Wind-Tunnel Investigation of Control-Surface Characteristics. 2 - A Large Aerodynamic Balance of Various Nose Shapes with a 30-Percent-Chord Flap on an NACA 0009 Airfoil

摘要

Tests have been made of an NACA 0009 airfoil with a 30-percent-chord flap having a 49.5-percent flap-chord balance with various nose shapes and two gaps. The results have been presented in the form of aerodynamic section characteristics. These results indicated the flap to be overbalanced when deflected, regardless of nose shape. There was only a slight change in hinge moment with angle of attack. A blunt-nose shape gave the greatest reductions in hinge moment and the smallest increment of drag over that of a plain airfoil. The small gap investigated affected the aerodynamic characteristics only slightly. A method has been proposed for reducing the control forces to any desired value while, at the same time, markedly increasing the lift effectiveness of the airfoil-flap combination over that of a plain flap of the same chord. In addition, the flap can be made to float against the relative wind thereby causing the stability with controls free to exceed that with controls fixed. These results are accomplished by using a differentially operated balancing tab on an overbalanced flap to increase both the lift and the hinge moment of the flap.