Investigation of Boundary-layer Control to Improve the Lift and Drag Characteristics of the NACA 65(sub 2)-415 Airfoil Section with Double Slotted and Plain Flaps

Abstract : A two-dimensional wind-tunnel investigation has been made of the relative effectiveness of two methods of boundary-layer control in increasing the maximum lift coefficient of an NACA airfoil section. Boundary-layer suction was applied at the percent-chord station of the airfoil equipped with a louble slotted flap and in the vicinity of the hinge line of the airfoil with a deflected plain flap. The investigation also included the determination of the effectiveness of small deflections of the plain flap in conjunction with suction at the hinge line and of suction at the percent -chord station of the airfoil with the double slotted flap retracted as a means of reducing the drag.