Increasing Camber or Energy Additions to the Boundary Layer
AMT 280 LaboratoryAirfoil Slat & Flap Effects•One of the ways to improve the versatility and flightcharacteristics of an airplane is to install wing flaps andslats.Flaps are designed so that when extended theynot only provide higher lift but also have higher drag.This allows a steep angle of descent at slow airspeedswith low engine power output•Objectives–Observe the effects of the flap and the slat on a model airfoilwith respect to lift and drag.–Observe the general airflow pattern over the airfoil while usingflaps and slats.–To observe the creation of wing tip vortices
Airfoil Slat & Flap EffectsEffect of high lift devices•The primary purpose of high lift devices(flaps, slots, slats, etc.) is to increase theCLmaxof the aircraft and to reduce the stallspeed.•Take-off and landing speeds are alsoreduced.
Split flap –larger changein dragbecause ofturbulent wakeproduced bythis type offlap
Slotted flap – high-energy air from thelower surface is ductedto the flap uppersurface.This air from the slotaccelerates the uppersurface boundary layerand delays airflowseparation to somehigher lift coefficient.This flap causes muchgreater increases inCLmaxthan the plain orsplit flap and sectiondrags are much lower
Slats or leading edge devicesThe leading edge slats allow the aircraft to fly at a high angleof attack (lower speed) by accelerating the air between theslat and the wing (venturi effect).This increases the drag, but improves handling at lowspeed.
When the slot on a wing is open, the air flows through the slot and over theairfoil. This results in a delay of airflow separation (figure a). Use of a slat allowsthe airfoil to be flown at a higher angle of attack before a stall would occur.