Patent GB-163341-A (GB)
Title: Improvements in predicters for anti-aircraft and other gunnery
IPC: F41G5/08
Filed: 1918-07-09
Abstract: 163,341. Barr & Stroud, Ltd., Barr, A., and Stroud, W. July 9, 1918. Sights and methods of sighting.-An instrument for use in gunnery which predicts the position of an aircraft or other rapidly-moving target after an interval corresponding to the time of flight of a shell to that position, and which indicates the ballistic data for use on the gun, comprises mechanism for indicating the projected position on a chart. In the diagram, Fig. 3, AB represents the telescope, H is a rod. representing the height, and DE a rod equal to OA, A and O being fixed points. OE being equal to AD equals the horizontal range and E represents the chart position and movement of the target. The mechanism, Figs. 2, 4, consists of the telescope 13, with right-angled eye-piece operated by the vertical rack 7 and pin-and-slot connection 11, 12. The rack slides in a nut 14 and is adjusted for height by the hand-wheel 1, worm and wheel 8, 9, and elongated pinion 10, the height being indicated by screws 2, nut 3, and pointer and scale 4, 5. The nut and rack are moved horizontally to keep the telescope on the target by a screw 15 and handwheel 18, the nut being fixed vertically by a forked extension which engages a guide rod 16. A rod 17 carrying a pointer E is fixed to the nut 14. The apparatus can be rotated about axis OO<1> and the distance O-E represents the horizontal range as in Fig. 3. The means for determining the ballistic data for the gun, Figs. 5 and 6, comprise a drum 22 having a chart thereon, Fig. 7 or 8, and having its axis set parallel to the direction of motion of E by the operator rotating the apparatus. The movement of the drum in keeping the pointer E on a sloping line is a measure of the chart speed. Means are provided for multiplying the chart speed by the time of flight and the dif-* ferential gear 36, 37, 38 adds this product to the chart speed, the sum being indicated on the chart by the pointer E<1> for use on the gun. In the diagram, Fig. 9, XY represents the chart speed v, ZV represents times of flight T, and and therefore represents the product of chart speed by time of flight. The corresponding mechanism, Fig. 5, comprises a slotted rocking bar 27 having a fixed pivot 26, a pin 25 corresponding to the point Y, and a pin 28 to the point W, working in slots as shown. The pin 28 and drum 22 are moved by the head 21 and gearing shown. By setting off the time on a drum 29 and pointer 60, a frame 32 carrying pin 28 is adjusted through pinions 30 on the shaft of the drum and racks 31 on the frame. The frame 32 has a rack 34 engaging a long pinion 35 on a spindle carrying the jockey element 36 of the differential. The bevels of the differential gear have pinions 39, 40 fast thereto, and racks connected to pointers E and E<1> gear therewith, as shown, and the movement of E<1> indicates on the chart the movement of E plus the product v.T. To determine the time of flight, a rack 50 connected to the pointer E' engages a pinion on a chart drum 6, Fig. 4, having time curves, Fig. 10. for height and horizontal range thereon. Specification 4651/15 is referred to.