# An Automated Framework for Streamlined CFD-Based Design and Optimization of Fixed-Wing UAV Wings
## 2 Design Space
### Geometric Design Space and Parametrization Techniques  
To enable fully autonomous geometry generation without human intervention, the wing planform must be parameterized in such way as to account for the degrees of freedom necessary for a designer during the conceptual and preliminary stages of UAV design. For the wing parametrization, the current study employes \"low-level\" variables, such as wing chords (\(c_{r}\), \(c_{i}\)) and wingspan (b), which offer a clearer and more practical representation of geometry. The design space accommodates both conventional and BWB UAVs. Conventional UAV wings are typically defined with one or two sections (i.e., the distinct trapezoidal planform surfaces that constitute the wing, are referred to as wing sections), as seen in \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Class** & **Category** & **GTOW [kg]** & **Altitude [f]** & **Cruise Speed Range [km/h]** & **Reynolds Number Range** & **Flow Regime** \\ \hline \multirow{3}{*}{Class I} & Micro & \textless{}2 & \textless{}200 & 30–100 & \multirow{3}{*}{\(10^{4}\)–\(10^{6}\)} & \multirow{3}{*}{\(10^{4}\)–\(10^{6}\)} \\  & Mini & 2–15 & \textless{}3000 & 30–100 & & \\ \cline{1-1}  & Small & 15–150 & \textless{}5000 & 50–150 & & \\ \hline Class II & Tactical & 150–600 & \textless{}18,000 & 100–400 & \(10^{6}\)–\(10^{7}\) & Predominantly turbulent \\ \hline \multirow{3}{*}{Class III} & MALE & \textgreater{}600 & \textless{}45,000 & 200–300 & \multirow{3}{*}{\(>10^{7}\)} & Fully turbulent \\  & HALE & \textgreater{}600 & \textless{}65,000 & 400–800 & & \\ \cline{1-1}  & Strike & \textgreater{}600 & \textless{}65,000 & 400–800 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Design space regarding the UAV types that this framework can handle. Figure 1, and are differentiated from the rest of the aircraft. In contrast, BWB UAVs have a more integrated structure, where the \"fuselage-body\" and wings blend into a continuous aerodynamic shape, as seen in Figure 1.  
In most cases, and especially for BWB configurations, accurately capturing the complexity of the geometry requires multiple sections [26]. However, each additional section increases the number of design variables, leading to higher dimensionality in the design space. While greater dimensionality allows for detailed representations and subtle geometric variations, it also significantly increases computational costs during optimization. This framework restricts the design space for both conventional and BWB UAVs to two distinct trapezoidal sections which are smoothly blended to avoid sharp transitions, as explained in Section 3.1. While this parameterization includes non-planar features (dihedral), it does not currently incorporate additional non-planar elements like winglets, flaps, or slats. This limitation simplifies the geometry and meshing processes at this stage, providing a stable basis that can be extended to more complex design spaces in the future. The necessary parameters and their respective range that define the planform of a wing instance for both configurations are tabulated in Table 2 and are also depicted in Figure 2.