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Aviation History
1910
1910 - 0774.PDF
(/jjCHT) SEPTEMBER 24, 1910. SPEED-ALARMS FOR FLYERS. SOME MORE COMPETITIVE DESIGNS FOR OUR £5 PRIZE. [II] I enclose a design for a safety speed alarm. The action is as follows i— A. Metal plate to be lifted by the pressure of air in idirection of arrow. W. Weight for regulating miles per hour. B. Whistle. C. Shutter. H. Air collector. Gateshead. • A. R. WILLMOTT. (<•) It is easily adjustable to suit maximum speeds between 30 and 80 m.p.h. (d) The governing action is positive, not controlled by mere wind pressure. The device consists of a horn, blown by the rush of air past the aeroplane when opened by the governor, G, driven by the fan, F. One of the spokes of F is of f-in. tube, polished on the inside. In this slides a lead plunger, L, thrown out by centrifugal force against a light spring, which can be more or less compressed by the nut, N, so that greater or less rotational speed is required to bring the plunger into a given position, according to the safe critical speed of the aeroplane. The f-in. tube is expanded at the centre into a boss for the other spokes. It is held by two nuts to a piece of hard brass tube, which forms the bearing, turning on a fixed shaft. The lead plunger carries an arm, A, which racks into the pinion, P, turning a disc valve in the throat of the horn, against the small springs, either way. Where the rack is not toothed, the valve remains closed, the positions of the plunger corresponding to either critical speed bringing the racks into play. The horns and reed-box, R, turn with the fan ; the mouths of the horns are cut so as to make use of the turning as well as the forward movement. The whole is protected by a fixed outer ring of brass, which is fastened to the bracket carrying the fixed axle. I have designed a governor having no forward motion, as the frequent sudden changes of forward speed in a gale would hopelessly upset such a device. An aeroplane never has any appreciable change of speed perpendicular to the planes, so my governor moves in that direction only. My governor is not worked by a piston pressed back by direct air pressure. I think that the sudden pressure drop on opening the whistle would let tho plunger back again to close the valve, and no steady blast could result. The pinion turning the disc-valve of the horns is small, thus a small change of plunger position (hence of speed) is enough to open it fully. Battersea. ARTHUR D. TURNER. [12] I submit the enclosed design, for which I claim the following advantages:— («) It sounds at both a dangerously slow and a dangerously high speed. (*) It warns some 3 m.p.h. either side of the limit, being in full blast at the dangerous speed. [13] This instrument consists essentially of three parts : the propeller, magneto and telaupad-gear. The propeller, A, is keyed direct to the magneto-shaft, B. The magneto, C, is of very light construction, as very little current is required. The left end of the magneto-shaft is squared to receive the clutch and governor ; the method of working is as follows :—The arms, D, of the governor are pivoted at the centre of the squared shaft and pass through slots in the sleeve, E, which revolves with and is free to slide on the square shaft. When, owing to centrifugal force, the arms extend, the sleeve is moved to the right, and in so doing engages the cone- shaped clutch into the small gear-wheel, F, which is free to revolve loosely round the main shaft. This pinion engages in the larger gear-wheel, G, which operates the make-and-break. This is so constructed that when at rest there is always contact, but the toe of the cam, II, " throws off" sufficiently when in motion to effect a break, thus preventing any chance of "dead centre" causing a continuous break in the circuit. The current goes from the positive brush through the make-and-break to a pair of "telaupads" (telephone receivers), which are worn over the ears of the aeronaut, and then back to the negative brush. The action of the complete instrument is as follows :—Up to a certain speed a gradually increasing buzzing is heard, then at an easily adjustable speed, i.e., the speed considered dangerous to the construction of the particular 772
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