# Parametric Analysis for Hybrid-Electric Regional Aircraft Conceptual Design and Development
## 3 Simulation Results and Discussion
### Battery Technology Impact on Hybrid-Electric Regional Aircraft Design
#### 3.1.2 Effect of Varying Design Range
The results for the _PREE_ optima are reported in Table 4, and the trend for the optimisation sets with the constraint MTOW = \(W_{c}\) is reported in Figure 9. In particular, with respect to the reference case with a design range of 600 nm, in this scenario, increasing the MTOW resulted in combined improvements in both the _PREE_ and \(m_{fb}\) for \(BED\) = 500 Wh/kg; for the _PREE_ optimum, a \(m_{fb}\) = 52 kg and a _PREE_ = 1.335 with a MTOW = 32,686 kg\({}_{d}\) are obtained; the trend of _PREE_ with respect to MTOW (see the right part of Figure 9) increases up to this maximum, then it starts to rapidly decrease. In the reference case (i.e., 600 nm), on the other hand, increasing the MTOW resulted in a very slight, almost imperceptible, peak with a similar trend to that seen for the case at \(BED\) = 300 Wh/kg for the reduced range. Reducing the range to 400 nm, therefore, would enable an effective implementation of hybrid-electric propulsion with \(BED\) values reasonably achievable in the next decade. Configurations with potentially low-to-zero fuel consumption in the operating mission can be achieved by considering reduced values for the design range, which in any case would cover the largest share of the regional market [24]. Furthermore, as demonstrated in [36], design range extensions can easily be obtained for hybrid-electric aircraft with parallel powertrain architecture, at the expense of a slight oversizing of the thermal propulsion unit and/or a higher \(m_{fb}\) in these extended-range conditions, considered as off-design routes. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \begin{tabular}{c} \(BED\) \\ **(Wh/kg)** \\ \end{tabular} & \multirow{2}{*}{\
\begin{tabular}{c} **PREE** \\ **(kg\(\prime\))** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **MTOW** \\ **(kg\(\prime\)/m\({}^{2}\))** \\ \end{tabular} } & \multirow{2}{*}{\(\mathbf{H_{P}}\)} & \multicolumn{2}{c}{\(\mathbf{\Psi_{S}}\)} & \multirow{2}{*}{\(\mathbf{\Phi_{cl}^{t}}\)} & \multirow{2}{*}{\(\mathbf{\Phi_{cl}^{e}}\)} & \multirow{2}{*}{\(\mathbf{\Phi_{cl}^{e}}\)} & \multirow{2}{*}{\(\mathbf{\Phi_{cl}^{e}}\)} & \multirow{2}{*}{\(\mathbf{\Phi_{cl}^{t}}\)} & \multirow{2}{*}{\(\mathbf{\Phi_{de}^{t}}\)} & \multirow{2}{*}{\(\mathbf{\Phi_{de}^{e}}\)} \\ \hline
200 & 0.889 & 15,918 & 0.08 & 322 & 0.559 & 0.406 & 0.429 & 0 & 0.238 & 0 \\ \hline
300 & 0.908 & 17,651 & 0.203 & 325 & 0.432 & 0.913 & 0.47 & 0 & 0.215 & 0.399 \\ \hline
400 & 1.001 & 35,102 & 0.375 & 325 & 0.183 & 1 & 0.088 & 0.714 & 0.163 & 0.165 \\ \hline
500 & 1.335 & 32,686 & 0.421 & 325 & 0.126 & 1 & 0 & 1 & 0.126 & 0.779 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Main data of _PREE_-optimised configurations varying _BED_ @400 nm. Increasing the design range with respect to the reference case, on the other hand, leads to opposite observations. This is evident from the trends in Figure 10 and the results in Table 5, obtained by applying the optimisation procedure described in Section 2, using \(FoM\) equal to \(m_{fb}\) for a design range of 800 nm. In addition to the obvious increase in \(m_{fb}\) due to the higher energy demand of the route, there are substantial differences compared to the 600 nm and 400 nm cases. Specifically, increasing the MTOW does not introduce any significative benefit in terms of \(m_{fb}\) for any \(BED\) value (not even for the most optimistic forecast), as shown in the left part of Figure 10. In fact, the opposite effect is obtained, with deteriorations in fuel consumption for all \(BED\) values except for \(BED=500\) W/kg, where an almost indifferent trend is obtained. In general, even in this latter case, increasing MTOW does not bring any benefit, as there is also an associated penalty in terms of the \(PREE\) (see the right part of Figure 10).