Some flaps are slltted elsewhere. Fowler flaps increase the area of your wing by extending out on rails or tracks. This in turn allows a much higher suction peak at the nose of the airfoil, so that the suction force over the whole chord of the airfoil with the slotted flap is much higher than on the airfoil with the plain flap.It's the most commonly gift card roulette instrument approach in the airline world. Control line model aircraft built for precision aerobatics competition usually have a type double slotted flaps maneuvering flap system that moves them in an opposing direction to the elevators, to assist in tightening the radius of a maneuver. Some flaps use multiple slots to further boost the effect. They were first used on the Martin prototype inand in production on the Lockheed Super Electra and are still in widespread use on modern aircraft, often with multiple slots. The higher lift and drag associated with fully extended flaps allows a steeper and slower approach to the landing site, but imposes handling difficulties in aircraft with very low wing loading i.