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Aviation History
1910
1910 - 1035.PDF
DECEMBER 17, 1910. JQSSTJ SPEED-ALARMS FOR FLYERS. SOME MORE COMPETITIVE DESIGNS FOR OUR £5 PRIZE. £29] I enclose a design for an aeroplane speed whistle. The •explanation is as follows :—A is a funnel, having at one end a -disc, B, and adjustable screw bearing, C, and at the other end a bearing, D, on its support, E. In the bearings runs shaft, F, which •carries at one end a windmill, G, and at the other a disc, H. "Discs, B and H, are pierced with two or more concentric rings or holes, the radii of corresponding rings being the same in both discs. The bearings must be adjusted so that the discs run in contact without appreciable friction. The higher the speed of the aeroplane the higher is the rate of revolution of the windmill and consequently the higher is the note. Halifax. E. RAMSDEN. 30] May I submit the enclosed design of a speed alarm for competition for the £5 prize which you have so generously offered. The great point about my apparatus is that it is already invented, in the form of a steam pressure gauge, and will therefore require very little experimentation to be brought to perfection. This aerial speedometer, for such it may be called, consists of a small cone, similar to a miniature talking machine trumpet, and, as I stated before, a sort of steam pressure gauge. The cone, F, is fixed to the aeroplane with the opening facing the direction of flight, in a posi tion where it may meet an undisturbed body of air ; the air received in the cone is then transported down a tube, connected to the said cone, as per diagram, to the gauge, which is placed by the aviator. DIRECTION The mechanism of this gauge consists 01 a very delicate tube, C, made of rubber or goldbeater's skin; inside this there is a weak steel wire spring, B, whose natural position is as shown in the plan. The air which is forced into the gauge-tube has a tendency to work the tube into the straight, like the toy which is sometimes found in a Christmas bonbon, which, when blown into, stretches out into an elongated body, but as soon as the pressure of air is released rolls itself up again' But to return to the speedometer. When the tube uncurls itself it takes a needle, G, with it, moving the pointer along a scale denoting miles per hour; the scale is omitted from the diagram, as it can only be decided upon by experiment. At A there is a very delicate spring, for the purpose of keeping the needle in tension with the gauge-tube. . An alarm might easily be arranged on my apparatus by making the needle, when it registers a certain speed which is deemed too fast for the aeroplane, complete an electrical circuit, and thus cause a bell to ring. The electric bell arrangement need only weigh about 5 MS. , for the necessary current of electricity could be obtained from the aeroplane engine's accumulator or magneto. On the plans, E is a metal angle tube, to which the rubber or goldbeater's skin tube is attached. The speed alarm is drawn at a scale of about half and the cone one-third actual size. In the event of this apparatus being attached to an aeroplane with a tractor, allowance would have to be made in the scale. Bexhill. DUDLEY G. O. HISCOX. [31] A bell-mouthed whistle, A, is clipped to a convenient vertical strut on the aeroplane, and carries on its rearward extension a rotating sleeve, C, to which is fixed a lever arm, B. One end of the lever arm, B, carries an oblique wind vane, and the other is connected to a tension spring. The extension of the whistle barrel behind the whistling orifice has four narrow longitudinal slots, E, placed at equal distances around its circumference, and the outer sleeve, C, has four wide slots corresponding with these. Clearly, so long as the four narrow slots remain uncovered there is free egress for all the air entering the bell-mouth without any considerable volume being forced through the whistling orifice and the alarm is therefore silent. The vane on the lever-arm, B, faces obliquely forwards and upwards, and therefore the pressure of the air upon it when flying will force it downwards against the pull of the spring. As the arm, B, is carried down it rotates the outer sleeve. C, upon the whistle barrel until the limit of safe speed is reached. At this point the air pressure upon the vane will have become so great as to force the arm, and consequently the sleeve, C, round upon the barrel until the four narrow slots are closed and the whistle comes into action. A stop, F, prevents the arm rotating further, and so passing the danger-point should speed still further increase. In designing the above, the following requirements have been kept in view as essential for a device of the kind : Simplicity ; freedom from rapidly- moving parts ; the necessity that the alarm shall be positively sounding or entirely silent (a whistle commencing with a low note at safe speeds and rising as the danger-point ir; reached would be likely not to be heard among the other noises). This requirement is met in the present arrangement by making the slots very narrow, say, i in. wide only, so that a very small movement of the covering-sleeve makes the difference between an alarm signal and silence. A further desideratum is that there shall be a minimum of parts that can go wrong, and in the event of failure the alarm shall sound at once. This also is provided for, because the only detail that could well ail would be the spring, and should this break, the arm immediately falls to the alarm position, and the whistle will sound as soon as there is sufficient air entering the funnel. Birmingham. G. BOOCOCK. [32] This instrument is worked by a four-bladed metal propeller with adjustable blades. The boss is a casting with four sockets projecting radially, into which the blade-arms fit, where they are held at the required angle by set-screws. The rotary motion of the propeller is imparted to a vertical shaft by means of gearing with a reduction of 10 to 1. On the vertical shaft are pivoted a pair of centrifugal balls, which, when rotated at sufficient speed, raise a sleeve, S (which slides on the shaft to which they are pivoted), which revolves at the same speed as the balls. 1033
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