High Lift Devices
From SKYbrary Wiki
High lift devices are movable surfaces or, in some cases, stationary components that are designed to increase lift during some phases or conditions of flight.
High lift devices are most frequently utilised during the takeoff and initial climb and the approach and landing phases of flight but may also be used in any other low speed situation. The incorporation of high lift devices allows aircraft designers to reduce the overall size and surface area of the wing reducing its drag thus making the aircraft more fuel efficient during the cruise phase of flight.
The most common high lift devices are flaps, slats and Krueger flaps but the category also includes less common installations such as leading edge root extensions, which are found on high performance fighter aircraft, and boundary layer control devices inclusive of blown flaps.