NACA-TN-1545

Abstract

An investigation was made to determine optimum double-slotted-flap configurations for seven thin NACA airfoil sections. The airfoils tested were the NACA 63-210, 64-208, 64-210, 64₁-212, 65-210, 66-210 and 1410 airfoil sections. Each of the airfoil sections tested was equipped with a main flap of 0.250 chord and a fore flap of 0.075 chord. In addition, the NACA 66-210 and the NACA 64-208 airfoil sections were also tested with a 0.100-chord and a 0.056-chord fore flap, respectively. Lift measurements were made at a Reynolds number of 2.4 x 10⁶ to obtain the configuration giving the highest maximum section lift coefficient (ideal position) for each of the airfoil section tested. The lift characteristics were measured for Reynolds numbers up to 9.0 x 10⁶ in order to obtain an indication of the scale effects. The section pitching-moment characteristics and the effect of leading-edge roughness on the lift characteristic were measured for each of the airfoil sections at a Reynolds number of 6.0 x 10⁶ for a double-slotted-flap position close to the ideal which also allowed the double slotted flap to be retracted as a unit into the wing contour (optimum).