# Design, Manufacturing, and Flight Testing of an Experimental Flying Wing UAV
## 5 Manufacturing Experimental Flying wing UAV  
Designers must select suitable materials during manufacturing. The experimental flying wing UAV can be manufactured using different methods. However, it is necessary to consider how to manufacture a firm and lightweight UAV that can meet all aerodynamic configurational requirements. Composite materials are preferable for this purpose. Therefore, the proposed flying wing UAV is manufactured using composite materials. The above-described conceptual design is validated and then the experimental flying wing UAV is manufactured. Aerodynamic configuration design determines the aircraft size. However, the internal space and aircraft structure are not defined and designed. Aerodynamic configuration and mission requirements \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Symbol** & **Value** \\ \hline Zero lift drag coefficient & \(C_{D_{0}}\) & 0.009 \\ Induced drag factor & \(K\) & 0.0516 \\ Cruising speed & \(V\) & 17.6 m/s \\ Maximum speed & \(V_{Max}\) & 21.15 m/s \\ Wing area & A & 1.07 m\({}^{2}\) \\ Wing root chord & Cr & 0.54 m \\ Wing tip chord & Ct & 0.22 m \\ Wing span & b & 2.83 m \\ Wing aspect ratio & AR & 7.48 \\ Wing sweep angle & \(\Lambda\) & 30 deg \\ Wing twist angle & \(\alpha_{\text{twist}}\) & \(-4\) deg \\ Wing dihedral angle & \(\Gamma\) & 2 deg \\ Wing attack angle & \(\alpha\) & 4 deg \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Main aerodynamic characteristics. Figure 5: Relationship between the lift coefficient and the angle of attack and relationship between the pitching moment coefficient and the angle of attack. are important constraints of the detailed design. These constraints are specified through engineering drawings for the manufacturing processes. Engineering drawings must be prepared at the start for ensuring smooth manufacturing processes. Simultaneously, manufacturing cost and schedule should be considered carefully in the detailed design to manufacture the aircraft in time. The engineering drawings also consider composite material manufacturing molds and assembly installation works. Once the engineering drawings are complete, the flying wing UAV's external and internal structures are well defined, as shown in Figure 6, and therefore, it is ready to manufacture. Based on the aerodynamic configuration and manufacturing and structural considerations, the flying wing UAV is divided into main and secondary structural modules. The main structural modules are the fuselage module and the left and right wing modules. The secondary structural modules are the left and right wing tip modules. The main structural modules must have certain structural strengths and be able to bear the forces generated during flight. If these modules are damaged during flight, a serious failure can occur. Therefore, these modules are crucial in system engineering and should be reviewed and checked before flight testing. Secondary structural modules are designed to adjust the lift distribution in the wingtip. If they suffer damage, a safe landing is still possible. The detailed design generally considers the structural strength and assembly tolerance of all modules. After the modules are designed and manufactured, if the module interfaces cannot be integrated together, the detailed design is adjusted or redesigned. The flying wing experimental UAV has a low weight and small size. Its aerodynamic configuration, manufacturing, and structural integration works are simpler than those of a commercial aircraft. Therefore, its detailed design could be handled by the Tamkang University (TKU) UAV team, although several adjustments were required. Figure 7 shows the main structural modules and secondary structural modules in the flying wing UAV. The size and shape of the aircraft cross section are governed by aerodynamic considerations and must be maintained for all loading generated by the flight environment. The fuselage and the left and  
Figure 6: (**a**) External structure and (**b**) internal structure of flying wing UAV.