How do leading edge slats improve aerodynamic performance?

Slats are movable leading edge devices that extend forward and down from the wing, creating a slot between the slat and main wing element. The slot allows high-energy air from below to flow over the upper surface, re-energizing the boundary layer and delaying separation. This increases CLmax by 30-50% and raises the stall angle by 6-10 degrees. Slats also increase the wing's effective camber. Types include fixed slots, retractable slats, and Krueger flaps. Slat design must balance aerodynamic benefit against weight, complexity, and noise penalties.