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Aviation History
1948
1948 - 0543.PDF
APRIL 22ND, 1948 FLIGHT 451 vees and funnels, are to be deprecated,because as visibility gets worse, less and )es<. of the pattern is seen, and mental calculations as to where the vanishing point would be if it could be seen get progressively more difficult. For this and other reasons, the lec- turer had come to the conclusion that the directional indication is best provided by a single line of lights along the ex- tended centre-line of the runway. The type of pattern recommended, therefore, consists of a centre-line of lights with bars of lights arranged at intervals across Pilots would probably all agree that they could fly level over a pattern con- sisting of a line with cross bars of equal length, since all they would have to do would be to fly so that successive bars jjibtended the same angle as they dis- appeared underneath the nose, and this would be little different from flying level over a runway. Because this type of pattern gives indications of alignment, bank and glide path in a manner which is free from ambiguity even when only a small portion of the whole pattern is seen, the lecturer suggested that some pattern on this principle will ultimately provide a solution which will be generally accepted. Light Wavelength and Blur One question which is often raised is whether fog will blur the sharp outline of the bars in the same way as the bulb of an opal lamp blurs the, outline of the light source. The answer is that some opal glasses do not blur the outline of the source, depending on the ratio of the dia- meter of the diffusing particles to the wavelength of the light. Anyone can satisfy himself by observing the sun in cloud or street lamps in fog that the sharp outline of the light source is not in fact blurred. This has also been demon- strated directly by observations of the bar pattern from a captive balloon, and there are now quite a number of ob- servers who can confirm that the bars appear with clear-cut outlines both by day and by night in all atmospheric, conditions in which they have been observed. Another question often raised is that of dazzle. The answer to this is that, with the intensities under consideration, i.e., 5,000 candles for the runway lights and 50,000 to 100,000 candles for <he centre-line approach lights, no trouble is experienced in daylight. At night, the runway and the centre-line lights will be dimmed to suit the atmospheric condi- tions. At the worst, the lights will not be dimmed, but in these instances, it should be remembered that the pilot will be landing by the light patterns and not by observing the texture of the fore- ground. If the pilot has been able to use the approach aids successfully, the aircraft should arrive over the threshold of the runway at a height such that the pilot's head is about 50ft above the ground. After the end of the runway has been crossed, the pilot has no further need to relate his height to any particular point of touchdown and a pattern which indi- cates direction, height and lateral dis- placement is sufficient. A pair of parallel lines indicates direction by means of their vanishing point and also indicates height and lateral displacement by means of changes in the perspective angle. The pilot is, therefore, able to judge his height from a bar of parallel lines only provided that he is familiar with the scale of the pat- tern. The importance of keeping the distance between the rows of runway lights constant has always been realized in this country, and this distance was maintained at 150ft on those airfields recently built in which the width of the runways has been increased to 300ft. This decision was far-reaching because it carried with it the implication that flush- type runway lights would have to be used and, as is well known, very high intensities cannot be obtained from this type of light. _ -••• .-•., International Differences The lecturer pointed out that there was some variance of opinion regarding British and American practices and sug- gested that, if the distance between rows cannot be standardized internationally, then it may be necessary to select some scale fixing pattern internationally agreed as regards dimensions, and add this to the normal runway pattern for a cer- tain distance on each side of the normal touch-down point. These scale effects, provided that they are not too large, are important only in fog and it is likely therefore that scale fixing patterns will only be required on instrument runways. After devoting some attention to the lighting patterns for taxy-ways, Mr. Cal- vert referred to the R.A.E. Simulator, built by J. W. Sparke and H. F. Ringe, two of his colleagues, with controls arranged as in a real aircraft so that an observer looking into the instrument and operating the controls, would see the light patterns behave exactly as they would do in reality. The Simulator was designed and built in less than three months and has proved to be a most useful research tool. It was completed in October, 1947, and since then demonstra- tions have been given to about 400 people, which has meant about 8,000 simulated landings. Function of Day Markings The lecturer then observed that, up to the present, day markings have not been seriously considered in this country, but there is no doubt that they could be made to serve four very useful func- tions, (a) to increase the distance at which the runway can be picked up, (b) to assist the pilot in making his judg- ments of height by accentuating the per- spective angle and by giving texture to the surface, (c) to provide accurate guid- ance in the horizontal plane when the aircraft is close to the ground, or taxy- ing, and (d) to remove ambiguities from the ground indications. The lecture was concluded with the suggestion that, from the considerations put forward, there is good ground for belief that a landing system which inte- grates existing radio approach aids with properly designed high-intensity visual aids, a scientific arrangement of day markings and perhaps FIDO, and also utilizes a training device such as the R.A.E. Cyclorama, would provide almost a complete solution to the problem of landing aircraft in bad visibility. If operational experience should prove this to be the case, then those improvements in regularity and punctuality which.are necessary to the success of air line opera- tion would be in sight, traffic control would be simplified and the way would be open to the more economical utiliza- tion of airports and aircraft. NEW ANSON VARIANTS TDENTICAL in construction, and •^powered with Armstrong Siddeley C^Rtah XV engines (425 h.p. for take- off), the Avro Anson T.20, T.2r and T.22 are equipped respectively for training in Rhodesia, for specialized navigational in- struction and for radio training. Typical - data are: Gross weight 10,4001b; max. level speed 171 m.p.h.; max. cruising speed 167 m.p.h.; economical cruising 150 m.p.h.; sea-level rate of climb 790 ft/min; service ceiling 14,000ft; max. range 645 miles; fuel capacity 140 gal. CHIPMUNKS FOR THE V.R. "DEPLYING to a question by A. Cdre.1V A. V. Harvey, Mr. Arthur Hender- son, the Air Minister, has disclosed that D.H. Chipmunk trainers will be replac- ing Tiger Moths in the R.A.F.V.R. An- sons will continue to be used for the training of V.R. signallers and navi- gators. This most welcome news concerning the Chipmunk is not altogether unex- pected and will be received with the greatest satisfaction by instructors and pupils alike. It is reasonable to suppose that the British Service version may later be used by the R.A.F. and that it will have a blind-flying panel in both cockpits, a , battery for electrical '' intercomm.'' and night-flying equipment. '" SUPPLY OFFICERS' w .'CONFERENCE " THE first of what is hoped will be aseries of R.A.F. supply conferences, to which the Senior Equipment Staff Officers of all R.A.F. home and overseas commands, as well as representatives of all the Dominion air forces were invited, has lately been held at the Air Ministry. The conference was opened by the Vice- Chief of the Air Staff (Air Marshal Sir James Robb) in the absence of the Air Member for Supply and Organization (Air Marshal Sir Leslie Hollinghurst), who was away on an overseas tour, and during the two-and-a-half days that it was in session under the chairmanship of the Director-General of Equipment (Air Vice-Marshal T. E. Drowley), various problems of common interest were discussed. It is hoped that as a result of the conference greater standard- ization, both of supply and of methods, will be achieved. Later the delegates were to visit var- ious supply organizations in Maintenance1 Command to.see how the supply require- ments of the R.A.F. are met. GROUND-ATTACK VAMPIRES IT has been known for some time pastthat a version of the de Havilland Vampire is to become a standard fighter- bomber in the R.A.F., in succession to the Hawker Tempest. The variant con- cerned is the F.B. Mk. V and is generally similar to the Vampire III. With Swise markings, an essentially similar machine is known as the F.B. VI. The F.B. 50 is the type to be supplied under ths second Swedish contract, lately an- nounced.
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