Patent GB-663711-A (GB)
Title: Improvements in and relating to moving-target tracking systems
IPC: F41G5/08
Filed: 1944-04-05
Abstract: 663,711. Sighting apparatus. SPERRY GYROSCOPE CO., Inc. April 5, 1944. [March 10, 1942] No. 6408/44. Class 92 (ii). A gun-fire directing system has a targetposition finder adapted to transmit to a director data determining the present position of a target, and the director is provided with means enabling secondary quantities to be produced corresponding to the data received, these quantities being fed to a computer of the director, the system also including means for transmitting the magnitudes of the secondary quantities back to the position finder whereby the latter may be set either in accordance with the position of the target or with the data received from the director. Director. The gun director apparatus shown in Fig. 1 is rotatable as a whole in azimuth on a fixed ring 1, the angular rate of movement being determined by the displacement of a handle 3 which actuates one member of a differential 17 and also a variable speed device 13 whose output shaft actuates a second member of the differential. Output shaft 18 of the differential has a worm 5 for moving the apparatus about ring 1, drives a transmitter 19 which is used to inform the remote position finder unit, Fig. 4, of the present azimuth position of the director, moves a dial 37, and conveys the present azimuth position data to a computer 25 of the type described in Specification 474,225. The operator of handle 3, or of handle 4 directly connected to device 13, follows the target either by using a telescope 27 or by matching the dial 37 with a dial 31 driven by a repeater which is actuated by the remote position finder. In a similar manner the target is followed in elevation either by using a telescope 49 or by matching a dial 51 with a dial 53 actuated by the remote position finder, the mechanism for this purpose including handles 39, 41, variable speed device 43, and differential 45, and a transmitter 84 being provided for informing the position finder of the present elevation of the director. The shaft 47 from the differential 45 is geared also to a shaft for supplying present elevation data to a solving mechanism 57 as described in Specification 418,670. The third necessary coordinate, which may be either the slant range or the height, is determined at the remote position finder, and is received at the director by a receiver 83 which actuates the innermost dial 81 of three dials 81, 77, 89. The operator at the director matches the intermediate dial 77 with the dial 81 when the latter indicates slant range by operating handles 63 or 65, via variable speed device 71 and differential 69, the output shaft 67 of the differential being geared also to a shaft supplying the slant range data to mechanism 57. The solving mechanism produces in its outer shafts 61, 59, rotations proportional to the present altitude and horizontal range of the target, and a shaft 61 is geared as shown to dial 89 to indicate present altitude thereon. Thus when the remote range finder is used to give present target height on dial 81, the director operator manipulates handle 65 so that the dial 89 matches dial 81, whereby it follows that handle 65 is supplying slant range data to mechanism 57. Shafts 61, 59, from the solving mechansim lead to smoothing mechanisms 97, 99, details of which are described with reference to Fig. 5 (not shown), the output shafts of these smoothers being led to the computer 25. Output shaft 133 of the computer leads to a transmitter for controlling the gun or for indicating to the gunner the future azimuth position of the target, and output shafts 105, 121, which correspond respectively to future horizontal range and future altitude serve to.position cams 115, 117, 119 in angular and axial positions respectively. Cam 119 is designed to correspond to the reciprocal of the time of flight and its follower 125 actuates a shaft 127 leading back to the computer. Cam 115 is designed to impart a movement to its follower corresponding to future elevation, such data being fed to a transmitter 131 similar to 135. Cam 117 communicates data through a differential 139 to a fuze transmitter 141, and apparatus is provided for providing a correction for the dead time. It is stated that the change in fuze setting is approximately equal to product of the rate of change of fuze setting and the actual dead time. The apparatus consists of a control 143 graduated inversely proportional to the dead time and serving to position a ball carriage 145 of constant speed motor 151. The driven cylinder 153 drives the turntable 155 of a second variable speed device the ball carriage of which is operated by a control 171 and the driven cylinder of which drives an indicator 163. In operation the control 171, the shaft of which adds to its motion to shaft 137 through differential 139, is constructed until the indicator 163 is rotating at the same speed as an indicator 165 driven by shaft 137. Remote position finder. This device in the construction shown schematically in Fig. 4, comprises tracking telescope 233, 239, and a height or range finding device 253, rotatably mounted on an adjustable platform, but may alternatively be used with a device such as a searchlight, sound-locator or radio-locator capable of following a moving target. For tracking in azimuth a seated operator using telescope 233 actuates a handwheel 243 which drives one element 257 of a differential 259 and also, through gearing which includes a gear 267 frictionally engaged with shaft 262, the A-end of a variable displacement hydraulic pump and motor unit 271. Output shaft 274 drives a second member 275 of differential 259, the output shaft 283 of which drives a shaft 299. Shaft 299 has a pinion 295 which meshes with teeth on a fixed azimuth ring 301 whereby the whole apparatus is driven round in azimuth by unit 271 at a speed proportional to the displacement of handwheel 243. Shaft 299 also actuates azimuth indicator 249 and gear 309 on which actuates a transmitter 313 which transmits its data to the receiver 29 of Fig. 1. Transmitter 19 of Fig. 1 transmits its data to a receiver 315 which operates a dial 251. The operator by matching the dials 251, 249, ensures that he is tracking the same target as the operator at the director. A hand lever 289 is provided for actuating a pivoted fork 293 which can move gears on shaft 283 for enabling the unit 271 to rotate the device in azimuth at a great speed when required. Instead of operating the handwheel 243, the operator may use knob 238. This knob does not affect handwheel 243 since friction gear 267 then slips on shaft 262. The shaft 264 of knob 238 is suitably geared to the A-end of unit 271 and thus a pure azimuth rate control is obtained. Locking means incorporating a detent 280 actuated by a control 282 may be provided for holding the rate control shaft in any adjusted position. Similar mechanism is provided for moving telescope 239 in elevation, such mechanism including handwheel 237, control knob 246, locking control 290, difierential 319, hand lever 351 functioning as in the case of lever 289, transmitter 367, receiver 391, and dials 247, 248. The elevating mechanism also includes means for raising and lowering the operators' seat 231, and a limit stop device 381. The latter comprises concentric washers carrying oppositely directed lugs, the outer washers being mounted respectively on a shaft driven by the A-end of elevation hydraulic unit 341, on a shaft 387 geared to the elevating telescope. Thus if the instrument is elevated beyond the desired limits the output of unit 341 will drive its input back to zero. Specifications 418,670 and 663,047 are referred to.