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Aviation History
1940
1940 - 0193.PDF
and AIRCRAFT ENGINEER FIRST AERONAUTICAL WLEKLY IN THE W6RLD .• FOUNDED 1909 Editor C. M. POULSEN Managing Editor G. GEOFFREY SMITH Chief Photographer JOHN YOXALL Editorial, Advertising and Publishing Offices: DORSET HOUSE, STAMFORD STREET, LONDON, S.E.1 Telegrams : Truditur, Sedist, London. Telephone : Waterloo 3333 (SO lines). 8-10, CORPORATION ST., COVENTRY. Telegrams : Autocar, Coventry. Telephone : Coventry 5210. SUBSCRIPTION RATES : GUILDHALL BUILDINGS, NAVIGATION ST., BIRMINGHAM, 2. Telegrams: Autopress, Birmingham. Telephone; Midland 2971 (5 lines). 260, DEANSGATE. MANCHESTER, 3. Telegrams : Iliffe, Manchester. Telephone: Blackfriars 4412. 26B. RENrlELD ST.. GLASGOW, C.2. Telegrams : Iliffe, Glasgow. Telephone: Central 4857. Home and Canada : Other Countries : Year, £1 13 0. Year, £1 16 0. 6 months, 16s-. 6d. 6 months, 18s. Od. 3 months, 8s. 6d. 3 months, 9s. Od. No. 1622. Vol. XXXVII. JANUARY 25, 1940. Thursdays, Price 66. The Outlooks Cleaning UpV ERY great interest in the subject of escort fighters has been aroused by the article we published in our issue of January n, judging from the corre- spondence received. Some of the letters are published this week; others were not intended for publication, but raised interesting problems. Of these, some are tactical, but some lead to the much broader question of cleaning up the aerodynamic design. It appears quite probable that even our present single- seater fighters could be still further improved ; not much, but probably enough to make the attempt worth while. Frequently the setting of the wings on the fuselage is critical, and there is reason to think that a slight reduc- tion in the angle might reduce the body-wing interfer- ence drag. The shape and location of the pilot's wind- screen, and the shape of the cockpit roof, are apt to be sensitive spots. One recollects that some years ago, when Boulton and Paul were making aeroplanes at Norwich, in the days before the present separate com- pany was formed, they built a machine for commercial work, and the type of windscreen which the operating company asked for was found, from wind tunnel tests, to reduce the cruising speed by many miles per hour. How much more is this particular excrescence likely to offend on machines twice as fast ? But playing about with such minor items ia in the nature of a palliative only. If we are to expect either startling increases in speed or a greatly extended range (for, of course, aerodynamic fineness can be used for either objective) something more will be required. New Engine ArrangementsI N his speculative sketches of possible escort fighters Mr. King adhered to the orthodox two-engines-on- the-wings arrangement. Other arrangements are, however, possible and their advantages are not, of course, confined to, nor possibly even especially useful for, escort fighters. That engines on the wings add very greatly to the drag cannot be denied. Engines in tandem are attractive from the point of view of drag reduction, but a price has to be paid for the lower drag. This price takes the forms of extra weight and extra complication. With engines placed in tandem, three alternatives appear possible. The engines may be made to drive two airscrews in opposite directions, as was done by that clever Italian engineer Castoldi in his Macchi design. That machine, be it noted, still holds the world's speed record. But it had to fly for a very short time only, carried no military load, and as it was to be used in ideal weather only, a high landing speed could be tolerated. On the other hand, it was built in the days before flaps were used, and so -did not have that modern aid to high lift. Another alternative is to place the engines themselves inside the fuselage, but to mount the airscrews outboard, ahead of the leading edge of the wing. This introduces the problem of shafting strong enough to transmit the high powers of the modern engines. The design of such shafting, however, is straightforward engineering and should not present great difficulties. The main question is one of weight, and one imagines that the weight of shafting and the necessary gears might well amount to something of the order of one pound per horse-power. The reduction of drag which would result from such an arrangement (we visualise the shafts being buried in the wings, of course) would certainly be very great, but the extra weight involved would probably not be justi- fiable except for machines intended to have a fairly long range or an exceptionally high speed. Still further drag reduction would attend the placing of the airscrews behind the wings. This is really a variant of the second way of using engines in tandem. The old argument against " pushers," that the fore-and- aft weight distribution would be upset, could probably be overcome by suitable placing of the engines in the fuselage. With airscrews behind the wing, however, the wheels would have to be well supplied with mudguards, otherwise there would be likely to be trouble with stones and dirt being thrown into the airscrews. And, of
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