The effects of sampled signals on the flight control system of an agile combat aircraft with a flexible structure

The introduction of digital flight control systems in modern aircraft has created an additional factor in the analysis and prevention of aeroservoelastic interactions. This paper focuses on the propagation of signals through an aeroservoelastic system incorporating a digital flight control system. It is shown that the digital system will increase the seriousness of the aeroservoelastic effects due to aliasing. The contribution to the process of the zero-order-hold is explained, and additionally the possible consequences of high-frequency signals on the performance of the actuation system is examined. Finally, the paper offers general guidelines when designing filters for the attenuation of structural modes, including the significance of the phase, in the digital flight control system.