Flapping Flight Stability in Hover: A Comparison of Various Aerodynamic Models

Abstract

The interest in flapping wing MAVs has been rising progressively in the past years. The complex aerodynamic mechanisms responsible for high manoeuvrability and energy efficient lift production have been modelled by multiple techniques. Here we present a comparison of several models from the perspective of flight stability in hover. We estimated the stability derivatives by aerodynamic models of various levels of complexity, ranging from analytical expressions derived from a quasi steady model to CFD results that were taken as a reference. The stability of the complete 6DOF linearized system, split into longitudinal and lateral part, was evaluated in terms of eigenvalues and eigenvectors. While the pole locations and modes of longitudinal system were consistent for all the models (two stable subsidence modes, one unstable oscillatory mode), the lateral dynamics showed that quasi steady models with only translational force are insufficient and revealed the necessity of including the rotational lift to obtain pole locations that are in accordance with the CFD study (one slow divergence mode, one fast subsidence mode and one stable oscillatory mode).