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Aviation History
1946
1946 - 1604.PDF
I76 FLIGHT AUGUST 15TH, 1946 CORRESPONDENCE The Editor docs not hold himself responsible for the views expressed by correspondents. The names and addresses of the writers, not necessarily for publication, must in all cases accompany letters. LAMINAR FLOW Wing Section and Boundary Layer HTHERE is much talk these days on the subject of laminar J- flow wings, but in spite of the vast amount of data thai have accumulated I doubt whether there is a single aircraft in use to-day (with the possible exception of experimental machines) which preserves a laminar boundary layer over any large percentage of its wing surface. What the designer needs is a section which, when built on to a practical structure, will still give laminar flow—i.e., one which is not upset by the tiny waves ana irregularities which are inevitable. Now as I understand it, the boundary layer remains laminar so long as the local flow is accelerating; thus it seems to me that the section most likely to give useful results is the section with the greatest general value of this acceleration. It is generally true to say that the peak velocity on the upper, •surface (and, therefore, the greatest velocity gradient) occurs on the thickest section. In the recent Wright Memorial Lecture by Mr. Relf, a suction section some 38 per cent thick and a normal laminar flow section some 15 per cent were mentioned. At CL O the smallest advantageous velocity gradient of the former divided by the smallest advantageous velocity gradient of the latter is approximately 10. The comparison is taken from th'' back end of the upp«r surface of the laminar flow region in each case. It would, therefore, seem logical that the thicker section should permit maximum "waves" in the skin of ten times the amplitude, i.e., of about one-hundredth of their length instead of one-thousandth as in the case of the thinner sec- tion. J. DUBBURY. IN THE AIR Memory, and the Sub-conscious Mind WRITING as one who, like "Indicator," was luckyetiough to have had the opportunity of flying quite a few types during the late war, I must say that it is a per- manent source of surprise to me that this writer manages to remember so much. It would be sufficiently surprising if he remembered only the features and the control systems—and these could, pre- sumably, be "mugged up" from handling notes and other sources if necessary. The interesting thing is that "Indi- cator" remembers his own feelings and first impressions so well that, in reading any ot the series, one automatically says to oneself, " Now that is exactly what / thought and felt." Yet such thoughts and teelings have never been con- sciously remembered until a particular type is dealt with in ihe scries of handling impressions. No doubt the same writer will eventually be describing air- craft which he has flown more recently, and it will be inter- esting to the amateur psycho-analyst to see whether his impres- sions are as accurate and " basic." The subconscious mind has a way of sorting and clarifying in a timeless way not pos- sible to the poor old mechanical life-saving conscious mind. But, in order to do it, the subconscious mind must, I feel, have been much more deeply concerned in remembering experiences than the conscious mind would ever admit! "E. F. T. S." " Indicator " Reaps a Whirlwind MAY I contribute to the protests which will inevitably l>eprovoked by " Indicator's " remarks on the Whirlwind in Flight, August 1st. 1 will deal with the various points in the order in which he deals with them. First, there were two fully operational squadrons operating simultaneously in 1942 and 1943, although in the ultimate squadron we took over the aircraft of the other one in June, 1943- Secondly, you suggest that in any climb it was necessary to use the radiator flaps to maintain reasonably low coolant tem- peratures. This gives an entirely false impression as, in fact, it was only necessary in a very prolonged climb or in, shall vve say, "operational' climbs, but certainly never in any average climb unless there was something wrong. Thirdly, you make no mention of the dive-bombing acti- vities of the Whirlwind which were indulged in frequently— in fact almost as frequently as low-level activities. Fourthly, in your remarks on the use of Whirlwinds on bigger airfields with long taxi-tracks, you seem to forget £& perhaps you never knew) that Whitlwinds were operated \>?fflL_ some success from such airfields as Hum, Exeter, Tangmere and Predannack. In spite of some cf the inevitable take-off delays one experienced from time to time, I consider your description of "two delightful fountains of steam" to be grossly exaggerated. Fifthly, surely any aircraft shudders in a really tight turn, if it is pulled tight enough. The Whirlwind cannot be con- demned on that point. However, I must agree with you on one score, namely, that from the flying point of view, the Whirlwind was magnificent, and I would suggest to you that the one peculiarity was not the shudder* but that the port wing had a marked tendency to drop as airspeed increased. EX-WHIRL WIND PILOT. ["Indicator" replies: " The words 'I believe,' which intro- duced the suggestion that there was only one squadron of Whirlwinds, seems to cover the possibility of error there— and ' low-level attacks' surely include dive-bombing. For the rest, the points are matters of personal experience, which, in my case, was small. The shudder mentioned was no normal pre-G-stall affair, but, even so, neither did it 'condemn' the type; it was just an interesting characteristic."] CIVIL FLYING POLICY Are Our Wartime Assets to be Wasted ? AS one whose chief interest in life is British civil aviationmay I appeal, before it is too late, to those now responsible for our civil flying policy to reconsider some of their decisions ? In this recently passed gigantic war, and in what compara- tively may now be called the 1914-18 episode, every British taxpayer has subsidized flying to the limit of his ability to pay. This, in the interests of himself and the nation and to the con- fusion of our competitors. We have, at no small expense, constructed hundreds of airfields, trained thousands of pilots, and produced almost unlimited aircraft. Is most of this work and toil to be dis- sipated and its fruits fall into ruin and decay ? If only the Government (that is ourselves, I hope) would lease these airfields at a nominal figure, renew the Civil Air Guard subsidy (a few thousands only) and hire or sell cheaply their surplus aircraft in FULL airworthv condition ! I suggest they have, or have had, sufficient men and materials under their command to enable them to do this. Would it not, to a very great extent, create full employment and housing for all those demobilized from the R A.F., Fleet Air Arm, A.T.A., etc., who still wish to continue their interest in flying? It would also keep the aviation industry going and, by the conse- quent external flying, in no small measure increase our export trade and also enhance our prestige. It would appear that some of us might even be able to fly to Ostend or Brussels for a sustaining bowj of bread-and-milk ! What, may one enquire, is the purpose of these expensive 1'inding fees? Whilst one assumes it is an attempt to raise funds in order to support the new airport manager and his staff, will it not, on the contrary, act as a deterrent and mainly aid to stifle the new-born infant, Civil Aviation, who, at moment, needs much succoui and more nourishment? >H A little help and encouragement would see every airfield a thriving busy place, an asset to the country, an outlet foi ' enthusiastic youth, and the basis of a colossal export trade. Instead, in a few years (even now the signs are showing), most of these lovely airfields will be derelict. Clubs will gradually peter out, enthusiasm will wane, and in about ten years' time we shall be seeking another Lady Housotn to finance the design and construction of an aircraft fast enough to enable us to compete for a Schneider Trophy. There was, in 1923, an excellent airfield at Alexandra Park, Manchester, some ten minutes' ride, in a tramcar, from their well-known centre, Piccadilly. A little foresight then, how useful it would have been to-day? Is the same thing going to occur again? V.L.DICKINSON.
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