Patent GB-511724-A (GB)
Title: Improvements relating to compass and like steering apparatus particularly for aircraft
IPC: G01C19/00
Filed: 1938-09-06
Abstract: 511,724. Fluid - pressure servomotor - control systems. SPERRY GYROSCOPE CO., Inc. Sept. 6, 1938, No, 26039. Convention date, Sept. 11, 1937. [Class 135] [Also in Group XX] An automatic steering system for aircraft includes a gyroscope supervised by a magnetic compass acting through a pneumatic pick - off and servomotor to adjust the base-line of the gyroscope pick-off. The rudder 23 is operated by a power cylinder 9 supplied with fluidpressure from a pump 22 under the control of a relay valve 21 the actuating chambers of which are coupled by pipes 19, 19<1> to nozzles in a frame 7. These nozzles are more or less obstructed by a semi - circular baffle 5 carried by the vertical gimbal ring of the gyroscope 1. To give a follow-up action the frame 7 is coupled by differential gearing 13 and cable 12 to the power device 9. The setting of the gyroscope can be adjusted through the differential gearing 13 by manipulating a knob 90 on a shaft 74 or by restricting the flow through one or other of the nozzles 66, 66<1> to cause a turbine 67 having opposed notched discs to act through worm gearing 75 to rotate the shaft 74. The flow of air through the nozzles 66, 66' is controlled by a valve device 24 actuated by a magnetic compass manually adjustable from a remote point by a knob 57 geared to an indicator and connected to the compass by a flexible shaft 55. The compass is shown in Fig. 8 and comprises permanent magnets 28 secured to a member 27 held in a part spherical bearing 31, through which air is continuously drawn, by a jewelled bearing adjustably secured in a bracket 35 on the adjustable base 26. The bearing engages a pin 36 mounted in the member 27 and extended into a central passage in the bearing pedestal to prevent undue movement of the member 27. An annular indicator card 44 is secured by arms to the member 27 and has a single index mark adapted to co-operate with similar marks on a central disc 50 secured to the bracket 35 and an outer bezel 48 fixed beneath the window 49. The member 27 is formed with a nozzle 38 from which a jet of air is drawn, adapted when the magnets are deflected to impinge on one of a pair of spring-loaded hinged plates 39<1> and to close one of the hinged valves 41<1> secured thereto and thereby prevent air being drawn through the associated passage 42, annular groove 59 in the adjustable base, pipe 32, and nozzle 66. The adjustable base forms part of a worm wheel 52 co-operating with a worm coupled by a flexible shaft 55 to an adjusting knob 57 on a remote fitting provided with an indicator and housing a manually operable valve 62 whereby the adjusting turbine can be put out of action during turning. The indicator comprises a graduated disc 77 co-operating with a fixed pointer and mounted on a sleeve 79 rotatable on a fixed pin 80 by worm gearing 81, 82 and bevel gearing 83. A vernier dial 84 co-operating with a second pointer is rotatable on the same fixed pin by toothed wheel 85, 87 coupled by an idler pinion 86. Specifications 416,813, and 466,864, [both in Group XX], are referred to.