Patent GB-354178-A (GB)
Title: Improvements in or relating to nomographic calculating apparatus applicable for use in gunnery and other calculations
IPC: G06G1/16
Filed: 1930-04-04
Abstract: 354,178. Calculating-apparatus. DEHN, F. B., 103, Kingsway, London.-(Askania-Werke Akt.-Ges. vorm. Centralwerkstatt Dessau und C. Bamberg-Friedenau ; 87, Kaiserallee, Friedenau, Berlin.) April 4, 1930, No. 10802. [Class 106 (i).] Gunnery calculators.-Apparatus for effecting, with the aid of nomographic curves, calculations relating to functions having n+3 variables comprises relatively movable indicating means to explore the curves of a basic nomogram correlating three of the variables when the remaining n variables are assumed to have fixed values and means for use in conjunction with " influence " nomograms for causing displacements of the indicating means in accordance with variations of the remaining n variables. In order to obtain the correct relations between the basic and influence nomograms, a " co-ordinating " nomogram is used. This is a nomogram correlating two of the variables of the basic nomogram with an "auxiliary" variable y<1> the influence nomograms then being constructed to correlate y<1>, one of the variables of the basic nomogram and the particular influence concerned. In one form of apparatus, Figs. 4 and 5, to a disc 71 is detachably secured a card bearing a basic nomogram a, influence nomograms e1, e2, .. and a coordinating nomogram b. In the basic nomogram a, the distance of the target is represented by an angular displacement E, the gun elevation by the length of the radius vector and the elevation of the target by the curves shown. In the co-ordinating nomogram the target elevation is represented by an angular displacement, the auxiliary variable y<1> by the length of the radius vector and the range by the curves. In the influence nomograms the correction to be made to the gun elevation is measured in an angular direction, the auxiliary variable radially and the value of the particular " influence " by the curves. The nomograms are observed through a microscope U4 which slides along a radius of the disc 71 in a slide 128, the part of the aperture not containing the microscope being covered by a blind 135 working on rollers. The slide 128 is itself moved in guides by a screw 112 which is coupled to a knob T3 when one of two buttons controlling levers 38 is depressed. The knob is also permanently geared to an annulus 11 bearing a scale read by a fixed microscope U5. The disc 71 carrying the nomograms is rotated by a knob and can be coupled to the annulus 11 by depressing a button which moves rods 77 radially outwards to engage a recess in the annulus 11. In use, both couplings are released and the basic nomogram is brought beneath the microscope U4 which is then moved to the outer edge thereof. The disc 71 is now rotated until the target distance is read in the microscope U4. The zero of scale 11 is brought under microscope U5, the knob T3 is coupled to the screw 112 and the microscope U4 moved radially to the appropr:ate nomogram curve, the distance of this movement being indicated by the scale 11, which then gives the gun elevation under basic conditions. The coupling is then released and the co-ordinating nomogram b brought under the microscope U4 which is radially set to the value y<1> corresponding to the given values of target elevation and range. The first influence nomogram is next brought beneath the microscope U4 which is maintained at its radial setting y<1> and the disc 71 is coupled with the scale 11. The disc 71 is then adjusted until the curve representing the given value of the particular influence is under the cross-wires, the scale 11 also moving the same amount and so automatically correcting the reading of the gun elevation in microscope U5. Any number of influences may thus be taken into account. In a second form, Figs. 11 and 12, the basic nomogram No and a series of nomograms N1, N2, .. each comprising an influence part and a co-ordinating part are arranged around a centre O about which are pivoted a disc T and an arm L2. The disc T carries an arm L1 which can slide radially and the arm L2 carries a sliding index R. The arm L1 is set angularly to the zero of the basic nomogram No and the disc T locked by a catch q. The index R is then set on the first co-ordinating nomogram and the arm moved to the zero line of the first influence nomogram, whereupon the arm L2 is frictionally connected to a disc s which carries a pinion u1 meshing with a rack on the end of the arm L1. The angular setting of the pointer R according to the first influence nomogram thus moves the arm L1 radially to modify subsequent readings thereon. The coupling of arm L2 and disc s may be effected automatically by a spring-pressed member K1, Fig. 12, carrying a detent K2 normally bearing against the outside of a ring g1 on the disc T. In the proper position this detent slips through an aperture d1 in the ring g1 and then through an aperture D1 in a second ring g2, the member K1, attached to the arm L2, engaging the disc s. The coupling is broken by withdrawing the member K1 by means of a lever h connected thereto by a wire i. Stops a prevent the movement of the arm L2 from one nomographic field to another without a previous uncoupling. In a modification of this form, the arm L1 does not move radially but is constructed in two parts which are given a relative angular movement by the movement of the arm L2. In a further modification of this form shown in the lower portion of Fig. 11, a series of nomograms n<1> .. n<5> is employed, these nomograms being constructed so that each takes account of its own variable and of the effect of the preceding variables. The arm L2<1> is moved over each nomogram in turn, two riders R<1>, R<11> facilitating reading from the curves, and is finally moved into the field of a nomogram n<6>, where it is automatically coupled to the disc s as above described to modify the position of the arm L1. In a fourth modification, angular movement of the arm L2 is converted into radial movement of the arm L1 by coupling the latter to the former and moving the two over a plate having a spiral slot engaging with a projection of the arm L1. A fifth modification in the form of a gunnery calculator is shown in Fig. 15. A basic nomogram correlating, in polar co-ordinates, the range as a radius vector OH, the gun elevation as a vector angle # and the target height by the curve number (h1, h2, &c.) is mounted on a panel P rotatable about a point O on a rectangular plate K. Fixed to the plate K is an upright U having a reading edge V and carrying a slider T with an index H. To the slider T are pivoted arms L1, L2 sliding in sockets pivoted to sliders G1, G2 working in grooves in the plate K. A catch M locks the arms L1, L2 together when they are at right-angles to each other. Arms d1, d2 are fixed to the sliders G1, G2 and carry a ruler L3. On the left-hand half of the plate K is mounted a slide B, after the manner of a slide-rule, and this slide similarly carries a further slide C. The distances OG1, OG2 and OH are graduated logarithmically so that, when OG1 = horizontal range and OG2=target height, OH=actual target distance. The basic results obtained from the nomogram P are modified by moving the slider T through members d1, d2, G1, G2, L1, L2 in accordance with influence and co-ordinating nomograms on the slides B, C and on the plate K. Specification 132,307, (Class 106 (i), Calculating &c.], is referred to.