Flight Controls – Leading Edge Slots and Slats

in Physics

Leading Edge Slots

Leading edge slots are ducts or passages in the leading edge of a wing that allow high pressure air from the bottom of the wing to flow to the top of the wing. This ducted air flows over the top of the wing at a high velocity and helps keep the boundary layer air from becoming turbulent and separating from the wing. Slots are often placed on the part of the wing ahead of the ailerons, so during a wing stall, the inboard part of the wing stalls first and the ailerons remain effective.

Leading Edge Slats

Leading edge slats serve the same purpose as slots, the difference being that slats are movable and can be retracted when not needed. On some airplanes, leading edge slats have been automatic in operation, deploying in response to the aerodynamic forces that come into play during a high angle of attack. On most of today’s commercial airliners, the leading edge slats deploy when the trailing edge flaps are lowered.

Figure 3-73. Boeing 727 flight controls.

Figure 3-73. Boeing 727 flight controls.

The flight controls of a large commercial airliner are shown in Figure 3-73. The controls by color are as follows:

  1. All aerodynamic tabs are shown in green.
  2. All leading and trailing edge high lift devices are shown in red (leading edge flaps and slats, trailing edge inboard and outboard flaps).
  3. The tail mounted primary flight controls are in yellow (rudder and elevator).
  4. The wing mounted primary flight controls are in purple (inboard and outboard aileron).