Multimode Controller design and flight test for Tailsitter UAV without elevon

There have been ongoing interests in hybrid aircraft that are capable of vertical takeoff/landing (VTOL) and highspeed horizontal flight capability for maximal mission range. Tailsitters are a possible solution. In this work, we introduce an example tailsitter UAV and propose a novel tailsitter model based on double Euler-angles structure. We design attitude controllers for horizontal and vertical mode respectively based on conventional multi-loop feedback method. A switch-logic mode transition strategy is proposed and mode transition is guided with pitch angle command. The proposed controllers and control strategy are validated in actual flight tests to successfully demonstrate its capability to control the vehicle over the entire operating range.