Slats, Slots and Spoilers – Lift Modifying Devices on Airplane Wings

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Slats are lift augmentation devices on the leading edge of airplane wings. Photo Credit: Enrique Galeano Morales.

What are Slats?

When the angle of attack (angle between the wing and the relative airflow) is increased, the point from which the streamlined airflow separates from the back of the wing (separation point) moves towards the leading edge of the wing. This results in a loss of lift.

One method of avoiding this is by re-energizing the airflow over the wing so that the separation of the streamlined airflow is delayed. Devices such as slats help re-energize the boundary layer, and help the air to maintain its streamlined, parallel flow over the wings.

How Slats Work:

Slats are attached to the leading edge of an airplane wing. This is how they work:

  1. Slats are deployed.
  2. The slat moves outwards and/or downwards to create a slot.
  3. The region of low static-pressure over the wing is now connected to the region of high static-pressure pressure under the wing.
  4. The energized airflow from under the wing is sucked up above the wing.
  5. The separation of airflow over the wing is delayed.

The slats of a TA-4J can be seen in the above image. Photo Credit: Bill Abbott.

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