Patent GB-941005-A (GB)
Title: Aircraft automatic control systems
IPC: G05D1/04
Filed: 1960-12-02
Abstract: 941,005. Automatic control of aircraft. SPERRY RAND CORPORATION. Dec. 2, 1960 [Dec. 2, 1959], No. 41560/60. Heading G3R. In an aircraft automatic pilot the rudder servomotor is controlled by a signal, having components dependent on accelerations of the aircraft about its yaw and roll axes, which is derived from a single angular accelerometer device. In Fig. 1, short term stabilization is provided by accelerometers 11, 12 which are respectively arranged below and above the longitudinal axis of the aircraft, on either side of the centre of gravity, so that electrical signals which are dependent on both yaw and roll acceleration are obtained by combining their outputs, these signals being converted to rate signals by an integrator 21 and applied through an amplifier 26 to control a rudder servomotor 31. The acceleration signals are also applied to amplifier 26 through a noise filter 22. Servomotor 31 also operates an inductive device 36 and a tachometer generator 33 which apply position and rate feedback to the input of amplifier 26. Feedback from the output to the input of amplifier 26 is provided through a low pass filter 41 to eliminate drift and permit manual rudder trim with the automatic pilot engaged. Electrical signals from a gyro-magnetic compass 42 are applied to an inductive device 44 the output of which is applied to an amplifier 46 of a servo-system 45 which adjusts the rotor of inductive device 44 so as to reduce its output. The time constant of servo-system 45 is such that high frequency variations of heading are transmitted through inductive device 44 to amplifier 26 of the rudder servo-system and to a smoothing circuit 60 controlling the aileron servo-system 76 which is also responsive to signals from the roll pick-off of a gyro-vertical 73. Low frequency variations of heading, however, are only effective to cause servo-system 45 to adjust an inductive device 54, output signals of which are applied to aileron servo-system 76. Turns may be effected by a potentiometer 70, manual operation of which applies a signal to the aileron servo-system and de-energizes a clutch 53 to disengage automatic control by inductive device 54. During such turns or when the automatic pilot is otherwise disengaged, the time constant of servo-system 45 is reduced by altering the ratio of gearing 52 so that the output of inductive device 44 is maintained at zero in readiness for a new heading under automatic control. A switch 65 may be set to introduce a further heading selector 80. When it is desired to introduce ILS radio control a switch 47 is changed from the position shown and a switch 61 moved to the position shown so that signals from a radio receiver 69 control integrating servo-system 45 and thus adjust the position of inductive device 54 which controls the aileron servo-system. Switch 65 introduces a circuit 64 so that both the radio signals and their rate of change control the aileron servo-system through smoothing circuit 60. For VOR radio control switch 65 is moved to cut out rate circuit 64 and introduce a bearing selector 66. A switch 67 is also closed to introduce signals from inductive device 44 to the aileron servo-system. In the zone of confusion over the VOR transmitter a detector of erratic signals (not shown) operates a switch 56 to clamp servo-system 45 until the zone is passed. When automatic control is disengaged de-energization of an electromagnetic device 55 re-centres inductive device 54 in readiness for re-engagement. Specifications 854,732, 941, 006 and U. S .A. Specification 2, 883, 176 are referred to.