Model and Longitudinal Hover Control of A Conceptual Thrust-vectored Unmanned Tail-sitter

Vertical take-off and landing (VTOL) aircraft are more and more important as they combine the benefits of both fixed-wing aircraft and rotary-wing aircraft, and tail-sitting is the simplest way to achieve VTOL maneuvers. However, conventional tail-sitting airplanes are made with propellers or duct fans, which have less thrust and less efficiency. This paper introduces a conceptual thrust-vectored unmanned tail-sitter which is controlled only by thrust vectors (2 engines) while no other control surfaces, thus, they can achieve larger thrust and better maneuverability. However, this configuration is extremely unstable and hard to control. In order to verify its feasibility, a dynamic model is constructed and a linear control strategy has been established to stabilize the platform in hover mode. Simulation results with reference aero data are presented to show the performance, with small disturbances, and its feasibility is validated.