Patent GB-474225-A (GB)
Abstract: 474,225. Anti - aircraft gun - fire control. STEVENS, A. H. (Sperry Gyroscope Co., Inc.) Jan. 23, 1936, No. 2184. [Class 92 (ii)] The anti-aircraft fire-control system described in Specification 418,670 is, according to the present invention, adapted for gliding targets as well as for targets flying horizontally. For this purpose, means are provided for mechanically resolving the displacement of the target from a reference point and the velocity of the target into components parallel to three fixed mutually perpendicular axes, one of which is vertical, and for mechanically computing the future position of the target by multiplying these components by the time of flight of the shell which time is mechanically computed to suit the calculated future position of the target. In carrying out the invention, as applied to controlling the fire of guns mounted on unstable ships' platforms, a range - finder R, Fig. 2, is stabilized in azimuth and elevation from a gyro-compass C and gyro-vertical V through a trunnion-tilt corrector M as described in Specification 455,207. Transmitters TA, TE, TR then feed the true angles of azimuth and elevation and the slant range D<0> into a computor I through the lines 1, 2, 3 respectively. The elevation angle E<0> and slant range D<0> are fed as known quantities into the part of the computor shown in Fig. 1A, through the lines 2, 3, the unknown horizontal range R<0> and height H<0> then emerge through the lines 33, 43. By operating a hand wheel 14 to drive a screw 13 and slotted sector arm 9, the coarse and fine pointers 7, 7<1> are made to follow the indications of the elevation dials E<0>, E<01>, the rotation imparted to the screw being proportional to cot E‹ and the solid cam 15 being translated by this amount through a screw 17 and arm 18. This cam is rotated proportional to H<0> by hand wheels 26 or 27 and the lift imparted to a pin 19 causes a pointer 20 to match the slant-range dial D<0>. A second solid cam 16 fast with the cam 15 also receives translation proportional to cot E<0> and rotation proportional to H<0> and lifts a pin 21 to rotate dial R<0> proportional to horizontal range, the dial being followed by pointer 23 by rotating handle 28. A variablespeed gear 36 driven by a constant-speed motor 37 and adjusted by the handle 26 enables a gliding motion of the target to be taken into account by varying H‹ to keep the pointer 20 matched against the slant-range dial, the variations of H<0> passing out of this part of the computer by the shaft 43. Since R<0>=H<0> cot E‹, changes in R<0> are obtained from a variable-speed gear the disc 70 of which is driven from the shaft 17, the radially-adjustable roller 71 being driven from the shaft 43. The changes are added to the original settings through differentials 73, 29 and pass out by the shaft 33. For small angles E<0>, D<0> is taken as equal to R<0> and a triangle is set up by an arm 47 inclined proportional to E<0>, and an adjustable nut 46 a slider on which bears on a bar 49 the vertical adjustment of which gives H<0>. The azimuth reading is shown on coarse and fine dials A‹, A<01> and leaves the apparatus by shaft 56 when the dial pointers are followed by rotating a hand wheel 52. Fig. 1B shows the use of apparatus x, y, as in Specification 418,670 for resolving the values of A<0>, R<0> into North-South and East- West component rates of movement which are measured by tachometers 68, 68<1> and multiplied by the time of flight by cams 69, 69<1> and the products added to the present components to obtain the future components. As described in Specification 418,670, similar resolving apparatus x<1>, y<1>, is used in the reversed sense to determine the values of Ap, Rp which are the predicted values of the azimuth and horizontal range. The future height Hp is also obtained by multiplying rate of change of height obtained from tachometer 88 by time of flight obtained from a rotary cam T translated by a screw gear 85 proportional to Rp. The value of Ap leaves the apparatus by line 130 and cams F and QE give the fuze time and quadrant elevation which leave by the lines 132, 131. The lines 130, 131, 132, leave the computor T as shown in Fig. 2 and are connected to a second trunnion-tilt corrector M<1> as described in Specification 455,207, this being used in the reverse sense to the corrector M to convey to the gun G the adjustments in elevation and azimuth relatively to the ship's deck. As described in Specification 418,670, correction for true wind is introduced by apparatus 118, 119, Fig. 1B, as component rate corrections in the North- South and East-West directions and the ship's " own-speed " treated as apparent wind in the opposite direction is corrected for by similar apparatus 125, 126. Specification 14379/15, [Class 92 (ii)], also is referred to.