GB574982A - Improvements in aerodrome ground lighting - Google Patents

Abstract

574,982. Luminairs for aerodromes. HOLOPHANE, Ltd., and ENGLISH, S. Jan. 14, 1944, No. 769. [Classes 75 (ii) and 75 (iv)] A luminair for aerodrome one-way landing strips comprises a low-lying substantially flattopped housing having an annular wall fitted with a window or refractor by which light from an electric lamp is concentrated into a beam of small elevation and vertical divergence and having an azimuthal distribution of 180 degrees or less, its greatest intensity being opposite to the direction of landing. Figs. 1 and 2 show a lighting unit comprising a pot-like container 1 to be set at the edge of the runway with its flange 2 flush with the ground, a concentrated filament electric lamp 3, an outer conical refractor 5 secured on a rubber gasket 6 to the flange 2 by a ring 7, an inner refractor 14 secured to container by clips 15, a brass cap 11 resting on a rubber gasket 12 above the refractor 5 and secured to the container by bolts 13, and a reflector 4 for redirecting upwardly the downward rays from the lamp 3. The refractor 14 is formed on its inner surface with vertical prisms 17 of varying size concentrating the rays from the lamp 3 into a beam of 270 degrees divergence horizontally and on its outer surface with annular prisms 19 and a toroidal surface 20 concentrating the beam vertically. The refractor 5 is formed on its inner surface with prisms 22 of varying size concentrating the 270 degrees beam into a beam of 180degrees or less angle horizontally. The outer surface of the refractor 5 may be parallel or converge upwardly towards the inner surface or may be part spherical as shown in Fig. 2 of Specification 566,720. Fig. 3 shows a tubular incandescent or discharge lamp 24 arranged in a trough reflector 25, of elliptical section to direct the light through a window 29 in the direction of the landing strip. The reflector is adjustable about its pivot 26 by a screw 28. The reflector 25 may be constructed as described in Specification 567,568. Figs. 4 and 5 (not shown) illustrate two reflectors preferably elliptical in vertical section and parabolic in horizontal section fitted with concentrated light sources and mounted back to back in a casing fitted with windows which are straight in horizontal planes and at right angles to the beam axis. The windows may have curved or concave inner faces according to the focal length of the reflectors. Either lamp may be switched on according to the direction of landing. Specification 561,541 also is referred to.