Patent GB-637993-A (GB)
Title: Improvements in or relating to gyro-verticals
IPC: G01C19/44
Filed: 1946-03-13
Abstract: 637,993. Gyroscopic apparatus. STEVENS, A. H. (Sperry Gyroscope Co., Inc.). March 13, 1946, No. 7913. [Class 97 (iii)] [Also in Group XXXV] Relates to gyro verticals having gravitycontrolled erection devices of the type in which the erecting torque is substantially proportional to the relative displacement between the gyro and the gravity controller and having the axis of total angular momentum directed at a small angle to the vertical to correct for acceleration errors during turning. Means are provided for adjusting the magnitude of the horizontal component of the angular momentum whilst the gyro is in operation so as to eliminate turn errors and linear acceleration errors for all rates of turn and at any speed of the craft. As shown in Fig. 1, the rotor casing 1 pivots on a transverse axis 3 in a U-shaped frame 4, pivoting on a fore-and-aft axis 2. Erecting torques are applied by motors 16, 16<SP>1</SP>, controlled by transformer pick-offs 14, 14<SP>1</SP>, which are associated with pendulums 7, 8, pivoted to the frame 15 carrying the pick-offs by leaf springs 11, 12. The frame 15 is carried by a bail 9 which is independently pivoted on the axis 3 and may be angularly adjusted relatively to the rotor casing 1 by gearing 18-22 and motor 23. The latter is controlled by the output of a Selsyn signal generator 28 connected with a transmitter 27<SP>1</SP> tuned by the movement of the bellows 25 of a true air speed indicator of the type described in Specification 596,968, [Group XXXV]. The horizon bar 5 is carried by the bail 9, which is maintained in the true vertical whilst the casing 1 is tilted forward by the motor 23 through an angle proportional to the true air speed. In a modification in which the erecting torques are derived from the eddy currents induced by a pendulously mounted magnet in a conducting cup fixed to the rotor spin axle, the pendulous magnet is caused to hang at the required angle to the vertical by a mass which is laterally thereon under control of an air speed indicator. In the form shown in Fig. 2, the rotor casing 11 is erected into the vertical under control of the pendulums 54, 54<SP>1</SP>, and the horizontal component of angular momentum is provided by an auxiliary gyroscope 50 pivoting on casing 1<SP>1</SP> about a transverse axis and tilted through the required angle X by a motor 23<SP>1</SP> controlled by the true air speed indicator 25. To effect a control proportional to the tangent. of the angle of relative displacement between the pendulum 54 and casing 1<SP>1</SP>, a follow-up motor 61 drives a shaft 58 in accordance with the amplified output of a Selsyn signal generator 57 mounted on shaft 58 and connected to a Selsyn transmitter 56 at the pendulum 54, and the shaft 58 operates a tangent computing autotransformer winding 70 energized between spaced taps 71, 72 and provided with a centre tap 73 which is equidistant from the taps 71, 72 and the shaft 58. The voltage output between the centre tap 73 and a slider 74 on the shaft 58 is then proportional to the tangent of the angle of rotation of shaft 58 and is used for controlling a solenoid 62 for applying torques to an armature 63 connected to the transverse trunnion 3<SP>1</SP> of the gyro 1<SP>1</SP>. The pendulum 541 controls erecting torques about the fore and aft axis in a similar manner. The correcting torque applied to the main gyro by the auxiliary gyro 50 during turns is proportional to the centrifugal force and in order that this may be measured and transmitted as a correction to other apparatus, the auxiliary gyro 50 may be mounted in a gimbal ring which is journalled about a fore and aft axis on the main gyroscope and anchored thereto by stiff springs. The force exerted between the two gyros will result in a small tilt of the gimbal which may be measured by a pick-off and transmitted to a distance. In further modifications, a single gyro, tilted forward at a constant angle corresponding to the normal airspeed, has its rotor speed automatically adjusted under control of an air speed indicator so as to compensate for variations in the speed of the craft. Specifications 492,670 and 624,564 also are referred to.