Gyroscope

“ All the world has learned to call them gyroscopes. The vehicle that they balance may conveniently be termed a gyrocar—a name that has the sanction of the inventor himself.
Let it be understood once for all that a gyroscope is merely a body whirling about an axis. A top such as every child plays with is a gyroscope; a hoop such as every child rolls is a gyroscope; the wheels of bicycles, carriages, or railway-cars are gyroscopes; and the earth itself, whirling about its axis, is a gyroscope. You can make a gyroscope of your own body if you choose to197 whirl about, like a ballet-dancer. ”

“ The gyroscope is, as everyone knows, a top, and I might have called the hat I invented a top hat, except that any tall cylindrical silk or beaver hat is called a top hat, so I was forced to adopt the name of gyro-hat.
A gyroscope is not an ordinary top. It is like a heavy fly wheel, revolving on an axle; and if it is spun, the speed of the revolutions maintains the axle in the perpendicular. A huge gyroscope is used to steady the channel steamers, which would otherwise stagger and reel. ”

“ A gyroscope has been adopted to the monorail cars, and so long as the gyroscope gyrates the monorail car cannot stagger or reel. If a proper gyroscope was fastened on the end of a knitting needle and gyrated at full speed, that knitting needle could be stood on end and it would not fall over.
Therefore, if a gyroscope was placed in the top of a top hat, and the top hat firmly fastened to the head of a man, and the gyroscope set going, that man would remain perpendicular in spite of anything. ”

“ GYROSCOPE AND GYROSTAT. These are scientific models or instruments designed to illustrate experimentally the dynamics of a rotating body such as the spinning-top, hoop and bicycle, and also the precession of the equinox and the rotation of the earth.
The gyroscope (Gr. γῦρος, ring, σκοπεῖν, to see) may be distinguished from the gyrostat (γῦρος, and στατικός, stationary) as an instrument in which the rotating wheel or disk is mounted in gimbals so that the principal axis of rotation always passes through a fixed point (fig. 1) . ”

“ The compass needle is virtually insulated from the terrestrial magnetism by the surrounding steel hull. But, fortunately, the gyroscope may be used as a compass and it is in no way affected by magnetism. Once the gyroscope is set spinning with its axis pointing to the North Pole of the heavens it will continue to point in that direction no matter how devious a course the vessel may pursue. If pointed in some other direction, the precessional forces set up by the rotation of the earth will turn it due north. ”

“ Try it yourself: you must grip the frame firmly, because when the gyroscope turns over it gives you quite a shock and you must be careful not to drop it. The reason why it turns over may be put in this way: that it insists on spinning in the same direction in which the holder is turning. If he turns in the opposite direction, then the somersault of the gyroscope will practically make it spin in the other direction. ”

“ One of the most remarkable recent developments of the gyroscope is its use as a stabilizer in ships to keep them from rolling in a heavy sea. A comparatively small wheel is mounted in the hold of the vessel with perfect freedom to turn in any direction. If the wheel is clamped so that it cannot precess, the vessel will roll and pitch, but the instant the gyroscope is released it exerts its wonderful powers. ”

“ The balancing action of the gyroscope seems no whit less remarkable after it is explained. It should be said, however, that the force exerted by the mechanism is not213 so tremendous as might at first thought appear, for the gyroscopes are by no means called upon to counteract the entire force of gravity brought to bear on the car. They do not in any sense lift the car; they only balance its two sides, which when left to themselves are approximately of equal weight. ”

“ As he directed, a mechanician wheeled the aeroplane out on the runway in front of the hangar.
“This is the gyroscope,” began Sinclair, pointing out a thing encased in an aluminum sheath which weighed, all told, perhaps fourteen or fifteen pounds.
“You understand,” he continued, “the gyroscope is really a flywheel mounted on gimbals and can turn on any of its axes so that it can assume any angle in space. When it’s at rest, like this, you can turn it easily. But when it is set revolving, it tends to persist always in the plane in which it was started rotating.” ”

