SOME EFFECTS OF ASPECT RATIO AND TAIL LENGTH ON THE CONTRIBUTION OF A VERTICAL TAIL TO UNSTEADY LATERAL DAMPING AND DIRECTIONAL STABILITY OF A MODEL OSCILLATING CONTINUOUSLY IN YAW

摘要

A fuselage—vertical-tail combination with tails of two aspect ratios, each of which was tested at four tail lengths, was oscillated in yaw through a range of reduced-frequency parameter corresponding to the lateral motions of airplanes. The tail force caused by yawing, and hence, the approximate contribution of the tail to the damping in yaw was measured for each condition as a phase angle between the lateral force on the vertical tail and the displacement in yaw of the model. These phase angles were measured with the tail in the presence of the fuselage.nA reduction in the contribution of the vertical tail to the lateral damping took place as the frequency was reduced to low values and became more pronounced as the aspect ratio and tail length were: increased.