GB825131A - Improvements in automatic control systems for aircraft - Google Patents

Abstract

825,131. Automatic steering control systems. BENDIX AVIATION CORPORATION. April 30, 1956 [May 13, 1955], No. 13233/56. Class 38 (4). In an aircraft automatic pilot a first electric signal dependent on aircraft displacement from a reference position is applied to an electromechanical device which produces a second signal proportional to the first signal for longterm variations of the first signal but produces no appreciable signal for short-term variations, the two signals assisting each other to restore the aircraft to its reference position. As shown, deviations in the pitch attitude of an aircraft from a value determined by the setting of a manual knob 46, are detected by a gyroscope 10, signals from the inductive pick-off 13 of which are applied through an amplifier 16 to operate a servomotor 18 correcting pitch by adjusting elevators 20. Position and rate follow-up signals are fed back to the input of amplifier 16 from an inductive device 23 and an A.C. generator 25 operated by servomotor 18. To maintain constant altitude a switch 27 is closed to energize an electromagnetic clutch 30 coupling an inductive pick-off 33 to an aneroid bellows so that deviations from the altitude obtaining when switch 27 is closed are automatically corrected by signals from pick-off 33 applied to the input of amplifier 16. Signals from pick-off 33 are also applied through an amplifier 37 to operate a motor 38 which, by virtue of rate feedback from a generator 45, runs at a speed dependent on altitude error. A pick-off 41 adjusted by motor 38 thus applies to the input of amplifier 16 a signal dependent on the integral of altitude error. When knob 46 is moved from a central position to change pitch by adjusting an inductive device 47 to apply a further signal to the input of amplifier 16, a switch 27c is opened to de-energize clutches 30 and remove the altitude and integral of altitude control signals. The resultant control signal is also applied through an amplifier 50 to operate a servomotor 51 which by virtue of positional feedback from an inductive device 53 introduces a further signal dependent on pitch error into the input of amplifier 52. Large rate feedback from a generator 16, however, delays the build-up of this further signal so that it is only effective to combat slowpitch oscillations corresponding to " porpoising " of the aircraft. Specification 662,853 is referred to.