Patent GB-863267-A (GB)
Title: Computer
Inventor: IMM LEWIS WILLIAM
IPC: F41G5/20
Filed: 1957-03-19
Abstract: 863,267. Mechanical calculating-apparatus; indicating-apparatus. GENERAL PRECISION Inc. March 19, 1957, No. 9049/57. Classes 106 (1) and 106 (4). Calculating-apparatus includes a constantly driven integrator, a rate-entering device connected to the ratio-varying member of the integrator, and a value-registering mechanism driven by the integrator and connected also to a value-entering device, the rate- and valueentering devices being coaxially arranged so as to facilitate their simultaneous adjustment. Thus if the rate changes after the rate-entering device has been set, or if the setting of the latter proves to be incorrect, the value may be corrected by adjustment of the value entering device, and the rate-entering device may be adjusted at the same time. The apparatus is incorporated in a computer for use on a destroyer in depth-charge attacks on submarines and having an integrator, Fig. 33 (not shown), which is referred to below and is associated with coaxial range rate and range entering knobs 177, 176, Fig. 2. Certain factors involved are constant throughout an attack and are initially set by hand on the main computer, Fig. 2. These are the submarine depth D set by a knob 119; the dead time W (knob 182); the time lag S + F, i.e. the sum of the sinking time of the depth charge and the time of flight (knob 184); and, in a stern attack, the distance L from the sound projector head to the dropping station (knob 259) or, in an ahead attack, the distance Re the charge would have travelled from the position of the sound projector head when the charge is thrown to the point where the charge strikes the water if the charge had been thrown with the destroyer at a standstill (knob 248). Other data varies throughout the attack and is entered on manually operated follow-up indicators which transmit their settings electrically to the main computer. Thus follow-up devices 52, 75, and 1, Fig. 1, are continuously adjusted from observation of other instruments to enter the destroyer's speed Vd, the destroyer's compass course j, and the target bearing e. In Fig. 47, A is the destroyer which is proceeding along AM, B is the submarine proceeding along BJ and J is the future position of the submarine when the depth charge explodes. AJ represents the course the destroyer should follow. The transmitted value of e is the value obtained by averaging (by means of a differential gear) the left and right cut-on values indicated by the sound-detecting equipment of the destroyer. In addition, the range knob 176 on the main computer is set initially so that the slant range as indicated by a pointer 156 on a scale 157 corresponds to that indicated by the sound equipment. The movement of the knob 176 itself corresponds to the horizontal range R, the slant range Rs being derived as described below. The slant range, as well as being-indicated by the pointer 156, is also transmitted by electrical means to a band indicator 174. During the attack, the changing range is continuously computed by the computer and if the indicated slant range becomes different from the value given by the sound equipment, the knob 176 is moved to effect correction. At the same time, the coaxial range rate knob 177 is moved in the same sense in an attempt to prevent a further error. The setting of the knob 177 corresponds to the component of the submarine's velocity Vs in the direction away from the destroyer and thus corresponds to Vs cos a, where a is the submarine's course relative to the line of sight from the destroyer A to the submarine B, Fig. 47. The value Vs cos a entered by the knob 177 is used in the computation of the slant range. The bearing e of the submarine from the destroyer as transmitted from the follow-up device 1 is indicated by a ring dial 50, but a calculated value of e is also indicated by an inner ring dial 103, which is initially set to correspond to the dial 50 by a bearing knob 593. During the attack, the knob 593 is moved, if necessary, to bring the dials 103 and 50 into coincidence and when this is done, a coaxial bearing rate knob 541 is also moved in the same sense in an attempt to prevent further error. The setting of the knob 541 corresponds to the component Vs sin a of the submarine's velocity at right angles to the line of sight and is used in the computation of the target bearing e. Should the submarine change course during the attack, a switch 627 is actuated to the left or right according to the sense of the change in course to cause a motor to correct the bearing and range rate settings. The switch is actuated for a time corresponding to the extent of the change in course. In addition to the pointer 156 which indicates the slant range Rs and the dial 103 which indicates the calculated target bearing e, other indications are given as follows. A pointer 116 marked on a disc 109 is actuated by a differential mechanism having inputs connected to