Compensation of motor torque asymmetry during the take-off phase of an X-tail unmanned aerial vehicle

The use of Unmanned Aerial Systems is expanding rapidly across civil and military domains, with sustained growth anticipated in the coming decades. The X-tail UAV configuration, characterized by the absence of ailerons and higher wing loading, offers excellent maneuverability for loitering munition applications. However, the design requires extreme control derivatives to maintain flight quality, and the minimal air-speed is determined by both lift capability and the ability to counteract propulsion torque. This research systematically examines the latter factor. Brushless direct current motor was first characterized experimentally, followed by testing with five propeller types to evaluate maximum revolutions per minute and power input. Among the tested configurations, the 18×11-inch propeller achieved 6,390 revolutions per minute at peak power, demonstrating the most favorable trade-off between thrust and torque. Wind tunnel tests at zero airspeed and simulated take-off velocity validated the integrated propulsion performance, showing excellent agreements with the theoretical predictions. The results confirm the suitability of the chosen motor-propeller combination and establish a minimum launcher-assisted take-off speeds as a function of altitude for defined UAV mass. These findings provide a robust basis for propulsion optimization in similar UAV configurations, supporting reliable and efficient operational deployment.