Patent GB-103131-A (GB)
Title: Improvements in Anti-air-craft Guns.
Inventor: DUNPHY AUGUSTINE LOUIS
IPC: F41G3/00
Filed: 1916-01-06
Abstract: 103,131. Dunphy, A. L. Jan. 6, 1916. Sights and methods of sighting; ordnance, discharging by means external to breech mechanism. -Relates to sighting-apparatus for anti-aircraft guns, of the kind provided with cam-controlled adjusting-means which, after an initial adjustment for range, automatically determines the firing angle as the sight is laid on the target. The invention comprises an arrangement wherein the cams are designed according to horizontally-projected ranges, and which is used in conjunction with a range-finding device embodying a topographical chart upon which the projection of the target is indicated by the intersection of a pair of azimuthal pointers, operated or controlled respectively from the gun and from a distant observation station. The sighting-telescope h, Figs. 2 and 3, is carried by a bridle frame d straddling the gun barrel and pivoted on the gun trunnions. Upon a shaft e mounted in the frame d is secured a pair of pinions f in engagement with a pair of fixed quadrantal racks c on brackets a fixed to the main carriage or support. The pinions and racks may be supplemented by smooth rolling tracks b. The main carriage is rotated about a vertical axis to bring the gun into the vertical plane containing the target, whilst the frame d is adjusted to bring the sighting- telescope on to the target by means of gearing comprising a hand-wheel j operating a worm l to rotate the shaft e by means of a worm-wheel f<1> fixed thereon, thereby causing the pinions f to roll on the fixed tracks c, carrying with them the frame d. At the gun station, a chart or map, Fig. 5, of the surrounding district is fixed in position. The centre of the chart represents the gun station, and a series of equally-spaced circles are drawn, representing distances to a specified scale. Topographical features may be indicated, and also the positions of one or more neighbouring observation stations or the like. In order to indicate on the chart the position over which an enemy aircraft is passing, a pair of azimuthal pointers V, a<8> are arranged to follow the movements thereof, the pointer a<8> being centred about a spot a<6> on the chart corresponding to an observation station a<7>, from which its movements are directed by telephone, whilst the pointer V is centred at the gun position, and is caused to indicate the azimuthal direction of the gun, being rotated as the gun is moved about its vertical axis, by means of transmission gearing s, t, u. The position over which the target is passing is indicated by the intersection of the pointers as at b<3>, and the distance of such spot from the gun, termed the horizontally-projected range, is denoted by the circle graduations. The pointers may comprise silk threads stretched on bows or frames. To facilitate directing the pointer a<8>, the edge of the chart is graduated in degree divisions from the centre a<6>. The range correction on the gun is effected by means of a cam-device g, consisting of a series of edge cam-plates, each cam being designed to impart the required angular displacement between gun and sight, for a series of heights of target at a certain horizontallyprojected range. Thus, a cam-plate g may be provided corresponding to each circle depicted on the chart. The series of cam-plates are bolted together to form a cam-barrel slidably keyed to the bridle shaft e and adjustable axially to bring the desired cam-plate into action, by means of a hand-wheel z, gearing b, b, and a rack and pinion a'. As the sight is brought on to the target by adjustment of the frame or bridle d, the camplates g are rotated together with the shaft e, thus bringing into action the portion of the camperiphery corresponding to the height or angle of site of the target. The gun is then elevated by ordinary means until a spring-mounted stud n carried on the gun barrel or cradle comes into contact with the selected cam, thereby enabling the gun to be fired by a trigger r, or effecting firing-contact electrically. The cam-plates may be marked to indicate required fuse-timings. For extreme adjustments, the sighting-telescope, instead of being a fixture, may be adjustable relatively to the bridle frame, being carried on a bracket or arm a<2> having an indicator a<3> and adapted to be displaced by means of a handwheel a' and worm gearing, as shown. The gun may be so balanced about its trunnions that, when loaded, its muzzle tends to rise.