Patent GB-191222616-A (GB)
Title: Improvements in and relating to Sighting Devices for Airship Repelling Guns.
IPC: F41G1/393
Filed: 1912-10-04
Granted: 1913-02-27
Abstract: 22,616. Krupp Akt.-Ges., F. Nov. 7, 1911, [Convention date]. Sights and methods of sighting.-Relates to sighting - devices f o r guns intended to fire at air-ships, and consists in graduating the drum upon which the required elevation of the gun for range and angle of site is indicated with two sets of graduations, one set corresponding to a definite range at any angle of site within the limits required, and the other set corresponding only to the angle of site. The pointer is automatically set to correspond to the angle of site of the target, and the sight is correctly set for a given range at that angle of site when the pointer coincides with the intersection of the two graduations for range and angle of site respectively. The sighting- device, shown in Figs. 1 and 2, is mounted on a sleeve a<2> carried by an arm A<1> on the slide carrier A, the sleeve acting as a pivot for the casing C which carries the sight C'. The sight is of the usual double telescope kind, having an cyepiece c<2> for observations taken from above. and an eyepiece c<3> for the gun-layer for lateral observation. A worm D gearing with teeth on the sleeve a<2> rotates the sleeve to elevate the sight for range, a drum E being geared to the casing C in such a manner that it rotates through a multiple of any angle of rotation of the casing C relatively to the sleeve a<2>. A rotatable sleeve G' on the casing carries a spirit level G by which the angle of site is determined. Worm teeth on the sleeve G<1> gear with a worm h<1> rotated by the head h<2>. A second worm h<3> on the shaft of the worm h<1> gears with teeth i<1> on a sleeve J, Fig. 3, which can rotate but not move longitudinally. A bar K screwed within the sleeve J can move longitudinally but cannot rotate, and carries the pointer k<2> of the sighting-device, which pointer moves over the surface of the drum E. When the longitudinal axis of the spirit level, the two main sighting-lines of the double telescope, and the longitudinal axis of the gun barrel are all parallel, the pointer k<2> occupies an invariable position on the drum E. A line c<2> drawn through this point is the zero line for range, and a circle c<3> drawn through the point is the zero line for angle of site. If the sighting-device is now set to the angle of elevation corresponding to a definite range and angle of site of a particular target, the drum E rotates. and the pointer k<2> moves along the circle c<3> to a definite point. After the sighting-device has been set to the target, the spirit level is rotated to the horizontal position, and the pointer k<2> then moves parallel to the axis of the drum by an amount corresponding to the angle of site of the target. The point so obtained is plotted on the drum. For each range of target for which a curve is to be drawn, corresponding points are similarly plotted for angles of elevation and corresponding angles of site; the line joining these points is the required graduation for the particular range. The drum is graduated in this way for ranges at equal intervals of 100 metres, thus obtaining a series of graduations e<4>. In using the sighting-device, the gun-layer, by manipulating the pointing-gear first, lays the sight lines on the target. The observer then brings the spirit level G to the horizontal position, and afterwards sets the sights, by means of the worm D, to the range of the target which has been previously determined by a range-finder. The gun-layer then again adjusts the sight lines on the target, whereby the gun is correctly laid for firing.