Summary
Highlights
The video introduces the gyroscopic system, which is fundamental to flight instruments like the attitude indicator, heading indicator, and turn coordinator. Unlike instruments using air pressure, these rely on gyroscopic principles.
A gyroscope is defined as any symmetrical body rotating at a speed sufficient to exhibit gyroscopic effects. It consists of a high-speed rotor, a spin axis, one or more gimbals, and a supporting frame. This design allows for freedom of movement across three axes.
One key effect of a spinning gyroscope is rigidity in space, meaning its plane of rotation remains fixed regardless of the movement of its gimbals or frame. This rigidity is directly proportional to its rotational speed (RPM) and moment of inertia (mass and effective radius of the rotor).
The second gyroscopic effect is precession. This states that any perpendicular force applied to a rotating gyro's plane of rotation will be felt 90 degrees in the direction of rotation. The magnitude of precession is directly proportional to the applied force and inversely proportional to the rotational speed.
Gyroscopes are classified into displacement gyros and rate gyros. Displacement gyros include free gyros (or space gyros) with three degrees of freedom, mainly found in older inertial reference systems. Tied gyros, like those in heading indicators, incorporate a control system to maintain a specific axis orientation. Earth gyros, a variant of tied gyros found in attitude indicators, use Earth's gravity to maintain their axis perpendicular to the horizon.
Rate gyros have only two degrees of freedom. When they attempt to rotate in the constrained plane, the gyroscope precesses, and this precession can be measured to determine the rate of angular variation. The turn coordinator uses a rate gyro to measure the rate of turn.
Gyros in aviation can be driven by electricity (typically direct current) or air (vacuum suction or positive air pressure). In light aircraft, the attitude and heading indicators are often air-driven, while the turn coordinator is electrically driven. This separation ensures that a single system failure doesn't disable all gyroscopic instruments.
Beyond basic flight instruments, gyros are used in more complex modern aircraft systems such as gyromagnetic compasses, inertial navigation and reference systems, yaw dampers, and autopilots.