Patent GB-733086-A (GB)
Title: Improvements in and relating to computing devices
IPC: G06G7/80
Filed: 1952-10-20
Abstract: 733,086. Electric analogue calculating systems; variable capacitors. CONTRAVES AKT.-GES. Oct. 20, 1952 [Oct. 20, 1951], No. 26250/52. Class 37. Apparatus for determining polar co-ordinates of the point on the path of a moving target at which it will be struck by a projectile comprises a first set of electrical computing devices rotatively responsive to the polar co-ordinates of the current target position producing a first set of electrical signals proportional to the velocity components of the target in cartesian co-ordinates, a second set of electrical computing devices adjustable proportionately to the time of flight of the projectile to the striking point to derive a second set of product electrical signals proportional to the displacement components of the target in cartesian co-ordinates relative to the striking point, and a third electrical computing device receiving the second set of electrical displacement signals and arranged to produce a set of control signals operating a third set of electrical computing devices comprising servosystems arranged to relatively drive output members to represent in polar co-ordinates the angular displacements of the current target position from the striking point and also the time of flight and range to the target; the servosystems also driving devices producing auxiliary follow-up signals fed back to the system inputs. Fig. 1 shows a target aircraft moving in space along a course MT whose position is currently defined by cartesian coordinates (xm), (ym), (zm) referred to an origin O corresponding to an observation station, from which the current position M of the target is currently defined by the polar co-ordinates of range (rm) = OM, angular elevation (#m) = MOM1, and angular azimuth alpha(m) = XOM1. The predicted point of impact T of a projectile with the target after a time of flight t is defined by cartesian co-ordinates (xt), (yt), (zt) and by the polar co-ordinates of range (rt) = OT, angular elevation (#t) = TOT1, and angular azimuth (alphat) = XOT1, while the deviations.existing between the current position M and the point of impact T are given by in cartesian co-ordinates, where t is the time of projectile flight from O to T given by the ballistic equation and by By trigonometry it is shown that (Figs. 3, 4, not shown) and that (Fig. 6, not shown) and that (Fig. 7, not shown) and that (Fig. 9, not shown) and by differentiating equations (8), (9), (10), (11) that Fig. 5 shows an electrical predictor wherein the currently measured range (rm), elvation (Am) and azimuth (alpham) of a target are set in by cranks and dials to shafts 12, 22, 32. Shaft 12 adjusts a multiplier P1 (Fig. 11) energized by a unitary alternating voltage to derive a range voltage (rm) energizing a component analyser P2<1> (Fig. 12, not shown) adjusted by shaft 22 to derive voltages (Zm), (rm1) given by equations (8), (9) above. Voltage (rm1) energizes a component analyser P2<2> adjusted by shaft 32 to derive voltages (ym), (xm) given by equations (10), (11) above e and these voltages are applied to differentiating circuits P3<1>, P3<2>, P33 (Fig. 13) to derive velocity voltages (xm), (ym), (zm) energizing multipliers P1<1>, P1<2>, P1<3> adjusted by a shaft 43 rotated by motor NM3 in accordance with the predicted time of flight t as derived below. The output voltages represent the deviation components #x, #y, #z as given by equations (1), (2), (3), and are applied to an 8-pole transformation network P5<1>(Fig.15) adjusted by shaft 36 in accordance with the currently measured azimuth (alpham) on shaft 32 to derive output voltages B, A<1> given by equations (12), (13). Voltages A<1> and (rm1) are added in a summation circuit P4<1> (Fig. 141) to give a voltage A according to equation (14), and the A and B voltages are supplied to an 8-pole transformation network P5<2> adjusted by shaft 62 driven by induction motor NM1 energized by the-amplified network output to satisfy equation (15) and rotate the shaft through an angle corresponding to #alpha, such that the motor energization is reduced to zero. Equation (16) is then solved, and the remaining output of the network gives voltage (rt1) which is combined with the phase reversed voltage (- rm1) from P2<1> in summation circuit P4<2> to give a voltage #(r1) according to equation (5) representing the range deviation. This voltage together with the #z voltage from P1<3> is applied to an 8-pole transformation network P5<3> adjusted by shaft 26 in accordance with the currently measured elevation (#m) on shaft 22 to derive output voltages D, C<1> according to equations (17) and (18). Voltage D is combined with voltage (rm) from the output of P1 in a summation circuit P4<3> to give a voltage C according to equation (19) and voltages C and D are applied to an 8-pole transformation network P5<4>, adjusted by shaft 52 driven by induction motor NM2 energized