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Aviation History
1939
1939 - 0285.PDF
FEBRUARY 2, 1939 lights of up to 1,000 watts each are now being carried. Although the efficiency of the light units is not so high and their value during the approach to the boundary is natur ally restricted in comparison with the aerodrome floodlight, with lengths of run increasing to 800 yards, a point is reached where the aircraft lights have to "take over " from the floodlights, owing to the shorter distance and higher angle from the ground, and experienced pilots place great reliance in their aircraft lights for completing a landing. Light fog or mist alter conditions entirely, and this has led to the de velopment of runway marker lights set flush in the surface of the land ing ground, a development which was strongly advocated by the writer in an article published by Flight two years ago. The lights are laid out along the centre line or along each side of the runway. One line makes an improved flare- path, two lines indicate positively the plane of the landing ground; three lines may look dazzling to some, but others will prefer to have them all "on." Those who have seen the runway marker lights in use at Newfoundland, Man chester, and elsewhere agree that they provide a very valu able aid in all weathers. A well-known problem here arises: what directions of landing are to be catered for? At present, lighting along four runways giving eight directions of landing is wisely advocated, and conforms with the recommendations for the Standard Airport, but it is not everyone who is pre pared to accept even this limitation of the '' all-way '' prin ciple. Calculations show that the shock of landing at 30 deg. out of wind should not be very much greater than at 22^ deg., and this would allow a reduction in the number of runways to three. Tricycle or four-wheeler under carriages and other developments may bring further free dom for cross-wind landings, but it is generally agreed that for heavily loaded, high-speed aircraft at least two run ways approximately at right angles will be needed for a long time to come. FLIGHT. e One of tiie three G.E.C. 6 kW floodlights recently installed at Ringway. Runway marker lights are of particular value for so-called fog landing runways, and here a spacing of 50ft. between lights in the centre of the runway and along the equi-signal axis of the radio beacon transmitter is being stan dardised. In the case of new aerodromes which may be of sufficient importance to be de veloped as "super terminals," it has been thought wise to provide for construction in the future of two runways at right angles, each four hundred yards wide, with ap propriate lighting in conjunction with radio guidance from four directions, thus allowing for land ing in low cloud and nocturnal rainstorms, as well as in the usual still-air fog conditions. Apart from the one fog land ng runway required at present, three single lines of lights at 50 yards spacing are considered adequate both as an aid to landing in accordance with article 16 (2) d. (ii) of the Air Navigation (Amendment) Order, 1937, Schedule IV, Section 2, and as a guide to the unobstructed lines of approach or flightways which are required to comply with Air Ministry Pamphlet No. 76. For the latter purpose runway marker lighting is more effective than the system of "range" lights used in America, where corresponding groups of green lights at each end of a runway have to be "lined up " to give the direction of landing. The American system is economical in capital cost because the range lights are fed from the same cable as the boundary lights, and they are all switched "on" together. It might be thought that mis takes could be made when a rainstorm or an aircraft landing ahead obscured a light at the far end of the run way, but there is no record of an accident due to this cause. First Experiments The first installation of runway marker lighting to be completed in this country is at the Manchester Corpora tion's new airport at Ringway, and a demonstration was described in last week's issue of Flight. The complete installation (including, besides the marker lights, orthodox boundary and obstruction lights and three fixed flood lights) was designed nearly two years ago, by the consult ing engineers, Messrs. Norman and Dawbarn, in collabora tion with the Corporation Electricity Department, taking into consideration the extensive additions to the landing ground and building area which can be made in the future. At the same time an illuminated model of the runway marker lighting and approach lights was constructed, and this has proved very useful in the subsequent discussions (Above) The control-tower panel for switching of the con tact-light strip. Note the representation of the strip, in which tell-tale lights repeat what is happening outside. (Right) One of the Chance flush-fitting lights in the contact strip. They are stressed to take heavy loads.
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