FREE-FLIGHT-TUNNEL INVESTIGATION OF THE EFFECT OF THE FUSELAGE LENGTH AND THE ASPECT RATIO AND SIZE OF THE VERTICAL TAIL ON LATERAL STABILITY AND CONTROL

摘要

Tests have been made in the NACA free-flight tunnel to determine the affect of the fuselage length and the aspect ratio and size of the vertical tail on lateral stability and control. Fuselages of two different lengths and various vertical tail surfaces were used on a powered model in the investigation. Both flight and force tests were made.nThe tests indicated that a deficiency of tail area could not be overcome by an increase in fuselage length because the unstable moment of the fuselage as well as the tail effectiveness increased directly with the tail length. With a positive degree of directional stability, however, an increase in tail length provided increased stability. An increase in the aspect ratio of the vertical tail from 1.00 to 2.28 increased the tail effectiveness by 67 percent. Power had a stabilizing offset on directional stability for single vertical tails;whereas a destabilizing effect was observed for twin tails. Dorsal fins improved the directional stability at large angles of yaw.