Longitudinal flying qualities evaluation of UAV system in remote mode

The unmanned aerial vehicle (UAV) system model was established. According to the characteristics such as the communication data-link exists time delay, the UAV pilot can not directly feel the UAV g-load, etc, with the reference to piloted aircraft flight quality criterion, a means to evaluate the longitudinal flying qualities of UAV system in the remote mode is proposed.The short-period flying qualities and the pilot-induced oscillations (PIO) tendency of an unmanned aircraft were evaluated. The results show that, the communication data-link has little effect on the short period frequency and damping characteristics of the UAV. However, when the UAV pilot control the aircraft in the ground control station, the data-link delay time increases the equivalent delay time of the UAV system, which result in the closed-loop short-period flying qualities of the UAV system becomes poor, and the UAV has PIO tendency. To avoid the PIO tendency, missions of fast maneuvering flight should be avoid when the UAV was remotely piloted.