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Aviation History
1925
1925 - 0031.PDF
JANUARY 15, 1925 slotted wing, but the percentage increase in lift is not so great. So far we have no knowledge of the effect of the presence of the rotor on the L/D of a wing section. It appears likely that the shape of the nose which the rotor will necessitate may adversely affect the drag. The American tests on a com- pound strut indicated that, at a channel air speed of 10 m./s., the drag coefficient was considerably greater at high than at low peripheral speeds. On the other hand, when the air speed was 20 m./s. the drag coefficient of the compound strut remained sensibly constant from 500 r.p.m. to 2,000 r.p.m., with, if anything, a slight decrease in drag with increase in rotational speed. The American tests, however, were carried out with the compound strut placed at 0 angle of incidence, and are, therefore, scarcely a criterion of what the effect would be if the angle were altered. A vast amount of research work remains to be done on rotating cylinders in their application to aerodynamics, but already it can be said that the preliminary tests have given • <s> good promise. One application to practical aeroplanes which suggests itself is that of the use of the rotors for lateral control at or above the stalling angle. The Dutch experiments have shown that the effect of the rotor is to raise the critical angle as well as the maximum lift coefficient, and it should thus be possible to fit two rotors, operated by a differential and pro- vided with brakes so that as one rotor is slowed down the other is speeded up. Unfortunately, the Dutch tests indicate that a very considerable change in speed will be necessary before any considerable righting moment is applied. On the other hand, the American plain rotor was very sensitive to changes in r, so that it almost appears that some compromise between the plain rotor and the rotor built into the leading edge will have to be made. At any rate, the best size and disposition of the rotor has not yet been determined, but the subject of control at large angles is one of paramount importj^ce, and no avenue should be left unexplored which gives hope of a solution of the problem. MALLOCK-ARMSTRONG EAR DEFENDER WE give below some brief particulars of a simple but effective device that is employed in the British Naval, Military and Air Services (as well as in the U.S. Army and Navy) as a protection for the ears against " gun-deafness " and other ill effects likely to be caused by any abnormal noise or explosion. This device was originally intended for use by gunners, but it has proved equally successful when employed in a variety of other fields, such as engine testing, for pilots (or passengers) of aircraft, deep-sea diving, etc. The principal advantage of the " Ear-Defender," which is supplied by the Mallock-Armstrong Ear Defender Co., of 86, Petty France, London, S.W.I, is that while it protects the ears from the effects of loud explosions it preserves small sounds generated at a distance, which can be heard as under normal conditions. Thus, conversation and commands, telephone and voice-pipe messages can be heard as usual whilst wearing the Ear Defenders. As may be gathered from the accompanying sketch, the principle of the Mallock-Armstrong Ear Defender is extremely simple. It consists of a pair of small ebonite plugs which are made to fit into the ear. In the outer end of each plug is a diaphragm, on either side of which, but spaced a certain distance from it, is a protective disc of gold wire gauze. Normal sounds cause the diaphragm to vibrate freely and so transmit the sound waves to the ear drum. Any violent vibrations of the diaphragm, caused by loud explosions, etc., are checked or damped by the gauze protectors, and the ear drum is not. therefore, unduly affected. The " Defenders " are made in a variety of sizes, to accom- modate all dimensions of ear-orifice, and the presence of the Defenders " in the ear is soon forgotten and is by no means uncomfortable. The advantages of these " Ear Defenders " in connection with aircraft will at once be apparent to readers of FLIGHT, The Airship Base in Egypt CAIRO has been referred to as the " Clapham Junction " of future air routes. Whether that idea has been dropped or not, we are not in a position to know, but at any rate it now appears fairly certain that the mooring mast to be erected in Egypt will be situated at Ismaiha and not, as at first expected, at Cairo. The decision to place at Ismailia the mooring mast for airships operating on the London- Eg-ypt-India-Australia air route is a little difficult to under- stand. Ismailia, although possibly the cleanest town in Egypt, is not a great centre like Cairo, but possibly it has been chosen from political and strategic considerations rather than on account of its immediate suitability. Ismailia is situated on the banks of the Suez Canal, a little more than half-way down from Port Said to Suez, on the Bitter Lakes, and is in railway communication with these towns. Pre- sumably the location would be convenient in the event of the airship service working in co-operation with steamship lines running through the Canal, although to the lay mind it would appear that Port Said might have been a more suitable location. However, doubtless there are very good reasons for choosing Ismailia, even if they do not appear on the surface. Autres Temps, Autres Moeurs IN striking contrast to the attitude of the late Lord Northcliffe, who not only personally and spontaneously wrote to the Editor of FLIGHT in appreciation of the work done by the paper, but who went farther and expressed the and when once employed the extraordinary benefit obtained will, we feel certain, be appreciated very considerably. In conclusion, we may add that the Mallock-Armstrong Ear Defenders are made up in very neat outfits, consisting of a The Mallock- Armstrong "Ear De- fender,'' which, in- serted in the ear orifice as shown, pro- tects the ear against the effect of loud explosions, etc., at the same time al- lowing normal sounds to be heard as usual. Details of the ear protector are shown in the top sketch. dark green metal pocket-case, distinctively marked outside, containing one pair of Defenders secured in the case by- strong rubber holders. * wish that so far as possible quotations should be given from FLIGHT and the source acknowledged, was the publication in the Daily Mail of January 12, in an article dealing with "Rotor-plane Tests," of the statement that "laboratory researches which—as stated exclusively in Saturday's Daily Mail—indicate that rotors . . ." Whatever the ultimate value, if any, of the rotor in its application to aeronautics, it would seem to be at least but courteous to " render unto Caesar, etc." As far as this country is concerned, FLIGHT, on November 27, 1924, published the first article on the possibilities of applying -the rotor principle to aeroplanes, and followed this up, on December 4, with another article suggesting a method of testing the rotor on a light 'plane. The "exclusive" announcement, which was accompanied by an illustration which is more than in first-cousin .relation- ship to FLIGHT'S original sketch, to which the Daily Mail refers as having appeared in their issue of Saturday last (January 10), commences as follows : " It became known last night . . ." Curiously, the issue of FLIGHT of January 8 contained the results of tests made in America, which were sent to us by the Director of Aeronautical Research in the United States, as a direct result of our previous articles on the rotor. We are content to let our readers draw their own conclusions, and would merely state that to us it seems that a newspaper in the unexampled position of the Dailv Mail should be able, without loss of dignity, to afford to be generous in giving " place of origin credit to other workers in the interests of progress who may be on a less exalted comwcrcial pinnacle. 31
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