Patent GB-261444-A (GB)
IPC: F41G5/08
Abstract: 261,444. Lanstad, H. F. May 27, 1925. Gunnery calculations.-Anti-aircraft fire-control apparatus for determining continuously the gun range, fuse settings and other sighting data, comprises a combination of sighting apparatus and computing apparatus wherein the gun range is continuously determined by first producing automatically the ground course and the ground speed of the target from initial settings of the ascertained rate of change of range and speed across of the target. As shown in Figs. X and XII the computing apparatus is a rate clock in which the ground course and speed of the target are indicated by the position of the pointer 65 in a radial slot in a course dial 69. The dial and the pointer are set by slides 74, 77 moving at right angles. The slides are set by pinions 80, 82 respectively operated in accordance with the rate of change and range and the speed across of the target ascertained from a range finder and target observing apparatus. The course dial 69 is carried by a toothed ring 70 to which it can be locked, the ring receiving rotation in accordance with the bearing of the target by gearing operated by a spindle 72 connected to target observing apparatus. The position of the slides 74, 77 in combination with the position of a slide 98 controlled by an angle of sight cam 104, controls the position of the driven roller 85 of a variable speed transmission device, the disc 87 of which is driven at a constant speed by a motor 88. The rotation of the shaft 86 driven by the roller 85 is proportional to the rate of change of range. A rotation proportional to the initial target range is superimposed on this rotation by differential gearing 120, the resultant rotation of the shaft being proportional to the present range of the target. On this rotation is superimposed by differential gearing 125 a correction for the speed along the line of flight of the projectile, the resultant rotation of the shaft 126 being thus proportional to the gun range. This is transmitted to the gun station by a transmitter 218. A time lag correction proportional to the rate of change of range is added by a differential gear 127, the resultant rotation, which is proportional to the predicted range, being communicated to a screwed spindle 142 forming part of the fuse chart apparatus. The correction applied by the differential 125 is determined by mechanism, shown in Fig. XVII, comprising a lever 149, connected to a sliding bar 146 at one end, a sliding rack 154 connected to a sleeve 152 on the lever and sliding in a guide 155 which is adjustable, by means of screw spindles 156, 157, to vary the distance of the rack from the pivot 150 of the lever, and a pinion 161 driven by the rack and geared to the shaft 163 connected with the differential gear 125. The bar 146 is moved an amount proportional to the rate of change of range and the rack is displaced sideways an amount proportional to the time of flight, by the rotation of a shaft 158. A correction for the inclination of the target course to the horizontal is applied by impressing a rotation, by means of a differential gear 115, on the spindle 105 which actuates the angle of sight cam 104. The apparatus is fitted with three charts 145, 178, 200 from which are determined the fuse setting, the time of flight correction in seconds and the correction to gun range due to elevation in yards. The fuse setting is indicated on the chart 145 at the intersection of a pointer 143 and a bar 168. The pointer 143 is moved by the screw spindle 142 in accordance with the predicted range, and the bar 168 is moved by a screw spindle 170 in accordance with elevation to point of burst. The screw spindle 170 receives its rotation through differential gearing 173 combining the rotation of a shaft 176 rotated in accordance with the vertical defection by the target observing apparatus, and of a shaft 105 rotated in accordance with the angle of sight by the target observing apparatus. The fuse settings are transmitted to the gun station bv a transmitter 219 set by a handle 220 in accordance with the indications of the chart. The chart 178 is for the time of flight corrections in seconds which is to be applied to the spindle 166 connected to differential gearing 167 operating the shaft 158, Fig. XVII. The chart is marked with time of flight curves starting from an evenly divided datum line at the top. An index 158 carried by a slide 184 moves along the datum line and a pointer 179 carried by the slide 184 can be moved relatively thereto by a screw spindle 181 splined on the shaft 182 of a handle 186. The slide 184 is moved by a cam groove in a barrel 189 which receives rotation from the gun range spindle and the pointer 179 is adjusted until it passes through the intersection of the bar 168 with the curve indicated by the index 185. The rotation of the shaft 182 is a measure of the desired connection and is applied by gearing to the spindle 166. The chart 260 is for determining the correction to gun range corresponding to the time of flight variation due to elevation, and is marked with curves of time of flight starting from a datum line marked in yards. The pointer 201. is carried by a slide which also has an index 207 and is moved relatively to the slide by a handle 208 and screw mechanism. The slide is moved by a screw spindle 210 on the same shaft as the barrel 189 and the pointer is adjusted so that it passes through the intersection of the bar 168 with the curve indicated bv the index 207. The rotation of the handle 208, which measures the desired correction. is subtracted from the gun range by differential gearing 216 the result being transmitted to the gun station by the transmitter 217. A modification is described in which the apparatus is adapted for the case in which the gun and control apparatus are on a moving base.