Patent GB-445265-A (GB)
Title: Improvements in or relating to gun sighting attachments for direct and indirect firing at moving targets
IPC: F41G5/08
Filed: 1934-08-02
Abstract: 445,265. Anti-aircraft gun sights. HARLAS, J., and TECHNICKY PRUMYSL AKCIOVA SPOLECNOST, 80, Kralovska, Prague. Aug. 2, 1934, No. 22565. [Class 92 (ii)] Relates to sighting devices for attachment to anti-aircraft guns which are adapted not only for use in direct firing but also permit of a ready change to indirect firing, the sight being then controlled from a remote observation post. According to the invention, the projections of the parallax and lead triangles in the horizontal plane are reproduced to a constant scale in the sighting apparatus by mechanical triangles which have a common side represented by the horizontal range. In the explanatory diagram, Fig. 1, G shows the gun, N the observation post, M and Z the present and future positions of a target moving at height y an a direction inclined at an angle B to the chosen .base GN(. =b). NGM<1> is the projected parallax triangle mechanically realized to a scale q as shown in Fig. 2, and GM<1> Z<1> is the projected lead triangle, shown similarly in Fig. 3, whereby the lead angle ## and the future horizontal range Dz are determined. The parallax and lead triangles have a common side represented by qDg where Dg is the present horizontal range. Fig. 4 shows diagrammatically the arrangement of the correcting mechanism of the sighting device 60 in relation to the gun G. The elevation #n and bearing #n of the target measured at N, Fig. 1, are conveyed electrically to pointers on receivers 6, 5 shown to the right of Fig. 4. By turning a handle 10, the coarse and fine bearing pointers are followed and the angle #n is conveyed to an arm 13 of the parallax triangle carrying on a screw 14 the pointer 1 (see also Fig. 2). The screw is rotated to move the pointer 1 through a distance qDn, by operating a handle 16 in following the pointer of the receiver 6, through the medium of a right-angled triangle apparatus 20 which introduces the height factor into the rotation #n. The joint G, Fig. 2, is realized in the apparatus shown in Fig. 4, by a system of rings displaceable as a whole through a distance qb by a screw 25, the ring 27 carrying another arm 29 of the parallax triangle with its screw 30 and pointer 2. After the screw 30 has been rotated to move the pointer 2 through a distance qDg given by the sight 60 through a right-angled triangle apparatus 69 the pointers 1, 2 are registered with one another. The consequent rotation of the ring 27 then gives the parallax-corrected bearing angle #g which is conveyed to the gun training gear 35 by rotation of a handle 36 after introducing the lead angle ## by a differential gear 38. The lead triangle is materialized by an arm 43 screw 44 and pointer 3 and by an arm 48 screw 53 and pointer 4. The arm 43 is rotated through an angle w (= #z + #) by a differential gear 42. The screw 44 is rotated to move the pointer 3 through a distance qvt by apparatus to be described later. The screw 53 of arm 48 is rotated to move the pointer 4 through a distance qDg by a shaft 57 this pointer being then brought into register with the pointer 3 by rotation of a handle 40 moving the arm 48 through the lead angle ##, and bv rotation of a handle 51 through Dz to determine the future horizontal range. To find the product vt as well as the gun elevation e and fuse time c corresponding to the distance Dz already found, the drums shown to the left of Fig. 4 are employed. From the firing tables, graphs for constant values of y are plotted with c and e as ordinates and Dz as abcissµ. These are wound on drums 70, 71 respectively which are rotated proportional to Dz by the handle 51 and sleeve 52. By operating a handle 72 to set a pointer 74 to the known, height curve on the drum 70, the fuse-setting machine 91 is rotated. Similarly, a handle 75 sets a pointer 77 to the curve on the drum 71 and elevates the gun. To obtain the value vt integration curves of the time of flight function f (Dz) are obtained which curves have the property that increments in intervals v are equal to vt. Curves for constant y values are plotted and wrapped on a drum 79. The bar 87 is set to (Dz+v/2) by rotation of the handle 51 and by turning a knob 85 to set pointer 86 to a scale of v the screw 84 giving the desired increment v/2 corresponding to the mid interval. The drum is rotated to bring the pointer 88 against the known height curve and the reader 90 moved by hand wheel 89 to bring it to the point where the bar 87 intersects the continuation of the same curve. The rotation of hand wheel 89 then conveys the product vt to the lead triangle apparatus by way of shaft 46. Since the following of the target with the gun telescope is effected by the same hand wheels 34, 36 which are used to balance the pointers 1, 2, it is possible quickly to pass from direct to indirect firing and vice versa. U.S.A. Specification 1,894,788 is referred to.