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Aviation History
1911
1911 - 0939.PDF
OCTOBER 28, 1911. THE GYRO COMPASS. DURING the past three years the German navy has been largely replacing the familiar magnetic compass with a gyroscopic instru ment developed by Dr. Anschutz, which device is now being made in England by Elliott Bros., and is finding its way on to British ships. At the moment, there is no likelihood of its application to aero planes, but this fact hardly discounts the very interesting nature of the apparatus, and the fact that practical pilots are only too willing to give attention to compasses of all descriptions is, we think, sufficient excuse for referring to the matter in the columns of FLIGHT. Everyone knows that a gyroscope is a spinning fly-wheel mounted in gimbals, and that its principal characteristic is the manner in which it keeps its axle fixed in space irrespective of the manner in which its supporting framework m >y be moved around it. It is less generally known that if the framework is so arranged that the gimbals provide for free movement in two instead of three directions in space, a gyroscope will persistently point its axis due north and south. An explanation of this action calls for a more involved treatment of the science of prece-sional motion than we have space to give here. The main point to bear in mind is that, in a system as above defined, the gyroscope revolves with its axis parallel to that of the earth and constitutes, as it were, a small planet imitating the action of its sun. To those who care to mike a study of gyroscopic motion, the problems involved in the gyro compass are of the most fascinating character, and incidentally no better example could be found to show how very far from being the result of a casual inspiration is the production of this apparently simple device. Although the essential underlying principle has been known since the year 1851, failure overtook every effort to apply it in practice until 1906, when Dr. Anschutz arrived at the turning point of his long series of experiments. In the gyro compass as it exists to-day, the gyrostat is driven by a small three-phase electric motor, and its normal revolutions are 20,000 per minute. Ninety-five per cent, of the energy used in driving the flywheel is absoibed by the air friction, and the makers state that after a gyro has run a few thousand hours its surface is noticeably smoother than when it left the finishing process in the grinding machine before being put into use. We commend this remark to the attention of those who profess to ignore skin friction in the problem of flight. One of the chief practical difficulties associated with the develop ment of the gyro compass was to find a means of damping its natural oscillation and a particularly ingenious method has now been devised. The rotation of the gyro wheel is utilised for draw ing air into the casing, whence it is discharged from an orifice partly covered by a moving vane. The balance of the gyro auto matically controls the position of the vane and the reaction of the rejected air from one corner of the orifice or the other creates the steadying force r« quirt d. From the fact that it is electrically driven, may be gathered its ansuitability for aeroplanes in its present form ; nevertheless it behoves aerial navigators to keep their eye on an instrument which is so far superior to the magnetic compass as to indicate a true geographical north and to be absolutely unaffected by the presence of iron and steel in its vicinity. ® ® ® ® THE ROMANCE OF AERONAUTICS. IT cannot be denied that the story of Man's conquest of the Air from the fanciful tale of the wings constructed with the aid of feathers and sealing-wax by Dsedalus down to the practical achieve ments of to-diy is one of the most romantic which the world has ever known, and in writing a volume on the subject for the " Libr >ry of Romance " Mr. Charles C. Turner has had abundant material to draw upon. Many books have been written during the past few months, some authors purporting to deal with the subject from an historical point of view, and others confining their attention to what might be termed the practical side, being mainly con cerned with recording the results of experiments made by those who have worked at the variety of infinite problems presented and the many theories which have been evolved therefrom. Of all these volumes it is the historical books which appeal to the general reader, but speaking generally, th >se which have hitherto appeared lack a sense of reality, mainly for the reason that their writers have had little knowledge of the subject, and so were unable to treat it in that sympathetic way which alone can make history delectable. Mr. Turner approaches his task well equipped, for not only has he studied his subj -ct for a long time, but he has a practical acquaint ance with it, having graduated in ballooning, and then gone on fjTJGHf] from that to acquire the art of tin homme oiseau, his abilities in that direction being testified to by a Royal Aero Club certificate. And apart from this Mr. Turner is no apprentice in the art ot weaving a story. The result is one of the most welcome volumes which have appeared lately, and one which will be found enthralling by everyone who takes the slightest interest in aviation. And who does not The dwellers in this " tight little island " may not be so demon strative as the bourgeois across the Channel, but there are few now who do not realise that the aeroplane has come to stay, and that before long it will play a part—how large or how small it is impos sible to say just yet—in our daily life. Considering that for several centuries many able men had been working at the problem, it is astonishing how rapid has been the development of the aeroplane, since the memorable day in November, 1906, when Santos Dumont succeeded in keeping his unwieldy machine in the air for a distance of 238 yards. Now—well, it is unnecessary to specify, as each week the pages of FLIGHT record performances which three years ago the most sanguine prophet hardly dared to predict as possible. The twenty-nine chapteis which go to make up this book of three hundred odd closely-written pages are each brimful of interest, while there is an admirable selection of illustrations, both photogiaphic and line drawings to help the reader. It is a book written in simple language, and should do a great deal to spread knowledge of aviation in this land. The Library of Romance is published by Messrs. Seeley, Service and Co. at $s. each volume. ® ® ® ® Two interesting views secured from the dirigible which has been stationed at Lucerne for regular passenger carrying. The top- photograph shows a general view of Lucerne, one of the elevating planes of the airship and the tip of one of the propeller blades being seen in the left-hand upper corner. In the lower picture the housing shed for the dirigible is seen through the framework of the car. 941
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