#WING AIRFOIL SKIN#
Though those wings are lighter in weight compared with the hinged morphing mechanisms that made of aluminum or steel to retain structure strength due to stress concentration, the whole morphing structures are still too “heavy” in the weight of skin and driving mechanisms for a compliant wing aircraft, especially for high altitude long endurance UAVs that may operate for days even months (such as solar-powered UAVs by Google and Facebook for providing free Wi-Fi access).
It can be easily discovered through the more recent studies above that the newly proposed morphing mechanisms are generally consisted of seamless and continuous skin made of carbon fiber or composite material and actuators that drive the deformation of the skins. Superior aerodynamic performance of seamless skin variable camber wing due to morphing leading edge and trailing edge and span wise wing twist has been demonstrated by Joo et al.’s VCCW concept through wind tunnel testing (seen in Fig. 1(a)). This wing demonstrates that sufficient control of the rolling motion of aircraft and maximization of the lift-to-drag ratio can be achieved through active wing twist. developed a warp controlled wing twist without relying on extremely powerful actuators.
By introducing variable torsion, through rotate ribs around a fixed aluminum rod, to a wing made of carbon fiber skin (except for the trailing edge) that is stiff in torsional direction, Vos et al. developed a variable geometry morphing airfoil using corrugated structures to actuate a flexible seamless flap by a wire system in the leading part of the structure, through comparison between experimental results of morphing trailing edge and that of a hinged wing, showing great potential in the improvement of lift coefficient (Seen in Fig. Other advantages of morphing wing technologies have also been verified by wind tunnel tests and flight tests in the above programs and other researchers’ work. Several morphing concepts, such as Mission Adaptive Wing in 1980s, Smart Wing Program in 1990s, Mission Adaptive Compliant Wing in 2000s and a very recent Variable Camber Compliant Wing (VCCW) concept by the Air Force Research Laboratory (AFRL), have been proposed. In addition, morphing wing technologies were also proved to be useful in increasing the critical flutter velocities and improving wing aeroelastic efficiency. Power consumption, noise emission and overall aircraft environmental impact can be significantly reduced with enhanced flight performance by morphing technologies. Morphing wing technologies have been widely studied recently due to the demands for safe, affordable and environmental compatible aircrafts. Keywords: variable camber compliant wing, CST, MOPS, artificial muscle, trailing edge morphing. The results show that this method is capable of designing airfoils for this special wing in a quick and effective way. A new selector is introduced to facilitate the searching process and improve the robustness of this method. Targeting this innovative design, an airfoil design approach, employing CST parametric methodology, XFOIL and Multi-Objective Particle Swarm (MOPS) optimizer, is developed for the preliminary design of this innovative wing. The demonstration wing section shows that the trailing edge morphing mechanism designed and simulative driving skin work good, with a –30°/+30° trailing edge morphing achieved. A demonstrative wing section with simulative driving skin mechanism and the compliant skin was manufactured. To demonstrate the feasibility of this design, a simulative experiment of this kind of artificial muscles was designed and carried out. Consisted of a compliant base plate and seamless and continuous compliant skin with the artificial muscles embedded in, this trailing edge morphing mechanism is extremely light in weight and efficient in reconfiguration of the wing sectional profile. In this study, an innovative adaptive variable camber compliant wing, with skin that can change thickness and tailing edge morphing mechanism that is designed based on a new kind of artificial muscles, is designed.
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