Patent GB-494895-A (GB)
Title: Improvements in sight correction devices for guns firing against moving targets
IPC: F41G5/08
Filed: 1937-01-29
Abstract: 494,895. Anti-aircraft gun sights. BJORK, H. L. Jan. 29, 1937, No. 35648/36. [Class 92 (ii)] Relates to means for correcting the aim of anti-aircraft guns of the kind in which the angle between the gun and sight is automatically modified for tangent elevation and for the vertical and lateral components of the speed of the target and in which, after setting a pointer 7, Fig. 1a, to the appropriate height curve on a drum 1 rotated for gun elevation, the fuze setting is automatically communicated to a fuze-setting machine 29. Further, the invention is concerned with apparatus of the kind in which a spacial triangle OTG, Fig. 3, is materialized, OT being kept constant and TG being in the form of a rotary crank arm which is adjusted parallel to the path of the target and the length of which is made proportional to Vt/Wm , where Vt is the speed of the target, and Wm is the mean speed of the projectile. According to the invention, the adjusting gear 9, 82 of the fuze-setting machine 29 is operatively connected partly with a rod 2 and linkage 3, 4 for adjusting the tangent elevation and partly, for the purpose of introducing the time of flight, with the apparatus for adjusting the crank arm factor Vt/Wm. The elevating and training sighting telescopes 34, 38, Fig. 1c, driven by shafts 24, 25 are supported on a trainable mounting 92 carrying the gun on trunnions 50. The lead triangle is represented to scale on the mounting by the points TOG, Fig. la, which correspond to the spacial diagram shown in Fig. 3 in which OE represents the present position of the target and OF the future position. T is materialized by the axis of rotation of a table 17, O is a fixed point connected with a sector 23 moved in accordance with gun elevation by a sector 5 moving on the trunnion 50, and G is a point set to a radial distance on the table corresponding to Vt/Wm. The point G revolves with the table and the line TG is set parallel to the path of the target by a ruler 18 adjusted in azimuth by turning the table by a handle 16 and in elevation by a knob 19. The apparatus for calculating and applying the factor Vt/Wm is shown to the left of Fig. 1a. Elevation of the gun by gears 87, 88, causes through linkage 3, 4 motion of the sector 5 which through sector 23, rods 21, 22, gears 37, 36, and shafts 24, 25, moves the sights in elevation on to the target. The sector 5 through gearing 49, 6 rotates the drum 1 showing fuze settings as a function of height. The rotation of the hand wheel 9 to set the fuze is conveyed through gearing 54, 56, 58 to a shaft 14 which raises the rod 2 of the linkage 3, 4 to correct for tangent elevation, and, through worm 45, sets a crank arm 39, a block 40 on which moves in a slot 41 in a slider 42 geared to the member 15 on the table. The block 40 is set radially on the crank 39 to suit the target speed. Further, a block 43 on the crank 39 engages a cam slot in the worm support 44 to apply a correcting movement to crank 39 so that the ultimate movement of the slider 42 is proportional to Vt/Wm. It follows therefore that, as the sight is moved in elevation by moving the gun, the vertical deflection angle TOG between the gun and the sight is set up by movements of the gears 36, 37 and shafts 24, 25 which are conveyed to the gears 32, 33 at the telescopes. Fig. 4 shows how azimuthal movements of the table 17 cause deflection of the rod 20 which is conveyed by gearing 35, shaft 78, and rod 22, to the gear 36 thereby causing relative movement between the gears 36, 37 to effect relative rotation of the gears 32, 33 of the telescopes to deflect the sight line in azimuth. The effect of gun training on the table 17 is neutralized by pinion 26 and differential-gear 28. Specification 382,288 is referred to.