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Aviation History
1910
1910 - 0839.PDF
OCTOBER 15, 1910. [/yGHT] SPEED»ALARMS FOR FLYERS. SOME MORE COMPETITIVE DESIGNS FOR OUR £5 PRIZE. [17] I herewith enclose sketch of a safety whistle for aero planes. The wind enters the apparatus at A, and passing beneath the baffle-plate rotates the turbine, B; this in turn acts upon the governor-balls through the medium of a belt and pulleys, or through a worm-gear. At normal speeds the plunger, D, is in the position illustrated, allowing the air to pass through a hole in it, into the whistle, E, which being plugged at the other end emits a low note. When the wind pressure increases the turbine revolves faster, causing the governor balls to fly outward, thus depressing the plunger, D, so that the hole in it takes up a position opposite the mouth of the whistle, F, which being open at the other end emits a high note. By screwing the plug at the end of E in or out a difference of one or two octaves between the two notes can be obtained, and the sudden change from a low note to a high one would not pass unnoticed by the aviator. The apparatus can be adjusted to the speed of the aeroplane on which it is fixed by altering the size of the pulley-wheels, or fitting an Iris diaphragm in front of the baffle-plate. Hull. E. G. EVANS. [18] In the enclosed designs for a speed-whistle, Fig. 1 is a sectional elevation through line Y, Z, on plan, Fig. 2. Pig. 3 shows front view of bracket, O ; bracket, D, is of similar design, but the whisle is of smaller size. The action of the alarm takes place as follows :— Air passing into funnel and up tube, A, is allowed to pass through holes, B, which are round tube, A, into annular passage, C, in bracket, D, and blows slow-speed whistle, E, until the speed is attained that may be considered safe, the tension-springs, LL (one end of each of which is fastened on peg, H, and the other to end- plate, J, screwed into end of tube, A), keeping tube, A, in position against wind pressure. When the speed is increased from this point, the pressure, acting on funnel, is greater than the tension in springs, LL, and tube, A, which is an easy sliding fit in brackets, G, D and O, begins to travel in direction of arrow, M, the holes, B, move away from annular passage, C, and whistle, E, ceases to blow. As the speed increases, the tube moves further back until holes, B, are in connection with the annular passage, N, in bracket, O, and the high-speed whistle, K, begins to blow, and this is of a distinctly different tone to whistle, E. The supporting bracket, G, which may be fastened to the framing of machine, carries the bosses, PP, holding indexed tubes, FF, which carry brackets, I) and O. The tubes, FF, have a small slot running their full length, and are sprung to give a tight sliding (it in brackets, D and O, and are also indexed on side, allowing whistles to be set to blow at any desired speed before starting. Leicester. G. A. CHAPMAN. [19] I enclose herewith drawing of my idea for a speed alarm. You will notice an absence of springs and funnel arrangements. As the alarm has to be reliable I think weights are more reliable than springs, which, with constant use (as on an aeroplane) are liable to lose some of their tension and, therefore, unless renewed, are not accurate. With regard to funnel arrangements I think, when an aeroplane is travelling through the air, the draught, if measured through a funnel, will be considerably accelerated when it gets through the narrow opening. For instance, when water is forced into a narrow gulf it rises and obtains more force, as in the Bay of Fundy, between Nova Scotia and New Brunswick, in Canada, and as the air through the funnel has no room to rise, it consequently gains more speed. I think you will consider the enclosed drawing of alarm very neat, compact, light, reliable, and undoubtedly accurate and cheap. Fleetwood. FRANK ROBRKTS. - SECTIONAL CLFVATIQW THWO' YZT 837
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