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Aviation History
1938
1938 - 1277.PDF
MAY 5' J938- FLIGHT. 449 -ELECTRIC MOTOR CONTACTS FORWARD AND REVERSE ELECTRIC MOTORSVUPHOM BELLOWS p.CABIN PRESSURE Automatic e lectric- ally - operated dis- charge valve. DISCHARGE MK. I)-. L. HOLLIS WILLIAMS thought our aim ought to be to offersea level conditions at all heights as there were many travellers who suffered considerably at a height of even a few thousand feet.With reference to heating the cabin air, he thought it might be possible to get the heat direct from the pressure rise. PROF. YOUNOEK agreed that maintenance of sea level conditionswould be desirable, especially for sleepers, as passengers who were asleep often suffered considerably from changes in altitude duringa night flight. The heat by pressure rise was not sufficient, and additional heat had to be supplied. I'KOF. (',. T. K. HILL had been struck by the simplicity of thesolutions found for the various problems. He thought pressure cabins ought to be made easily airtight. Flying boat hulls were,and they had to stand much higher pressures. He did" not appear to agree with the lecturer on the subject of windows, and thoughtthe circular type was right and logical. He expressed the view that the saving in fuel which arose from flying high would soonmake up for the extra weight, and reminded the audience that when the retractable undercarriage was suggested there were many whosaid it was too heavy and complicated. Yet it was now in universal use. He regretted that the lecturer had made no mention of thework done by Famian in flying, work which anti-dated the American. AIR COMDRE. K. H. VERNEY, C.B.F., Director of TechnicalDevelopment at the Air Ministry, pointed out that in Europe at any rate one encountered cloud below S,oooft. on .50 per cent, of thedays of the year, and that it was an advantage to get above them in bad weather. PROF. YOUNGER explained that he had limited his paper to thework done in the U.S.A., but that this did not mean that he was either unaware or unappreciative of the work done by others, in-cluding the Farmans. If it came to that, patents were taken out by Louis Breguet many years ago on all the essential features of thehigh altitude aeroplane. MK. F. M. SJMITH, project engineer of the Lockheed Co., was at thispoint asked to reply to some of the questions of which he had particular experience. He said that in one flight at 20,000ft. withnormal rigging the elevator control w«it slack. Afterwards they got over the trouble by so rigging the cables that they were very-tight on the ground. On one flight of the Lockheed there was a national pick-up on America's radio, and they broadcast a descriptionof the flight from 20,000ft. This was approximately at noon, and they learned afterwards that the reception had been perfect through-out the U.S. The noise in the XC-35 was less than in the Electra, a fact which he put down to the heavier plating used and to theairtightness of the cabin, but also possibly to the pressure itself. MK. FRANK KADCLIFFE asked whether on flights of five hours'duration or so, ten cubic foot per hour per passenger was sufficient. To this MR. SMITH replied that they had found it enough in theLockheed. In one three hours' flight at 20,000ft. the temperature was 65 to 70 deg., and they worked comfortably in shirt sleeves. DISCHARGE HOLES IN CABIN WALL. ^—SOFT ROBBER SEAT FOR VALVE DISCHARGE HOLES IN VALVE VALVE SPRING. PRESSURE REOULATEO FROM (NSIOE OF CAOiN Safety valve for pressure cabin. Mk. M. L. BKAMSOX reminded the audience of the fact that almostevery great development of recent times had been turned down by most speakers at Society lectures as not being worth while and said they ought tO be Carefel tkt ttstory did not repeat itself in connection with pressure cabins MR. AMHKRSI VILLIERS stated that Mr. Tomlinson had found a30 per cent, increase in speed at height. He wanted to know if the exhaust driven blower was sufficient for supplying the' cabins whenthe engines were throttled. The lecturer replied that he thought there should be a separatesupercharger for the cabin, and thought it might be possible to develop a bellows type which could be placed in the wing. Oaewould then get absolutely pure air. MR. SMITH replied that in the XC-35 the skin was rather rough,and they had made no attempt at getting extra speed, but it might be interesting to mention that at 20,000ft. the speed of the Electrawas 220 m.p h., and that of the XC-35 243 m.p.h MK. K. J. R. WILKINSON asked what was the limiting height, andwhether the Americans had had any trouble with ignition. To this SPRING ADJUSTMENT AND GUIDE FOR VALVE SYLPHON BELLOWS FILLED WITH LIGHT OIL -VALVE CABIN INTERIOR A discharge valve which worked satis- factorily at high pressures. At low pressures there was a certain amount of lag. ; I SYLPHON BELLOWS j 1 j FILLED WITH ; i J I LIGHT OIL ! ( AIR AT PRESSURE TO BE HELD IN CABIN' P. the lecturer replied that the limitation in height was set by theengines. They had had a certain amount of trouble with sparking and also with the petrol supply. MK. FISCHELES enquired about icing troubles, and was told thatthere was no icing at 30,000ft. as there was no moisture, but that ice could occur on the way through the lower layers, CAPT. J. LAURENCE PRITCHARD, referring to Mr. Bramson's remarks,said he would point out that not everything that was good had come from America. For instance, one very good product of thesame name as the lecturer's came from this country. In connection with this altitude flying he was interested to know how much itwas going to cost and who was going to pay. Every passenger carried in an aeroplane at present was largely paid for by peopleon the ground who never flew at all. He would like to know if the Americans had found that larger control surfaces were necessaryfor high-altitude flying. MR. F. HANDLEV PAGE, who was in the chair, added his voice tothose who had been asking for a profit and loss account. He wondered what was the position of pressure cabins in relation tomilitary aircraft as bombs required holes through which they could be dropped. Perhaps it would be possible to keep the crew in asmall cabin, leaving bombs and such like at atmospheric pressure. PROF. YOUNGER pointed out that the title of his paper had beencarefully chosen, and that it meant all it said. (The title was " Engineering aspects of commercial high altitude flying " and thesub-title " With particular reference to recent development in the U.S.") After the lecture the Royal Aeronautical Society gave a smallinformal dinner to Prof. Younger at the Park Lane Hotel, at which were present representatives of the industry and the Air Ministry.
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