NACA-TN-3818

Abstract

An investigation was conducted in the Langley high-speed 7- by 10-foot tunnel to determine the horizontal- and vertical-tail contributions to the static lateral stability of a complete-model swept-wing configuration at high subsonic speeds. The results indicate that, in general, Mach number effects within the range studied and wing effects on the tail contribution were small and the overall trends of the data of the present investigation agreed with those which have been established at low speeds. The contribution of the vertical tail to the directional stability C_n&#946; at zero angle of attack increases slightly with Mach number and can be adequately predicted when the load is assumed to act at the aerodynamic center of the vertical tail cV/4 and when the end-plate effect of the fuselage on the theoretical lift-curve slope of the tail is considered. The vertical tail contributes a stabilizing increment to the directional stability C_n&#946; at all angles of attack; however, at the higher angles of attack the tail contribution is greatly reduced. The vertical-tail contribution to the effective-dihedral derivative C_{<em>l</em>&#946;} at zero angle of attack increases slightly with Mach number and can be estimated satisfactorily when the geometric center of load cV/4 and the end-plate effect of the fuselage on the theoretical lift-curve slope of the tail are considered.