ANALYTICAL STUDY OF THE LONGITUDINAL RESPONSE OF AIRPLANES TO POSITIVE WIND SHEAR.

Wind shear, the vertical variation of the horizontal wind, has been a causative factor in several airplane accidents and may have been a contributing factor in others. The study concentrates on the longitudinal mode of the airplane with specific reference to the role of the speed (u) stability derivatives in the interaction of the airplane and its environment. The relative importance of the u-stability derivatives was determined. As a result of this study, the wind shear tolerance was found. This factor can be used to determine, in a qualitative manner, the stability (tolerance) of an airplane to wind shear. A further study of the control problem showed that the criteria for good control could be reduced from two to one automatic control system. Only a speed control system is necessary for good control in wind shear.