Patent GB-139765-A (GB)
Title: Improvements in or relating to range keepers and like instruments
IPC: G01C3/00
Filed: 1920-02-25
Abstract: 139,765. Ford, H. C. March 1, 1919, [Convention date]. Range-keepers. - A range and bearing keeper for moving targets is provided with means whereby the generated range and bearing can be compared with measurements obtained from actual observation so that any errors in the estimated course and for speed of the target can be corrected. The means for generating the range and bearing are as described in Specification 128,569. the velocities of own ship and of the target being respectively represented bv vectors EF and BD, Fig. 1, which are resolved along and at right-angles to the line of fire, corresponding components being mechanically added and the sums integrated in order to obtain total changes in range and in deflection. The features constituting the present invention comprise a pair of wires 200, 201 mounted at rightangles to each other above the target dial 6 and adapted to be displaced when there are differences between the observed and generated rates of change of bearing and range respectively. The bearing is observed by a telescope the motion of which operates a, repeater 212<a> geared to a shaft 215 carrying a wheel 225 gearing with a. wheel 226 secured to a sleeve which carries the element 227 of a differential, the element 230 of which is driven by gearing 228, 229 from a shaft 58 rotated proportionally to the generated bearing. The shaft 215 also actuates, through gearing 216. 217, 218, an " actual-bearing " pointer 219 coaxial with the target-bearing pointer 3. The shaft 233 carrying the elements 231, 232 is connected by a flexible drive device 234 to a shaft 236 driving the element 239 of a differential, the elements 240, 241 of which are secured to a shaft 243 driven from the component-adding mechanism of the range-keeper at a. speed proportional to the deflection due tb motion of own ship. The motion of the element 242 is thus proportional to the difference between observed and estimated bearings, corrected by an amount proportional to the deflection due tb the motion of own ship. The element 242 is secured to a sleeve carrying pinions 252, 253 gearing with racks 254, 255 on the slides 202, 203 carrying the wire 200. A crank 215a is provided for turning the shaft 215 by hand. The wire 201 is displaced to indicate errors in the rate of change of range due to incorrect estimation nf the speed and for course of the target, by means shown in Fig. 5. The counter 132 is actuated from the range-keeping mechanism by the shaft 133<a> which also drives a shaft 292' to which is secured the elements 294, 295 of a differential, the elemenr 293 of which is integral with a wheel 299 driving the " predicted range " counter 302. The wheel 299 also normallv drives a wheel 304 carried by a shaft 305 on which is a wheel 306 gearing with a wheel 307 which is loose on a shaft 308 and is integral with the element 310 of a differential, the elements 311, 312 of which are secured to the shaft 308 while the element 313 is integral with a wheel 315 driven from a roller 317. The roller 317 is driven from a constant-speed disk 318 by balls 325 carried in a frame displaceable by a rack 327 and pinion 328, the pinion 328 being secured to a shaft 282 which is driven from the shaft 308. The " actualrange " counter 335 is driven by the shaft 292<1> through gears 338 - - 341 and shaft 337 but can be set periodically or continuously by hand to agree with observed ranges by pushing in and turning the crank 340<a>, the gears being moved thereby into the positions shown in dotted lines by means of bell-crank levers 347, 350. The gear 306 is slidable on the shaft 305 and remains in mesh with wheel 307 so that rotation of the crank 340a operates the wheel 307 proportionally to the actual range. By the above-described arrangement, the shaft 282 is turned until the speeds of the wheels 307, 315 are equal and its rotation is thus proportional to the actual rate of change of range. The shaft 282 carries a wheel 281, Fig. 1, gearing with a wheel 280 which is integral with the element 278 of a differential, the elements 276, 277 of which are secured to a shaft 29 driven by a shaft 287 which is rotated from the component-adding mechanism of the rango-keeper proportionately to the rate of change of range due to the motion of own ship. The rotation of the element 275 is thus proportional to the actual range rate due to motion of the target and is transmitted to the wire 201 by pinions 272, 273 gearing with racks 270, 271 on the slides 206, 207. The intersection of wires 200, 201 should be over the point D if the speed and course of the target have been correctly estimated. The predicted-range counter 302 may be manually set by pushing in the knob 365 to move the wheel 304 out of gear and then turning the crank 360. Means are provided at the telescope station for indicating coincidence between the pointers 3, 219, Fig. 1.