Wind-Tunnel Investigation of Control-Surface Characteristics an NACA 0009 Airfoil with 0.25- and 0.50-Airfoil-Chord Plain Flaps Tested Independently and in Combination

摘要

Wind tunnel tests have been made to determine the aerodynamic section characteristics of an NACA 0009 airfoil with plain flaps 25 and 50 percent of the airfoil chord. The flaps were tested independently and in combination. Results of the investigation indicated that the larger flap would provide greater lift increments but would lose lift effectiveness at the higher deflect ions and at a lower angle of attack than would the smaller flap. The hinge- moment and lift-effectiveness parameters for each flap indicated good agreement with curves predicting the variation of these parameters with flap chord. Although the effect of sealing the gap was small, it generally increased the lift effectiveness and the lift-curve slope. Theoretical calculations of aerodynamic characteristics made by the use of parameters measured in the present investigation indicated close agreement with calculations made by the use of parameters estimated from pressure-distribution data for a model having similar flaps that were linked to give balance.