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IN this issue appears a summary of a paper prepared by two of the research workers of the National Advisory Committee for Aeronautics which is most opportune. A number of minds, both among designers and scientists, have been exercising themselves with thoughts as to what may be the effect on a modern aeroplane of meeting a vertical current, commonly referred to as a “bump.” There are those who believe, or at any rate wonder, whether the ever‐increasing speeds at which aeroplanes fly may not give rise to added danger from this cause. They argue that the higher velocity at which the aeroplane meets the bump results in the impact of the blow received on the structure being accentuated by the reduction of time over which it is felt, with a consequent increase in the effects. There is, on the other hand, the directly opposite view that the aeroplane of higher speed changes its angle of incidence, and therefore yields, more quickly, and so the force of the impact is lessened.

BY a coincidence, which is purely accidental, the same lesson is indicated in three separate articles published in this issue. The occurrence is rendered even more striking by the fact that the provenance of the articles is from such widely separated sources as Germany, America and England.

ON September 12, 1931, Flight‐Lieutenant J. N. Boothman, of the British Schneider Trophy team, won the trophy outright for Great Britain by covering the distance of 350 kilometres (217.45 land miles) round a triangular course at an average speed of 340.08 m.p.h., in a Supermarine S.6.B. seaplane No. S.1595, putting the 100‐kilometrc record up, during the first two laps, to 342.9 m.p.h. The following day Flight‐Lieutenant G. H. Stainforth, in a similar seaplane, No. S.1596, made a new world's air speed record of 378.05 m.p.h., which he increased on September 29, in S.1595, to 408.8 m.p.h.

LAST month we wrote of the value to the development of aircraft of the now defunct Schneider Trophy Contest, setting forth as far as possible on the one hand the benefits in the way of increased knowledge that it has brought, and on the other the price paid, with some attempt to strike a balance. We came to the conclusion, on the whole, that so far as England is concerned, participation has probably been worth while.

READERS of AIRCRAFT ENGINEERING have reason to be grateful to Messrs. Rolls‐Royce. Exactly two years ago, the firm showed its interest in this paper by allowing it to publish the only complete description of the Kestrel and Buzzard engines—then known as the “F” and the “H” respectively—which has appeared, this article remaining the best available source for information on the details of the design of these engines. Two months ago we were able to publish a full illustrated account of the evolution of the Schneider Trophy racing engine from its prototype the Buzzard. This month the premier motorcar firm in the world places us still further in its debt by enabling us to print an article on its aero‐engine production methods by Mr. Handasyde in the series from his pen that has aroused so much interest and discussion in the last few months.

IT seems rather strange that while the general property of wing flaps of putting up both the lift and the drag of a wing at the same time has been known for many years, so little practical application of this result has been made until quite recently.

THE development of modern aeroplanes designed for high speeds, with their thin, almost symmetrical wing sections, has led inevitably to high landing speeds and small gliding angles with the normal wing arrangement.

THIS issue of AIRCRAFT ENGINEERING might without excess of exaggeration almost be described as a special number for inspectors and ground engineers—for, indeed, that elusive individual, to whom we have on occasion referred before, the “practical man.”

MR. SERBY'S article on trimming and balance tabs gives a very concise theoretical explanation of the working of trimmer and balance tabs, and explains certain characteristics which have baffled most designers.

IT is not only feminine attire that is subject to the vagaries of fashion. Anyone who has watched the evolution of the aeroplane over any considerable period of time will have noticed how subject it also is to the dictates of Fashion's decrees. Springing up from no one quite knows where, one suddenly becomes conscious that there has been a subtle change in the appearance of the aeroplanes seen about. There are always, of course, a few “ frumps ” whose type remains readily recognisable owing to its resemblance to its parents and ancestors. But it is none the less the fact that at any given period the bulk of the aeroplanes of the day have a similarity of appearance. This is indeed a constantly recurring pitfall for the enthusiast who for one reason or another does not have the opportunity of making very frequent visits to an aerodrome. On one of the rare occasions when he makes his presence felt he is apt to incur the contempt of his more knowledgeable colleagues by an unfortunate propensity for confusing the aeroplanes produced by the designers of different, and perhaps closely rival, firms. The position in this respect seems to get worse. Twenty‐five years ago no one but the veriest ignoramus could mistake a Blriot, say, for a Farman or an Antoinette. Nowadays, however, it is comparatively easy— or so we confess we find it—to be confused about the make of half a dozen different types of aeroplane. A few years ago it still remained easy at any rate to segregate machines by the eye into their respective classes. There was a stateliness, possibly even a suspicion of clumsiness, about a bomber which distinguished it instantly from a fighter. But even this superficial distinction is nowadays denied to those unfortunates of whom we write.