*3.2. Size of the Adjusted Vertical Tail*

The results for the resizing of the vertical tail are shown for all four configurations, in form of the surface areas and corresponding volume coefficients, are given in Table 3. The difference in the surface areas of the original vertical tails for the different wiring options results from the distinct cable lengths, as described in Section 2.3. The cross-wiring option needs longer cables than the on-wing wiring and therefore has a higher OME and MTOM. The resulting aircraft needs a larger wing to account for the increased lift demand. Since MICADO is set to calculate the size of the vertical tail based on a fixed volume coefficient this results in a larger vertical tail, as shown in Equation (3).

As can be seen in Table 3, the size of the vertical tail strongly depends on the chosen wiring option and the configuration. In case of the PT2025 aircraft, the required vertical tail area for the on-wing wiring (Configuration 1) is twice the surface of the cross-wiring option (Configuration 2), since the remaining thrust in the case of a gas turbine failure is accumulated on one side of the aircraft. The large lever arm of 8.6 m of the electric engine at the wing tip, in addition to the lever arm of 2.5 m of the turboprop engine, increases the yawing moment compared to the conventional reference for which the vertical tail was originally designed. For the cross-wiring option the residual yawing moment is still larger than for the reference aircraft, as the span-wise distance between the integration positions of the electric and the turboprop engine is 2.4 times the distance between the turboprop engine and the fuselage centreline in the reference configuration. This equalizes the fact that the electric engine only produces half the thrust of the turboprop engine in the conventional reference aircraft. As expected, the more outward position of the gas turbine in the PT2025opt aircraft results in a larger difference in the VTP size between the two wiring options. Here, the vertical tail in the on-wing wiring (Configuration 3) case is almost nine times as large as the one for the cross-wiring (Configuration 4) and even supersedes the wing, which has a surface area of 32.15 m2. The cross-wiring option, on the other hand, results in a vertical tail smaller than the original one, because the distance between the electric engines at 8.3 m and the turboprop engine at 6.0 m is smaller than the lever arm in the reference aircraft, while the electric engine also produces only half the thrust.


**Table 3.** Surface area and volume coefficients of the original and resized vertical tail for the four considered aircraft and wiring configurations.
