NACA-TN-702

Abstract

INTRODUCTION <br>If the stalling of the wing tips of highly tapered wings can be delayed to a higher angle of attack than that of the center section, the lateral stability and the useful maximum lift coefficient of-the wing will be greatly improved. Various-methods have been used to make the tips of the, wing stall after the center section. Some of these methods are: changing the airfoil section along the span, washout at the wing tips, and -either fixed or movable wing slots. If a change in the airfoil section along the span and washout are to be effective in delaying the tip stall with highly tapered wings, they will probably give poor aerodynamic characteristics in the high-speed and the climbing ranges, Leading-edge slots over the tip portion of the wing appear to give the most- practical Solution of the problem because they have little effect on the span lift distribution for the high-speed and the climbing ranges. Movable slots give a large increase in the angle of attack for the stall and an increase in the maximum lift coefficient. Fixed slots give about the same increases in the maximum angle of attack and the maximum lift coefficient as the movable slots, but they considerably increase the minimum drag coefficient (references 1 and 2). The fixed slots, however, are simpler to construct and are less likely to give operational troubles than the movable slots. <br>The purpose of this investigation was to determine the effect of some fixed-slot parameters on the aerodynamic characteristics of an N.A.C.A. 23012 wing with a slotted flap. One of the slotted-flap arrangements reported in reference 3 was used because that arrangement appears to be one of the most promising high-lift devices developed up to the present time. The slots were varied in position along the chord, in gap, and in width. The data given in references 1 and 2 for a Clark Y section were used in choosing the slot, forms and the slot locations.