Design Criteria for High-Authority Closed-Loop Primary Flight Control Systems.

摘要

A study to develop improved design criteria for primary flight controls which feature feedback techniques is reported. The study consisted of eight parts,including a survey of operational problems, a review of system-gain changing (requirments and techniques),stabilization criteria for high-frequency control modes,an analysis of stall/spin maneuvers, a catalog of dominant performance characteristics which affect flying qualities,an analysis of system/airframe compatibility testing,definition of criteria for built-in test equipment,and a catalog of flight control actuator designs. Operational problems include high angle-of-attack stability and potential control loss. A math model of a spinning F-4was used to study basic effects and associated control criteria. Nominal control laws in pitch and yaw tended to be benificial for departure inhibition;roll control degraded controllability. Spin recovery demands full surface deployment without detraction by feedback. The controllability limit for spin recovery was defined. The compatibility test analysis featured closed-loop simulation of structural response. Compensation for surface aerodynamics and special airframe support to avoid bending mode distortion were justified. Criteria for built-in test equipment in redundant flight controls to produce adequate flight safety and mission reliability were expressed in terms of test thoroughness,latent failure probabilities,and false indication rate. Test quality was shown to have a highly significant effect on system reliability that becomes more critical with the number of redundant channels and system life. (Author)