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Aviation History
1950
1950 - 0247.PDF
FLIGHT. 2 February 1950 163 A manually retractable version, 8KD, designed for helicopters. FOR "LIGHTER" LANDINGS . . path, whereas with the TK' lamp the beam was too harsh for objects on the other side of it to be clearly observed, and the runway lights beyond the beam were completely cut off. With the Harley lamp fully extended landing was pleasant and easy. The illuminated area increased gradu- ally in size on the descent and height above the flare-path could be judged without distraction caused by the beam. " With the ' K' lamp," continues this particular report, "the patch of brilliant light became harder and brighter as height decreased and height above the flare-path could not be judged so effectively. Although neither light had sufficient depth of beam to cater for both tail-down and tail-up attitudes, and consequently adjustment by means of the ' inching' control fitted in each lamp actuator cir- cuit was necessary, the greater depth of the Harley com- pensated to a large extent for a change of fore-and-aft attitude on the approach. The Harley lamp in its fully extended position illuminated objects on the ground from about 400ft and at 200ft the view of the ground was quite good. The ' K' lamp, depressed to 80 degrees, also iUui- minated objects at 400ft, but at 200ft gave a spot which, although well lit, had a harsh, black surround." Some idea of the graduated spread and diffusion in com- parison with the harsh, impenetrable beam of the "K" type can be obtained from two photographs in the heading. The runway lights are 100yd apart and the height of the lamps above the runway is 30ft. One pilot reported : "At 400ft, the aerodrome was seen as in daylight. When the aircraft was just about to touch down, light extended the whole length of the flare-path (800yd). When coming in over the boundary at 100 to 150ft the area illuminated was from a point just below the aircraft to a point about 500yd up the flare-path, which on the night of the test was about 300yd up-wind from the boundary." There are over 30 different types of landing lamps in the Harley range, each made for a specific purpose. Models are available from 6 to 14 inches in diameter and from This view of the FDT mobile floodlight emphasizes the ease of access to generators and floodlights. 144 to i,000 watts in power. Versions are available for fitting in nose-fairings, in leading edges and on the under- surfaces of wings. For wing installations there are both electrically and mechanically retractable types ranging from 6 to 11 inches in diameter and up to 750 watts in power. Speed of retraction even on the largest models was an impressive feature of a demonstration witnessed by a member of the staff of Flight. Models have also been designed for helicopters and light aircraft. Among other developments by the same firm are taxying lamps, which provide a circular pool of light around the aircraft, the upper limit of the beam being horizontal and the diameter of illumination approximately 400yd. Harley portable floodlights, with self-contained genera- tors, suitable for use on emergency or small airfields, give adequate illumination for landing. Fitted with red indi- cator-beacons, they obviate the necessity for boundary lighting, illuminated wind-indicators and mains-power floodlights. During the demonstration to which reference One of the largest fa in the Harley ranees 11K, as fittedCwto Ambassador and BrabcCioA. has been made, one model—tne well-designed and robustly constructed F.D.T. trailer unit shown below—illuminated a ground area of adequate width and up to 1,000yd in length, at which distance it was still possible to read a newspaper with ease. This floodlight undoubtedly provides lighting conditions in which the pilot of any aircraft in the medium-twin category would not hesitate to land. Because development in one field often results in pro- gress in others, it is not out of place to observe that the activities of the firm's workshops are by no means restricted to aviation, Harley lighting units being adaptable to a multitude of transport and industrial uses. The I+4-watt 6VS taxying and manoeuvring lamp, fitted in either retractable or static form.
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