The analysis of lateral stability of tailless CAMAR-3 with winglets

Abstract

This paper analyses the lateral stability of tailless CAMAR-3 Unmanned Aerial Vehicle (UAV) when its tail fin (i.e. V-tail) is reconfigured to the wingtips. A tailless UAV may have longer endurance time, compared to the present configuration of V-tail. Nevertheless, a tailless UAV may experience reduction in lateral stability due to loss of yaw control surfaces. In the preliminary design of tailless-winglets UAV, semi-empirical method is applied to estimate the aerodynamic lateral stability derivatives, in order to investigate the stability of both configurations of UAV. ThenThen, a dynamic test rig based on pure yawing motion is built, to measure the lateral stability derivatives of C_(n_β ) and C_(n_r ) in transient conditions. The time response data of pure yawing oscillation give the natural frequency and damping ratio that describe the aerodynamic derivatives as a result from wind-on and wind-off tunnel tests. The result indicates that UAV with either configurations are laterally stable. However, the tailless-winglets CAMAR has a 13.86% reduction in aerodynamic yawing-moment-due-to-sideslip derivative C_(n_β ), compared to CAMAR-3 with V-tail; whereas the aerodynamic yawing-moment-due-to-yaw-rate derivative C_(n_r ) of tailless-winglets CAMAR is 5.55% lesser than that of the CAMAR-3 with V-tail. The lateral stability degrades, as expected, caused by tail stabilizer removal. In conclusion, the idea of tail removal and using winglets as the directional controllers is feasible.