## 5 Adaptive Wing Design and Manufacturing
### Adaptive Wing In-House Manufacturing  
The new wing design must replace the actual rigid wing of the UAV S45; therefore, the new design must have the same span length, a tip chord length of 0.40 m, a base chord length of 0.65 m, and an approximate weight without any instruments of 4.5 kg. The design of the adaptive wing structure has the same internal structure as a rigid wing in the sense that it consists mostly of spar and rib structures. The difference between a rigid wing and an adaptive wing structure is the configuration of the wing box structure to support the actuators. Rigid wing structures rely on ribs to support the skin and maintain their airfoil shape. In the case of the proposed adaptive wing prototype, the rib structures have to change forms, allowing additional shape variations. These ribs are also intended to support the chordwise bending moments occurring through the pressure differential between the upper and lower surfaces. Furthermore, the ribs provide the sliding mechanism that allows the leading and trailing edge structures to change their shape, as shown in Figure 17. The additional torsional loads are supported by spars located as specified in Section 5.1. To manufacture an adaptive wing prototype with improved performances compared to those of the original S45 wing, it is necessary to consider not only the flight phase conditions of the UAV, as presented earlier, but also the additional loads of the actuators. The fabrication of the wing parts requires CAD files and a program supported by Windows operating systems, as well as scripting capabilities. The ANSYS software package allows the CAD design to be exported into files of a format (Step files) that can be used by the FEA and CFD programs. The manufacturing of the adaptive wing was carried out in several stages. As the scope of this thesis is the design and fabrication of a prototype, further descriptions are given below. The flexible upper surface or skin used on an adaptive wing prototype must support the surface pressures resulting from the flow over the wing while allowing a controlled wing shape change. Compensation for the additional loads is included in the design of the adaptive wing structure. To obtain the desired optimized shapes, the polymer skin material is incorporated in the design and fabrication of the adaptive wing to allow for a precise and smooth transition during the shape changes. The skin material must have the required structural properties for the flight conditions of the UAV S45 and be able to sustain the original rigidity while allowing a quick transition and a very good recovery force, as the skin must return to its original shape when the adaptive wing system is not functioning. A material with increased modulus and toughness is desired so that the transfer of the surface pressure can proceed with minimal skin deflection. In order for the polymer skin to be stretched to a new configuration, while activated, a specific polymer material with a well-suited modulus value is needed. Figure 17: (**a**) Top view of the leading edge adaptive wing prototype; (**b**) actuator design is composed of a servo motor and a push/pull rod. Other factors for the selection of the wing skin material are the yield and ultimate strengths, thermal resistance, stiffness, and density. Moreover, the manufacturability, cost, and availability are important factors. Finally, polycarbonate polymer was chosen for the prototype upper surface (skin). The material properties [31] and dimensions are shown in Table 1. The mass ratio is calculated with the equation shown in the last row. A more detailed equation for the mass ratio (\(\mu\)) is shown here:  
\(\mu\) = Density fluid \(\times\) foil length/Density foil \(\times\) foil thickness = 1.225 \(\times\) 150 mm/1200 \(\times\) 1.02 mm = 0.15. The optimal design of the wing structure involved restrictions for the actuators and a skin support mechanism.