GB827199A - Compass direction indicating system - Google Patents

Abstract

827,199. Direction indicator systems. BENDIX AVIATION CORPORATION. June 19, 1956 [June 30, 1955], No. 18979/56. Class 40 (1). In a direction indicator system for aerial navigation, indication is derived from a magnetic compass, or from a directional gyro, compensation being provided for drift, or from the gyro corrected by the magnetic compass. As shown, when a selector switch 36 having five ganged three-position contact arms 31-35 is in its uppermost position, the system is operated by a magnetic compass 10, preferably of the flux gate type, connected to the energized rotor 12 of a selsyn transmitter 11, rotation of which upon deviation from course produces in the rotor 16 of a selsyn receiver 15 a signal which is fed via a pre-amplifier 37 to an amplifier 38, the output of which is applied to a motor 39 which rotates the rotor 16 and an indicator dial 17 until the rotor 16 is in its null position; motor 39 also drives autopilot apparatus 41 and a transmitter 42 for remote indication. The output from a rate generator 43 driven by the shaft of motor 39 is dropped across a potentiometer resistor 44, a point on which is connected to the amplifier 38 to maintain the speed of the motor 39 constant. When the selector switch 36 is in its lowest position the system is operated by a directional gyro 18 through selsyns 20 and 23, a signal from the rotor 24 of the latter being fed to a gyro amplifier 45 whose output is transmitted to the motor 39. Gyro drift is compensated by the angular displacement of the stator 22 of the receiver selsyn 23 by a motor 62, fed through amplifier 38 with a signal from a potentiometer 50, the position of the pointer 51 on potentiometer resistor 49 being determined by manual operation of a knob 54 associated with a latitude scale 56, or of a knob 59, the speed of motor 62 being kept constant by utilizing the output of a rate generator 70. The stator 22 may be manually set by operation of a knob 67. When the selector switch 36 is in its intermediate position the system is operated by the gyro 18, stabilization being provided by the magnetic compass 10, any error signal produced in selsyn receiver rotor 16 due to non-correspondence of the positions of transmitter rotors 12 and 19 being fed after amplification to motor 62 which displaces gyro selsyn receiver stator 22. In an alternative embodiment (not shown) maintenance of motor 62 at a constant speed is effected by a mechanical escapement, the rate of drift compensation applied to stator 22 being determined by the position of the roller in a disc and cylinder drive between the escapement and the stator 22, said position being set in accordance with latitude. Specification 550,399 is referred to. Reference has been directed by the Comptroller to Specification 747,207.