NACA-TN-1212

Abstract

INTRODUCTION <br>In selecting the airfoil sections to be employed in the design of a tailless airplane, an important consideration is the wing pitching moments which, for trim requirements, must remain moderate. Because of their low drag qualities, NACA 6-series airfoils are desirable for high-speed and long-range operations and, if symmetrical, have moderate pitching moments. The lift coefficients encompassing the cruising conditions are, however, generally above the low-drag range of practical symmetrical airfoils. Adding camber and reflexing the mean line offers a possibility of shifting the low-drag range of the wing to include higher lift coefficients without materially affecting the pitching moment. Tests were conducted in the Langley 19-foot pressure tunnel of two highly tapered, moderately swept-back wings of identical plan form. One of the wings was of NACA 6-series symmetrical airfoil sections and the other wing incorporated the same basic airfoil sections but had cambered and reflexed mean lines. The Reynolds number range for these tests was from 3,000,000 to 8,000,000.