Vehicle Dynamic Model based navigation represents a novel approach to autonomous navigation for small UAVs. It significantly improves the navigation solution under GNSS outage condition without adding additional sensors to the platform. This paper proposes an alternative method for determination of the aerodynamic coefficients characterizing the system dynamics needed to enable VDM-based navigation. It relies on the usage of post-processed traditional INS/GNSS navigation solution for the estimation of initial values of the aerodynamic coefficients. The importance of optimal selection of experimental data is highlighted, proposing an evaluation criterion whose benefit is the increase of the statistical significance of the coefficient estimation.