Determining the lateral-directional handling characteristics of a Skysurfer X8
J.A.H. Kuijpers (TU Delft - Aerospace Engineering)
R Vos – Mentor (TU Delft - Flight Performance and Propulsion)
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Abstract
With standard aircraft configurations reaching their limits in efficiency, new aircraft configurations are being theorized and analyzed. One type of analysis is remotely piloted scaled flight tests. One of the aspects that can be analyzed through remotely piloted scaled flight tests is the dynamic behavior of the aircraft. This thesis shows a method to determine the lateral-directional stability and controllability of a remotely piloted scaled flight model. The objective of this research is to show a method to determine the lateral-directional stability and controllability of a remotely piloted aircraft. The aircraft used to demonstrate the method is the X-UAV Skysurfer X8. This aircraft is equipped with a Pixhawk 4 flight controller running a custom version of the PX4 software stack. The Pixhawk 4 records measurements of many different sensors as well as the control inputs given to the servos. From the acquired data a linearized state space model for lateral-directional stability and controllability is created through the optimization of a cost function depending on the difference between the estimated model and the measurements. From the optimized state space system the lateral-directional handling characteristics are determined from an eigenvalue analysis. The results show that the aircraft as configured during the flight test has an unstable spiral mode, damped Dutch roll mode and a highly damped roll subsidence mode. The results for the lateral-directional dynamics are analyzed further according to military specification MIL-HDBK-1797. This analysis shows the aircraft has level 3 behavior with respect to the spiral mode, meaning constant attention is required from the pilot if no control augmentation system is used, but it is still controllable. The roll subsidence and Dutch roll mode are of level 1 which is considered satisfactory behavior. The roll performance of the aircraft is of level 2, meaning it is acceptable behavior.