Gyroscope

The earliest known gyroscope-like instrument was made by German Johann Bohnenberger, who first wrote about it in 1817. At first he called it the "Machine".[3][4] Bohnenberger's machine was based on a rotating massive sphere.[5] In 1832, American Walter R. Johnson developed a similar device that was based on a rotating disk.[6][7] The French mathematician Pierre-Simon Laplace, working at the École Polytechnique in Paris, recommended the machine for use as a teaching aid, and thus it came to the attention of Léon Foucault.[8] In 1852, Foucault used it in an experiment involving the rotation of the Earth.[9][10] It was Foucault who gave the device its modern name, in an experiment to see (Greek skopeein, to see) the Earth's rotation (Greek gyros, circle or rotation),[11] which was visible in the 8 to 10 minutes before friction slowed the spinning rotor. During World War II, the gyroscope became the prime component for aircraft and anti-aircraft gun sights. A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum.[1] In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation. Although this orientation does not remain fixed, it changes in response to an external torque much less and in a different direction than it would without the large angular momentum associated with the disk's high rate of spin and moment of inertia. Since external torque is minimized by mounting the device in gimbals, its orientation remains nearly fixed, regardless of any motion of the platform on which it is mounted. Within mechanical systems or devices, a conventional gyroscope is a mechanism comprising a rotor journaled to spin about one axis, the journals of the rotor being mounted in an inner gimbal or ring; the inner gimbal is journaled for oscillation in an outer gimbal for a total of two gimbals. The outer gimbal or ring, which is the gyroscope frame, is mounted so as to pivot about an axis in its own plane determined by the support. This outer gimbal possesses one degree of rotational freedom and its axis possesses none. The next inner gimbal is mounted in the gyroscope frame (outer gimbal) so as to pivot about an axis in its own plane that is always perpendicular to the pivotal axis of the gyroscope frame (outer gimbal). This inner gimbal has two degrees of rotational freedom. The axle of the spinning wheel defines the spin axis. The rotor is journaled to spin about an axis, which is always perpendicular to the axis of the inner gimbal. So the rotor possesses three degrees of rotational freedom and its axis possesses two. The wheel responds to a force applied about the input axis by a reaction force about the output axis. The behaviour of a gyroscope can be most easily appreciated by consideration of the front wheel of a bicycle. If the wheel is leaned away from the vertical so that the top of the wheel moves to the left, the forward rim of the wheel also turns to the left. In other words, rotation on one axis of the turning wheel produces rotation of the third axis A gyroscope is a rotating mass that operates on the principle of "Rigidity in Space". What this means is that once the gyroscope is spinning, it tends to remain in its position and resists being moved. A good example is a bicycle wheel. If you were to hold a wheel by its axle and then spin it faster and faster, you would see this. As the wheel begins to spin, it is easy to tilt it back and forth, however as it gets spinning faster, it gets harder and harder to tilt it. This is what "rigidity in space" means. The greater the spinning mass and the closer that mass is located to the spinning axis, the better the gyro will be. Imagine the above illustration as that biclycle tire. Notice that as the gyro spins faster, it becomes harder and harder to deflect the gyro. Once the gyro is spinning, it can be used to show movements around a given axis. The illustration shows how the gyro can be used in an attitude indicator to show pitch and bank. This illustration shows a vertical gyro, not a horizontally aligned gyro as actually used in the attitude indicator. This is merely used to show the similarity between the bicycle tire and the spinning gyro that will serve to steady the attitude indicator. The gyro in the upper right that is paired with the attitude indicator's movements is actually the way the gyro is mounted. It works on the principle of conservation of angular momentum, and consists of a spinning wheel supported on an axis that is free to move on its own. The spinning wheel, or rotor, is mounted on a pivoting support that allows the rotation around a single axis, called a gimbal. By using two gimbals at a time, one mounted inside the other, the gyroscope gives the rotor three degrees of rotational freedom. Gyroscopes have a quality known as 'rigidity in space', meaning that in a 3-D space, they will not move, as long as they have sufficient spinning speed. Buy a gyroscope and spin it very quickly while atop something like a pencil. If you try to push it, it will resist you pushing it and will try to return to it's original orientation. That's rigidity in space. There are 3 basic flight instruments that use gyroscopes: 1. They can be used as a reference to know your attitude, which tells you your angle of bank and your pitch up or down. This is known as the attitude indicator, one of the most important basic flight instrument, because you can be upside-down and not be able to feel it, so you need to know the orientation of the aircraft. 2. They can tell you which direction you are facing, basically replicating a compass. This is known as the heading indicator. Although all airplanes have a compass, a compass tends to have errors under certain conditions while turning or accelerating, so a heading indicator is used for this purpose. 3. They can also tell you how quickly you're turning. This is part of the instrument known as the turn coordinator. I do not know the relative importance of this instrument other than telling you when you're turning 2 degrees per second for a standard rate turn A gyroscope in an airplane is firstly a gyroscope, so it works by maintaining its orientation in space. The instruments in an airplane that use a gyroscope are the altitude indicator, the heading indicator and the turn coordinator. The altitude indicator and heading indicator's gyroscope runs when the vacuum pump on the airplane sucks air in and over the blades to cause the gyroscope to spin. When the gyro spins rapidly (up to 18000rpm) it aligns itself upright and the airplane's instrument aligns itself. A freely rotating disk, called a rotor, was mounted on a spinning axis in the center of a larger, stable wheel. A device consisting of a wheel or disk mounted so that it can spin rapidly about an axis that is itself free to alter in direction. The orientation of the axis is not affected by tilting of the mounting; so gyroscopes can be used to provide stability or maintain a reference direction in navigation systems, automatic pilots, and stabilizers