Development of Avionics Infotainment System
Directional Gyro
The Directional Gyro, also known as a Heading Indicator is usually driven by vacuum. It looks like a compass but the difference between them is that the Directional Gyro doesn’t depend on the earth’s magnetic field to operate. When the gyroscope is spinning it has a principle of remaining rigid in space, the spinning wheel will resist any change in position. When an airplane is turning the gyroscope will resist moving together with the turn, the energy used to resist the turn will move the compass card which will indicate the heading of the airplane. There is no magnetic sensing element therefore; the pilot needs to synchronize it with the magnetic compass.
Principle Of Directional Gyro
It is a horizontal axis gyro. The outer gimbal (vertical ring) can rotate 360º about the inner gimbal. During a turn, the aircraft and the instrument casing turns the vertical axis bearing the outer gimbal, while the gyro rotor, inner gimbal and compass card remains fixed due to rigidity. The caging knob will lock the inner gimbal in the right axis and rotates gyro to synchronise with the magnetic heading. Latitude adjustment nut corrects for apparent drift by producing equal opposite precession force.
Errors In Directional Gyro
Errors such as real and apparent drifts, transport wanders, gimballing errors and unstable rotor RPM can occur. Gimballing error occurs when the aircraft is banking due to the movement of the outer gimbal against the stabilized inner gimbal during a large banking turn, these errors can cause erratic rotation of the compass card even in a steady turn. Unstable RPM affects the precession rate and causes the latitude nut to either over or under correct.