Patent GB-499265-A (GB)
Title: Improvements in apparatus for determining the magnitudes required for parallax correction for laying anti-aircraft guns
IPC: F41G5/08
Filed: 1938-06-03
Abstract: 499,265. Gunnery calculators. ZEISS, C., [Firm of], and PAPELLO, K. June 3, 1938, No. 16621. [Class 106 (i)] An apparatus for determining the magnitudes required for the correction of parallax in laying an anti-aircraft gun comprises three cam systems arranged for longitudinal and rotational displacement and connected to driving mechanisms for entering the known magnitudes E, s, alpha and #, representing respectively, the range of the target from the apparatus, the horizontal distance of the gun from the apparatus, the lateral angle between the lines of sight from the apparatus to the aircraft and to the gun, and the elevation angle from the apparatus to the aircraft. The cam systems obtain the differences #alpha, ##, and #E in accordance with the following equations : Figs. 1 and 2, show diagrammatically how the sought magnitudes are deduced : A is the apparatus, B the gun, and H the aircraft. In the apparatus shown in Fig. 3, the magnitudes #alpha, ## are substituted for the sines as these values can be considered equal for small angles. The values alpha, # and E are entered by rotating shafts 2, 3 and 4 and the distance s by rotating a hand wheel 5. These shafts are connected by differential and other gearing to effect displacement and rotation of the cam systems 30, 31 and 32, 59, 60 and 61, and 59, 93, for obtaining #alpha, ## and E respectively. By the arrangement shown cam 30 displaces a feeler 37 and thereby the cam 31 in accordance with the value S/E+#E while the cam 31 rotates in accordance with sine alpha to displace the cam 32 which receives a rotation in accordance with #+## and transmits its movement through a feeler 45 and rack 47 to a shaft 51 indicating #alpha. The cam 59 is displaced according to distance s and by differential 53 is rotated according to alpha + #alpha/2, so that a feeler 67 displaces the cam 60, as well as the cam 93, in accordance with s Cos (alpha + #alpha/2). The cam 60 rotating in accordance with the value # displaces the cam 61 which is rotated from the differential 23 associated with the shaft 4 and causes a feeler 81 and rack 83 to be displaced according to the value ##. The cam 93 is rotated from the shaft 3 through a differential 87 according to the value # + ##/2 and, by the displacement imparted to the cam by the feeler 67, another feeler 96 and rack 98 is moved in accordance with the value #E. A modified form of apparatus is shown in Fig. 4. the equations being simplified by neglecting the values of #E, #alpha and ## in the above equations which may be written In this form the differential gears are unnecessary. The displacement of the feeler 45 by movement of the cams 30, 31 and 32, is indicated by a follower mechanism comprising a contact mechanism 101 . . 103 and a slide 104 driven in one or other direction by a motor 107, the rotation of the shaft 105 on which the slide is mounted giving the value #alpha. Cams 108, 109 control the operation of a second follower mechanism to obtain the value ## and cams 59, 93 control the operation of a third follower mechanism to obtain the value #E.