GB547345A - Improvements relating to lights for guiding aircraft - Google Patents

Abstract

547,345. Signalling by visible signals. CHANCE BROS. & CO., Ltd., and HOLMES, J. G. April 5, 1941, No. 4575. [Class 118 (ii)] A device for guiding aircraft consists of a light-projecting apparatus with a moving screen which bears a pattern that interrupts the light beam and projects flashes. The pattern is so arranged that the sequence of flashes seen by the pilot of an aircraft differs according to the position of the aircraft relatively to the projector. In one construction, the apparatus comprises an electric lamp a, Fig. 2, a reflector b, a condensing lens e, a projecting lens c, and a screen consisting of an endless band d of opaque flexible material carried by rollers h one of which is driven by a motor. The band d has transparent or translucent portions arranged in a pattern as shown in Fig. 3, to provide groups of signal flashes. The parts of the pattern between the lines 1, 2 give a succession of equally-spaced dot flashes, the parts between the lines 2, 3 give a sequence of dot and dash flashes, and the part between the lines 3, 4 give a sequence of groups of flashes. The image of the pattern is projected upwards, and a pilot of an aircraft knows that he is on his proper course if he sees the flashes emitted by the central part of the pattern. Deviation from the course will bring him into the regions covered by the outer ports of the pattern. The screen may reciprocate instead of being driven in one direction, or it may consist of a rotating disc. In another form, the pattern may be formed on a frusto-conical screen j, Fig. 5, or on the edges of two such screens, or rotating discs, which touch or overlap one another on the optical axis O-A of the projecting lens.,