Effect of Wing Height and Dihedral on the Lateral Stability Characteristics at Low Lift of a 45 Deg Swept-Wing Airplane Configuration as Obtained from Time-Vector Analyses of Rocket-Propelled-Model Flights at Mach Numbers from 0.7 to 1.3

Lateral-stability flight tests were made over the Mach number range from 0.7 to 1.3 of models of three airplane configurations having 45deg sweptback wings. One model had a high wing; one, a low wing; and one, a high wing with cathedral. The models were otherwise identical. The lateral oscillations of the models resulting from intermittent yawing disturbances were interpreted in terms of full-scale airplane flying qualities and were further analyzed by the time-vector method to obtain values of the lateral stability derivatives. The effects of changes i n wing height on the static sideslip derivatives were fairly constant in the speed range investigated and agreed well with estimated values based on subsonic wind-tunnel tests. Effects of geometric dihedral on the rolling moment due to sideslip agreed well with theoretical and other experimental results and with a theoretical relation involving the damping in roll. The damping in roll, when compared with theoretical and other experimental results, shared good agreement at supersonic speeds but was somewhat higher at a Mach number of 1.0 and at subsonic speeds. The damping in yaw shared no large changes in the transonic region.