Stability and Flying Qualities of an Unmanned Airplane Using the Vortex-Lattice Method

The purpose of the present work is to evaluate the static stability and open loop dynamic stability for unpowered condition of the Unmanned Aerial Vehicle for Ecological Conservation. Forces and moments were obtained by the vortex lattice method. These were computed for different values of angle of attack, sideslip angle, aileron, rudder and elevator deflection, and pitch, yaw and roll rates. Static stability and control derivatives were obtained and used for the analysis of airplane open loop dynamic stability and response. The longitudinal and lateral–directional derivates show that the airplane is statically stable. The short period mode and phugoid mode correspond with damped mode. Dutch roll mode and roll mode of the airplane matches with damped mode and convergent mode, respectively. However, spiral mode response prediction corresponds to a divergent mode. The airplane reaches flying qualities equal and better than those of Level 2 Nomenclature c = mean aerodynamic chord CD, CL, CY = drag, lift and side force coefficients CM, Cn, C = pitching, yawing and rolling moment coefficients