POA * ONLINE SUBSCRIPTION ONLY

ESDU 81014 presents a method of estimating the planform contribution to the yawing moment due to roll-rate, (Np)w, and the sideforce due to roll rate, (Yp)w, of swept wings at subsonic speeds. The method applies to wings without dihedral, camber or twist, in the "clean condition", i.e. with any high-lift devices retracted. The method was originally developed for untapered wings but data have been provided to take into account the small effect of wing taper. The method for the sideforce derivative applies only over the range of lift coefficients for which the flow is attached to the wing surface and (Yp)w varies linearly with lift coefficient. In the case of the yawing moment derivative, however, the data provide an empirical means of extending the estimation into the range of lift coefficients in which areas of flow separation exist and (Np)w varies non-linearly with lift coefficient and often changes sign at a moderate to high lift coefficient. The knowledge provided by the data of where such a change in sign occurs is very important to the designer in assessing the stability of an aircraft. The data cover an aspect ratio range from 2 to 12, wing sweepback angles up to 60 degrees and AtanΛ ¼ ≤ 6. The first-order effects of subsonic Mach number are also catered for. A computer program of the method is provided as ESDUpac A8114.