GB191516856A - Improvements in or relating to Sighting Apparatus for Anti-aircraft Guns. - Google Patents

Abstract

16,856. Dawson, Sir A. T., and Buckham, G. T. Nov. 30. Sights.-Relates to anti-aircraft sighting- apparatus of the kind in which means, adjusted in accordance with the ascertained height of the target, are provided for automatically correcting the angle of tangent elevation for varying angles of sight during the elevation and depression of the gun. The invention comprises an arrangement in which a cam is provided, adapted to be adjusted initially according to the height of the target, and so designed as to impart the required corrections. In the ar rangement shown in Fig. 1, a stationary profile cam B is employed, initially adjusted about its pivot B<2> on the carriage A in accordance with the height of the target, by means of a hand-wheel (not shown) mounted on the righthand side of the gun and operating through gearing b<3>, B<3>. A graduated " height " dial is provided in conjunction with the operating hand-wheel, such dial being also graduated in terms of ranges or fuse timings and co-operating with a pointer passing across the face thereof as the gun is elevated. The cam B<1> acts upon the sight-arm B through the medium of a roller b<1>, which moves along the cam edge as the gun is elevated or depressed to bring the sight on to the target. A check roller b<1Î> engaging a groove B'X in the cam may also be provided. In Fig. 1, cross-connected sights are shown with gearing for effecting vertical and lateral deflexion corrections. A modification is shown in Fig. 3, in which the profile cam B<1> is pivoted on the cradle at B<2> and moves therewith without any bodily rotation, under the constraint of a parallel-link motion b<9> connected at its forward end to a bracket a on the carriage. Gearing may be substituted for the parallel motion b<9>. Instead of the profile cam, a surface or laminated cam may be used, in which case settings for different heights are obtained by relative axial adjustment of the cam or the roller. A surface cam may be used to superimpose a further correction for speed of target. In this case, the cam is adjustable angularly for heights as in the form shown in Fig. 1 and axially or longitudinally for speed of target, the centre lamination corresponding to zero speed and the laminµ on either side corresponding to targets approaching or receding at various speeds.