Flight Mechanics and Control of Tilt Rotor/Tilt Wing Unmanned Aerial Vehicles: A Review

A literature review of the Tilt Rotor/Tilt Wing (TR/TW) Unmanned Aerial Vehicles (UAVs) is presented in this paper from the flight mechanics and control points of view. Firstly, the advantages as well as the challenges of the TR/TW UAVs are studied, from the design, aerodynamic, flight dynamic and control viewpoints. Next, a chronicle of the most important researches conducted about the TR/TW UAVs is reported. Then, these TR/TW UAVs are categorized based on the overall configurations, rotor arrangements, engine/rotor positions, and engine/rotor types. Next, a comprehensive flight dynamic modeling of the TR/TW aircraft is introduced that may provide a complete and consistent set of the dynamic equations for any type of the TR/TW regardless of the configurations and rotor arrangements. Afterwards, a survey is carried out about the trim and stability of the TR/TW within the hover and transition phases of flight. Finally, different control methods and control strategies utilized for the attitude and altitude control of the TR/TW UAVs are categorized based on their pros and cons. Since this paper covers the flight mechanics and control of the TR/TW UAVs, it may assist designers in making decisions about the most critical aspects of a new design based on the previous studies.