“ It is believed by many aviators that the problem of automatic stability will be solved by some form of the gyroscope. A great many experiments are being made with various forms of the gyroscope, although no machine has as yet been actually fitted and flown with such a device. The general principle of the gyroscope is very simple. It consists of a wheel which is made to revolve at very high speed. When such a wheel turns fast enough it will remain in a fixed position. Every one is familiar for instance with the gyroscope top. ”

“ Bearing in mind that the gyroscope itself is perfectly balanced and hence tends to maintain its axis O F in a fixed direction, we shall be able to understand what must happen when the car is tipped from any cause whatever—as the shifting of its load, the pressure of the wind, or the centrifugal action due to rounding a curve. ”

“ Only a force that tends to change the axis of rotation produces precession.
If a gyroscope is placed at the equator with its spin axis pointing east-west, as the earth turns on its axis, gyroscopic inertia will tend to keep the plane of rotation constant. To the observer, it is the gyroscope which is seen to rotate, not the earth. This effect is called the horizontal earth rate, and is maximum at the equator and zero at the poles. At points between, it is equal to the cosine of the latitude. ”

“ In principle the action of this wheel is not different from that of an ordinary top on your table which wabbles221 to the right or to the left when you push its axis straight away from you. Yet to the untechnical observer it seems as if the Schlick gyroscope were a living thing, governed by almost human motives. If you apply a brake to prevent the longitudinal oscillations of the gyroscope, the effect, even though the fly-wheel still revolves at full speed, is precisely as if you pinioned the arms of a strong man, so that he saw the futility of resistance and made no struggle to free himself. ”

“ What we have already seen has made it clear that the revolving wheel of the Schlick gyroscope, to be effective, must bear an appreciable relation to the mass of the entire ship. Such a weight, revolving at a terrific speed and oscillating like a tremendous pendulum, obviously represents an enormous store of energy. ”

“ It is all one to the gyroscope whether the car moves on the level or up or down hill, so long as it moves straight ahead.
Nor do the gyroscopes interfere in the least with the turning of the car in passing round a curve, when the two of them are linked together, as Mr. Brennan links them, so that any lateral change in the axis of one is balanced by an opposite change of the axis of the other. With the single gyroscope, such as Mr. Brennan used when he first began his experiments, the car encounters difficulties at curves in the track. ”

“ To demonstrate the rotation of the earth by the constancy in direction of the axis of a gyroscope is a suggestion that has often been made; by E. Sang in 1836, and others. The experiment was first carried out with success by Foucault in 1851, by a simple pendulum swung in the dome of the Pantheon, Paris, and it has been repeated frequently (Mémoires sur le pendule, 1889) .
A gyroscopic fly-wheel will preserve its original direction in space only when left absolutely free in all directions, as required in the experiments above. ”

“ To make a car run on a single rail, with its weight above the [202] rail, was impossible until the use of the gyroscope was discovered. In the monorail-car invented by Brennan (Fig. 104) there are two gyroscopes, each weighing fifteen hundred pounds, driven at a speed of three thousand revolutions a minute by an electric motor. Each gyroscope wheel with its motor is mounted in an air-tight casing from which the air is pumped out. The wheel will run much more easily in a vacuum than in air, for the air offers very great resistance to its motion. ”

“ It has indeed been entitled the paradox of mechanics; for though it depends on gravitation, gravitation yet appears indifferent to it. In order to render the operation of the Gyroscope as continuous as possible, so as to facilitate the profound study of its working, and also to unite another influence with those of the ordinary Gyroscope, producing phenomena of which this instrument affords us the spectacle, a learned American has employed electricity as a motive power. ”

“ I realized that as soon as I began making airships, and so I devised what I call a gyroscope equilibrizer or stabilizer. A gyroscope, you know, is a heavy wheel, spinning at enormous speed, on an anti-friction axle. Its great speed tends to keep it in stable equilibrium, and, if displaced by outside forces, it will return to its original position. ”

“ I replied. “Isn't it just barely possible that Norton is on the wrong track in applying the gyroscope to an aeroplane? I can't say I know much about either the gyroscope or the aeroplane, but from what I hear the fellows at the office say it would seem to me that the gyroscope is a pretty good thing to keep off an aeroplane, not to put on it.”
“Why?” asked Kennedy blandly.
“Well, it seems to me, from what the experts say, that anything which tends to keep your machine in one position is just what you don't want in an aeroplane. ”

