasing the maximum lift the wing can produce before it stalls. Slats are used to boost takeoff and landing performance and are retracted at cruise to reduce drag. Flaps also increase lift but do so by increasing wing camber behind the leading edge (a trailing-edge device), not by energizing the leading-edge flow. Ailerons control roll on the trailing edge, and the rudder controls yaw.