Theory for Roll-Ratchet Phenomenon in High-Performance Aircraft

Roll ratchet refers to a high-frequency oscillation that can occur in pilot-in-the-loop control of roll attitude in high-performance aircraft. The frequencies of oscillation typically are well beyond those associated with the more familiar pilot-induced oscillation. A structural model of the human pilot, which has been employed to provide a unified theory for aircraft handling qualities and pilot-induced oscillations, is employed here to provide a theory for the existence of roll ratchet. It is hypothesized and demonstrated using the structural model that the pilot's inappropriate use of vestibular acceleration feedback can cause this phenomenon, a possibility that has been discussed by other researchers. The possible influence of biodynamic feedback on roll ratchet also is discussed. (Author)