Patent GB-385331-A (GB)
Abstract: 385,331. Gunnery calculators. VICKERS-ARMSTRONGS, Ltd., and WATSON, J. P., Vickers House, Broadway, Westminster. June 20, 1931, No. 17942. [Class 106 (i).] The invention relates to apparatus for determining the course and speed of a moving target from the ranges and bearings observed from a ship or other moving platform. According to the invention, rates of change of range and of bearing have deducted from them rates due to the motion of the observing ship and members moved in accordance with the resultants move cross-wires (or their equivalent) over a dial, the point of intersection of the wires. indicating the target course and speed. On a dial C is a representation C1 of the target. This is moved angularly to represent target inclination (i.e., the target course relative to the line of sight) by a hand-wheel C5. The representation carries a radial scale along which a pointer C2 is moved by a knob C7 to represent target speed. In operation, the pointer C2 is kept beneath the intersection of the cross-wires A, B which are moved to represent rate of change of target range and of linear bearing respectively by means described below, rate of change of linear bearing being defined as the rate of change of angular bearing divided by the range. The setting means C5, C7 also adjust angularly and radially a pin D, of an " analyser " such as is described in Specification 381,147, the pin engaging two slides D2, D3. The slide D2 is accordingly moved a distance corresponding to the rate of change of target range and the slide D3 to rate of change of linear bearing. The movement of the slide D2 is conveyed to a shaft G through two differential gears E, F. Through the former gear E adjustments effected by a range-rate " tuning " handle E1 may be incorporated and the adjusted value is transmitted, by a screwed shaft A1, to the rangerate wire A. The second differential gear F allows the addition of a value corresponding to the rate of change of range due to " own " ship's motion, this value being obtained from a second " analyser " F, set in accordance with " own " ship's course and speed. The shaft G moves the ball-carrier H of a variablespeed gear radially along a disc H1 rotating at constant speed. The ball drives a roller H2 connected through a differential gear H4 with a screwed shaft H5 moving a pencil H6. The pencil, the position of which corresponds to the range, is moved over a chart H7 to trace a curve which follows the mean path between a number of points which have been marked by an independent range finder. The pencil is adjusted by a range " tuning " handle H3 operating through the differential gear H4. The shaft G also has splined to it a screwed sleeve G1 on which is a nut G2 carrying a straight-edge G3 pivoted about the pencil H6. The sleeve is coupled to the carrier of the pencil H6 to slide therewith, and the straightedge is kept tangential to the range curve. The linearbearing-rate wire B is moved from the slide D3 through a differential gear K connected to a linear-bearing-rate " tuning " handle K1. A differential gear L allows the addition of a value, obtained from the second " analyser," corresponding to the rate of change of linear bearing due to " own " ship's motion, the combined value being transformed by a device M1 into rate of change of angular bearing and transmitted to a shaft M2 controlling a straight-edge maintained tangential to an angular bearing curve on a chart N7. The shaft M2 also controls a variable-speed gear N driving a shaft N5 moved in correspondence with the angular bearing and controlling a pencil N6 which is made to draw a mean path through points marked on the chart N7 by an independent bearing finder. The pencil is adjusted by a bearing " tuning " handle N3 operating through a differential gear N4. The motion of the shaft N5 is combined by a differential gear C4 with that given to the handle C5 and, by a differential gear P, with that derived from a yaw receiver P1, the latter combined movement being transmitted to the disc of the " own " ship " analyser." Clutches Ex, Kx are operated either mechanically or electrically by pushing the knob C7 on handle C5 inwards.