Abstract: A method and apparatus for reducing the unwanted sideways motion of an airplane by reducing the lateral side loads and upsets caused by atmospheric turbulence and gusts is disclosed. A rudder modification command that causes the rudder command of the airplane to be changed in a manner that relieves the net force across the vertical stabilizer of the airplane caused by atmospheric turbulence and gusts is produced. More specifically, the pressure differential across opposite sides of the vertical stabilizer is measured and used to produce a rudder deflection value that is roll rate and yaw rate compensated. The compensated deflection value is high-pass filtered with a corner frequency that is twenty-five percent (25%) of the Dutch roll frequency of the airplane. The result is a first rudder deflection value that is subtractively combined with a second rudder deflection value.

Abstract: A method and apparatus for detecting oscillatory phenomena indicative of airflow separation or sensor common mode oscillatory failure is disclosed. The oscillations of a differential pressure transducer that senses the pressure difference on the opposite sides of an airfoil are bandpass filtered to remove oscillations lying outside of a band of interest. Oscillation peaks lying within the passband that exceed a positive or negative threshold produce pulses that are counted. The counter value is decremented each time an alternating peak is not detected within one-half cycle of a minimum frequency. If the allowable count threshold is exceeded, a latch is set. Setting the latch produces a command that can be used to inhibit the operation of systems that rely on data produced by the differential pressure transducer. An alternative path senses the position of a control element (e.g.

Abstract: When an aircraft is operating in an asymmetrical flight condition, such as during a landing decrab maneuver or during inflight engine out, the pilot is normally required to make precise compensatory roll control inputs to keep the aircraft moving along its original track angle. The pilot is relieved of this compensatory roll control task by providing a control system which automatically banks the aircraft to maintain the flight of the aircraft along the selected track angle while in the asymmetrical flight condition. Further adjustments in the bank angle of the aircraft are made automatically by a track angle feedback control system so that the aircraft remains on the selected track angle even when subject to external disturbances such as crosswind gusts and shear.

Abstract: There is provided a controller for aiding a pilot to control an airplane's track over the ground. While the airplane is in the air, a lateral control subsystem is provided for automatically holding the aircraft aligned with a desired track angle. Control is initiated when the pilot places the airplane in a wings level condition and centers his roll axis controller (e.g., wheel or stick). An in-air track rate control subsystem is also provided. While the airplane is on the ground, a directional control subsystem is provided which enables the pilot to command track rate or heading rate with rudder pedal inputs. The track/heading rate commands are integrated to generate track/heading angle commands. Feedback control is used to position the rudder and nosewheel steering as required to make the airplane's actual track/heading follow the track/heading commands. Provisions are made to initialize the in-air lateral and on-ground directional control subsystems to provide smooth transitions during takeoff and landing.

Abstract: A controller for apportioning high amplitude and low amplitude control signals between two aircraft control surfaces, such as for example, between an elevator and an associated movable horizontal stabilizer. The signals are separated along a first path and a second path. Signals along the first path are fed to a low pass filter where the low frequency signals are separated and an elevator position error signal is generated. Those signals exceeding a predetermined elevator position error are fed in the form of stabilizer rate signals to a stabilizer position module where a stabilizer positioning signal is generated and then fed to a stabilizer servo system to reposition the horizontal stabilizer. The stabilizer positioning signal is also fed to a multiplier where it is multiplied by a predetermined pitch effectiveness ratio representing the amount of elevator deflection required to achieve the same pitch moment as one degree of stabilizer deflection.