Two-dimensional wind-tunnel investigation of four types of high-lift flap on an NACA 65-210 airfoil section

An investigation was _de in the L%ngley tw$-dimensional low-tu_bulence tunnels to develop flap configurations for maximum lift of the NACA 65.-210airfoil section equipped with four types of high-lift flap.Lift and pitchin@moment data were obtained for the optimum configurations.Scale effect and the effect of standard leading-edge roughness an maximum lift coefficient were also dotetrained.Tests were made of three 25--percent-chordsingle slotted flaps with the trailing edges of the slot lips located at 84, 90, and 97.5 percent of the airfoil chord, and of a 31.2-percent-chorddouble slotted flap.For the model with each of the flaps, the maximum llft was shown to becom_.<_more sensitive to small movements of the flap as the flap deflection was increased.The maximum lift coefficient of the airfoil with each of the single slotted flaps was shown to be about 2.47 and that with the double slotted flap was 2.73 at a Reynolds number of 6 × 106.The maximum lift coefficient was shown to increase as the _eyno!ds number was increased in the range of Reynolds ntu_berfrom 2 to 4 or 6 >_106, but in some cases the maximum llft coefficient decreased at higher Reynolds numbers.The decrement in maximum lift caused by standard _oughness decreased as the flap deflection was increased and at the higher deflections was approximately the same as the decrement obtained with the plain airfoil.