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Aircraft Engineering THE MONTHLY SCIENTIFIC AND TECHNICAL ORGAN OF THE AERONAUTICAL ENGINEERING PROFESSION VOL XVIII No 212 OCTOBER 1946 them by the blockade of war and their failure—from whatever cause—to continue to develop superchargers of ever-increasing S with so many other wartime developments it has long been efficiency and performance as did British designers. In the result, the a secret de Polichinelle that certain British aeroplanes were British went in for a pressure-system of nitrous-oxide carried in A equipped with systems for increasing the performance at high-pressure bottles while the German aeroplanes were equipped altitude by injecting oxygen in some form or other into the engines. with an atmospheric-pressure installation of twice to three times the It was also known—though probably to a smaller circle of initiates total weight—though, be it said, when the specific weight of the —that the Germans were using the same device. With their charac two systems per hundred horse-power increase per minute be taken teristic gift for imaginative publicity the Americans from time to as the comparison the position is almost exactly reversed, taking the time put out eye-catching stories of the injection of water to obtain Mosquito and the Ju 188. (See MR. HAWTHORNE'S Table III.) a more or less momentary increase on somewhat similar lines— obviously a method with a more striking appeal to the popular mind. Some Minor Points Practically nothing, however, has been published on either the We do not propose to go into all the details which were so clearly scientific aspects of the matter or the experimental work involved— brought out and which are best studied in the text of the article let alone of the technical details of the installations actually used. itself. There are, however, a number of interesting minor points, Readers will, therefore, be grateful to the authorities concerned for such as the effect of the differing characteristics of the DAIMLER-BENZ permitting the publication of the very complete account of all three and B.M.W. engines in fuel-supply at altitude, which in the one case sides of the subject which has been written for AIRCRAFT ENGINEER necessitated the fitting of a fuel-enrichment device to compensate for ING by MR. E. P. HAWTHORNE and appears in this issue. the weakening of the mixture by the introduction of nitrous-oxide, while in the other this was not required. Another point of detail is An Alternative to Supercharging that—and here the oxygen method contrasts with water injection— As an alternative to supercharging, this method of obtaining above a certain ratio the injection of further oxygen increases greater output is, of course, a fairly obvious development and it is liability to detonation. perhaps somewhat surprising that it was not tried—or at any rate There is indeed quite a lot to be learnt about the idiosyncrasies of investigated—sooner, but had to await the stimulus of war. At first the internal combustion engines under varying atmospheric condi sight, one would have thought, it might have seemed the more tions from a close perusal of this most informative article. attractive and simpler proposition of the two; though on the evidence now produced it has serious disadvantages in requiring separate The S.B.A.C. Exhibition equipment of a special nature involving considerable increase of There is no room for doubt that the S.B.A.C. Display held at the weight which make it clearly more suitable as a supernumerary rather HANDLEY PAGE aerodrome at RADLETT from September 12-15 was than alternative device. A supercharge becomes, after all, an integral a most impressive exhibition of British aeronautics. Everyone who part of the engine and, even with the modern complications of two attended came away, we suppose, with certain definite reactions to stages and two speeds, is on the whole a simpler, and certainly less it. Our own impressions may be summed up as follows. First and cumbersome, auxiliary. It is indeed interesting to recall that when the foremost, the extraordinary beauty of the curvilinear shape of some height record was gained for Great Britain by the BRISTOL AEROPLANE modern aeroplanes—and the extreme angular homeliness of others. COMPANY in 1936, the additional engine performance required from The striking variation in the standard of flying not only between the Pegasus engine was gained by adding an exhaust-turbine super different individuals of presumably equal competence as test pilots charger to the normal centrifugal blower and this alternative method but, even more, between the brilliance of the same pilots as exhibited was not, so far as we are aware, even considered. Actually, it does on the Friday during the display proper and on the Sunday when the not appear that oxygen injection has in fact been used for the purpose occasion was the ROYAL AERONAUTICAL SOCIETY'S Garden Party. of increasing the ceiling of an aeroplane; its employment up to the The latter contrast, whatever may have been the reason for it, was present having been confined to attaining higher performance in the most noticeable and the subject of considerable comment. The other aeroplane in the realm of increased speed at an already obtainable outstanding impression was that a two-day exhibition—for the operational height. How far it could be employed without other Saturday was practically an "off day" and the Sunday for a different changes to "boost" the attainable maximum height of an aeroplane audience—of which one is mainly devoted to flying is much top specifically designed for that special purpose we do not know; it is short for adequate study of the stands comprising the Static Display. an interesting, and possibly not wholly unprofitable, speculation. We certainly found this ourselves and imagine others suffered from the same sense of surfeit. German and British Practice The contrast between the size and weight of the German and We suggest that next time an Aero Show—on the lines of the Paris Aero Salon to be held from November 15 to December 1—combined British installations is instructive. Generally speaking, it is, we think, with a one- or two-day flying display at a convenient aerodrome true to say that the Germans as a nation are less "weight conscious" would better fill the bill. Incidentally, in common with many others than the British, but in this matter other more practical considera who had stands at RADLETT, AIRCRAFT ENGINEERING will be in the tions operated. We primarily desired to increase the performance over comparatively short periods of our fighter aeroplanes. The GRAND PALAIS where it is again hoped to renew acquaintance with many old friends and welcome new ones. By courtesy of the manage Germans, on the other hand, were forced to develop a system of ment of that famous periodical we hope to be represented on the oxygen injection for their long-range bombers to overcome defects stand of the French paper, L'AIR. inherent in their power-plant as a result of conditions imposed on
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Oct 1, 1946
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