Response and Control of an Aircraft in the Presence of Wind Shear

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1. Expressions for aerodynamic forces and stability derivatves in wind shear have been given considering effects of spatial wind distribution over the aircraft. It has been found by a numerical example that the eigenvalues of longitudinal motion are influenced by the potitional relation between the wing and the horizontal tail.2. Effects of temporal wind variation in wind shear have beeen investigated and formulation of acceleration derivatives has been made. It has been shown that the acceleration influences the phugoid-mode motion and the aerodynamic disturbance forces due to the acceleration cannot be neglected.3. Measurement of aerodynamic forces on a two-dimensional wing-tail combination model has been performed in various wind shear conditions generated in a wind tunnel. The results show the validity of the theoretical expressions for the aerodynamic effects of wind distribution. The existence of forces depending on the wind acceleration has also been verified qualitatively.4. A method of experimental prediction of the stability derivatives has been tested by giving forced oscillation to the afore-mentioned model, and it has been confermed that the effects of wind shear can be detected.5. A method of real-time onboard estimation of wind variation has been developed as follows: Optimal estimation of the ground speed is made by using the data of onboard navigational instruments, the inertial navigation system and others, and the difference between the estimated ground speed and the measured airspeed is considered as the wind speed. The results of simulation has shown the availability of the method.6. Utility of an automatic flight control system. operating as an optimal regulator, in preventing deviation of the flight course due to wind shear has been examined by a simulation applying the system for the alleviation of gust response of the aircraft and extent of the effectiveness has been found.