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Aviation History
1912
1912 - 0190.PDF
[/JJCHT) For the maintenance of course, which is a form of stability— directional stability—the gyroscope has been made use of in the Whitehead torpedo, and in this instance it has proved successful because the "flight" of a torpedo only occupies a period of a few minutes and during this time no serious alteration in the direction of the spindle of the gyroscope is likely to occur. The gyroscopic stabilizing instrument (Fig. I), which M. Paul Kegnard exhibited in 1910 at the Physics Exhibition of the French Society for the encouragement of National Industry, has many points to cammend it. It consists of a gyroscops (a) set in gimbals (b) and c) in order that it can maintain its initial direction inde pendent of any movement that the machine may make. The gyroscope (a) is kept in rotation by means of an electric motor (d), the armature of which is concentric and rotates with the spindle of the former. To the tuseboard of the instrument are attached, in addition to the standards (e) supporting the gimbals, the brushes, g) and (A), which are electrically connected to a suitable solenoid or system of solenoids. Its action can be readily seen. If the machine were travelling in the direction indicated and tended to dive, the relative disposition of the gyroscope and brushes, (j>) and (/;), would alter, thus bringing the stud (/), which is directly attached to the inner gimbal (b), in connection with the brush (g). The electric current entering the gyrocope and gimbal system by the connection (/ •) would thus be " distributed " to the brush (f), and led thence to a solenoid which would operate the elevator so that a horizontal flight path be regained. To my humble way of thinking M. Regnard's system needs some modification to correct its two main shortcomings; firstly, that the spindle of the gyroscope would alter in direction by minute degrees in consequence of the resistance to free movement offered by the friction of the stud on the brushes ; secondly, that no variable elevator control, according to the variable amount of tilt and dip, is provided for. 2. Pendulum Divices. — Various means have been brought forward to arrive at automatic stability, by making use of the function that the simple pendulum possesses of tending to maintain a vertical position. The chief drawback to this system is_ the fact that after once being deflected from its normal position, the pendulum does not return to it again until after it has described a series of oscillations. One experimenter in France, M. Moreau, however, has succeeded in obtaining a certain measure of success from Fig. 2.—M. Moreau's pendulum-operated automatically- stable monoplane. this scheme, and we produce herewith a diagrammatic sketch of the Moreau monoplane (Fig. 2). The pilot is seated in a kind of cage (a), which is suspended from the main framework of the machine, and any oscillation relative to the machine that it makes owing to the attitude of the aeroplane changing, is transmitted to an elevator arranged at the tail of the machine. In this manner the elevator is constantly being adjusted, so that the machine may always maintain a horizontal flight path. Lateral stability is maintained in a similar manner by the con nection of the ailerons to the sides of the pilot's nacelle. The striking success that M. Moreau has achieved with his system is demonstrated by the fact that just lately he, ascending alone, has been practising rifle shooting from his machine at a small target on the ground, and on one occasion of thirty shots, fired from a considerable distance, four found their mark. He is credited with scarcely ever flying with his hands on the controls. That he should have experienced no inconvenience from the oscillatory action of the pendulum is surely remarkable as this has for so long been considered the chief drawback of the pendulum idea. Perhaps some explanation of his success is due to the fact that the pendulum as Moreau employs it, would, to a certain extent, be rendered dead beat, by reason of the damping action of the elevator to which it is connected. The mercury bath or curved tube idea (Fig. 3) is essentially another form of the pendulum system. The latter of these two ideas would, no doubt, in practice exhibit superiority above the former method, on the score that it would be more dead beat. Into a curved glass tube [a), filled with some viscuous non-conducting fluid, is introduced a globule of mercury (6), which, despite any_ inclination of the tube, is in constant contact with a platinum wire (c) supported along the middle of the tube. Arranged MARCH 2, 1912. along the base of the tube are a series of platinum studs, each one connected to an exterior wire. In the action of the device the mercury globule acts as a distributor, leading the current entering by the wire (c) or to the several studs, according to the varying inclination of the tube from the horizontal. The studs are con nected with some form of solenoid or electro-magnet in such a manner that contact of the mercury globule with these studs at the Fig. 3.—The curved mercury tube system of automatically maintaining stability. extremities of the tube produces a greater pull on the core of the solenoid, and consequently a greater amount of deflection of the correcting rudder than with those situated near the centre. An important point to remember in connection with this is that the solenoids or electro-magnets should be so devised as to give various pulls on the controlling rudder, which should progress in intensity as the tube becomes inclined, and as the globule travels along the series of studs. This point has considerable bearing on the subject of the construction of relays suitable for application to devices for the maintenance of longitudinal stability, for as soon as the elevator has been adjusted to correct any longitu dinal oscillation, the power operating the elevator should be shut off progressively at the same rate as the aeroplane returns to its normal state of equilibrium. 3. Velocity Pressure Devices.—The Wright Brothers, even though they were strongly of the opinion that there was no more need for an automatic stability device on an aeroplane than there would be on a bicycle, must certainly have been awake to the possible requirements of the future, for in 1909 they took out a patent covering the means whereby they could render their flyer automatically stable. Some time since, vague rumours reached us from America that the famous pioneers had commenced practical experiments with a glider equipped with their automatic stability system, but no truth need be attached to these reports. However, the fact that they have a glider already fitted with the device is sufficient evidence that they intend to commence experimenting upon it at the first possible opportunity. A fall description of the Wright system appeared in FLIGHT of July 10th, 1909, but for the benefit of those who have not this copy in their possession, a brief description is appended. <MZ/OH7 Av~OMAT-C SfA0l*-tTy C&*ACt Fig. 4.—Diagrammatic sketch of the Wright stabilizer. A flat vane, A (Fig. 4), is mounted on a parallel motion frame work, B, which is suspended from a pivot, L, solid with the body of the aeroplane, and which is counterbalanced by the weight, K, in such a manner that the vane, A, is constantly maintained in a horizontal plane relative to earth. Let us suppose the head of the machine were to dip.
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