Design and Preliminary Results for Eagle of Taihu, a Canard-Configured Tail-Sitter eVTOL

Compared to tilt-rotor or dual-system eVTOLs, tail-sitter eVTOLs eliminate tilting mechanisms and redundant propellers, offering a structurally simpler solution. However, large-scale tail-sitter aircraft remain rare due to several challenges. During the transition between vertical flight and level flight, actuators must generate sufficient pitch moment during the entire 90-degree aircraft rotation. Additionally, propulsive fans must deliver high thrust in vertical flight while maintaining efficiency in forward flight. Oblique freestream flows to the propeller disk during transition also induce blade vibration. To support the development of a future series of large-scale tail-sitter eVTOLs, Eagle of Taihu 100 (ET100) with a maximum take-off weight of 120 kg was designed as a technology demonstrator. An empirical-based parametric design workflow is introduced for initial phase development. Next, the aerodynamic design of the ET100 is discussed, which features a canard configuration and custom propellers. Computational fluid dynamics is employed for performance assessment. The numerical simulations for the propeller are validated through experiments conducted using in-house test rigs and good agreement can be observed between the two. A model is developed for the propeller thrust with oblique freestreams. Next, transition envelopes of the ET100 are analyzed, in which an optimal transition path is highlighted to guide flight control strategy. Finally, preliminary flight tests are reported, and directions for future work are discussed.