Patent GB-218716-A (GB)
Title: Improvements in fuze and deflection indicators for artillery
IPC: G01C3/04
Filed: 1923-04-04
Abstract: 218,716. Courage, D. G. April 4, 1923. No Patent granted (Sealing fee not paid). Gunnery calculators. -In apparatus for obtaining fire control values for anti-aircraft guns the values, such as the fuze and deflection indications, are determined by members whose movements are functions of two independent variables for each of a series of discontinuous values of a third variable. In the apparatus as shown Figs. 1, 2, 3 and 5, a pair of cursors and a set of fuze and deflection curves for a number of heights are provided the co-ordinates of which are functions of the position and speed of the target, preferably the ground range and linear speed of approach or recession. The curves are marked on a strip 107 of soft steel, celluloid, &c. wound on bobbins 106, 106<a> and guide rollers 240, and driven by a gear wheel 173 from an operating handle 108 in order to select the set of curves corresponding to the height as obtained by a height-finder. The strip 107 is mounted in a casing 118-120 having a circular table bottom 110 rotatably mounted on a stand to which is fixed a worm wheel 112 gearing with a worm shaft 113 rotated by a crank 114. The casing carries two telescopes 115, 116 at opposite ends of a shaft 117 which are operated by cranks 114, 121 to follow the target in azimuth and elevation ; the cranks are also geared to speedometers 122, 222 respectively so as to indicate the angular velocity in azimuth and speed of approach or recession of the target. The telescope 116 carries a flanged plate 131 which rests on a ball race 132 the centre of which is in line with the optic axis of the object glass of the telescope and is mounted on a collar 133 adapted to move along a screwed rod 134 by operating the crank 121. so that when the axis 130 is aligned on the target the distance, from the centre of the ballrace 132 along the rod 134 to the position vertically beneath the shaft 117 is proportional to the ground range divided by the height. In order that this distance may be proportional to the ground range the axis of the shaft 117 is adapted to be raised and lowered in accordance with the height by arranging the shaft in slots 160 and bearings mounted on screws 163, 164 operated by gear wheels on shafts 165, 166, the shaft 166 being rotated by the crank 108 that sets the curve strip 107. The spacing of the sets of curves is varied from end to end of the strip 107 to ensure that the revolutions of the crank 108 shall be a linear function of the corresponding height, allowance being made for the varying diameter of the spool. The rotation of the crank 121 controls the position of a cursor 104 that is adjustably mounted on a wire 136. which passes over pulleys 137, 139 and is attached to the collar 133, the displacement of the cursor corresponding to the ground range of the target. Associated with each speedometer is a following pointer which is kept in coincidence with the indicating pointers. The follower of the speed indicator 122 is actuated by a crank 152 which is also connected through bevel wheels 153 with a screwed shaft 154 on which is mounted a carriage 155 bearing a manually adjustable cursor 105, the displacement of which corresponds to the linear speed of approach or recession of the target. The follower of the speedometer 222 is connected through a computing mechanism to means for indicating the lateral deflection and complementarv error. Each set of fuze and deflection curves is marked with a pair of scales 210, 211 graduated in fuze numbers and so spaced that the length of the scale corresponding to a particular fuze is proportional to log and log(T) respectively where T is the time of flight, x is the ground range of target, and 8 is the lost time in seconds. A pointer 213 which is set to the selected fuze by rotating the screwed rod 214 carries a pulley 185 over which passes a wire 182 that is attached at one end to a restoring spring 187 and is connected at its other end to a fusee 181 so designed that the length of wire unwound therefrom is proportional to the logarithm of the present ground range. The wire 182 carries two pointers 188, 189 which co-operate with scales 191, 190 respectively graduated to read the lateral deflection and complementary error. These pointers in addition to the adjustment which they receive by a movement of the pulley 185 and fusee 181 are affected also by a movement of a pulley 186 to which movement is imparted by the follower of the speed indicator 222, in accordance with the logarithm of the angular velocity in azimuth. The fusee is rotated by means of a shaft 180 provided with a square end fitting a similar socket on the pulley 138 around which passes the wire 136. A screwed portion 183 of the shaft 180 passes through a nut so as to move the shaft longitudinally to maintain the wire 182 vertical. The pulley 186 is carried by a screwed collar on a screwed shaft 217 rotated through gearing on shafts 218, 220. The shaft 220 is rotated by a crank 221 which is connected as shown in Fig. 12 to the following pointer on the pinion 223 loose on the speedometer shaft 249 so that the angular movement of the shaft is proportional to the logarithm of the angular movement of the follower. The complementary error is manually applied to the cursor 105 by its adjustment against a scale 158 on the carriage 155. To enable the operators to pick up a new target rapidly the shaft 108 may be, provided with a change speed gear and the collar 133 with a device to release it from the screw 134 to facilitate its adjustment thereon. The curves may be drawn to represent quadrant elevation or tangent elevation plus vertical deflection and they may be inscribed on separate metal plates stored in a magazine or on ground glass plates illuminated by transmitted light. For intermediate heights the shaft 166 may be provided with a differential gear and be partly driven by the wheel 173. Adjustments may also be provided for temperature variation.