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Aviation History
1936
1936 - 1461.PDF
598 FLIGHT. JUNE 4, 1936. late others in the search for the truth. Aviation, being a science and not a religion, must always keep a mind open for new truths: its greatest heresy is prejudice. \V. E. GRAY. Edgwarc, Middlesex. P S.—Since writing the above I learn from Mr. Collins, Messrs. Putlnam's test pilot, that the fully stick-forward setting of the front wing is needed so that the present design of Pou may be jerked off the ground. I also understand from him that there is no tendency of the nose to rise on closing the throttle so that the thrust cannot be much above the e.g., and the drag is more likely to be above than below the e.g. at the lower speeds. WHILST agreeing in general with Capt. Necdham's remarks (p. 556, May 21) on the danger points of the Pou, my own impression is that the vital point in Pou construction is to be certain that the C.G. is exactly in the right place. The distance between the C.P.'s cf the two wings is very small, and small changes in the fore and aft position of the C.G. make big differences in the loading of the two wings. As the C.G. moves forward, the front wing has to be held at increasing angles of incidence to maintain trim If the front wing is stalled while at a considerably greater angle of incidence than the rear wing, the rear wing may still be lifting strongly and promote a sudden catastrophic dive. (Incidentally, is there any information on the stalling properties of the unusual wing section employed?) 11 the stick is held hard back, the trailing edge of the front wing is so near to the leading edge of the rear wing that there is bound to be reaction between the two, which may well make recovery impossible until the stick is pushed hard forward again. In my own contacts with amateur Pou constructors I have found them very casual about making alterations and " im provements," and a matter of two or three inches of variation in the position of the C.G. might weil be ignored. My advice, for what it is worth to anybody about to fly a Pou, is to make quite certain before he goes up that the position of the C.G., both vertical and horizontal, is exactly where Mignet specifies, not forgetting his own weight, which may differ considerably from that of the last pilot to fly the machine successfully. Braincote, Notts. R. F. J. GRANGER. POUX AND THE LAW YOU say on the " Outlook " page of Flight of May 14 that the third-party insurance is a sound method of looking attei the safety of Poux-du-Ciel and other light aircraft (as you have also said previously) because the insurance com panies would not insure machines of this type which were not sound, 1 thought this a sound argument, until fairly recently, when I heard of a Pou being built and the builder having it insured without the insurance company so much as looking at it. Moreover, he would have actually preferred to have his machine inspected for his own satisfaction as he had had no previous aircrafl experience. I have now learned that actually very lew Poux are inspected, although I know that the Air League of the British Empire inspects them on request. But optional inspection is beside the point; the fact is that Poux are allowed to, and do, fly (if they are able) without being so much as seen by an inspector or anyone else, and they can be built by the most incompetent persons, too. I have heard of a case of a person who knocked up his machine with 2in. nails ; having ha<l no experience of making fittings, he some how used nails to supersede them, and honestly expected someone to test-fly it for him. You also say that "the Air Ministry accepted in principle that small private aircraft should be exempt from the usual airworthiness regulations." Is this borne out in fact ? The Pou and the Super Drone are exempted. Are the Hillson Fraga and the Aeronca, to take two examples? This state of affairs with the Pou is particularly galling to those who have had years of shop and drawing office experi ence and are well qualified for the job they want to undertake, yet, on enquiring of the Air Ministry, after stating the extent of their experience and qualifications, if it would consider allowing an ultra-light, aeroplane of conventional layout to be designed and built and be exempted from the full C. of A. formality, are informed that they will need the well-known necessary Air Ministry Publication, and that nothing can be considered further until the C. of A. fee stated in the Air Navigation (Consolidation) Order 1923 is paid. This, after the usual wait, turns out to be £25 for a machine up to 5oolb.- tare weight. I understand that all tests and everything else are charged up extra. In other words, the Air Ministry effectively prevents any one without considerable private means from producing an ultra-light machine, whilst some veritable death-traps for those on the ground as weil as those flying them are allowed to proceed unhindered I do not wish it to be thought from what I have said about Poux that I think that they should return to the full Air Ministry control, but I do consider that all light machines for private use should come under a body like the B.G.A. (as has, I believe, been officially recommended), who go into the strength and airworthiness of sailplanes and gliders as well as inspecting machine? during construction and after completion and issue C.s of A. for them, and charge a very reasonable sum for doing so N. NEW. London, S.W.16. THE SUBSIDY SITUATION From Admiral Sir Murray F. Sueter, C.B.E., M.P. AS one who has devoted a great deal of time and thought to air questions I fully endorse all that Lord Elibank said in your columns (p. 530, May 21) about the need for central ising civil air administration and adopting a cautious policy with regard to the administration of the commercial airline subsidy. The latter may seem small—in fact, according to Lord Elibank's comparative figures, it is small—but combined with efficiency of machines and personnel it should be adequate to ensure the commencement of a British air system second to none. We have always been the great carriers of the world by sea; is there any reason why we should not be the same by air? There is another point about this air subsidy which should not be lost sight of. The more the subsidy is spread, the greater danger is there that the people will be tempted to invest their money in aviation concerns which are entirely speculative. There are far too many of these and the greatest safeguard for the uninformed investor is the concentration of subsidies upon those operating companies which have either proved their worth or can show definite evidence of a capacity to produce results. I was particularly pleased to see Lord Elibank taking up the cudgels so effectively against those who have paid brief visits to the United States and seen evidences of superficial achievements in air matters and come back to decry our own system. If the economies of flying are studied it will be found that America has lost very many millions in developing her civil aviation, and now we are informed by no les? an authority than the American Federal Aviation Commission that "finan cial disaster is in the making for a larger part of the present air transport system." On the whole, I think our more cautious British air policy is wise. The Air Navigation Bill now before Parliament is on the right lines. It embodies very largely the good work of Lord Gorell and his Committee, and is a measure of outstanding importance to all those who desire the full development of air transport and air mail services throughout the Empire. MURRAY F. SUETER. House of Commons. ULTRA-LIGHT T HE Perman light aeroplane described in Flight of May 21, with the 10 h.p. Ford engine, is a very interesting effort and should, I think, supersede the Pou. The latter would appear to have a very stable wing arrangement for one setting of the wings, but one would expect it to exhibit vicious tendencies for wing settings outside a certain range. A solution might be to have both planes fixed and control by a conventional elevator fixed to the aft wing. A light monoplane of conventional wing arrangement should be very little more costly to build than the Pou, and though perhaps not quite as stable as the Pou in its most stable attitude, it would be far more stable over the full range of flying attitudes. I have wondered if it might not be desirable for drawings and prints of such a machine to be made avail able, so that amateurs keen on building a plane for themselves might expend their energy to the best advantage. Returning to the Perman machine, there is difficulty over one point in your description. Take-off revs are given as 3,300, and cruising revs as 3,100; should these figures be reversed, or is this an indication that optimum aircrew con ditions have not yet been obtained? [The makers give the take-ofl r.p.m. as 3,300; maximum. 3,600; and cruising. 3,100.—ED.] J. F. Cuss. Gloucester.
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