the dial 103 (e) and the compass follower 75 (j) so as to move in accordance with p = j - e. The pointer 116 reads against the dial 103 and so actually indicates the angle j thereon. The angular move. ment corresponding to p is converted, Fig. 45 (not shown), into linear movements corre. sponding to sin p and cos p. The value cos p is fed to a multiplication linkage together with the value Vd (fed from the knob 117 and follower 52) and the output Vd cos p is fed to a lever which subtracts the value Vs cos a fed from the range rate knob 177. The output movement of the lever, which it is shown corresponds to - dR/dt = Vd cos p - Vs cos a is applied to a pointer 515 to indicate the range rate. This value is continuously integrated by a ball-anddisc integrator, Fig. 33 (not shown), to give R, the output of the integrator being coupled to the knob 176 by which an initial value of R and subsequent corrections are entered. A pointer 115 is moved, as described below, in accordance with b, the angle between the line of sight AB and the course the destroyer should follow. The pointer reads against the dial 103 which moves according to e and consequently indicates thereon the course to steer, b + e. The value sin b, from which the movement of the pointer 115 isderived, is also balanced against the value sin p, obtained as described above, by means of a lever 385, Fig. 27. A rod 390 connected to the lever 385 controls a resistance 392 by which an indicator 394, Fig. 1, is positioned. This is arranged by the helmsman and indicates whether the destroyer is on the required course (p = b) or whether he should alter course and in which sense. The pointer reads against a compass rose positioned by the compass follower 75 so that the approximate number of degrees of change is indicated. Indicating speed and course by one pointer.- The speed and course of the submarine are indicated by a pointer 468, Figs. 2 and 44, the end of which is moved in two dimensions over a dial 469 geared to the dial 103 which is moved according to e. The dial is marked with concentric rings indicating the speed and with radial lines indicating the course. The pointer 468 is mounted on a universal pivot 530 and its other end is actuated by two rods 535 and 528 at right angles to one another and coupled respectively to the bearing rate knob 541 and the range rate knob 177 which are continuously moved to represent Vs sin a and Vs cos a, so that the extent and direction of movement of the end of the pointer correspond to Vs and a respectively. Signalling the time to fire.-Three lamps 179, 180, 181 are lit to indicate when the depth charge should be fired. In the present instance they are lit 30 secs. before firing time, 15 secs. before and at the instant of firing respectively. The lamps are energized by switches actuated by cams on a shaft driven by a motor energized at 30 secs. before the instant of firing. It is shown that R = K cos p + (T + W + S + F) dR, -, where K is the distance between the desdt troyer and the position of the charge when it explodes and T is the time remaining to the instant of firing. Thus, by substituting for T a value 30 secs., which is done in fact by suitably adjusting the initial position of the member set by the knob 182 which enters the value W, a value R o  may be obtained equal to the range 30 secs. before the instant of firing. For this purpose, the movements derived from the knob 182 on shaft 186, Fig. 26, i.e. W, to which 30 secs. is added, and the knob 184 on shaft 189 (S + F) are added by a lever 193 and applied, together with the value dR/dt obtained as described above on a link 212, to a multiplying linkage, the output of which on a rod 214 is added by a further lever 216 to a value K cos p received on a rod 218 and obtained as described below. The lever 216 thus applies to an arm 220 coupled to a rod 223 a movement corresponding to R 0 . A lever 227 is coupled to the range knob 176 and so is moved continuously in accordance with the changing value of R. This lever 227 carries a switch 225 arranged to be actuated by the rod 223 when R = R 0 . This switch energizes the motor controlling the indicating lamps. Solving right-triangles.-The slant range R s  of the submarine C from the destroyer A, Fig. 46, is derived from the horizontal range R and the depth D: AE is drawn equal to AC and it is shown that Rs = R + cR s  = R + D<SP>2</SP>/2.38 R as an approximation. The value D<SP>2</SP>, entered from the knob 119 in co-operation with a suitable scale, is applied to a division linkage, Figs. 24 and 25 (not shown), together with the value 2.38 R derived from the range knob 176, and the output is applied to a differential gear together with the value R again derived from the knob 176. The output of the differential gear represents R s  and is applied to the pointer 156 and range indicator 174. Determination of K and K cos p.-For an ahead thrown attack; the distance between the destroyer and the charge at the time of explosion, K = Re + 4.4 Vd - Vd(F