Chapter 13 - Remote Indicating Compass

Question 1

What is the principle of operation of a Remote Indicating Compass?

Answer 1

Combines the short term accuracy of the gyro combined with the long term accuracy of the magnetic compass, so providing a stable and accurate heading reference.

Question 2

What can a remote indicating compass also be known as?

Answer 2

Magnetic Heading Reference System

Remote Indicating Compass

The Gyro-magnetic Compass

Slaved Gyro Compass

Question 3

What is the detector unit of the remote indicating compass?

Answer 3

The Detector Unit or Flux Valve detects the Earth’s magnetic field, that magnetic information is sent to the Error Detector.

Question 4

What is the principle of operation of a remote indicating compass?

Answer 4

Detector unit - error detector - if error detected torque motor precesses the gyro - when zero error exists, the system is said to be synchronized

Question 5

What is the task of the flux valve?

Answer 5

To monitor the horizontal component of the Earths magnetic field (H)

Question 6

Why is the flux valve (detector unit) located in the wing tip or top of the fin?

Answer 6

ensure that it is as far as possible from sources of deviation. (keeps deviation to a minimum)

Wing tip is the preferred option as it is easier to access for servicing.

Question 7

What is Selsyn?

Answer 7

Error detector

Question 8

What is the Gyro Heading Indicator?

Answer 8

Provide a stable directional reference in straight and level flight, and during turns.

Question 9

What is the signal path of a RIC?

Answer 9

F - FLUX VALVE
E - ERROR DETECTOR
A - AMPLIFIER
T - TORQUE MOTOR

Question 10

What is slaved mode?

Answer 10

SLAVED: Normal mode, gyro synchronised by magnetic feed from flux valve

Question 11

What is Free mode?

Answer 11

FREE: Acts like normal DG – used if flux valve in doubt or high latitudes

Question 12

What does the annunciator do?

Answer 12

1. Shows the compass is synchronising the gyro
2. Indicates which way the pilot needs to synchronise for manual initial alignment

Question 13

What are the advantages of an RIC over a DRC?

Answer 13

• Reduced deviation
• Reduced turning & acceleration errors as flux valve is fixed to the aircraft’s axis so stopping rotation due to acceleration.
• Improved presentation (full compass rose)
• Power output of HDG can be fed to EFIS, Autopilot, Flight Director etc.

Question 14

What are the dis-advantages of the RIC over a DRC?

Answer 14

• Needs electrical power
• Heavy & expensive
• Complex to maintain
• Suffers from acceleration, turning & deviation errors, just like the DRC but to a lesser degree.