Patent GB-418670-A (GB)
Abstract: 418,670. Gun fire-control apparatus. SPERRY GYROSCOPE CO., Inc., Manhattan Bridge Plaza, Brooklyn, New York, U.S.A.-(Assignees of Chafee, E. W.; 320, Lincoln Place, Murtagh, H. ; 141, Montague Street, both in Brooklyn, and Myers, S. G.; 20, Wilson Place, Freeport, Long Island, all in New York, U.S.A.) March 25, 1933, No. 9092. Convention date, Jan. 28. [Class 92 (ii).] For directing gun fire against aerial or other moving targets, a sighting instrument is provided for continuously following the target in elevation and azimuth so as to furnish a horizontal projection of its course and for resolving the course into rectangular coordinate movements with respect to two fixed directions such as North-South and East- West, the rates of such co-ordinate movements generated by the sighting instrument being first determined and then multiplied by the time of flight of the projectile to predict continuously the future target position corresponding to the point of impact. In the diagram. Fig. 2, P<1>, P<2> is the course of the target and B, B<1> its horizontal projection. Then O, B, the initial horizontal range R‹, is obtained from the formula R‹ = H‹/tan E‹ where H‹ is the height of the target and E‹ the initial angle of elevation. A‹ is the initial azimuth angle. The apparatus according to the invention continuously calculates the predicted horizontal range OB<1>(=R#) and computes therefrom the future azimuth angle A#, the quadrant elevation E<g> and the fuze-time for use at the gun. The apparatus shown in Fig. 1 comprises elevating and training telescopes ET, AT carried by a rotating table 1 and moved by handwheels EH, AH respectively, the movements being shown on coarse and fine dials E‹, A‹. The formula R‹= H‹/tan E‹ is continuously solved by a solid cam 10, which is rotated by shafts 20, 17 in accordance with H‹ set up on a pointer by a motor 2, and translated by a screw 12 rotated from a horizontal range handle 13. The cam is so designed that the lift conveyed to a rack member 19<1> and communicated to a pointer 23 on the dial E‹ gives a definite angle of elevation corresponding to each ratio of H‹ to R‹. It follows therefore that motion of the handle 13 necessary to register the pointer 23 with the dial E‹ gives the instantaneous value of the horizontal range. Rate of change of horizontal range can be introduced by an alternative handle 24 operating a variable-speed gear 29 in known manner. The resolution into co-ordinates is effected by a present-position resolving mechanism 34 comprising a disc provided with a radial slot and rotated for azimuth by a shaft 39 which disc is superposed on a disc with a spiral slot rotated for range by a shaft 32. A pin 48 controlled by both slot and spiral serves to move the coordinate slides 51, 52 the North-South and East-West rates of movement of which are obtained by comparison with tachometers 67, 68 when handles 65, 66 are operated. The products of these rates with the time of flight obtained from a solid cam T are effected by links 74, 75 and T-piece 77 and appear as translations of the sliders 79, 78 which are conveyed to electric contacts 83, 86. The future-position resolving mechanism 35 is similar to the mechanism 34 but receives the extra movements from a range difference motor 96 through a differential gear 97 and from an azimuth difference motor 98 through a differential gear 101 such extra movements being sufficient to make the co-ordinate slides 51<1>, 521 move the contact members 831, 86<1> into register with the contacts 83, 86. The future azimuth is thus obtained at the dials Ap, Ap<1> and communicated to the gun by the shaft 106, whilst the future horizontal range is used through a shaft 93 to rotate a cam QE giving quadrant elevation and half cams F, T giving fuze times and time of flight. The cams QE and F, T are translated by a shaft 91 and slide 90 in accordance with height H‹. The correction for North-South, East-West components of wind are set up on the tachometer dials. Azimuthal parallax components are superposed on the slides 78, 79 by handwheels 133, 1331. Vertical parallax corrections are applied to the slide 90 by a sector 109 operated from a futurealtitude hand wheel 107. Present altitude corrections are applied by a handwheel 3, fuze corrections by a handwheel 120, quadrant elevation corrections by a handwheel 116, and lateral corrections by a handwheel 104. Since the relative importance of East-West and North-South rates of movement vary according to the quadrant in which the resolving mechanism 35 is operating, means comprising a change-over switch on the axis of mechanism 35 and a relay mechanism is provided to cause motors 96, 98 to operate either of the contact members 83<1>, 86<1>. When firing at land or sea targets, range movements are conveyed from shaft 30 to the height dial 16<1> by operating a clutch 150 and the pointer H‹ is then set from outside by a range finder, the dial E‹ being kept at zero.