The first gyroscope was devised by a German, G.C. Bohmenberger, in about 1810. But it was named thus by a French Physicist Leon Foucault in 1852, when he used the device to demonstrate the rotation of Earth. Its name has its origin from two Greek words: gyros mean turn or revolution; and skopein means ‘to view’. Therefore, gyroscope means, “to view the turning”.
This instrument is based on the same principle as that of a spinning top. We know that as long as the top keeps rotating, it remains upright and resists the force of gravitation. Similarly in a gyroscope, a wheel is mounted at such an angle to the rest of the apparatus that it is free to revolve around any axis.
According to the basic principles of motion — any spinning object resists an attempt to change the direction of its axis — the imaginary straight line around which it revolves. Thus you can move a gyroscope up, down, forward, sideways or backwards, and feel no resistance. But the moment you try to turn it through an angle you will meet opposition.
A gyroscope basically has a heavy wheel. Most of its weight is concentrated in the rim. This gives the wheel a large moment of inertia. It resists attempts to change its position. If an attempt is made to tilt its axis, it will start moving in another direction, in a circle. This is known as precession.
Gyroscope is used to pilot the airplanes and ships. Ordinary compasses rely on Earth’s magnetic field to point out the right directions. But Earth’s magnetism varies from place to place. Hence the magnetic compasses are not fully reliable and are extremely misleading near the North and South Poles. Here gyroscope serves a useful purpose. It is not affected by Earth’s magnetism. There are several types of gyrocompass. They are used together with magnetic compasses for navigation.
Ships and submarines have marine gyrocompasses. These have specially weighted frames. The weight acts at right angles to the axis of the gyroscope. The axis is set to point towards Earth’s geographical North Pole. No matter what direction the ship takes, the axis always points towards the North. And this helps the navigator to set the ship’s course accurately by the axis.
An aircraft may have several gyroscopic devices. One of the major ones is the directional gyro. It is used for navigation along with a magnetic compass. The other important device is called the artificial horizon. It has a vertically mounted gyroscope. Whatever be the position of a plane it would always accurately point in the ‘up’ and ‘down’ direction. These two devices are used in an automatic pilot system in many airplanes.
Gyroscopes also resist the rolling movement of ships and keep the ship steady. These gyroscopes are called gyrostabilizers.
In most gyroscopes, electric motors keep the rotors spinning. Smaller gyroscopes may be driven by jets of air blowing on the rim of the rotors.