Patent GB-718210-A (GB)
Title: Magnetic indicator-recorder system
IPC: G01C21/14
Filed: 1952-05-26
Abstract: 718,210. Course-recording apparatus. BENDIX AVIATION CORPORATION. May 26, 1952 [June 7, 1951], No. 13334/52. Class 97(2) [Also in Groups XIX and XXXV111] Course-recording apparatus comprises plotting mechanism suitable for indicating the distance and bearing of an aircraft from a given point and its heading. The mechanism comprises a magnetic positioner 12. Fig. 1, on a distance carriage 13 which, moves on a track 19 in response to rotation of a screw 14 driven through gears 10, 11 by a distance drive motor 15 which also drives through gears 10, 20 a distance self-synchronous generator 16, Fig. 3, and through gears 10', 21 a distance follow-up helical potentiometer 17. The position of the carriage 13 along the screw 14 is controlled by a voltage derived from a distance measuring equipment 55 which may be of the transponder type. This voltage is supplied via lead 56 to a D.C. comparator 57 where it is compared with a voltage derived from the potentiometer 17 whose input is provided by a D.C. power supply 58 over lead 59 and whose output on lead 61 is proportional to the setting of the carriage 13. A predetermined portion of this voltage appears on lead 62 from the output of a scale selector distance-calibrating network 63 and is applied to the comparator 57. The difference voltage existing between those on leads 56, 62 produces an output signal on lead 80 which controls a servo amplifier 64 and provides an output signal on lead 65 which drives the distance motor 15 in the direction which will reduce the voltage difference to zero. Mounted on the carriage 13 in geared relation with the position indicator magnet 12 is a heading repeater 18 which together with the generator 16, motor 15 and distance carriage assembly is mounted on a radial carriage 22 rotatably driven about an axis 23 by a radial drive motor 24 energized by a servo amplifier 66 controlled from the output signals of an omni-range device 67 and follow up device 25. The position of the heading indication of the positioner 12 is controlled by heading repeater 18 driven by a servo amplifier 68 under control of a heading information device for example a flux-gate compass 69 and the follow-up signal of a device 71 positioned by a repeater 26. The heading repeater 26 is attached to a heading indicator dial 27 and a distance repeater 28 is. attached to distance dials 29 with a scale mask 31 operated by a select distance dial 32 which also operates a selector switch 33 which together with a potentiometer 34, controlled by a calibrate distance knob 35, acts in circuit with the potentiometer 17 to control' the reference voltage in the distance servo. A pointer 37 fixed to the radial carriage 22 indicates the bearing of an aircraft from the reference position against a fixed peripheral scale 36 and a radial calibrating knob 38 provides a manual adjustment of the follow-up device 25 for calibration of the radial position of the carriage 22 and indicator 37. A map 41 of non magnetic material with a suitable backing is provided with the reference point at its centre coincident with the axis of shaft 23. A magnetically oriented rolling indicator 43 rolls on the upper surface of the map 41 in correspondence with the position of the magnet 12 moving along its under face. The magnet 12, Fig. 4, has a cone shaped pole 73, is pivoted about an axis 72 and has an offset arm 77 the tip of which is a magnetic pole if desired of opposite polarity to pole 73. The indicator 43 comprises a magnetic ball 74 which may be housed in a housing 75 with an ink supply 76 so that the ball prints its track on the map 41 while a magnetic tail portion 78 follows the arm 77 to indicate the heading of the aircraft.