Patent GB-563585-A (GB)
Title: Improvements in range-finders, height-finders and the like
IPC: G01C3/20
Filed: 1938-04-23
Abstract: 563,585. Range-finders. SPERRY GYROSCOPE CO., Ltd., and MURTAGH, H. April 23, 1938, No. 12216. [Class 97 (i)] Apparatus for determining the range or height of an aircraft &c. comprises an observation member rotatably adjustable by means including an element, the rotational or translational movement of which is a .function of the cotangent of the angular displacement of the member. The member may be combined with a calculating machine having a part operable in accordance with the movement of the element, the combination being provided with control means, the movement of which effects adjustment of the member and is transmitted to the machine. The apparatus may comprise a range-finder mounted on a post 1 and rotatable in azimuth by a training-wheel 2 and having arms carrying brackets 5, 6 for supporting the tube 7 which is rotatable in the brackets by an arm 13, Fig. 2, secured to the tube and formed with a slot 15<1> engaged by a pin 14 carried by a nut 12 threaded on an horizontal screw 9 driven through gearing from a shaft actuated by a hand wheel 8. For the greater part of its length the slot is straight, and its centre-line is substantially parallel to the line of sight. Thus, the translational movement of the nut and the rotation of the wheel 8 are proportional to the cotangent of the angle between the arm and the screw and also to the height of the aircraft. In order to deal with elevations below 5 degrees, the lower end of the slot is curved. The shafts actuated by the wheels 8, 2 respectively service electrical transmitters 104, 105 connected to receivers 104<1>, 105<1>, Fig. 3, in a gun-fire director, while the wheel 16<1>, Fig. 1, controlling the setting of the range-finder prisms is geared to a transmitter 106 connected to a receiver 106<1> in the director. The receiver 105<1>, which is driven in accordance with the azimuth adjustment of the range-finder, positions the pointer of a match-the-pointer indicator 51, the dial of which is adjusted through a shaft 55 operated by a hand wheel 52. The azimuth angle is transmitted through a shaft 56 to a predictor which may be of the kind shown in Specification 418,670, [Group XXI]. The receiver 1061 operates the pointer of a slant range indicator 20 kept'matched by hand wheels 26, 27 which control, through a shaft 40 and gears 25, 24, the rotation of a shaft carrying cams 15, 16 and thus the lift of a rod 19 adjusting the dial of the indicator. The cam-shaft is adjusted laterally by a nut 18 threaded on a screw 17 driven by the receiver 104<1>, the movement of the nut and the shaft thus being proportional to the cotangent of the angular displacement of the range-finder tube. The cam 15 is of such a form that the rotation of the shaft 40 required to keep the indicator matched is proportional to the height of the aircraft. The rotation of the shaft 40 is fed into the predictor through shafts 41, 43. The shaft 40 is continuously rotated by a variable-spaced gear comprising a constant-speed motor 37 driving a disc 36 which drives a cylinder 38 through a ball 35, the position of which is adjustable by the hand wheel 26. The cylinder shaft drives the shaft 40 through a differential gear 39 which permits correction of the angular position of the shaft 40 through the hand wheel 27. The shaft 40 is adapted, through the shaft 41, to position a ball 71 on a disc 70 proportionally to the height of the aircraft, while the disc is rotated through the receiver 104<1> proportionally to the cotangent of the angular adjustment of the range-finder tube. Thus, the resultant rotation of the cylinder 72 is proportional to the horizontal range which rotation is fed through differentials 73, 29 and shafts 30, 33 to the predictor. The variable-speed gear constituted by the parts 70, 71, 72 ensures that the horizontal range is obtained automatically and smoothly, since the gear will not do this with complete accuracy, a hand wheel 28 is provided for adjusting the angular position of the shaft 30. Correctness is judged by the matching of the indicator 23, the pointer of which is controlled.by a rod 21 actuated in accordance with the horizontal range by a cam 16, while the dial is controlled by a shaft 31 driven by the shaft 30. For low angles of elevation, the shaft is driven through a shaft 45 and the apparatus is operated through a hand wheel so that a revolution counter 44 on the shaft 31 indicating the horizontal range in yards matches a slant range reading on the dial of the indicator 20. In a modification, the range-finder is combined with calculating mechanism for determining the height and the horizontal range which are transmitted to a gun-fire director. Specification 479,018, [Group XXJ], also is referred to. I