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Aviation History
1936
1936 - 1948.PDF
JULY 16, 1936.^ FLIGHT. t7 7A<? Outlook- A Running Commentary on Ait Topics The Fighter of the Future C APTAIN NORMAN MACMILLAN, in his thought-provoking article this week, has some unkind things to say of the single-seater fighter as we know it to day. "Mac" must be listened to with respect, for he had great experience of air fighting in the last war, and as chief test pilot to a famous aircraft firm after the war lie naturally learnt tc know all there is to know about fighters and "chucking them about." It is scarcely to be expected that everyone will agree with Capt. Macmillan, but there is logic in his argument, and the vastly in creased performance of the modern bomber, plus the plac ing of its defensive armament, has changed the conditions very materially. The idea of '' broadsides'' from fast-flying fighters is provocative, and the arguments advanced are certainly worth investigation. There may be technical difficulties in the way, but other students of air fighting have foreseen other placings of the guns, such as in the taii, for example, and it may well be that outboard guns will be supplemented by guns built into_ the fuselage in such a way that the fighter will literally bristle with machine guns in all direc tions. Aiming of guns so placed will present problems of con siderable complexity, but possibly something may be done with mirrors or prisms ; should tacticians decide that some thing of the kind is wanted, the engineer will probably, as usual, supply the answer. The Redemption of a Parasite AERODYNAMIC ALLY and aesthetically the presence J~\ of the conventional radiator on a machine fitted with a liquid-cooled engine is much to be deplored. We have had perforce to become accustomed to an angular chunk of honeycomb jutting out below an exquisitely shaped fuselage where it ploughs up the smooth air flow obtained with the shapely cowlings possible with the modern liquid-cooled power plant. The continual stepping-up of power outputs threatened at one time to bring about such enormous radiating sur faces, even when using high-temperature coolants, that designers must have lost many an hour's well-earned sleep contemplating the hideous possibilities if things went on as they were going. But, lo and behold, when the Merlin appeared in the Spitfire and the Battle (the Merlin, of course, is far more powerful than any engine in service at the moment) the radiators were not the eyesores which might well have been expected, but were comparatively unobtrusive. Examination of the machines concerned will reveal that the radiators are "ducted." In other words, the cooling air is taken into a specially shaped tunnel before passing through and over the radiator proper. The coolant is ethylene-glycol. The velocity of the air can be controlled to a large extent by the shape of the interior of the tunnel, which is shaped first to retard and then to accelerate the flow. The pilot has control of a chute hinged to the rear of the duct. " is claimed that this arrangement gives as much cooling 3s previous radiator designs with only one-third the drag, jnd it has been demonstrated that the power expended ooling does not increase with the speed of a machine '° fitted, but that a thrust may actually be derived at weds in the region of 300 m.p.h. So now we find what was a formidable bugbear actually assisting instead of impeding performance. A parallel case is that of the momentum of exhaust gases which may also benefit the speed of a very fast aeroplane. Importance of the Trailing Edge L AST week reference was made to the discovery by Mr. Irving, of the N.P.L., that a tapered wing with trail ing edge swept forward stalled first at the root, whereas one with a backswept leading edge stalled first at the tips, and to an interesting theory evolved by a High I reader, Mr. W. E. Gray, to explain the phenomenon. Mr. Gray has now found further confirmation of his model experiments by full-scale flights in a B.A. Swallow with wool-tufted wings, and describes his work in an article on pages 94-97. The Swallow is famous for its gentle stalling characteristics, and it was, in fact, this machine which we had in mind when we rather challenged Dr. Lachmann's conclusions some months ago. According to Mr. Gray's theory, which certainly seems to fit in well with observed phenomena, the importance of trailing edge angle arises from the depression distribution on top of the wing. When the trailing edge is swept for ward, a point on the trailing edge has at right-angles to it, in an inboard direction, a point of deeper depression which causes an inward lateral flow. The more the trail ing edge is swept forward the greater the difference in de pressions between the two points, and the more, conse quently, is the flow deflected. The explanation sounds logical, and if a more searching study of the subject con firms it, there may be a possibility of employing wings of fairly pronounced taper without introducing unpleasant stalling characteristics and without such extra complications as slots, provided the taper is obtained by sweeping the trailing edge forward. An Opening / T is now a frequent occurrence for Flight to receive letters from young men enquiring about the chances of a career in aeronautical engineering. The position is that now there is a distinct shortage of skilled labour in the aircraft manufacturing trade. The country is suffer ing from its expensive policy of economy in the past. For years the orders which reached the trade were so few and far between that it was sometimes not possible for firms to keep together their highly skilled staffs. Some of the personnel drifted into other branches of engineering. Then, like a bolt from the blue, came the decision to multiply the squadrons of the Royal Air Force. Every firm at once begun to collect skilled labour wherever it was to be found, and to train promising recruits. In addi tion, there has been added the so-called Shadow Industry. It is known that the Austin firm is busily erecting the largest aeroplane factory in the world, and that other motoring firms are manufacturing aero engines. It is an immense undertaking and is taxing the organising abilities of those in charge of it. Fortunately, those abilities are of a high order. This Shadow Industry still further increases the demand for skilled men, and shows signs of attracting to itself skilled workmen from the motoring trade. Consequently, at the moment, aeronautical engineering offers prospects as bright as, or brighter than, any other branch of engi neering. Of course, this great demand will not last for ever, but in the meantime civil aircraft are steadily in creasing in number.
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