Patent GB-498745-A (GB)
Abstract: 498,745. Gun-fire control; calculating- apparatus. VICKERS - ARMSTRONGS, Ltd., and WATSON, J. P. June 9, 1937, No. 16059. [Class 92 (ii)] [Also in Group XIX] Relates to fire-control apparatus for antiaircraft guns which is also adaptable to surface firing of the kind including a predictor in which a plurality of vector components of target course and speed are used to determine the required data for the gun such as the horizontal and vertical deflections and the future range. The vector components chosen for a target moving in three dimensions at a speed V are mutually at right-angles and are represented by V1, V2, V3. The vector V1 is taken along the line of sight, the vector V2 at right-angles to a plan view of the line of sight, and the vector V3 at right-angles to the line of sight and in a vertical plane through the line of sight. For surface firing, the vector V3 becomes zero. According to the invention, a fire control apparatus for the prediction of deflection corrections comprises members whose movements represent the vector components of target course and speed, one vector V1 representing the linear rate of movement of the target along the line of sight, and the other or others constituting the additional vector component or components representing target movement which is or are employed to obtain approximate values of the deflection or deflections treated as a linear function of the vector concerned, there being mechanism for applying the complementary correction necessary to obtain accurate values of the deflection or deflections. The mathematical expressions involved are shown in the diagram Fig. 2 in which O and P represent the observer and target in elevation in the upper part of the diagram, the target displacement being shown in plan in the lower part, and projected on a vertical plane in the middle part. The accurate formulae for future range Rf, horizontal deflection D, and vertical deflection d are found to be (1) Rf=Rp-V1T+RfCos Sp.Cos Sf(1-Cos D)+Rf(1-Cos d) (2) Sin D=V2T/Rf Cos Sf (3) Sin d=V3T/Rf - Sin Sp.Cos Sf(1-Cos D). If a constant K be chosen so that Rf=KT, where T is the time of flight, the deflection d is mainly given by the first term V3T/Rf in equation (3) which may be written V3/K, the second term being a small complementary correction. In the case of the deflection D, a constant K1 is taken such that RfCosSf=K T, the deflection D being then V2/K1. The deflections are thus mainly linear functions of the quantities V2, V3. The vector component V1 along the line of sight is employed to predict the future range Rf. Fig. 3 shows at the upper part apparatus similar to that described in Specification 498,744 in which handles 1<A>, 2<A>, 3<A> set in the vector components V1, V2, V3 through gears in a unit 10 (described with reference to Fig. 4 not shown) to rotate a range dial 21, an elevation dial 27 and a training dial 48 so as to balance pointers 22, 28, 47 receiving the generated range from the range finder and the generated elevation and training from the sight 40. The present range Rp and present angle of sight Sp enter the unit 10 by shafts 11, 11A. A second unit 52 (described with reference to Fig. 5, not shown) which receives as input V1 by shaft 54, Rp by shaft 53 and Sf by shaft 55 calculates as output Rf by shaft 61 and T by shaft 62. A third unit 63 receives as input, in addition to Rf and T, the quantity Sp from the sight, the components V3 from shaft 64 and V2 from shaft 65, and the quantity Sf from shaft 68, the quantities d and D after calculation re-entering the unit by shafts 66, 67. The output from the unit 63 at shaft 69 is a rotation proportional to (d-V3/K) and at shaft 70 a rotation proportional to (D-V2/K), and these are set into differential gears 75, 78 on the shafts 3, 2 rotating in accordance with the vector components V3, V2 respectively, extensions 3B, 2B of the shafts moving in accordance with d and D. Further differential gears 81, 97 add the deflections to the present angles of elevation and training obtained from the sight. Tangent elevation and drift may be added by further differential gears 99, 98 which actuate the gun data transmitters 102, 103. The apparatus within the unit 63, described with reference to Fig. 6 (not shown), is for the purpose of calculating the complementary corrections to the range and deflections as deduced from the equations (1), (2) and (3). The complementary correction for range, shown on the right-hand side of equation (1) is calculated and emerges by shaft 55A. The complementary horizontal and vertical corrections (D-V2/K) and (d-V3/K), expressions for which are found by rearranging equations (2) and (3) as shown in the Specification, emerge from the shafts 70, 69 respectively when hunting gears within the unit effect a balance between shafts rotated in accordance with the calculated expressions on each side of the rearranged equations. Specification 414,742, [Group XIX], also is referred to.