Wind-tunnel investigation of the static lateral stability characteristics of wind-fuselage combinations at high subsonic speeds : taper-ratio series

James W. Wiggins, Paul G. Fournier
Oct 1957

An investigation was conducted in the Langley high-speed 7-by-10-foot tunnel to determine the effects of variations in taper ratio within the range of 0.3 to 1.0 on the static lateral stability characteristics at high subsonic speeds of wing-fuselage combinations having wings of 45 degrees sweepback at the quarter-chord line and an aspect ratio of 4. As has been shown in previous experimental investigations of other wing plan forms, the parameter which expresses the rate of change of effective dihedral with lift coefficient was found to increase at the high subsonic Mach numbers as the force-break Mach number was approached. Above the force-break Mach number, this parameter decreased in magnitude with the severity of the break increasing with a decrease in taper ratio. The experimental variation of the parameter increases negatively with taper ratio and agrees well with the predicted trend; however, the experimental values are shown to be appreciably larger than the predicted values. At low and moderate lift coefficients, the derivative of yawing moment due to sideslip and lateral force due to sideslip for the wing-fuselage combinations are contributed almost entirely by the fuselage alone; however, at high lift coefficients the effects of the wing are quite large.

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