NACA-TN-1071

Abstract

INTRODUCTION <br>A recent investigation (reference 1) was conducted on the NACA 65₃-018 airfoil section with boundary-layer control by suction to determine the increment in maximum lift coefficient that could be obtained by controlling& the turbulent boundary layer. The suction slots were located at and behind the minimum -pressure point. Laminar separation of the flow from the leading edge limited the maximum lift coefficient to approximately 1.85, which was only 0.45 greater than the maximum lift coefficient obtained without boundary-layer control. Abbott, von Doenhoff, and Stivers of the NACA have shown that in general greater maximum lift coefficients may be obtained with high lift devices on relatively thick highly cambered airfoil sections than on thin low-cambered sections, and that laminar separation often limits the maximum lift attainable with the thin low-cambered sections. It seemed. likely that further development of boundary-layer control for high lift would result from tests of a cambered wing. <br>Tests were made, therefore, in the Langley two-dimensional low-turbulence tunnel and the Langley two-dimensional low-turbulence pressure tunnel of the NACA 65₃-418, a =1.0 airfoil section with a single boundary layer suction slot located at 0.45 airfoil chord and a 0.29-airfoil-chord double slotted flap. Measurements were made of the lift and drag characteristics of this airfoil with various flap deflections and various amounts or flow through the boundary-layer-control slot. In addition, boundary-layer surveys were made at angle of attack near maximum lift, and pressure losses inside the suction slot were determined for several configurations.