GB805908A - Sighting telescope for firing at a moving target - Google Patents

Abstract

805,908. Telescopic gunsights. FRANCAIS ETAT. Oct. 11, 1956 [Oct. 24, 1955], No. 30956/56. Class 92 Relates to a telescopic gun sight by which the angular speed of displacement of a moving target can be determined and, suitably combined with a time of flight corresponding to a predetermined range, applied to the sight line in the form of angular lay-off. The sighting telescope has vertical and horizontal graticules 4 and 5 visible in its focal field 1 which may be displaced respectively laterally and vertically by turning control knobs 6 (Fig. 5, not shown) and 7 proportionally to the required lay-off, a and to the inverse of the time of flight, T, of the projectile respectively. A grid of vertical lines 3 is arranged optically to move across the field 1 at a speed controlled by the knob 6 such that, when the speed of the grid matches the target's movement across the field, the knob 6 will have set the required lay-off deflection on the graticule 4. Fig. 2 shows diagrammatically a form of the gun sight as illustrated in Figs. 1 and 3. A direct current motor 10 drives a drum 11 at constant speed. The motion of the drum 11 is transferred to a disc 13 by a ball assembly 12 whose position relative to the disc centre varies as 1/T, where a = #T is the required lay-off for a target moving at an annular speed # measured from the gun at a distance equivalent to a time of flight T. The knob 7 transmits its motions through pinions and linkages 20-23 to a lead screw 25 (Fig. 3, not shown), which carries the ball assembly 12; simultaneously, through a pinion 26 and a shaft 27, it displaces vertically in the focal plane of the telescope a glass plate 33 carrying the horizontal graticule 5 to apply to the line of sight the extra elevation due to range. Another ball assembly 14 transfers the motion of the disc 13 to a drum 15. The movement of the ball assembly 14 is effected through other pinions and linkages by turning the knob 6 and is proportional to a. Simultaneously, the same movement displaces in the focal plane of the telescope a glass plate 29 carrying the vertical graticule 4 by the amount of deflection required for lay-off. The speed of rotation of the drum 15 is thus proportional to # = a/T and it can be made to rotate at an engraved drum as at 16 in Fig. 2 or to displace a grating 35 (as in Fig. 3, not shown), either of which can be illuminated and projected optically on to the focal field of the telescope in the form of moving lines 3. In another embodiment the quantities a and 1/T are multiplied electrically by applying them to potentiometers which control the voltages in two inductor windings of a direct current electric motor. (Fig. 7, not shown).