Patent GB-606656-A (GB)
Abstract: 606,656. Sights. SPERRY GYROSCOPE CO., Inc. Nov. 17, 1944, No. 22921. Convention date, Sept. 26, 1940. [Class 92 (ii)] A computing gun-sight apparatus includes means for determining the lead angle in two components, one about a first axis, say a horizontal axis, and the other about an axis tilted with'respect thereto, means being provided for deriving a quantity proportional to the angular rate of movement of the line of sight about the tilted axis,and for deriving therefrom a correction, and means also being provided for applying the corrections to the displaceable sight to displace the line of sight with respect to the bore of the gun. In the construction shown, the target is viewed through a thinly silvered mirror 4 which is rotatably mounted on the top of a sighting box attached to the gun. On to this mirror is projected the image of reticle comprising two slotted plates 36, 37, whose slots 38, 39 are so adjusted that their images, as seen in mirror 4, circumscribe the target. The optical system associated with the reticle comprises a light source 44, reflector 45 and tiltable mirror 46. In operation, a knob 16 is rotated in accordance with known target dimensions to move, through rack and pinion 18, 19, a cam 17 axially, the cam being rotated by long pinion 21 in accordance with the target's range. These two movements of the cam actuate a toothed cam follower 28 which drives a pinion 30 which, as shown in Fig. 2, serves to move plate 36 in one direction and, by means of pivoted link 34, the plate 37 in the other direction, thus varying the distance between slots 38, 39. The long pinion 21 is rotated either by a range knob 24 through gearing 25, 26, 27, or by a knob 23 which adjusts the position of a ball carriage 40 of a variable speed device whose disc 41 is driven by a constant speed motor 42 and whose driven cylinder is geared to the pinion as shown. The range is also set in by shafts 54, 55 to a differential 56 whose other input is set in by the follower of a cam 58. This cam is axially displaced by gearing leading to a shaft 11 driven by the elevating gear of the gun, and is rotated by shaft 5 driven by the training gear, and is so designed as to impart to its follower and thence to differential 56 a ballistic correction which when added to the range gives the required total elevational ballistic correction on output shaft 65. To such correction is added in a differential 66 the predicted deflection in elevation. This latter quantity is obtained by mechanism comprising a variable speed device whose disc 80 is driven by motor 42 and whose ball carriage is displaced by a cam 81 which is rotated by range shafts 54, 57, and which is so designed as to convert the slant range into a factor inversely proportional to the projectile's time of flight. The driven cylinder 78 drives the disc 77 of another variable speed device whose cylinder 76 and also a shaft 73 driven by shaft 11 of the elevating mechanism serve to position the ball carriage 79. By this means the position of the ball carriage 79 represents the predicted deflection in elevation, this quantity then being led by shaft 67 to differential 66. The output of differential 66 serves to tilt the mirror 46 of the sight. The azimuth ballistic correction is supplied to a differential 69 bv the follower of a cam 68 displaced by shaft 57 in accordance with range and rotated as shown by the shaft 5. For obtaining the correction to be applied to the sight in the slant plane, the elevation shaft 11 serves to rotate a cosine cam 86 which displaces the ball carriage 88 of a device 89 whose disc 90 is driven by azimuth shaft 5. Driven cylinder 91 is thereby made to rotate at a speed proportional to the angular speed of the target in the slant plane and leads to a predicting mechanism 99 similar to that employed in the elevating part of the apparatus and supplying, by shaft 67<SP>1</SP>, a second input to differential 69. The output of this differential then serves to drive a shaft 47 which in turn drives the base 48 of the sight through the correct angle of lead.