Two-Dimensional Wind-Tunnel Investigation of Modified NACA 65(sub 112)-111 Airfoil with 35-Percent-Chord Slotted Flap at Reynolds Numbers up to 25 Million

An investigation has been made in the Langley two-dimensional low-turbulence tunnels to develop the optimum configuration of a .035-chord slotted flap on an NACA 65(sub(112)-111 airfoil section modified by removing the trailing-edge cusp. Included in the investigation were measurements to determine the scale effects on the section lift and drag characteristics of the airfoil with the flap retracted for Reynolds numbers ranging from 3.0 X 10(exp 6) to 2.5 X 10(exp 6). The scale effects on the lift characteristics were also determined for the same reynolds numbers for the flap deflected in the rotation found to be optimum at a Reynolds number of 9.0 X 10(exp 6).