What is the role of a stall fence?

The role of a stall fence is primarily to delay stall formation at the wing tips. When an aircraft approaches a stall, the airflow over the wings can separate, leading to loss of lift primarily at the tips, where the airflow is typically less effective. A stall fence, which is often located on the leading edge of the wing, helps to maintain smooth airflow over the entire wing surface longer, thus postponing the stall's onset.

This is achieved by re-energizing the boundary layer of air that flows over the wing, preventing premature airflow separation. By enhancing the stall characteristics, the stall fence ultimately contributes to improved control of the aircraft at lower speeds, particularly during maneuvers like turns or when operating near stall speeds. Thus, the presence of a stall fence enhances overall aerodynamic performance by helping to ensure that the aircraft remains controllable as it approaches critical angles of attack.