Directional Gyro Indicator

he DGI utilizes a Tied Gyro that uses a Horizontal Axis Gyro.

It suffers from following Errors-

In Northern Hemisphere headings decrease as follows-

East direction – DGI shows higher decrease in heading than the Earth movement.
West direction – DGI shows lower decrease in heading than the Earth movement.
North direction – DGI shows higher decrease in heading than the Earth movement.
South direction – DGI shows lower decrease in heading than the Earth movement.

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In Southern Hemisphere headings increase as follows-

East direction – DGI shows higher increase in heading than the Earth movement.

West direction – DGI shows lower increase in heading than the Earth movement.

North direction – DGI shows lower increase in heading than the Earth movement.

South direction – DGI shows higher increase in heading than the Earth movement.

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D.G.I.

It utilizes a Tied Gyro, which is a Horizontal Axis gyro.

Rotor movement is restricted to 1100 that is 550 either side of the rotor’s vertical plane, limiting the A/c’s maneuver in pitch and roll.

Rotor rpm is 12,000 rpm.

An instrument in good condition should not process more than 40 every 15 minutes.

  • Real wander occurs due to friction static, unbalance and air turbulence.
  • Apparent wander

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In Northern Hemisphere

              A/c flying towards East-  Readings decrease higher.

              A/c flying towards West- Readings decrease lower.

              A/c flying towards North-Readings decrease higher.

              A/c flying towards South-Readings decrease lower.

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In Southern Hemisphere

              A/c flying towards East-  Readings increase higher.

              A/c flying towards West- Readings increase lower.

              A/c flying towards North-Readings increase lower.

              A/c flying towards South-Readings increase higher.

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Compensation for apparent wander is done by a Latitude Nut.

In the S/H Latitude Nut is screwed outward to compensate for the Drift.

Gimbal error occurs when a/c is banked in a climb or descent, it disappear as soon as straight and level flight is resumed.