“ When a gyroscope is spun at a very high velocity on a vertical axis, with the point of support very much above the center of gyration, it has a tendency to maintain a vertical axis; a horizontal or swinging motion of its support will not cause it to swing like a pendulum. ”

“ Again, it is curious to observe how an old and familiar truth, coming up in a new form, startles us as an impossible paradox. I well remember some twenty-five years ago, when the little instrument the gyroscope first made its appearance, how it startled everybody by its seeming violation of the laws of gravity. Imagine a heavy brass wheel rotating rapidly at one end of an axle, while the other end is supported on a vertical column. ”

“ Robert explained, “is automatically controlled by a delicate device attached to the central upright gyroscope.”
“I was under the impression that the entire apparatus was unaffected by gravity.”
“This device is the exception. The Sphere’s weight is neutralized to an absolute minimum by the gyroscopic control, but it was necessary to maintain one point of gravitational contact in order to establish some permanent upright stability; otherwise, the Sphere would revolve at random when in midair.” ”

“ Of all machines in the world, the gyroscope is the simplest, for, in its essential form, it is no more than a wheel revolving. But a wheel revolving is the vehicle of many physical principles, and the sum of them is that which is known as gyroscopic action. It is seen in the ordinary spinning top, which stands erect in its capacity of a gyroscope revolving horizontally. The apparatus that holds Brennan's car upright, and promises to revolutionize transportation, is a top adapted to a new purpose. ”

“ This very useful, although unsymmetrical, system of angular co-ordinates was introduced by L. Euler. It is exemplified in “Cardan’s suspension,” as used in connexion with a compass-bowl or a gyroscope. Thus in the gyroscope the “flywheel” (represented by the globe in fig. 37) can turn about a diameter OC of a ring which is itself free to turn about a diametral axis OX at right angles to the former; this axis is carried by a second ring which is free to turn about a fixed diameter OZ, which is at right angles to OX.
We proceed to sketch the theory of the finite displacements of a rigid body. ”

“ The gyroscope is as submissively obedient to the laws of gravity as any other object or machine, but the forces which act upon it are so complicated that it is difficult for one to comprehend them without study. ”

“ This readout, being digital, can then be sent to a variety of devices which need heading information, such as helm, autopilot, and electronic chart systems.
A single ring laser gyroscope can be used to provide a one-dimensional rotational reference, exactly what a compass needs. The usefulness of ring laser gyrocompasses stems from that fact that they share many of the same characteristics of flux gate compasses. They are compact, light, inexpensive, accurate, dependable, and robust. ”

“ The gyroscope motion in fig. 4 comes to a stop when the rim of the wheel touches the ground; and to realize the motion when the axis is inclined at a greater angle with the upward vertical, the stalk is pivoted in fig. 8 in a lug screwed to the axle of a bicycle hub, fastened vertically in a bracket bolted to a beam. The wheel can now be spun by hand, and projected in any manner so as to produce a desired gyroscopic motion, undulating, looped, or with cusps if the stalk of the wheel is dropped from rest. ”

“ If, however, 143we cause a heavy disc to spin very rapidly, say in a horizontal plane, the disc cannot be moved out of the horizontal plane without the application of some force. A very well-made disc may be made to rotate for hours, and would, by preserving its original plane of rotation, even show the effect of the earth’s diurnal motion. Mr. Bessemer designed such a gyroscope to move the valves of his hydraulic apparatus, and so to keep his swinging saloon as persistently horizontal as the gyroscope itself. Mr. Bessemer’s ship was 350 ft. ”

“ This sequence of oscillations will be repeated over and over so long as any disturbing force tends to throw the car out of equilibrium. In other words, the gyroscope, when its balance is disturbed by a thrust due to any unbalancing of the car, will begin to wabble and continue to wabble until it finds a position where it is no longer disturbed, and this new position will be attained only when the car as a whole is perfectly balanced again. ”