Patent GB-191418546-A (GB)
Title: Improvements in Fire Control Apparatus-Means for Measuring the Course and Speed of a Target and thereby Determining the Rate of Change of Range and Deflection.
Filed: 1914-08-11
Abstract: 18,546. Barr & Stroud, Barr, A., and Stroud, W. Aug. 11. Modifying scale of readings, records, and integrations.-Relates to apparatus of the kind described in Specification 1510/11, [Class 97 (i), Optical systems &c.], and consists in various improvements of detail, in conjunction with which, angles in a horizontal plane may be measured, as described in Specification 11025/89, [Class 97, Philosophical instruments &c.]. In the apparatus shown in Figs. 3-7, the objective lens of a sighting telescope is made in two halves 1, 2, which are adjustable laterally by a screw 4 until the target appears as in Fig. 5. The rotation of the screw is then proportional to the angle # subtended by the target, and gives a proportional displacement to a nut B away from a point A. For measuring angles # in a vertical plane, a right-angle isosceles prism 150, Figs. 19 and 20, is placed outside the objective and turned through 45‹ to the position shown in dotted lines 151. Other screws 21, 22, Fig. 3, are rotated in proportion to the range R so as to make the distance o a proportional thereto. Hence the distance a b becomes proportional to # R, and this is converted by means of a rack 13 into a rotation of a toothed drum 19 and represented by the movement of an index drum 20. Pins 29, 30 are adjusted by means of a pinion 25 to a distance from each other proportional to the length L of the target or of a distinct part thereof. The plate 24 carrying these pins is turned to an angle a<1> equal to the angle between tne direction of the target and the line of sight. The pin 30, which bears on a spring controlled sliding plate 31, therefore moves it to an extent proportion to L sin a<1>; and this is converted by gearing 33, 34, 35, 36 into a proportional rotation of an index drum 23 opposite the drum 20. The marks on these drums should therefore coincide with each other when the various quantities are correct, hence any one quantity can be determined when the others are known. The angular speed # of the target is determined by means of three reflectors 45, 46, 47, Figs. 8 and 9. The reflector 47 is half silvered so that a direct image and a triple reflected inverted image are seen at the same time, and these images are brought into coincidence by an adjustment of the reflector 46 or 47. The coincidence is then maintained by a continuous rotation of the reflector 45 obtained from a rotating friction disk 41 through a friction pinion 42, which is adjusted along its shaft 43 by means of a nut 50 and screw 49. The rotational set imparted to the screw 49 to maintain the coincidence of the images is therefore proportional to the angular speed #. The speed # may also be determined by noting the time T taken for the target to pass a cross wire in a sighting telescope kept fixed in azimuth. Or again, the three reflectors may be used. 45, 47 being fixed and 46 controlled in azimuth by a gyroscope; the speed w is then found by noting the time for the target images to change from the positions of Fig. 17 to those of Fig. 18. The product # R is then multiplied by the reciprocal of the time T by the apparatus of Fig. 14 and the result given by the drum 120. The angular speed # determined by the screw 49 is combined with the range in the same manner as described above for the angle #, and the product # R is represented by the rotational set of an index drum 120. In the apparatus shown in Figs. 11 and 12, which is an improvement on the apparatus described in Specification 1510/11, the speed of the target and the speed of one's own ship are separately resolved at right-angles and parallel to the line of sight, and each set of components are then added up by means of differential gears. One's own speed is resolved by means of a screw 63, which is disposed in a fore and aft direction, and is given a rotational setting proportional to the speed, in conjunction with two slotted bars 66, 67, which are disposed at right-angles and parallel respectively to the line of sight L S and are moved by a nut 65 on the screw 63. The enemy or target speed is similarly resolved into movements of bars 82, 83. The movement of the bar 67 is transmitted through racks 68, 69, pinions 70, 71, and spindle 72 to bevel gear 73, 74, and is added up to the movement of the bar 83, similarly transmitted, by a differential gear 77, which therefore gives a set to a drum 123 opposite drum 120 proportional to the combined speeds at right-angles to the line of sight. Similarly, the other pair of components are added up and transmitted to a drum 124, which therefore indicates the rate of change of range. The exterior of the complete apparatus is shown in Fig. 13: F A represents the fore and aft line; L S, the line of sight adjustable relatively to F A by hand wheel 92; scale 90 moving opposite pointer 91, one's own speed set by nut 62; pointer 93 set over scale 94, the target length; scale and pointer 97, the target speed; 99 a box containing the sighting telescope, the reflectors 45, 46, 47 of Fig. 9, and a gyroscope for supporting the reflector 46; and the disks 20, 23, 120, 123, 124-equivalent to the correspondingly numbered drums in the other Figures-the products # R, L sin a<1>, # R, the combined speeds at right angles to the line of sight, and the rate of change of range respectively.