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Aviation History
1910
1910 - 0946.PDF
[fOGHT] 340 320 300 280 I 240 I 220 < £ 200 5 5 180 E 160 o 120 u 0 100 £ 80 1 60 tj 40 20 1 2. 3 4- 5 6 7 & 9 10 II 12 13 14 TIME TOR 90° IN SECONDS Chart showing the magnitude of the gyrostatic couple caused by changing the direction of flight to a line at right angles to the original path in the time stated. Graph A shows values for a rotary enpine weighing 100 kilogs. operating a propeller weighing 10 kilogs., -while Graph B shows values for a stationary engine driving a propeller weighing 5 kilogs. also at 1,200 r.p.m. \B A V \ 'H — NOVEMBER 19, 1910. first named representing the direction in which a particle of the disc at 0, was travelling before the spindle moved, while o, s represents the direction of the same particle after the spindle has been displaced. Now, it is very obvious that this change in direction of the movement of the particle can only have been brought about by the application of an upward force, and by Newton's laws it is equally obvious that the action has been resisted by a downward reaction, which I have represented by the line, 0, t, on the diagram. At the other extremity of the diameter, g, the reaction will, for the same reason, be upward. These reactions constitute a couple, called the precessional couple, that tends to turn the disc about a line, n, p, at right angles to the line, 0, q, and to the line, a, bt or axis of rotation of the disc. The particles of the disc at n and /, where n, p represents a diameter at right angles to o, q, do not give rise to gyrostatic reaction, because the new direction of their movement has remained parallel to their original path. From this diagram it should be quite evident that two similar discs rotating in opposite directions, but upon the same axis, would com pletely neutralise each other's gyrostatic reaction. In order further to assist any readers of FLIGHT who may be interested in this important subject, I have prepared a chart showing by means of a graph, A, the gyrostatic couple produced by the masses taken in the special case already discussed. The base line of the diagram represents the time taken to turn through 900 while the vertical scale represents the gyrostatic couple in kilogramme-metres. The lower curve, B, shows values for an ordinary stationary motor fitted with a single light propeller, weighing 5 kilogrammes, and having a diameter of 2 "40 m., making 1,200 revolutions per minute. A CLOSE THING.—Hubert Latham blown out of his course at Belmont Park (N.Y.) Meeting during the contest for the Gordon-Bennett Cup. 944
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