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Aviation History
1910
1910 - 0968.PDF
I/HCHTI NOVEMBER 26, 1910. SPEED-ALARMS FOR SOME MORE COMPETITIVE DESIGNS FOR OUR £5 PRIZE. [22] I have pleasure in submitting a rough sketch for a simple speed alarm, which I think would prove effective. Governor-balls are pivoted to a sliding collar, G, and to a revolving collar attached to a propeller, the whole being mounted on a hollow metallic tube, A. The wind pressure on the propeller causes it to revolve, and this rotates the governor-balls which, by centrifugal force, fly apart, thus drawing the loose collar, G, along the bearing-tube, A. The position of G on the shaft can be regulated by means of the collars and screws at H, H1, and, therefore, for a given pressure, the collar, G, can be made to fall on the insulated contact point, B. When this takes place an electric circuit is com pleted, and this can be arranged to light a lamp, and to ring a bell, or sound a siren. The electric circuit might be made by means of the magneto, or by accumulators, or a battery. Blackburn. JOHN MILTON JEPSON. [23] In the accompanying sketch, A, B and C are musical reeds or whistles, which give three distinct notes. The path of the wind is shown by arrows. As the wind increases and is unable to get away through C it will spew over the partition into path, B, and in like turn, with increase of wind, over partition, B, into path, A. J. H. WILKINS. [24] I send you herewith a design for a speed-whistle, in which the pressure of the air on the blast-funnel is utilised to operate the valve mechanism. The funnel, 1, is mounted on a swinging bracket, and is balanced about the axis, 2, by the weight, 3, so that the action will not be affected by any alteration of the flying angle of the machine. The neck of the funnel enters into the mouth of the whistle, 4, with enough clearance to allow the funnel to swing about, 2, so that the neck has a longitudinal motion of about & "»• The amount of this clearance of course depends upon the distance which can be allowed between 2 and the centre line of the whistle, 4. A rod, 5, is mounted to slide in brackets at the side of the whistle, and is coupled to the funnel by the link, 6. As the speed of the AcROPLANC SP f-f. P- *L>RI machine rises, the correspondingly increased pressure on the funnel, 1, forces the funnel and the rod, 5, to the right against the adjust able spring, 7. The collar, 8, coming in contact with the fork at the back of the trigger, 9, moves it so as to release the valve, 10, which flies open under the action of the spring, 11, thus allowing the whistle to blow. If the speed is reduced, the spring, 7, causes the funnel and rod, 5, to move to the left, and the collar, 8, coming in contact with the fork, 12, closes the valve, which is then locked by the spring, 13, returning the trigger, 9, to its former position. Springs, 11 and 13, are, of course, very light, and need not inter fere with the action of the main controlling spring, 7. It seems to me that an alarm of this type, in which the warning is given suddenly, will be more likely to attract the pilot's attention than one which opens gradually, and which might pass unnoticed among the various other noises on an aeroplane. Moreover, it will be seen that, as the valve opens suddenly and closes slowly, the speed corresponding to the closing of the valve will be lower than at which it opens. Consequently, if set 10 open at the "speed limit," the pilot, when he has reduced the speed until the valve closes, will know that his speed is below this limit, and not on the border-line between "safe" and "unsafe" as might be the case with one which opened and closed at the same speed. Of course, if necessary, it would be possible by increasing the movement of the rod, 5, to open other valves lower down the pipe, and so alter the pitch of the note to correspond to various speeds, though this might lead to confusion, especially in the case of a pilot with no ear for music. The alarm, as shown, is meant to be clamped to one of the vertical struts of a biplane by means of the clip, 14. But obviously, the instrument being self-contained, and working in any position, it could be fitted in desired manner. Stockport. A. E. BEYNON. [25] The three views represent my indicator diagrammatically. The speed-indicator can be placed in any convenient position horizontally, and is of a type that records the relative velocity of the aeroplane with the wind. The body of the indicator consists of two chambers, A, contain ing a movable vane, and B, containing the recording-gear. The indicator is so placed that the funnel-shaped opening is in front, so that the wind enters as at C, the pressure of the wind being taken by the vane, D. This vane is pivoted at one side, E, and is con trolled by the spiral spring, F. Fixed to the pivot, E, is a toothed segment, G, which is in gear with a pinion, H, which operates the pointer, J, moving over the scale, K, which is marked on the dial, L, the whole being cased in by the glass, M. The pressure of the wind entering at C, will cause the vane, D, to move until the wind pressure is balanced by the tension of the spring, F. The movement of the vane will cause the pointer to take up a definite position over the scale, which has been previously carefully calibrated. The pressure of the wind will, therefore, actually register in miles per hour, or any other con venient notation, the relative velocity between the aeroplane and the wind. This gauge may be arranged so that at any pre-arranged speed (i.e., wind pressure) the vane, D, will have moved to uncover a port as shown at O, which will allow the air to escape with a high velocity. The air is directed so as to impinge upon the edge of the whistle, P, so that audible warning of any excess speed is given. The advantages claimed for this gauge are :— 1. Accuracy. 2. Simplicity. 3. All speeds recorded. 4. Double record of excess speed. 5. Accuracy is not affected by slope of aeroplane. 6. Extreme lightness, being made entirely from aluminium. Dundalk. R. PENTONY. 966
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