Patent GB-103646-A (GB)
Title: Improvements in or relating to Sighting-devices for Anti-aircraft Guns.
Inventor: BELD CASPER MELCHIOR BALTHAZAR
IPC: F41G3/00
Filed: 1916-12-28
Abstract: 103,646. Beld, C. M. B. van den. Jan. 22, 1916, [Convention date]. Sights and methods of sighting.-Consists in anti-aircraft sighting-apparatus, characterized by the provision of a foresight surrounded by an open ring, the plane of which is maintained horizontal at any angle of elevation of the gun. The principle of the device is that, if the relation between the radius of the ring and the distance between the fore and back sights is suitably adjusted, a shot fired at the target is observed to enter the ring should intercept the target at or near the centre. The distance between the fore and back sights is adjusted automatically as the gun is elevated, in order to compensate for the increased time of flight of the projectile at increased angles of elevation. The distance is also regulated by hand for range and speed of target, whilst the inclination of the sight line relatively to the gun is automatically adjusted by means of a series of cam-grooves each of which is designed in accordance with a certain height of target. The effect of the arrangement is to give a " cone " of sight surrounding the " line " of sight, as shown in Fig. 2, the apex angle of the cone being varied by the adjustment of the distance between the foresight 1 and the backsight 8. In the construction shown in Figs. 6 and 7, the sight bar or carrier 7 is pivoted on the gun trunnion 5 and is adjusted relatively to the gun in accordance with selected target heights by means of a series of cam-slots 30 giving automatic corrections for high angles of elevation. For this purpose, the appropriate camslot 30 is engaged by a pin 29 on the end of a lever 28, 27, pivoted at 26 to the gun cradle, and constrained by a parallel linkage constituted by the fixed gun support 33, a link 32, the lever 27 itself pivoted at 26 and the gun cradle pivoted at 5 to the support. On the sight carrier the foresight 2 is surrounded by the open ring 1 pivoted about a transverse axis 10. The backsight comprises an aperture 25 in a plate 8, slidably adjusted on a support 23, which in turn is slidable in a guide-plate 24. The sight-plate 8 is adjustable on the support 23 in accordance with range and speed of target. The carrier 23 is automatically moved along the guide 24 as the gun is elevated in order to reduce the distance between the sights giving a correction for increased times of flight of projectile at high angles of elevation. This adjustment is effected by connecting the carrier 23 by a tie-rod 21 to a lever 12 pivoted at 15 on the sight-carrier 7 and constrained by a parallel motion constituted by the pivots 5, 15, and an extension of the lever pivoted at 17 to a link 18, pivoted to the gun support 33 at 19. The foresight ring 1 is maintained horizontal at any elevation of the gun by a further parallel motion constituted by the carrier 7, the lever 12, a link 11, and an arm 9 fixed to the ring. The gun support 33 is rotatable about a vertical axis 6. The backsight, instead of being formed by an aperture in a plate 8 as shown in Fig. 7, may be formed by an aperture 25 in a small ring 35, as shown in Fig. 8, this arrangement enabling the eye to be maintained clear of the recoil of the gun. Instead of adjusting the distance between the sights for speed of target, different-sized rings 1 may be provided for this correction