The purpose of this research is to evaluate certain performance characteristics of a morphing<br />wing system that uses Macro Fiber Composites (MFC) to create camber change. This<br />thesis can be broken into two major sections. The first half compares a few current MFC<br />airfoil designs to each other and to a conventional servomechanism (servo) airfoil. Their<br />performance was measured in terms of lift and drag in a 2-D wind tunnel. The results<br />showed MFC airfoils were effective but limited by aeroelasticity compared to the servo. In<br />addition, a morphed airfoil and a flapped airfoil were rapid prototyped and tested to isolate<br />the effects of discontinuity. The continuous morphed airfoil produced more lift with less<br />drag.<br />The second half of this thesis work focused on determining the ideal MFC configurations for<br />a thin wing application. Simulations were run on a thin wing with embedded MFCs such<br />that the whole wing morphed. Finite element and vortex lattice models were used to predict<br />deflections and rolling moment coefficients. Different configuration parameters were then<br />varied to quantify their effect. The comparisons included MFC location, number of MFCs,<br />material substrate, and wing thickness. A prototype wing was then built and flight tested.<br />While the simulations overestimated the wing deflection, the flight results illustrated the<br />complexity and variability associated with the MFC morphing system. The rolling moment<br />coefficients from flight were consistent with the simulation given the differences in deflection. / Master of Science

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Inflatable-wing Unmanned Aerial Vehicles (UAVs) have the ability to be packed in a fraction of their deployed volume. This makes them ideal for many deployable UAV designs, but inflatable wings can be flexible and don’t have conventional control surfaces. This thesis will investigate the use of wing warping as a means of autonomous control for inflatable wings. Due to complexities associated with manufacturing inflatable structures a new method of rapid prototyping deformable wings is used in place of inflatables to decrease cost and design-cycle time. A UAV testbed was developed and integrated with the warping wings and flown in a series of flight tests. The warping wing flew both under manual control and autopilot stabilization.

<p dir="ltr">The ability to change the shape of aerodynamic surfaces is necessary for modern aircraft, both to provide control while performing maneuvers and to meet the conflicting requirements of various flight conditions such as takeoff/landing and level cruise. These shape changes have traditionally been accomplished through the use of various mechanical devices actuating discrete aerodynamic surfaces, for example ailerons and flaps. Such control surfaces and high-lift devices are generally limited to their specific functionality and create surface discontinuities which increase drag and aircraft noise. Broadly speaking, the design and study of morphing wings typically seeks to improve the performance of aircraft by completing one or more of the following objectives: reducing the drag from discontinuities in the aerodynamic surface of the wing by closing hinge gaps and creating smooth transitions, reducing weight and/or mechanical complexity by integrating mechanism functionality into compliant structures that can bear aerodynamic load and maintain shape adaptability, and providing unique or optimal functionality to the aircraft by allowing it to adjust its aerodynamic shape to meet the needs of various flight conditions with conflicting objectives and constraints.</p><p dir="ltr">The concepts proposed in this work represent potential methods for addressing these objectives. In each case, a compliant structure with multiple stable states is embedded into the wing. Exploiting elastic structural instabilities in this way provides the advantage that a structure can be made relatively stiff while still allowing for large deformations. In the first case, the development of a 3D-printable rib with an embedded bistable element creates a truss-like 2D structure that allows for modification of the airfoil. Switching states of the elements changes their local stiffness, and therefore the global stiffness of the system. By optimizing the topology of the airfoil, a passive deflection of the trailing edge can be leveraged to change the camber to leverage different lift characteristics for varying operating conditions. Primary work on this concept has included the construction of multiple experimental demonstrators for validating the concept through static structural and wind tunnel testing. In the second case, a cellular material has been investigated incorporating a bistable unit cell with a sinusoidal arch. This provides a metamaterial that can exhibit large, reversible deformations with as many stable configurations as there are rows in the honeycomb. This metamaterial is incorporated into a beam-like structure which can serve as a spar for a spanwise morphing wing, providing sufficient bending and torsional stiffness, particularly when utilized at the wing tip. Extending and retracting the wing by switching the states of the honeycomb rows provides a significant change to the wing’s induced drag and wing loading, making it ideal for optimal flight in both loitering and cruising conditions. Contributions to this concept have been the development and characterization of the bistable unit cell and honeycomb, as well as the design and analysis of the metabeam and morphing wing concept.</p>