Document Type : Original Article
Aeronautical Engr. Dept., King Abdulaziz University P.O. Box 9027, Jeddah 21413, Saudi Arabia.
Wind tunnel simulation of the downcoming burst hazard, which is the most dangerous form of wind shear, is performed on an airplane model similar to the B-747. The performance of the airplane model is studied through its lift, drag and side forces along with the pitch, yaw and roll moments. The effect of the model sideslip angle was of particular emphasis in the study. The results substantiate that the lift was continuously depleted as the downcoming burst intensified. In order to maintain the same lifting force under increasing wind shear, the thrust should be increased. The sideslip angle did not demonstrate much influence on the lift and drag forces in the presence of wind shear. Meanwhile, the downcoming burst has been found to decrease the rolling moment induced by sideslip at low angles of attack only. For small sideslip, the downcoming burst contributes positive yaw at low angles of attack. Intensifying wind shear improves the stability margin while it displaces the equilibrium point towards negative lift values.