This research is concerned with the flight dynamic, pitch flight control and flyingqualities assessment for the reference BWB aircraft. It aims to develop thelongitudinal control laws which could satisfy the flying and handing qualitiesover the whole flight envelope with added consideration of centre of gravity (CG)variation.In order to achieve this goal, both the longitudinal stability augmentation system(SAS) and autopilot control laws are studied in this thesis. Using the poleplacement method, two sets of local Linear-Time-Invariant (LTI) SAS controllersare designed from the viewpoints of flying and handing qualities assessmentand wind disturbance checking. The global gain schedule is developed with thescheduling variable of dynamic pressure to transfer gains smoothly betweenthese two trim points. In addition, the poles movement of short period mode withthe varying CG position are analysed, and some approaches of control systemdesign to address the problem of reduced stability induced by CG variation arediscussed as well. To achieve the command control for the aircraft, outer loopautopilot both pitch attitude hold and altitude hold are implemented by using theroot locus method.By the existing criteria in MIL-F-8785C specifications being employed to assessthe augmented aircraft response, the SAS linear controller with automaticchanging gains effectively improve the stability characteristic for the referenceBWB aircraft over the whole envelope. Hence, the augmented aircraft equals toa good characteristic controlled object for the outer loop or command pathdesign, which guarantee the satisfactory performance of command control forthe BWB aircraft.The flight control law for the longitudinal was completed with the SAS controllerand autopilot design. In particular, the SAS was achieved with Level 1 flying andhanding qualities, meanwhile the autopilot system was applied to obtain asatisfactory pitch attitude and altitude tracking performance.
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