AN INVESTIGATION OF AN AUTOMATIC AIRSPEED CONTROL SYSTEM FOR THE KC-135 APPROACH AND LANDING SYSTEMS.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING
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The purpose of the study was to investigate the design of an automatic airspeed control system and its effect on the pitch handling characteristics of the KC-135 when used during landing approaches. The longitudinal equations-ofmotion for the KC-135 and the pitch channel of the Bendix PB-20D autopilot were simulated. Three configurations of an airspeed control system were designed, using root locus techniques, which were added to the simulation and their response tested. Performance was satisfactory for two of the configurations one for a manually flown aircraft, and one for an automatically flown aircraft. The study revealed a difference in the airspeed control system design requirements for a manually and an automatically flown aircraft. Also shown was that an airspeed control system with a response rapid enough to control the airspeed satisfactorily during landing approaches will cause several reversals of the pitch trim of the aircraft caused by the thrust changes and results in a deterioration of the pitch handling characteristic of the aircraft. Author