GB523763A - Improvements in or relating to maps and map-mountings for use in the navigation of aircraft - Google Patents

Abstract

523,763. Maps; optical projection apparatus. GRAVES, A., and ALLTOOLS, Ltd. Jan. 14, 1939, No. 1319. [Class 146 (ii)] [Also in Group XX] A map carrier for aircraft or ships has rotational and linear adjustment to register with a datum line on an optical enlarging device such as an optical projector or a microscope, the relative travel of the map being made to correspond with the speed of the aircraft, and, with the initial adjustment, being applied either to the map or the enlarging device. The map may be flat or curved. The photographic map is supported. on a seating 12, Fig. 2, in a turntable 13 rotated by a friction wheel 28 through a wormwheel 26 sliding on a square shaft 24 with a worm actuated by a worm-wheel 22 sliding on .a square shaft 21 connected to a flexible shaft c. The turntable 13 is mounted on a carriage 20 sliding on guides 35 and traversed by a threaded spindle 39 with worm actuated by a worm-wheel 37 sliding on a square shaft 36 connected to a flexible shaft a. The guides 35 are mounted to slide in channels 43 fixed to the casing 44 and are traversed by a threaded spindle 47 connected to a flexible shaft b. A lamp and reflector 15 are mounted on the casing which also carries an annulus 60 for the cross-wires 18a, 18b and the lens tube 16. The annulus 60 is fixed to a slide 59 mounted on a spindle 58 carrying pinions 31 engaging two racks 30 on the turntable 13 so that the cross-wire 18a will always remain parallel to the racks 30 and therefore to a given line on the map. The projection screen is provided with markings to indicate compass bearings, so that .the intersection of these markings with the image of wire 18a will show the course to which the map has been set. Shaft a is rotated through a spring clutch from a spindle carried by a control box 19, Fig. 7, and geared to a shaft 53 carrying a friction-wheel 54 driving a disc 55 connected to a disc 69 by epicyclic gears 71, 74, 75. The position of wheel 54 in relation to disc 55 is controlled by a slide 64 having a pin engaging a scroll-groove 62 in a disc 61 set by a handle A<SP>1</SP>. Discs 61, 55, 69 have calibrated flanges 67, 68, 70 visible through a window 49 and indicating respectively the speed at which the control is set, and the minutes and hours in the time of the flight. The clutch, in shaft a enables the indicator discs to be adjusted without alteration of the map, whilst a handle-operated cam 76 by raising disc 55 clear of wheel 54 enables the map to be adjusted without alteration of the indicator discs.