Abstract:
This report gives the results of measurements by a forced oscillation method of the direct derivatives (aerodynalaic stiffness and damping) for a horn-balanced elevator. The tests were made at low airspeeds on a complete wing-fuselage-tail model at 0 deg and 10 deg incidence in a wind tunnel. Some information was obtained on the effect of mean elevator angle on the derivatives when the model was at the high incidence. Measurements were also made with trailing-edge cords and transition wires in position. The experiments suggest that none of the above factors causes a reduction in damping, but the stiffness derivative was found to be considerably influenced by the elevator angle and by the presence ot trailing-edge cords and transition wires. In general the measured values are numerically considerably less than those calculated by simple strip theory using two-dimensional vortex sheet theory results.
