Patent GB-176763-A (GB)
Title: Apparatus for controlling the firing of guns against aerial objectives
IPC: F41G5/08
Filed: 1922-01-28
Abstract: 176,763. Marks, E. C. R., (Schneider et Cie). Jan. 28, 1922. Methods of sigliting. - Relates to means for correcting the aim of anti-aircraft guns based on formulµ which depend on the assumption that the target is moving at a uniform speed in a rectilinear path at a constant height. According to the invention, a self - contained " corrector " provided at the observing station has telescopes 1, 2 by which the observers con - tinuously follow the target in azimuth and elevation, the motion thereby imparted to the telescopes being conveyed to apparatus forming part of the " corrector " for calculating the various terms in exact mathematical formulµ which give the corrections in training, elevation and fusesetting to suit the movements of the target and also take in account the speed and direction of the wind, the corrected angles being applied to the gun through electric circuits which include a Wheatstone bridge. Fig. 2 shows diagrammatically the various parts of the " corrector " and the electrical connections with the elevating and training gear of the gun. Shafts are shown in chain lines and electric circuits in dotted lines. In the formulµ quoted below, # = angle of training; a = angle of site; #0' alpha0 = initial angles of training and site; #, # = corrections to angles of training and site for movements of target; H = height of target; f2 = time of flight of projectile; e = fuse setting; h = tangent angle of elevation; t3/W, time occupied in fuse setting and loading; W = wind speed: and # = deviation of wind direction from N-S. The following formulµ, developed in the Specification, give the angles #, #, The handles 8, 12 which are turned to follow the target in azimuth and elevation drive magnetos 20, 23 having fixed brushes 21, 24 and moving brushes 22, 25. The angle separating the brushes 22, 21 and 24, 25 being adjusted proportional to f2 by turning handle 86 and shaft 78, and the armature voltages being proportional to the brushes of the magnetos and across the resistances 26-27 and 34-35 are proportional to tated proportional to alpha0 and translated by screw gears proportional to #, rods 44, 60 bearing on the cams therefore displace arms 28, 36 over the resistances 26-27 and 34-35 to apply the cor- and pointers 29, 37 of voltmeters 30, 38 are displaced to give the corrections #, #. A cam 66 rotated proportional to alpha0 and translated proportional to # moves the zero point 39 of the voltmeter 38 to apply the correction #<2>/2 sin alpha@ cos alpha@ appearing in the site formulµ. Handles 31, 40, being continuously moved to bring the pointers back to zero, are rotated proportional to # orespectively and through differential gears 136, 93, the corrected angles (#o + #) and (alpha0 + o-) are obtained on the shafts 137, 92. For applying the tangent angle of elevation h, a cam 106 is rotated proportional to (alpha0 + #) and translated proportional to f2 and operates through a differential gear 123 to rotate a shaft 124 proportional to (alphao + # + h). The Wheatstone bridge principle set forth in Specification 131,635, [Class 40 (i), Electric signalling systems &c.], is employed to pass on the corrected angles to the gun. For this purpose arcuate resistances 179, 204 with diametral brushes 185, 202 and a voltmeter 205 are employed to control the training of the gun by hand-wheel 194, and similar resistances 182, 215 and a voltmeter 216 control the elevation of the gun by hand-wheel 206. To correct for speed and direction of wind, the resistances 179, 182 are rotated by cams 139, 166, rotated proportional to (# - #), the angle # being obtained by setting a pointer 152 to a scale on the wheel 148 by turning a handle 151. The wind corrections ## and ## are made in accordance with the known formulµ. The function F (Halphao) is read on a drum 218 and applied by rotating a handle 162 to set a pointer 163 to the value of this function shown on a drum 164 which has been previously set for W by a pointer and scale 227, 228. The cam 139 is therefore translated proportional to W F (Hαo). Similarly the setting of a pointer 177 to the appropriate H curve on a drum 178 by turning handle 173 gives translation to cam 166 proportional to 0.00025 HW. The fuse setting is obtained from curves for H, e, Fig. 7, arranged on a sheet 88 passing over rollers and advance proportional to (alphao + #). By rotation of the handle 86, a pointer 87 is kept on the appropriate H curve and pointer 101 which gives the fuse setting is moved relatively to pointer 87 by an amount t3(df2/dt) by a tachometer 102 working in conjunction with a voltmeter 103. To correct for the effect of wind on f2, the pointer 87 receives a vertical movement from the cam 166. Fig. 5 shows an alternative arrangement for giving t, (df2/dt)@ in which two tachometers 225, 226 of known type, the spindles 228, 229 of which are alternately operated according to the direction of rotation of the handle 86, move the pointer 101 through a differential gear 231 and rack 232. Fig. 6 shows a constant speed electric motor 248 for driving in known manner the telescopes and the magnetos 20, 23 through variable-speed friction drives 254, 253 controlled by hand-wheels 266, 265. Specification 127,280 is referred to.