Numerical estimation of longitudinal damping derivatives of a flying wing micro aerial vehicle

Longitudinal damping derivatives, Cmq,Cm(alpha)over dot, of an aerial vehicle is important from an aerodynamic stability point of view. Experimental calculation of longitudinal damping derivatives using wind tunnel is not a cost-effective method; therefore, researchers have developed numerical solutions as an alternative. In this research, the longitudinal damping derivatives of a flying wing micro aerial vehicle (FWMAV) were calculated using numerical simulations by adopting pull-up maneuver and forced harmonic motion in pitch axis. Pull-up maneuver with four steady rotational rates was simulated to obtain pitch rate derivative, C-mq. Combined derivative, C-mq+C-m(alpha)over dot, was obtained by simulating forced harmonic motion of FWMAV around a mean angle of attack of 0 degrees with amplitude of oscillation of +/- 3 degrees using four reduced frequencies (0.02, 0.03, 0.04, and 0.05). Unstructured surface and volume mesh was used in a spherical domain engulfed inside a large cuboid domain for moving reference frame strategy. Reynolds number taking mean aerodynamic chord as a reference length was 2.33 x 10(5). Spalart-Allmaras turbulence model was used. Pitch rate derivative, combined derivative, and acceleration derivative were found as - 0.03/rad, - 7.39/rad, and - 7.36/rad, respectively, by the use of a phase method at a reduced frequency of 0.03. During flight dynamic analysis, it was found that C-m(alpha)over dot has a significant contribution on damping in short period mode with no effect on Phugoid mode. The research concluded that for tailless configurations, acceleration derivative C-m(alpha)over dot can exist and can provide necessary damping in the longitudinal flight mode.