## 3 Performance Comparison  
This section presents a general assessment of the performance comparison between the TW and the BW regional hybrid-electric aircraft. The comparison is proposed following a wide sensitivity analysis, performed by varying the design variables summarized in Table 2 and taking into account the block fuel \(m_{fb}\) as the main figure of merit (FoM).  
The design variables selected have an impact on the powertrain sizing and on the aerodynamic and structural performance of the aircraft. In particular, the value of \(H_{P}\) defines the share between the electric and thermal installed power, while \(\Phi_{\text{CR}}^{t}\) and \(\Phi_{\text{CL}}^{t}\), named the supplied thermal power fractions, are defined according to Equations (6) and (7):  
\[\Phi_{\text{CR}}^{t}=\frac{P_{\text{CR}}^{t}}{P_{\text{i}}^{t}} \tag{6}\]  
\begin{table}
\begin{tabular}{l c} \hline \hline  & **Reference Thermal Powered TW** \\ \hline Wingspan & 24 m \\ Length & 21.9 m \\ Wing surface & 49.2 m\({}^{2}\) \\ Tail surface & 6.9 m\({}^{2}\) \\ MTOW & 16,020 kg\({}_{t}\) \\ OEW & 10,702 kg\({}_{t}\) \\ Payload & 40 \(\times\) 95 kg\({}_{t}\) \\ Total fuel @ 600 nm & 1479 kg\({}_{t}\) \\ Block fuel @ 600 nm & 1155 kg\({}_{t}\) \\ ICE power & 2 \(\times\) 2167 kW \\ \hline \hline \end{tabular}
\end{table}
Table 1: Main features of the thermal powered TW benchmark.  
\begin{table}
\begin{tabular}{l c} \hline \hline  & **Design Parameter** & **Range Value** \\ \hline \(H_{P}\) & [0.1, 0.2, 0.3, 0.4, 0.5] \\ \(W/S\) [kgf/m\({}^{2}\)] & [255, 265, 275, 285, 295, 305, 315, 325] \\ \(\Phi_{\text{CR}}^{t}\) & [0.35, 0.40, 0.45, 0.50, 0.55] \\ \(\Phi_{\text{CL}}^{t}\) & [0.35, 0.40, 0.45, 0.50, 0.55] \\ \hline \hline \end{tabular}
\end{table}
Table 2: Range of design parameters.  
Figure 5: Artistic view of a classical TW (**left**) and a BW (**right**) configuration.  
\[\Phi_{\rm CL}^{t}=\frac{P_{\rm CL}^{t}}{P_{i}^{t}} \tag{7}\]  
where \(P_{\rm CR}^{t}\) and \(P_{\rm CL}^{t}\) are the thermal power supplied in cruise and climb, respectively. Accordingly, the terms \(\Phi_{\rm CR}^{t}\) and \(\Phi_{\rm CL}^{t}\) indicate the share of the supplied power from the thermal engines, and consequently allow for also estimating the electric supplied power, as the requested power is known in each instant of the mission. Finally, the wing loading \(W/S\) has a direct impact on the matching chart, on the aerodynamic performance, on the geometry scaling of the lifting system, on the field performance, and on the structural weight. The selected values of the design variables used to perform the sensitivity analysis, reported in Table 2, allow for generating a set of \(10^{3}\) configurations for both the TW and the BW airframes. The technological parameters related to the electric components, in terms of specific energy or power, have been selected according to the 2035 time frame horizon forecast [21], and the selected values are reported in Table 3.  
The results of the sensitivity analysis are reported in 2D plots, where the \(x\)-axis reports the MTOW of the designed configuration, and the \(y\)-axis reports the selected FoM. Each point of the chart represents a designed configuration with the tool THEA-CODE.