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Aviation History
1921
1921 - 0075.PDF
FEBRUARY 3, 1921 Using the Stabiliser as an Indicator ": : Connected up with the relay electric circuit are two pairs of electric lights, one pair for the ailerons and one for the elevator. When the stabiliser is working these lights burn as soon as contact is made by the mercury. For instance, if the left wing tip drops, the mercury makes contact on the left-hand side, and the little lamp on the left lights up and continues to burn until the circuit is broken. Thus the pilot can see all the time what is taking place. For instance, if the machine commences to " hunt," i.e., overcorrecting the elevator control, the front and rear lamps of the indicator will light up alternately. When both go out the pilot will know that balance has been restored, and that the machine is flying at the angle and speed for which it has been set. If the two levers are swung back, the control is not working but if the switches are left "on," the light will still continue to act, and the inclinometer and relay circuit are working as indicators merely. ......... The Actual Working Cylinder It has been mentioned that the actual working cylinder of the machine is somewhat differently arranged from the arrangement shown in the diagram. For instance, the valves are not in the cylinder heads, but above, near the end of the up-elevator circuit, thus making the machine swoop. This is, however, only what happens in any longitudinally ing?e«,anH-lf the,,SW°P be to° greatf the differentialS^?S" bk Cl°SeScull That the invention is of more than ordinary interest from a technical point of view will, we think, be generally admitted What are its practICal applications ? In the first place the weight of the apparatus is considerable. Even granted that by future development and simplification the weight can be got down to, say 150 lbs., this will still mean that the equiva- lent of one passenger is expended on carrying the device. On the London-Pans journey this will mean, at the present fares, a loss of ^18 18s. on the double journey. This is a serious consideration, and unless the device can save the pilot from a considerable amount of strain it will not be tolerated. That it will do so is more than probable, and a fact which will have to be kept in mind when trying to form an opinion of the value of the device is that it is probably not on verv many journeys that the full complement of passengers or goods is earned. In that case there is no loss due to carrying the device other than a small one in petrol consumption, and that probably, is negligible. There is one sphere in which the stabiliser does appear to score heavily ; that of flying in fog or clouds. Normally, when the pilot is in a cloud he has, after a time, very little notion of what is the attitude of his machine. For all he knows he may be flying around in circles, and usually the only indication he has is that his compass appears suddenly to have gone mad. As to how to get out of his difficulty he ELEVATOA INCLINOMETER The Aveline Stabiliser: Diagrammatic sketch of the elementary principles of the control. The inclinometer is shown above the control quadrant. On the actual machine it is mounted on a smaller quadrant engaging with a still smaller one, as indicated by the dotted lines. The Aveline Stabiliser : Diagram of the elevator inclinometer. Here there is only one Venturi tube, the opening for the second one communicating with the atmosphere. The suction of the Venturi tube causes the mercury to rise in the forward branch, so that its normal level is at an angle to the horizontal. cylinder, as will be seen from the photograph. Also, normally all valves are closed, and when air is admitted to one end of the cylinder the exhaust valve of the opposite end is opened When all the valves are closed and the pistons are travelling towards their central position, a valve is opened above the CJL n^Ter and the air is allowed to Pass from the end towards which the piston is moving to the opposite end, where it fillsthe space vacated by the retreating piston. When this nappens, therefore, there is only the frictional resistance ofthe pistons and the air through the bypass tube to overcome. I o have shown all this piping would "have made the diagramcomplicated, and we have preferred to keep the diagram simple and to point out the difference between it and the actualarrangement. The Stabiliser in Practice Ihere are numerous other minor details of the stabiliser to which we should have liked to make reference, but space does not allow of doing this. Sufficient has, we think, been said 10 indicate the manner of working and to show the thorough way m which the inventor has grasped the problems to be solved. That the machine is absolutely perfect as yet is not, we think, claimed, but such difficulties as still exist are of a ery minor character and will doubtless soon be overcome. ?rwl e' St wiU be realised that when a machine fitted n the stabiliser meets a " head-on " gust, the Venturi will raise the mercury until it makes contact with the is very much in the dark. If his machine is very stable he may be able to put all control central and get back to normal in this way. In the meantime, however, he may have got the machine into positions involving stresses which are approaching the danger mark. Here the stabiliser would score heavily. If a pilot approaches a cloud he can set his elevator adjustment to what he wants, either a steady climb or horizontal flight, and so long as he keeps on his compass course by steering with the rudder, he has the satisfaction of knowing that the machine is proceeding normally. Again, for flying at night the stabiliser would be invaluable' as it would relieve the pilot of all control except that of steering. In the case of twin-engine machines also the stabiliser appears to be of advantage. If one engine cuts out all the pilot has to do is to give opposite rudder. The device looks after the lateral control, and it also puts the nose of the machine down to compensate for the loss of speed. Consider- ing all the assistance which the stabiliser can give to a pilot, and keeping in mind that more often than not machines are flying with less than their full paying load, it appears that for fairly large machines at any rate it is well worth fitting while for night flying it will prove a great boon. M. Aveline is to be congratulated upon his achievement in solving the conflicting problems and we wish him every success with his clever invention. 75 .. ' . . D2
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