## 3 Results
### General Results: Key Geometrical, Aerodynamic and Performance Parameters
Although no sufficient fit can be achieved for the \(W_{e}/W_{0}\) against W\({}_{0}\) plots, the general trend is decreasing for heavier UAVs, following the overall philosophy presented in aircraft design textbooks for this particular ratio [19; 20]. It must be noted, though, that every NATO category presents its own behavior and that UAV designers should consider each of them separately, depending on their respective design study. Figure 16 shows the data scatter for the ratio \(W_{e}/W_{0}\) against \(W_{0}\) with respect to region of origin. An interesting observation is that platforms that originate from the USA and Europe follow a quite similar trend, while platforms that originate from Israel feature a steeper trend. On the contrary, Asian UAVs  
Figure 14: Empty weight divided by GTOW as a function of GTOW for the general category. Figure 15: Empty weight divided by GTOW as a function of GTOW with respect to NATO classification. In these plots, clear trendlines exist for the general sample as well as for larger categories of the NATO classification system. Once again, given the large dispersion of the categories that are smaller in weight, it should be noted that, apart from R\({}^{2}\), the UAV designers should also take into consideration the range of the data, before evaluating a design against the suggested trendlines and finalizing their design choices during the conceptual design phase. Figure 19 shows the product of payload weight times the given endurance as a function of GTOW per region of origin. It is observed that, in general, all regions follow the same trendline. USA, Israel and Europe span the entire range of the chart, from the lowest to the highest values of GTOW, indicating market presence in all NATO categories. The American continent has a strong presence in the region of lower GTOW and, consequently lower W\({}_{\text{P}}\) - E products, while Asia focuses on higher GTOW. This can possibly indicate either a design philosophy or a marketing approach. \begin{table}
\begin{tabular}{c c c c c c} \hline  & **R\({}^{2}\)** & **A** & **B** & **_n_** & **Type of Fitting** \\ \hline All & 0.905 & 0.313 & 1.33 & 202 & Power \\ Micro-Mini & 0.2691 & 0.213 & 1.271 & 40 & Power \\ Small & 0.433 & 3.297 & 0.86 & 65 & Power \\ Tactical & 0.355 & 1 & 1.15 & 45 & Power \\ MALE & 0.814 & 0.109 & 1.538 & 29 & Power \\ HALE-Strike & 0.829 & 16.053 & 0.829 & 23 & Power \\ \hline \end{tabular}
\end{table} 
Table 8: Statistical data regarding the trend fitting for the W\({}_{\text{P}}\) - E vs. GTOW plots. Figure 18: W\({}_{\text{P}}\) - E as a function of GTOW with respect to NATO categories. Figure 20: Cruise speed as a function of GTOW for the general category. Figure 19: \(W_{\rm p}\cdot\) E as a function of GTOW with respect to region of origin. The cruise speed parameter is a typical example where the categories deviate significantly from the general trendline. It is apparent that the analyzed UAV sample depicts a large dispersion that can be explained based on that the cruise speed is dependent both on the airframe, as well as on the sensors and mission. Figure 22 depicts the same parameters with respect to region of origin. UAVs developed in Israel appear to have a common approach, featuring cruise speeds between 100 km/h and 200 km/h from a GTOW range between 10 kg and 1000 kg. UAVs developed in Europe and Asia, on the other hand, feature a large dispersion above 100 kg. Several Asian platforms, in particular, have a documented cruise speed that exceeds 800 km/h, indicating that they have been designed to operate in compressible flow conditions, at least based on their documentation. The USA and the rest of the American continent feature well-established trendlines, with the platforms marked in yellow concentrated again at the lower right corner of the data.