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In this research, experiment and computational fluid dynamics (CFD) are used to assess the performance of UAV with variable-span and sweep morphing wing under low speed conditions. Both wing area and aspect ratio are changed due to variations in span and sweep, whereas structure of the variable-span and sweep morphing wing remains constant. In this study, the numerical results of Fluent software and experimental data are presented. Results are achieved under a low wind speed (50, 60 and 70 m/s). In this case, full extension represents a 30% (10 cm) increase in wing span and 36% (12 deg.) in sweep angle relative to the original wing, with no extension. The results of this study show that the morphing wing is capable to improved aerodynamic efficiency, increased both range and endurance, reduced induced drag and in general reduced thrust required. According to experimental and numerical results, the use of morphing wing can increase the range by 13.6% and 13.5%, also, endurance of the vehicle by approximately 8.855 and 8.17%, respectively. The results of this study show that the maximum value of lift-to-drag ratio occurred at 6 degrees angle of attack and a speed of 70m/s. These results demonstrate that the use of morphing wing improve the lift-to-drag ratio by 10% compared to original wing. Finally, the numerical simulations are compared and show good agreement with the experimental results. This research also showed how morphing concept can be used as an alternative method for roll control.

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The scope of the current investigation incorporates the entire process involved in design and development of a Shape Memory Alloy (SMA) actuated wing intended to fulfill morphing missions. At the design step, a two Degree-of-Freedom (DOF) mechanism is designed that is appropriate for morphing wing applications. The mechanism is developed in such a way that it can undergo different two DOF, i.e. gull and sweep, so that the wing can have maneuvers that are more efficient. Smart materials commonly are selected as the actuators due to their suitable thermo-mechanical characteristics. Shape Memory Alloy (SMA) actuators are capable of providing more efficient mechanisms in comparison to the conventional actuators due to their large force/stroke generation, smaller size with high capabilities in limited spaces, and lower weight. As SMA wires have nonlinear hysteresis behavior, their modeling should be implemented in a meticulous way. In this work, after proposing a two DOF morphing wing, an aerodynamic analysis of the whole wing for unmorphed and morphed wings is presented. The results show that the performance of the morphed wing in special flight regimes is improved.