Description
Mini unmanned aerial vehicles (UAVs) have become increasing popular with the advancement and availability of commercial electronics. These advancements have led to recent developments in aerial vehicles with both vertical-takeoff-and-landing (VTOL) and forward-flight capabilities. A fixed-wing (FW) aircraft can have a thrust-to-weight of 0.1 or lower, while VTOL air vehicles have a thrust-to-weight of 1.2 or higher. Therefore, a VTOL air vehicle must use a lifting wing to extend its endurance. This paper aims to bridge the gap between typical multi-rotor and fixed-wing UAVs by applying sizing estimation methods to design a tri-rotor UAV. The selected tri-rotor configuration is an open-propeller setup with two front tilting-motors that operate in both VTOL and fixed-wing flight, and a rear asymmetric rotor that only operates in VTOL mode. Wind tunnel testing for the propeller’s transitional forces provides insight into the operational envelope of the aerial vehicle during the outbound and inbound transition. The actual vehicle weight is within 3.3% of the sizing’s predicted value of 1.762 kg. Performance of hover and forward flight is presented, and the aerial vehicle’s transition capability is proved. Flight testing shows that the energy consumption is larger than expected, indicating that the propeller efficiency is lower than predicted in the sizing.
