NACA-ARR-3H25

Abstract

<strong>INTRODUCTION</strong> <br>The Calculation by Wieselsberger of the wing damping moment for an untwisted elliptical wing in yawing is summarized and extended in reference 1 to the case of an untwisted rectangular wings and also for the special angle-of-attack distribution that results from the deflection of partial-span flaps of constant chord ratio when the rest of the span is at zero angle of attack. The results in reference 2 for the yawing derivative due to induced drag, however, contain inaccuracies because of the omission of an important term in the formula for the yawing moment. Also, as noted in reference 2, the results cannot be applied by simple superposition to the case in which the lift is contributed simultaneously by partial-span flaps and by the plain portions of the wing. This limitation follows from the fact that the damping moment varies as the square of the angle-of-attack distribution; hence, separate components of the lift distribution have interactions that contribute to the resultant value of the yawing derivative.