The calculation of lateral stability derivatives of slender wings at incidence, including fin effectiveness, and correlation with experiment

Abstract

Comparisons are made between low-speed experimental results and estimates based on attached-flow theory for the lateral stability derivatives of slender wings at incidence, and it is found that the flow separation has little effect on the sideslip derivatives. The reduction in lv due to part-span anhedral is evaluated, and a semi-empirical formula is derived to account for important second-order terms. For the rotary derivatives, an attempt is made to estimate the effect of the leading-edge vortices, but no satisfactory conclusions have been reached. The fin contributions to the derivatives are evaluated on the basis of treating the Wing surface as a total reflection plate. Good agreement with experiment is reached for the sideslip derivatives, and for the damping-in-yaw at moderate incidences. Sidewash is found to have a large effect on the rolling derivatives, and further information on the strength and position of the leading-edge vortices in non-symmetric flow is required before a complete calculation of the sidewash can be given.