Airplane Yaw Perturbations due to Vertical and Side Gusts

Abstract

the rotating airfoils are much higher than that for stationary airfoils in two-dimensional flow. The effect can be traced out to be due to the separation being delayed at larger angle of incidence. The displacement of separation is explained by Dwyer and McCroskey to be due to the appearance of a favorable pressure-gradient, cross-flow derivative, Coriolis forces and centrifugal forces. The Coriolis forces and apparent pressure-gradient are induced by the potential crossflow. The maximum benefits with regard to separation are due to favorable pressure-gradient, and it will be more when close to the axis of rotation. The detailed explanation is given in Ref. 2. The slope of the lift curve for two-dimensional flow is larger than the rotating case. Therefore, at smaller angles of attack the stationary blade in two-dimension al flow gives higher lift-coefficient than the rotating one, and is better in performance at those angles. However, at large angles of attack, the rotating airfoil has a better lift-coefficient. Conclusions From the results of the investigation the following conclusions can be drawn: 1) The over-all lift coefficient decreases with the increase of blade length. 2) The slope of lift curve for two-dimensional case is larger than the rotating. Lift coefficients at large angles of attack are greater for the rotating case. The rotating blade stalled at higher angle of attack than a stationary blade. 3) The present study confirms the experimental results obtained by Himmelskamp and theoretical results by Dwyer and McCroskey. Hopefully the present study will help pave the way for an extended study of rotating airfoils.