Patent GB-1111676-A (GB)
Title: Improvements in or relating to gyroscopic apparatus
IPC: G01C19/38
Filed: 1965-08-27
Abstract: 1,111,676. Gyroscopic apparatus. TELDIX LUFTFAHRT - AUSRUSTRUNGS G.m.b.H. Aug. 27, 1965 [Aug. 29, 1964; Sept. 9, 1964; Sept.15, 1964], No.36868/65. Heading G1C. A gyroscopic instrument in which the rotor spin axis is horizontal, may be selectively given rotational freedom about a vertical axis whereby the instrument becomes north-seeking and subsequently and additionally about a horizontal axis perpendicular to the spin axis whereby the instrument may be operated as a direction indicator. A gyro rotor 1 is mounted for rotation about a spin axis 2 in a bearing cylinder 3. This cylinder is mounted for rotation about a horizontal axis perpendicular to the axis 2 by means of a gas bearing in a housing 6. The housing 6 is provided with a bearing cylinder 11 and is mounted for rotation about a vertical axis by means of a gas bearing in a further housing 12. This housing is in turn mounted for rotation about a vertical axis on bearing balls 44, 45 in an inner gimbal ring 42. This ring 42 is carried by an outer gimbal ring 38 for rotation about an axis 43 and the outer ring 38 can rotate about an axis 41 in the craft in which the instrument is mounted. The vertical axes of the instrument are stabilized by a gyro-vertical 13 which may be provided with a ball erector (not shown). The gyro-vertical rotor has vanes 24 which act to provide the gas pressure necessary for the gas bearings and a cock 29 is arranged to allow the gas to pass either to support the cylinder 11 or the cylinder 3. Firstly, for operation as a north-seeking instrument, gas under pressure is supplied only to the vertical bearing cylinder 11, the bearing cylinder 3 being unable to rotate in its housing 6. With the spin axis 2 thus maintained horizontal the housing 6 tends to precess about the axis of the cylinder 11 to bring the spin axis 2 into alignment with the meridian. In so doing it flexes two leaf springs 18, 19 acting as a resilient tie between the housings 6 and 12. A position pick-off 46 detects any relative rotation between the two housings and feeds a signal to a motor 50. In this mode of operation of the instrument a switch 56 is moved to the position marked NS and this controls an electromagnet to bring a pinion 57 on the shaft of the motor 50 into engagement toothed rim 52 on the housing 12. In this way the housing 12 is slaved to the azimuth movements of the housing 6. A pick-off 58 detects the position of the housing 12 relative to the gimbal ring 42 and controls an indicator 60. When the spin axis 2 is aligned with the meridian, the switch 56 is moved to the position K disconnecting the pinion 51 and moving the cock 29 to supply gas under pressure through a passage 33 to the bearing for the cylinder 3. No gas is supplied to support the cylinder 11 and the housings 6, 12 rotate together on the bearing balls 44, 45. If the craft now moves to move the spin axis 2 away from the meridian the rotor will precess out of the horizontal. A pick-off 61 detects this movement and feeds a torquer 63 to rotate the housing 12 to return the spin axis 2 to the horizontal position. The indicator 60 then indicates direction in azimuth. A torquer 64 is also provided and connected to a setting device which delivers a torque dependent on the latitude to correct for drift due to rotation of the earth. In an alternative embodiment the vertical gas bearing cylinder 11 may be dispersed with and the housing for the gyro cylinder mounted so that the gas bearing axis is vertical during the north-seeking operation, the housing subsequently being turned so that the bearing axis is horizontal. In this case also, the gyro-vertical may be dispersed with, if desired.