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Aviation History
1952
1952 - 0225.PDF
FLIGHT, 25 January 1952 SIMPLICITY for CHEAPNESS Key to the Practical Ultra-light A Suggested Structural Conception FIRST let us assume that flying, for flying's own sake, is a thing to be encouraged. Then, having done so, we may go on to consider the odd fact that there is just no vehicle designed for letting people fly themselves cheaply. In every country, people lead interesting lives thinking up ever bigger, better, more complicated and more expensive aeroplanes, and yet they no more think of owning an aircraft than they do of sprouting wings. In fact, probably 99 out of every 100 of the world's aeroplanes will eventually be paid for by the taxpayer, who is in consequence left too poor to buy even half a one for himself. One of the chief reasons for this state of affairs is the complete lack of a cheap, mass-produced aircraft. By "cheap" we mean a machine which can be marketed for under £500. The cynical may remark, "Why not £100?"; but there was something approaching a hundred-pound light aircraft in 1939 and there ought to be a five-hundred pounder today. Let's have a look at it. Firstly, we must go about the business in the right way. We cannot take a present-day private-owner aircraft and go through it with a hacksaw and screwdriver until it is "simple." Our machine must be an efficient integration of mass- produced parts, with cost coming second only to soundness of design. The only country where mass-produced cheap aircraft can be found is, oddly enough, France, and even there people persist in sticking to time-honoured methods of construction which rule out the possibiUty of making anything really useful. On the other hand, the United States, while leading the world in lightplane structures, has so far been rather lukewarm towards any private-owner type which did not combine the furnishing of a Cadillac with the equipment of an airliner. This is becoming ever more clearly marked. As for the rest of the world, private flying is so hedged in by regulations and so overshadowed by professional flying as to be something less than a side-line. Small numbers of nice little aircraft are built in Czechoslovakia, Italy and the United Kingdom, but the number of licence-holders in these countries is not one-tenth of what it ought to be and compares most unfavourably with the number of private pilots in more fortunate places like Brazil and Southern Rhodesia, in spite of the fact that the latter countries are supposedly less developed, and have little industry of their own. Conception Outlined Before getting down to details, it may be remarked that our attempt cannot aim at more than the building of a cheap light- plane: we cannot now reasonably expect any great changes in things like fuel costs or landing fees. The accompanying sketch shows the type of thing we have in mind. It looks quite normal, and is quite normal, except that there is, at far as we know, nothing like it. The overriding factors governing the study have been that (a) The structure has been kept all- metal; (b) the stressed-skin monocoque principle has been carried to extreme; and (c) the number of parts has been cut to an absolute minimum. What about power ? It takes a long time to develop a good piston engine, even a very small one, and the best bet looks like one of the highly developed American flat fours. The 65 h.p. types are quite husky enough for our purpose; or there is the little McCulloch flat four, used in American radio-controlled targets—just the sort that is wanted, and if a way could be found to increase the engine life without greatly raising the first cost it might be ideal. When we have our engine, we merely mount it on the nose, using a few steel tubes and rubber blocks, and then let it drive the simplest possible airscrew. Turning to the main structure, wings are usually very expensive, even on a primary glider, simply because people will make them out of hundreds of tiny bits. At the risk of blowing America's trumpet to excess, we may perhaps recall the example given us by the Republic Corporation, whose little Seabee amphibian had just the sort of wing we are advocating. After the first few had been built, someone had the great idea of cutting down the number of wing parts from the nth power of ten to a couple of dozen. The secret was a clever combination of torsion-box design and corru gated skin. Our own little study has a hefty top-hat-section spar locating both top and bottom surfaces of the one-piece wing sheet. The latter has no double curvature, has constant section, and could very quickly be turned out by a Sheridan stretch-former. It must, of course, be of fairly heavy gauge. The ribs, of which there are but three on each side, are simple pressings divided into nose and rear sections by the spar, while the wing-tips are shallow pressings. The whole thing is held together by rivets, unless it could be more cheaply Reduxed, as is the remainder of the structure. Fuselage Simplicity Our fuselage is really a cylinder and cone, both rolled from heavy sheet. The only internal members are a keel, a heavy angle-section bulkhead locating the wing spar, and light angle-section rings at the fire-wall and at the joint between the cylinder and the cone. Further stiffening is provided by the cockpit floor, which is attached to the cylindrical section along each side above the wing. As regards the undercarriage, we can eliminate the usual precision engineering if we can accept a reduced performance from it. The actual "springing" here is by a simple undamped leaf spring a la Cessna. We rather like the Fairey Junior's brakes : a string of friction cubes threaded on a wire and wrapped round a brake drum integral with the wheel. Little more need be said. The greatest drawback to this sort of structure is that any damage is likely to be difficult to repair. However, this is partly counteracted by the fact that such a structure is-not easily damaged. One could quite easily taxi into a hedge without making a dent, and our airframe is quite free of "no step" notices. The whole design is such that, while the first prototype and tooling will be costly, mass production will be very simple and will lend the product great accuracy, inter- changeability of parts, and low cost. If ever flying is to become popular in the sense that cycling is popular, then this is the only sort of machine that can make it so. W. T. G. TECHNOLOGICAL EDUCATION THE London and Home Counties Regional Advisory Council for Higher Technological Education periodically publishes a comprehensive summary of special courses in higher technology available in the London Area. Bulletin No. 4, covering the period of Spring and Summer, 1952, announces an unusually large number of courses available at twenty-five colleges and institu tions. While none of these courses is of a purely aeronautical nature, many should be of value to technicians in the industry. In most cases, no hard-and-fast rules are laid down governing admission, provided the applicant is in a position to make good use of the course. The Council's Third Annual Report is also to hand, and shows Higher Technological Education to be in a very healthy state. Both documents are available from the Secretary of the Council at Tavistock House South, Tavistock Square, London, W.C.I. The Bulletin is priced at is. 6d. D
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