Patent GB-191420775-A (GB)
Title: Improvements in Apparatus for Computing the Deflection to be given to Gun Sights.
Inventor: REDIADIS PERICLES DEMETRE
IPC: G01C3/04
Filed: 1914-10-09
Granted: 1915-09-09
Abstract: 20,775. RÚdiadis, P. D. Oct. 9. Sights and methods of sighting.-Relates to means for automatically computing and indicating the necessary deflexion to be given to a gun when firing at a moving target, allowance being made for drift due to rifling, wind. and the rotation of the earth, and consists of n telescope, used in conjunction with a rangefinder, and having, in its field. means for measuring the rate of travel of the target. means actuated by the measuring - means for computing the deflexion, and a scale showing the result of the computation in the field of the telescope. The telescope comprises an eyepiece 20 with a wedgeshaped lens 31, a movable cross-lines glass 3 with a vertical crossline 3<A> for following the movement of the target, a roof prism 32, a pentagonal prism 33, and an objective 34, the object being sighted through an opening 18 in the casing 16, 17 within which the apparatus is mounted. The arrangement indicated shows an image of the target on. the upper half of the field of the telescope as shown in Fig. 4. A scale 2 and deflexion indicator 9 are simultaneously reflected on to the lower half of the field by means of lenses 36, 36, 37 and a triangular prism 38, the scales being illuminated by means of a window 19 in the casing. The cross-lines glass 3 is mounted in a slide carrier and is adjusted to cause the crossline 3<A> to follow the movement of the target across the field, by means of a milled head 4 acting through a shaft 5, bevel-gearing 5<a>, and a worm and rack 5<b>. The cross-line is caused to follow the target for a definite period, such as 10 seconds, the number of scale divisions passed over in this time being a measure of the speed of the target. For this purpose, the time may be measured by an electrically-controlled clock. Should the telescope be mounted on a moving ship, it may be retained in its initial position by means of a gyroscope when an observation is being made. In traversing the cross-line 3<A>, the milled head 4 simultaneously traverses a stem or rod 7 carried by a nut 6 mounted on a screw-threaded portion of the shaft 5. The stem 7 is pressed upwards by means of a spring 8 into contact with a suitably adjusted deflexion surface 10, so that, as the cross-line 3<A> is moved to follow the target, the stem 7 is simultaneously caused to traverse the surface 10 adjusted for range &c. and automatically indicates on the scale 9 the necessary deflexion to be given to the gun. The deflexion surface 10 is built up of a number of triangular sections corresponding to different ranges, the surface of each section being suitably inclined to indicate the necessary deflexions corresponding to various relative speeds of the target at a certain range. Two oppositely inclined surfaces 10 are provided to enable relative movement of the target to the right or to the left to be observed. The deflexion surfaces 10 are formed upon a member 10<a> pivoted at 21 to a carrying-slide 15<a> formed on its upper surface with a rack 15 engaging a pinion 14<X>, by means of which the parts 10, 15 are adjusted longitudinally, automatically or otherwise, in accordance with the indications of the rangefinders. A further correction for drift of projectile due to wind may be effected by means of a milled head 11 connected to a pinion 1 carried by the slide part 15<a> and engaging a rack 22 on the part 10, which may thereby be adjusted about the pivot 21 to one side or the other of its central position of adjustment. The milled head 11 may be provided with a pointer 13 passing over scale readings on the part 12. The deflexion surfaces 10 may be modified to allow for drift due to the rifling of the projectile and the rotation of the earth; in this case the oppositely inclined surfaces 10 would not be symmetrical. In a modification, Figs. 6 and 7, the deflexion surfaces 10 previously described are replaced by a single plane surface 1 mounted to be rotatable about an axis a-a in a carrier 2 which is, in turn, adjustable about an axis b-b in a second carrier 4, the carrier 4 being adjustable longitudinally in guides 4<a>. In this arrangement, the stem 28 is carried by a nut member 20 mounted upon a screwed spindle 19, which may be given an initial adjustment by means of a milled head 18 to effect a correction for the effect of side wind on the projectile. The stem is not, however, traversed as in the previous arrangement, the plane member 1 corresponding to the deflexion surfaces 10 being traversed instead. The cross-line 23<A> is traversed to follow the target by means of a milled head 22 acting through bevel-gearing 31 and a worm and rack as before. The slidable carrier 4 is simultaneously adjusted by the milled head 22 acting through bevel-gearing 25 and a worm and rack 26, 27. This traverses the plane 1, adjusted according to the range and acting upon the stem 28 to give the required deflexion indication of the pointer 30 on the scale 13. The plane 1 is adjusted according to the range indicated by the range-finder by mea.ns of universal shafting 9, 10 which, when rotated, rocks the plane 1 about the axis a-a through a worm 11 and wheel 3, while adjustment of the carrier 2 is simultaneously effected through bevel-gears 7, 8 engaging respectively with a bevel-gear 5 fixed to the carrier member 2 and a bevel-gear 12 fixed to the end of the shaft 9. When the shaft 9, 10 is rotated, adjustment of the scale 13 is automatically effccted by means of bevel-gearing 17 and a traversing-nut 15 having an upper cam-surface 14, this adjustment being intended to compensate for drift of projectile due to rifling and the rotation of the earth.