Patent GB-814336-A (GB)
Title: Aircraft control system
IPC: G05D1/04
Filed: 1957-01-02
Abstract: 814,336. Automatic control systems for aircraft. BENDIX AVIATION CORPORATION. Jan. 2, 1957 [Jan. 13, 1956], No. 225/57. Class 38 (4). An aircraft is manoeuvred by servomotors controlled manually by a controller which can be arranged, at will, to produce an attitude, about an axis, corresponding to the displacement of the controller, or to produce a rate of change of attitude, about the same axis, corresponding to the displacement of the controller. Straight and Leve flight.-As shown, roll of an aircraft is automatically corrected by signals from the roll pick-off 49 of a gyro vertical 52 which are applied through an inductive device 46 and valves 53, 30 to control an aileron servomotor 13. Follow-up signals are provided by an inductive device 23 adjusted by servomotor 13 and stabilizing signals from pick-off 56 of a rate of roll gyro 58 are applied to aileron control system through valve 30. Heading deviations of the aircraft are automatically corrected by an earth inductor compass 39 producing signals which are applied through a motor-driven repeater 36 and valves 44, 53, 30 to control the aileron servomotor 13. To produce co-ordinated turning during correction the signals applied to control the aileron servomotor are also applied through valves 61, 31 to control a rudder servomotor 14. Follow-up signals are provided by an inductive device 24 adjusted by servomotor 14 and short term yaw oscillations are automatically corrected by signals from pick-off 69 of a rate-of-turn gyro 67 which are applied through a high-pass filter 71 and valve 31 to control the rudder servomotor 14. Sideslip is automatically eliminated by signals from pick-off 64 of a dynamic vertical detector 66 which are applied through valve 31 to control the rudder servomotor 14. Deviations from a desired altitude are automatically corrected by signals from pick-off 86 of an aneroid 79 which are applied through valves 96, 106, 32 to control an elevator servomotor 15. Rate of change of altitude signals are added to the altitude deviation signals from a generator 84 driven by a motor 82 maintaining a further pick-off 80 associated with aneroid 79 in a null condition. Follow-up signals are provided by an inductive device 25 adjusted by servomotor 15 and stabilizing signals from pick-off 111 of a rateof-pitch gyro 113 are applied to the elevator control system through a high-pass filter 109<SP>1</SP> and valve 32. Pitch deviations produce signals from the pitch pick-off 102 of gyro-vertical 52 which are applied through an inductive device 99 and valves 106, 32 to control elevator servomotor 15 for a short time until a motor 103<SP>1</SP> automatically eliminates them by adjusting inductive device 99. Manoeuvring. When it is desired to obtain angles of pitch and roll corresponding to the extents and senses of movements of a manual control column 119 from a central position in which it is locked during straight and level flight, a push-button D on the column is operated momentarily to energize self-holding relays B and G which release control column locks 126, 128 and de-energize clutches 37, 89 to disconnect the altitude and heading detectors. The control column may then be moved about one axis to adjust an inductive device 94 which applies signals through valves 96, 106, 32 to adjust the elevator servomotor 15 to a corresponding position. Movement..of the control column about a perpendicular axis adjusts the inductive device 46 to set the ailerons in a corresponding position and hence produce a turn. When it is desired to apply rates of pitch and roll corresponding to the extents and senses of movements of the control column 119, a push button R on the column is operated momentarily to energize self-holding relays C and E which also release the control column locks and disconnect the altitude and heading detectors. Operation of relay E also ensures that (a) only signals from control column operated device 94 and the rate-of-pitch gyro 113 control the elevator servomotor to set the rate of pitch; (b) only signals from a control column operated device 160 and the rate-of-roll gyro 58 control the aileron servomotor to set the rate of roll; and (c) turn is prevented by disconnecting from the rudder control system the signals from the aileron control system and from the side-slip detector so that the rudder is controlled by rate-of-turn gyro 67 only. Operation of control column 119 to set rates of pitch and roll is opposed by motors 108, 109 controlled by the signals from control column operated devices 94 and 160 respectively, so that the control column returns to a central position when released. When switch A1 is operated to disconnect the control surfaces from their servomotors by de-energizing clutches 20, 21, 22, motors 108, 109 maintain the control column in positional correspondence with the pitch and roll attitudes in readiness for smooth re-engagement of control. Sustained follow-up signals due to trimming of the craft are eliminated from the control system by high-pass filters 26, 27, 28. Specifications 662,831, 662,833, 679,560 and 807,111 are referred to.