Avionics and instruments: Difference between revisions

The artificial horizon, also known as the attitude indicator, simulates the position of the horizon relative to the plane. The top half of the background of the artificial horizon is blue and represents the sky. The bottom half is brown, and represents the ground. This background moves as the plane pitches forward and backward, and rolls left and right. In the center of the attitude indicator is a small dot, representing the position of the nose of the plane. To the side of this dot are lines representing the position of the wings. These parts of the attitude indicator do not move, so, when the plane pitches backward 10 degrees, the blue background shifts down 10 degrees. Most attitude indicators have major lines for every ten degrees of pitch, drawn across the center of the background. At the top or bottom of the attitude indicator is an arrow pointing out. This arrow points to corresponding markings on a ring on the attitude indicator. This ring does not move with the pitch of the plane, it only moves as the plane rolls left to right. On this ring are generally markings for 10 degrees of roll, 20 degrees, 30 degrees and 60 degrees. It is important to note that the artificial horizon indicates the orientation of the plane, and not the direction of travel. During slow flight, most planes have a high angle of attack, meaning that for straight and level flight, the nose is raised above the horizon. In this case, the attitude indicator would show the nose above the horizon (in the blue) but the airplane would be going straight and level. The artificial horizon is normally controlled by a gyro which is driven by a vacuum generated by the engine. It is possible that this vacuum can fail, especially if there is an engine failure. For this reason, the turn and bank coordinator is generally powered by an electrical generator and can be used as a backup instrument.

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