GB543542A - Improvements in or relating to gun sights - Google Patents

Abstract

543,542. Gun sights. FAIREY AVIATION CO., Ltd., and HETHERINGTON, J. Nov. 17, 1938, No. 33459. [Class 92 (ii)] A periscope sight, more particularly for sighting exposed aircraft guns from within the cockpit, comprises three tubes, one 15, Fig. 1, of which moves with the gun or guns 13 about the trunnion axis 11, the second 16 moving with the gun or guns about the training axis 12 and the third 17 of which carries the eyepiece 35 and is stationary. Further, the sighting corrections in elevation and training respectively are effected within the sight itself by wedgeprisms 22, 27 mounted on the tube 16 and adjusted by turning graduated sleeves 24, 29. The tube 15 carries a total reflection prism 19 for the entering rays whereby a line of sight alongside one of the guns which carries a foresight may be reflected laterally along the axis 11. The tube 16 carries the angularly-adjustable wedge-prism 22 to correct for tangent elevation, a total reflection prism 25 at the intersection of the axes 11, 12, a trapezoidal prism 26 and the angularly-adjustable wedge-prism 27 for corrections in azimuth. The third tube 17 carries a field lens 30, a correcting wedge-prism 31, a roof prism 32, a graticule 33, and an eyepiece combination 34. The invention is shown applied to a pair of guns 13 mounted in a common cradle 14 turning for training in a fixed bearing 18. Fig. 5 shows the application of the invention to guns arranged in pairs at the upper and lower parts of the aircraft fuselage and adapted for movement to exposed or stowed positions as described in Specification 530,045. The tube 17 of the sight for the upper guns, shown for the exposed gun positions, telescopes with respect to the tube 17<SP>1</SP> of the lower guns. The binocular eyepiece 38 is fitted with prisms so arranged that the right eye sights the upper guns and the left eye the lower guns.