by the amplified network output to satisfy equation (20) and rotate the shaft through an angle corresponding to ## such that the motor energization is reduced to zero. Equation (21) is then satisfied and the remaining network output gives voltage (rt) which is phase reversed and fed back to a summation circuit P4<4> where it is combined with a voltage (rt*) derived from a non-linear multiplier P7 (Fig. 17, not shown) adjusted by shaft 43 driven by induction motor NM3 energized by the amplified output voltage of P4<4> to reduce such output to zero. Multiplier P7 is proportioned to solve the ballistic equation (4) above, and is energized by a unitary alternating voltage, so that the rotation of shaft 43 represents the time of flight t of a projectile to the predicted point of impact T, which also adjusts the multipliers P1<1>, P1<2>, P1<3>, and operates output dial 41 calibrated to display the predicted range (rt) to the point of impact. The rotations of shafts 52, 62 representing the polar deviation components ##, #alpha in elevation and azimuth are mechanically added to the rotations of shafts 24, 34 representing the currently measured elevation and azimuth angles of the target (#m), (alpham) to operate dials 51, 61 displaying the predicted elevation and azimuth angles (#t), (alphat) of the point of impact. In a modification (Fig. 8) the currently measured range, elevation and azimuth of the target are set in to shafts 12, 22, 32 adjusting multiplier P1, analysers P2<1>, P2<2> and differentiating circuits P3<1>, P3<2>, P3<3>, as in Fig. 5, to derive velocity voltages (xm), (ym), (zm) which are multiplied by t given by the ballistic equation (4) above in ballistic multipliers P7<1>, P7<2>, P73 adjusted by shaft 42 driven by motor NM3 correspondingly to the predicted range (rt) to the point of impact as derived below. Voltages (x0), (y0), (z0) representing the cartesian co-ordinates of the gun referred to the observation station are set in by cranks 100, 110, 120 adjusting multipliers P1<1>, P1<2>, P1<3> supplied with a unitary alternating voltage to derive voltages (x0), (y0), (z0), which are respectively combined with voltages (xm)t, (ym)t, (zm)t in addition circuits P4<1>, P4<2>, P4<3> whose outputs represent the deviation components #x, #y, #z. The 8-pole transformation network P5<1> and the summation circuit P4<4> derive voltages A<1>, A and B in accordance with equations (12), (13) and (14), and the 8-pole transformation network P5<2> and its adjusting motor NM1 solve equations (15) and (16) for (rt1) and #alpha as above. Voltages #z and (Zm) are combined in summation element P4<6> to derive a voltage (Zt) in accordance with equation (3) which is phase reversed and combined in a summation member P4<7> with an output voltage (Zt) from an 8-pole transmission network P5<3> supplied with voltages (Zt*) and (rt1*) and adjusted by motor NM2 energized from the output of P4<7> to rotate shaft 52 through an angle corresponding to ## to reduce the motor energization to zero. Motor NM3 rotates shaft 72 through an angle corresponding to #r to adjust a multiplier P1<4> energized by a unitary alternating voltage to develop a voltage #r energizing analyser P2<3> adjusted by shaft 22 in accordance with the currently measured elevation angle set in by shaft 22 to derive voltages #r sin (#m) and #r cos (#m), which are respectively combined with voltages (Zm) and (rm1) from P2<1> in summation circuits P4<8>, P4<9>, whereby voltages (Zt*) and rt1*) are obtained in accordance with equations (23) and (24) and supplied to network P5<3>. The output voltage (rt1) from P52 and the phase reversed output voltage (rt1) from P53 are combined in summation circuit P4<5> and amplified to energize motor NM3 to drive shaft 72 through an angle corresponding to #r and to adjust multiplier P1<4> until the output of P4<5> is reduced to zero, at which equations (22) to (26) are solved for #r and ##. The predicted values (rt), (#t), (alphat) for range, elevation and azimuth of the point of impact are derived by mechanically adding the deviation components #r, ##, #alpha to the currently measured values (rm), (#m), (alpham) for the target set in by shafts 12, 22, 32, and are displayed on dials 71, 51, 61 driven by shafts 76, 56, 66, while the predicted value of (rt) is also connected through gearing to adjust ballistic multipliers P7<1>, P7<2>, P7<3> as above. Fig. 10 shows a further modification in which the currently measured range, elevation and azimuth are set in by cranks and dials on shafts 12, 22, 32. Shaft 12 adjusts a multiplier P1 energized with a unitary alternating voltage to produce a voltage (rm) and also drives a differential generator DG1 (Fig. 20, not shown) producing a voltage (rm), together with a multiplier P1<1> supplied with a fed-back voltage (rt)/(rm) derived as described below to develop an output voltage (rt). Shaft 22 adjusts an analyser P2<2> supplied with a unitary alternating voltage to develop an output voltage (rm1)/(rm) = cos (#m);