Electric vertical take-off and landing (eVTOL) aircraft enable new transport options in regional and urban air mobility. One promising but only little investigated and understood subcategory comprises tilt-wing eVTOLs. They offer high efficiency and long flight ranges but come with a trade-off in increased complexity. Consequently, a critical step towards market entry is the development of mature and safe hybrid pilot-autonomy control systems, including fault detection, identification, and recovery (FDIR) concepts. That requires a mid-fidelity dynamic model with sufficient accuracy, which is not yet available despite a long history of tilt-wing research. Without a representative model, no detailed analysis and identification of a trimmed transition trajectory could be performed. This, however, is a crucial step in the development of a control system. We approach the problem by applying and combining current modeling approaches. Furthermore, a trim analysis of different flight phases, including the transition, is conducted. The identified model lays the foundation for a representative and detailed development and investigation of future control designs, bringing tilt-wing eVTOLs closer to airworthiness.

The development of fault-tolerant control concepts for tandem tilt wing aircraft in nominal and non-nominal conditions requires an aerodynamic modeling tool that captures relevant effects while maintaining modeling flexibility. In this work, a semi-empirical approach for aerodynamic modeling with focus on the propeller-wing interaction is presented. As a foundation, two-dimensional aerodynamics of an airfoil in interaction with propellers and flaps are considered. Combining the effects of numerous airfoil sections, the approach is extended to 3D in order to model a complete aircraft by applying strip theory. Finite wing effects on the lift distribution are taken into account. Without reference data for a full tandem tilt wing configuration, validation was performed on each subcomponent individually or combinations of components. The validation tests showed satisfactory agreement with the experimental data. Together with weight & balance and propulsion models, the tool allows performing trim analyses for the complete flight envelope, which is the foundation for finding flight corridor for stable transition flight. Failure cases, like loss of a motor or stuck actuators, and their impact on the flight envelope and transition corridor can be investigated in the future. Besides these analyses, the presented model can also be used for dynamic flight simulation or aerodynamic model identification.