LIGHT FOR NIGHT FLYING.

New Zealand Herald, Volume LXIII, Issue 19217, 5 January 1926, Page 7

LIGHT FOR NIGHT FLYING.

TESTS MADE AT CROYffON. PENETRATING MIST AND FOG. Steady progress is being made with the problem of perfecting some lighting scheme which will enable aircraft to land after dark on an aerodrome shrouded in mist or even enveloped in fog, and much useful information has been obtained by the uso of a military observation balloon over Croydon aerodrome, writes the aeronautical correspondent of a London paper. A few days ago' i" had the opportunity of making my own observations from the air in the balloon at heights ranging from 500 ft. tc 1500 ft., and after observations extending over three-quarters of an hour, it is abundantly clear that the early promise of the Neon gas-filled tube system of signal lighting is being fulfilled. Every one is familiar now with the advertisement signs which consist of thin tubes of a peculiar reddish light, to be seen over London shops, and it is enlarged editions of this tubing that have changed remarkably the whole problem of illumination through fog. This has the valuable property of piercing mist more effectively than any other form of coloured light, while a further advantage of the form in which it is used is that it is purely a diffused light and is not projected like that from the usual form of lamp which has a bright filament or arc. Thus, whereas the latter may very definitely confuse the pilot's vision owing to its refraction from the infinitesimal units of moisture in a white mist, the Neon light gives an even diffused glow over a considerable area without any dazzle effect other than that of changing the colour values of other lights in the vicinity. Unfortunately, from the point of view of the worst conditions, there was no thick fog about when I went up in the balloon, but there was a fair amount of mist to cause refraction in the beam of the large flood light used for landing of aeroplanes. London itself was hidden in a blanket of clond and not a great deal of the lights of Croydon could be seen, but of all the many night landing lights on the aerodrome 1500 ft. below, the Neon lights were infinitely more prominent.