On Time Domain Analysis Method for Longitudinal Flight Quality under Icing Conditions

Icing changes the aerodynamic shape of the aircraft, leading to deterioration of flight quality and severely threatening flight safety. For the problem of aircraft longitudinal flight quality after ice accretion, the icing impact model was optimized, and flight dynamics simulation was performed for different icing severities. Based on simulation results, parameters of low-order equivalent system were identified combined with the improved ant colony algorithm and damped least squares method. The longitudinal modal characteristics under icing conditions were calculated, and the effects of icing on longitudinal flight quality were quantitatively and qualitatively analyzed. The simulation results show that the icing causes the longitudinal modal characteristics to deteriorate and the flight quality is degraded accordingly. Severe ice accretion leads to a cliff-fall in flight quality and induces flight risks. The proposed method can directly apply the time-discrete sequence of the aircraft, improve the utilization of the test flight data, and can also be applied to the on-line quality assessment.