Patent GB-194826-A (GB)
Abstract: 194,826. Barr & Stroud, Ltd., Barr, A., and Stroud, W. Dec. 28, 1921. Gunnery calculators.-Relates to apparatus for use with anti-aircraft guns and consists in means for ascertaining the change of range and deflection in the vertical plane of sight and in a plane at right-anges thereto for the purpose of determining the quadrant elevation, fuse setting, and angle of bearing for the predicted position of the target assuming this to be travelling at a constant speed and at a fixed height. The sighting apparatus 15, 16 is maintained on the target by adjusting the handles 1, 30, 40, 60 and 61, for the known height of target, the initial angle of sight, the initial angle of bearing, the velocity of approach of target, and the angular velocity in azimuth respectively and by means of the predicting mechanism the pointers 96, 98, and 106 indicate the corrected quadrant-elevation, fuze setting, and azimuth angle respectively. The handle 1 through gearing 3-6 rotates surface cams 2, 7, and 8, and a long pinion 9 which gears with a rack 10 having a pin 11 engaging a slot in the arm 13 fixed to the shaft carrying the telescopes. The rack is guided in a transverse bar 22 having a nut 21 working on a screw actuated by an adjustable rate-changing mechanism 32 - - 37 associated with the handles 30 and 60, so that a plunger 25 engaging the cam 2 is raised in accordance with the time of flight by the cam being rotated through an angle representing the known height and by the plunger being shifted laterally in accordance with the horizontal range. The plunger 25 carries a rack gearing with a long pinion 70 to which is fixed a wheel 71 engaging a rack 72 that carries a pin 73 working in the slot of a pivoted arm 74. The handle 60 also sets a nut 81 carrying a rack 82 provided with a pin 83 engaging a slot in an arm 84 integral with the arm 74. The rack 82 gears with a long pinion 85 and rotates it in accordance with the change of range in the time of flight the motion being communicated to toothed wheels 86, 88 by means of screws 87, 89 laterally moving the frame 90 carrying the surface cams so that the plungers 26, 27 now rest upon portions of the cams corresponding to the predicted position and the indications are transmitted through pinions 95, 97 to the pointers 96, 98. Meanwhile the actuation of the handles 40, and the associated variable ratechanging mechanism 41, 47 actuates pinions 52, 53 gearing with wheels 54, 55, in such a manner that the dial 56 carried by the wheel 54 remains fixed relatively to the ground, the wheel 55 being fixed to the stand. To obtain the change of deflection in the time of flight of the projectile the handle 61 actuates a screw 102 that carries a nut 101 having a rack 103 with a pin 104, engaging the slot in the arm 74 and this rack gears with a long pinion 105 connected to the pointer 106. If the height of the target varies the height may be dealt with in much the same way as the horizontal speed of the target and rate of change of deflection by means of a rate-changing mechanism which imparts an additional rotation to the surface cams. The rate of change of height must be adjusted after setting the initial height so that a pointer associated therewith will follow the pointer of the height finder. In the case of using the instrument on board ship means such as described in Specifications 174,422, [Class 97 (i), Optical systems &c.], and 189,870 must be provided to maintain the frame axis vertical, to keep the frame in a fixed direction in space, and to compensate for the pitching, rolling and yawing of the ship. Specifications 125,455, 126,798, 129,345, [Class 97 (i), Optical systems &c.], 163,341, and 189,850, [Class 97 (iii), Thermometers &c.], also are referred to.