Patent GB-611011-A (GB)
Title: Improvements in or relating to devices for detecting or measuring rate of turn
IPC: G01C19/56
Filed: 1943-01-13
Abstract: 611,011. Measuring rate of turn of aircraft. SMITH & SONS (MOTOR ACCESSORIES), Ltd., S., and MEREDITH, F. W. Jan. 13, 1943, Nos. 667 and 15951. [Class 97 (iii)] Relates to a device for detecting or measuring rate of turn of, say, aircraft, about the X and Y axes and comprises means for forcing two masses, mounted on a common support in the Z axis, to oscillate rotationally and oppositely about the support or Z axis and means for measuring independently the oscillations of the support forced by the first mass due to turning of the device about the Y axis and those forced by the second mass due to turning of the device about the X axis. As shown diagrammatically in Figs. 1 and 2, a flexible mass loaded shaft 31 is supported at its nodal points by two flexible diaphragms 32. Two fourspoked rimless wheels 33, 34 are mounted on the shaft 31 and each spoke carries a mass 35 on its free end, the wheels being balanced about the nodal points by masses 30 at the free ends of the shaft 31. In operation, the two wheels are caused to oscillate in opposite directions so that the couples applied to the two diaphragms are balanced. If a rate of turn takes place about the X axis the top pair of masses shown in Fig. 1 will move towards, or away from, one another and the bottom pair will move in the reverse direction causing an oscillating bending moment to be applied to the shaft causing oscillations of the free ends of the shaft 31 in the plane of the paper in Fig. 1. A microphone operated by the deflection of the free ends will produce a voltage proportional to the rate of turn about the X axis. Similarly, the rate of turn about the Y axis will produce deflections of the free ends of the shaft 31 at right angles to the plane of the paper in Fig. 1 and may be similarly measured by a microphone. Fig. 3 shows a form of the device comprising a flexible shaft 31 formed in three parts, and carried by two flexible diaphragms 32 at its nodal points 36. The flexible diaphragms 32 are integral with a part of the shaft 31 and each is gripped between an inner casing 37 and a flanged sleeve 38 which latter has spokes and screws 39 to adjust the ends of the shaft 31 in relation to the four cores 41 of two pairs of electromagnets 42 as shown. A screw 48 is provided for adjustment of the nodal points so that they coincide with the diaphragm 32. At each end of the shaft 31 there is supported a spider 43 which has a certain mass and carries further masses 44 carrying cores 45 in the circuit of electromagnets 46 mounted as shown, one being a driving magnet and the other a pick-up magnet energized by the oscillations. The oscillations and directions will be referred to in terms of the X, Y and Z axis, the X and Z axes being as shown and the Y axis at right angles to the plane of the paper. Rotational oscillation about the Z axis is imparted to the masses 44 in opposite senses by the driving magnet 46. During a turn about the X axis, the reaction of the masses 44 deflects the diaphragm 32 so that the system vibrates in the plane of the paper in the direction of the X axis. The free ends of the shaft 31 are then vibrating between the cores 41 of the two magnets 42 lying parallel to the X axis and the rate of turn is measured by the voltages induced in the coils 42. Similarly, the rate of turn about the Y axis may be measured by reference to the magnets 42 disposed parallel to the Y axis. Specifications 611,005 and 611,021 are referred to. Reference has been directed by the Comptroller to Specification 601,051.