Patent GB-611029-A (GB)
Title: Improvements in or relating to automatic pilots
IPC: G05D1/08
Filed: 1945-01-04
Abstract: 611,029. Automatic control systems. SMITH & SONS (ENGLAND), Ltd., S., and MEREDITH, F. W. Jan. 4, 1945, No. 430. [Class 38 (iv)] [Also in Group XX] In an automatic pilot for aircraft the electric signal controlling the elevators contains a component proportional to the differential of the square of the rate of turn or varying with the product of the rate of turn and the differential thereof. In the form shown, the system automatically (or manually when desired) controls an aircraft about all three axes. The power for the various controls is from a 400- cycle source, not shown. To set the pitch datum a control column in the pilot's panel 13 is tilted backwards or forwards until the desired value shown by the attitude indicator 20 is reached, this tilting causing a pitch rate voltage from panel 13 (amplified at 16) to energize motor 17 which rotates shaft 4 carrying part of a pitch detector 5, the other part of which is on shaft 2 of gyro vertical 1. This detector, which may be a potentiometer or an induction pick-off, feeds a signal 6 to amplifier 59 for the elevator motor. To set the yaw datum, the column is tilted to one side or the other until the indicator shows the required setting, this tilting causing a yaw rate voltage from panel 13 (amplified at 25) to energize motor 26 which rotates the turntable 11 of gyro 10 which gives a signal to amplifier 59 for the rudder motor. The yaw rate voltage is also applied to motor 36 which adjusts a slider on one potentiometer (not shown) of bank computer 32, the voltage applied to this potentiometer being from generator 34 driven at air speed by air mileage unit 35. The voltage obtained from this potentiometer is fed to motor 43 driving one part of bank detector 8 on shaft 7 through banking unit 44. The other part of detector 8 is on shaft 3 of gyro 1 and feeds a signal to the aileron operating motor. The motor 43 also operates the roll element of indicator 20. A pendulum 50 pivoted about the pitch axis causes the feeding of a voltage proportional to its displacement from gyro shaft 2 to a motor 53 applying a torque to the roll gimbal axis to effect erection of gyro 1 about the pitch axis, while to effect erection about the roll axis a pendulum pivoted about this axis causes a voltage proportional to its displacement to be fed to motor 57 through amplifier 56 which is partly controlled by banking unit 44. The gyro 10 is stabilized against wander in the magnetic meridian by a compass 61 mounted on a turntable synchronized with turntable 11. The rudder, aileron and elevator motors also drive hysteresis generators and are of the twophase hysteresis type, one phase of each motor and generator being energized from the 400- cycle supply, the other phase of the generator feeding a voltage proportional to motor speed to the amplifier. Each amplifier is connected to a differentiating unit 60 stated to give a signal at terminal b proportional to the signal fed in directly at terminal a. The amplifier for the elevator motor also has a terminal c for an additional signal from computer 32. In a modification, Fig. 2, the motor-generators and associated amplifiers are replaced by motor units each consisting of an amplifier with terminals ABC to which up to three input voltages can be applied and which feeds one phase of a hysteresis motor driving a hysteresis generator also two geared shafts F, G, one phase of the generator feeding a terminal E also back into the amplifier and the other connected (with the other motor phase) to a 400-cycle supply, while three-phase output terminals D are connected to a transmitter on shaft F having its primary connected to the 400-cycle supply. With this arrangement the speed of the motor is proportional to the resultant of all the inputs. This modification, also the functioning of the gyroscopes, is described in greater detail in the abridgment of Specification 611,030. Specifications 576,248, 576,249,576,351 and 611,020 also are referred to.