NACA-ACR-3G20

Abstract

Force tests in two-dimensional flow have been made on an NACA 66-009 airfoil with a flap having a chord 30 percent of the airfoil chord and a tab having a chord 20, percent of the flap chord. A plain flap and flaps having overhangs of 35 and 50 percent of the flap chord were tested with two gap variations, sealed and unsealed. The results are presented as aerodynamic section characteristics. <br>The results indicated that the lift-curve slope was generally greater for this airfoil than for the previously tested NACA 0009 and NACA 0015 airfoils and the slope was decreased by unsealing the gap. Increasing the overhang increased slightly the lift effectiveness of the flap, and unsealing the gap caused a loss of effectiveness for the plain flap but increased the effectiveness for the %balanced flaps. The slopes of the hinge-moment coefficient curves were generally more negative for the NACA 66-009 airfoil than for the other two airfoils. Some overbalance occurred with the 50-percent-flap-chord overhangs . Unsealing the gap gave a slightly more negative slope to the curves of hinge-moment coefficient against angle of attack and had little effect on the variation of hinge-moment coefficient with flap deflection. The tab was effective in producing increments of lift and flap hinge moments for all conditions tested and was more effective when deflected in opposition to the flap.