Determination of Control Effector Rate Requirements for Highly Maneuverable Aircraft

This study focuses on the assessment of control effector rate capabilities that are crucial for the airworthy operation of highly maneuverable aircraft. The role of precise rate requirements for primary and secondary control effectors is outlined to ensure stable flight within the desired bounds of maneuver envelope while mitigating Pilot-Induced Oscillations (PIO) in various flight conditions. The analyses emphasize the nonlinearities due to control surface rate limitations linking the rate saturation to the corresponding reduction of phase margins and explore how these factors influence safe operation of aircraft via appropriate criteria. Methods are developed to determine control surface rates for compliance to the PIO, Open-Loop Onset Point and Control Anticipation Parameter criteria as well as suppression of kinematic and inertial coupling effects. Findings indicate that lower dynamic pressures pose challenges for maintaining desired stability and PIO margins due to low moment per surface deflection. The determining conditions and criteria vary across the control surfaces and recommendations are provided for controller design, including adjustments for command shaping and surface rate limits. A case study is performed on an open source F-16 nonlinear model. The dependence of the results on design decisions that are relevant to the operation of the aircraft are outlined. The study is therefore intended to layout an engineering approach to link the parameters of operation of aircraft to control effector rate requirements rather than suggesting exact values.