Alternative Terrain Following System Concepts,
AERONAUTICAL SYSTEMS DIV WRIGHT-PATTERSON AFB OHIO
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Three terrain following system concepts were evaluated, each based on a radar altimeter for sensing terrain clearance. The first concept develops an inertial altitude rate command in response to errors in terrain clearance altitude. This command is limited and summed with the actual rate of change of inertial altitude. The normal acceleration command is generated in response to errors in the inertial altitude rate. This command must be limited in order to maintain the vehicle within aerodynamic, structural, and engine-inlet distortion constraints. The second concept develops a clearance altitude rate command in response to errors in the clearance altitude. This command is limited and summed with the rate of change of clearance altitude. The normal acceleration command is generated in response to errors in the rate of change of terrain clearance. System Concept B describes a frequently used control law. The third concept incorporates the damping feedbacks of System A and System B. Both control laws are executed simultaneously and the most positive normal acceleration command is selected for control purposes. The most positive logic scheme assures smooth switching from one control law to the other.
- Flight Control and Instrumentation
- Air Navigation and Guidance