Heavy rain effects on aircraft longitudinal stability and control determined from numerical simulation data

Abstract

In this study, the effects of heavy rain on the longitudinal stability and control performance of the DHC-6 Twin Otter aircraft are determined based on data from numerical simulation. A two-way momentum coupled Eulerian–Lagrangian approach for two-phase flows developed in the authors’ previous work is adopted to obtain the basic aerodynamic coefficients in rain. Then the aerodynamic derivatives of the aircraft in rain are evaluated on the basis of the narrow-strip theory. Finally, the longitudinal stability and control performance of the aircraft in rain are analyzed. Our research results suggest that heavy rain can cause degradations in both of aerodynamic and flight mechanics performances to an aircraft. In practice, these short-duration rainfall encounters should be avoided as far as possible since rain mainly has significant adverse effects on the short-period mode characteristics.