Patent GB-132308-A (GB)
IPC: F41G5/08
Abstract: 132,308. Arter, J. J. B., and James Cycle- Co. Aug. 6, 1918. Speed indicators operating by sighting aerial objects.-Relates to means for determining the data necessary for laying of anti-aircraft guns and setting the fuses, in which a flank observing instrument is employed in conjunction with a position-finder near the gun position, and consists mainly in providing on the position-finder an elevation cam and a fuse cam both rotatable through an angle equal to the angle of site, readers being provided, one on each cam, displacable parallel tu the axes of the cams in accordance with the range, said readers being adapted to operate indicators on the gun or to actuate the elevating gear of the gun and an automatic fuse-setter. The invention also comprises (1) means for communicating the traversing-angle from the positionfinder to the gun, or indicating it thereat; (2) means tor obtaining corrections for speed of target, and (3) the employment of two guns, controlled from the position-finder, capable respectively of dealing with targets on opposite sides of the vertical, and (4) electrical means for communicating data from the flank observing instrument to the position-finder, or from the position finder to the. gun. The position-finder is mounted on a pedestal 1. Fig. 1, carrying a spindle 2 on which are mounted two fixed arms 3, 4, Fig. 2, set at right-angles to the base line joining the position-finder to the flank observing instrument, and each of length proportional to that. of this base line. Rotatably mounted on the pedestal 1 is a frame 5, carrying shafts 6, 7, on which are mounted sighting telescopes 10, and drum-shaped cams 8, 9, the cam 8 being shaped to displace a vertically slidable reader 14 by.an amount proportional to the fuse length, and the cam 9 being shaped to displace a similar reader 14, by an amount proportional to the quadrant elevation, for a determined angle of site and range. In one form, the flank observing instrument comprises sighting telescopes 28 mounted on a shaft 27 carried by a frame 26 rotatable in a pedestal 24. The telescopes may carry mirror " finders " and also back and fore sights, and may be duplicated in order that a target may be followed easily on either side of the vertical. One or more searchlights may be mounted on the same shaft. Separate telescopes may be employed for the numbers operating the instrument in altitude and azimuth. Th angle OPQ, Fig. 14, between the base line OP and the horizontal projection of the line of sight to the target Q is transmitted electrically from the blank instrument at P to the position finder at 0, and is so indicated on the arms 3, 4 that the sliders 12, 13, carrying the readers 14, may be slidden, parallel to the shafts 6, 7, into positions in which the line joining the slider to the indicator on the corresponding arm (SR, Fig. 14) makes with that arm an angle equal to the angle OPQ. The distance from O to either slider is then a measure of the momentary horizontal range. The telescopes 10, Fig. 1, are kept directed on the target so that the cams 8, 9 are rotated on the shafts 6, 7 through an angle which is equal to the momentary angle of site. The readers 14 are thus displaced vertically by amounts proportional respectively to the instantaneous values of the fuse length, and the quadrant elevation, and produce corresponding movements of the indicators at the gun. An additional indicator at the gun is adapted to follow the movement of the position-finder in azimuth to indicate the traverse necessary on the gun. To correct for speed of target, the movements of the indicators at the gun may be observed just before firing, to determine the rates of change of the quantities involved. These, together with the indicated time of flight, enable the deflections and the correction of the fuse length to be determined The same result may be achieved by adapting the motors that drive the elevating and traversing gears and the fuse-setting instrument to actuate speedometers with scales graduated to show the respective rates of change. Alternatively, the apparatus indicated in Fig. 11 may be employed, comprising a disk 51 driven from the gear employed to elevate or traverse the gun, or to set the fuse, and a friction disk 52 bearing thereon and adapted to bo displaced radially in respect thereto along a squared shaft in such a fashion that its distance from the centre of disk 51 is proportional to the time of flight. The speed of the disk 52, as indicated by the rise of the governor 53, determines the necessary vertical or horizontal deflection or fuse correction. The various corrections may be applied on the position finder by adjusting the zero of the traversing gear and by axial displacement of the cams. In order to transmit the indications of the readers 14 to the indicators at the gun, the device shown in Figs. 9 and 10 may be employed. With slight modification the same apparatus may be employed to transmit also the angle OPQ from the flank instrument to the position-finder, or the azimuthal deflexion of the position-finder to the gun. The reader 14, as it rises, rotates a disk 16 carrying peripheral contacts every successive three of which, e.g. 17<a>, 17<b>, 17<c> are connected respectively to circuits 18. 19, 20 having a common return including a battery, and connected to a fixed contact 21. Each of these circuits includes one of the solenoids 48, 47, 49 having armatures connected by rods 45, 44, 46 to cranks 42, 41, 43 mounted on the shaft of an indicator. Thus, as the disk 16 is rotated, the solenoids are energized successively, and produce the desired rotation of the indicator pointer. The various movements of the position-finder, the flank observing instrument and the gun, may be produced by electric motors, and the various data may be transmitted from the motors driving the instruments instead of from the instruments themselves. The elevation cam may be shaped to indicate tangent instead of quadrant elevation, and an angle of site indicator may in this case be provided at the gun and controlled from the elevating gear of the position-finder.