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Aviation History
1946
1946 - 0747.PDF
. Editorial Director G. GEOFFREY SMITH, M.B.E. Editor - -CM. POULSEN Assistant Editor - MAURICE A. SMITH, D.F.C and AIRCRAFT ENGINEER Art Ed/tor - (VV/NG CDR., R.A.F.V.R.) - JOHN YOXALL FIRST AERONAUTICAL WEEKLY IN THE WORLD .• FOUNDED WOQ Editorial, Advertising and Publishing Offices-. DORSET HOUSE, STAMFORD STREET, LONDON, S.E.I Telegrams : Flightpres, Sedist, London. Telephone : Waterloo 3133 (SJ lines). COVENTRY: 8-10, CORPORATION ST. Telegrams: Autocar, Coventry. Telephone: Coventry 5210. BIRMINGHAM, 2 : KING EDWARD HOUSE, NEW STREET. Telegrams : Autopress, Birmingham. Telephone: Midland 7191 (7 lines). MANCHESTER, 3: 2 6 0, DEANSGATE Telegrams: Hiffe, Manchester. Telephone : Blackfriars 441X GLASGOW. CJ: 26B, RENFIELD ST. Telegrams: Iliffe, Glasgow. Telephone: Central 4857. No. 1947. Vol. XLIX. SUBSCRIPTION RATES : Home and Abroad : Year, £3 I 0. Registered at the CJ'.O. as a Newspaper. April 18th, 1946. 6 months, Al 10 6. Thursdays, One Shilling. cMe Outlook This PressurizationD URING the past year or so there has been a good deal of uninformed general comment on the sub- ject of aircraft pressurization. The average member of the public has certainly learnt by now why such pressurization is necessary and, generally speaking, what it means. But the whole thing has usually been very much over-simplified, and just now people appear to have the idea that whereas we in this country are still floundering about in the "laboratory" stage, American citizens are already flying backwards and for- •wards in comfortably inflated civil aircraft. It is probably quite true to say that one American air- craft is now being flown in service with its pressurizing equipment in action, but we believe that the .differential is quite low, and certainly there is a very great deal more to be done in the way of humidifying and air con- ditioning. And, if one must be pointed, it may be said feat, over hfere, the production Tudor I has, for some time, been flying on test with a 5^1b differential. The trouble is that plain pressurization, difficult though this may sometimes be to organize, is only a part of any necessary system. On both sides of the Atlan- tic work is proceeding on refrigeration and humidifica- tion, andl no one can claim yet to have solved the pro- blems completely. Even pressurizing alone becomes progressively more troublesome as size and cubic capacity increases. Whereas a reasonable rate of leak over small internal areas can- easily be overcome by the available pressure supply, this same rate can become quite impossible when it is being experienced over a very large interior surface area. The " caulking " must, consequently, be much more thorough, the possibilities of leakage are considerably greater. The larger the aircraft, therefore, the more difficult the problem becomes—yet pressurization by itself is only one of the requirements in high-altitude air-condi- tioning. Noises OffE VEN when we have solved the problems of pres- surization and air conditioning, there will remain another troublesome teaser—the reduction of noise. That this is far from being easy was made abundantly clear by Dr. N. Fleming in his lecture to the Royal Aeronautical Society last week, when he spoke on the subject of the silencing of aircraft. v So far as the noise which reaches the passenger is concerned, the very provision of a pressurized cabin must help in reducing noise; the fact that there can, for reasons of airtightness, be no cracks or openings in such a cabin is in itself a large contributory factor in noise reduction. Curiously enough, this fact was not stressed by Dr. Fleming. It may be accepted that an airtight cabin will not necessarily, by itself, suffice to give the desired decibel and phon scale reduction, but there would appear to be an opportunity for obtaining relative silencing at a rather lower additional weight if the cabin has to be pressurized. This may have the effect of encouraging the use of pressurization in classes of aircraft in which it would not otherwise be deemed to be absolutely essential. As for silencing the noise at its source, the prospects do not appear very rosy. Not only piston-engine exhaust and airscrew noises, but those from the impellors and tail-pipes of jet engines are troublesome—just how troublesome we have hardly yet had time to discover. And even if these could be reduced by careful design, there must remain the noise caused by the passage of the aircraft itself through the air. With modern high cruising speeds this may become very noticeable rf the noise level of other sources is successfully reduced. And what will happen when we come to supersonic speeds no one can foresee. Altogether there is no risk that our designers will get rusty during the next few years. They have plenty of problems to keep them on their toes.
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