NACA-TN-1668

Abstract

An investigation was conducted to determine the effects of geometric dihedral on the low-speed static stability and yawing characteristics of an untapered 45&#176; sweptback-wing model of aspect ratio 2.61. The results of the tests indicated that an increase in positive dihedral resulted in an increase in the rolling moment due to sideslip and also caused the maximum value of rolling moment due to sideslip to occur at increasingly higher lift coefficients. Increasing positive or negative dihedral caused a decrease in the lift-curve slope and an increase in the variation of lateral force with sideslip. Dihedral had no appreciable affect on the yawing moment due to sideslip. <br>The rolling moment due to yawing became more positive with increasingly positive dihedral and became less positive with increasingly negative dihedral. The rate of change of rolling moment due to yawing with dihedral angle was nearly independent of lift coefficient. The yawing moment due to yawing was nearly independent of lift coefficient for low and moderate lift coefficients and showed no definite trends at higher lift coefficients. The lateral force due to yawing became more positive with an increase in positive or negative dihedral and showed little variation with lift coefficient through the low and moderate range of lift coefficients. At higher lift coefficients, the lateral force due to yawing became more positive.