14 The Directional Gyro (DG) Flashcards
1
Q
What is the principle of operation of the Directional Gyro?
A
- Gyro is horizontally Tide
- 2 degrees of freedom (i.e. 2 gimbals)
- Displacement gyro
- Allow free movement in pitch and roll
- Provides a datum against which changes in Yaw can be measured
- Uses the principle of Rigidity
2
Q
What are the alternative names for a Directional Gyro?
A
- Directional Gyro Indicator (DGI)
- Direction Indicator (DI)
3
Q
What form of accuracy does a DG provide?
A
Short Term accuracy
4
Q
For a DG, describe what is used to apply:
- Coarse Erection of the gyro
- Fine Erection of the gyro
A
- Coarse Erection is applied via an Air Jet
- Fine Erection is applied via a Wedge Plate
- Both of which employ the principle of precession
5
Q
What is the equation for the Total Drift experienced by a DG?
A
Total Drift = ER + TD + RD + LN
- ER: Earth Rotation
- TD: Transport Drift
- RD: Random Drift
- LN: Latitude Nut
6
Q
What is the value of the Earth Rate at each pole?
A
- North Pole: -15.04 degrees per hour
- South Pole: 15.04 degrees per hour
7
Q
What is the equation for the Earth Rotation for each hemisphere?
A
North:
- Earth Rotation = -15.04 x Sin(Lat)
South:
- Earth Rotation = 15.04 x Sin(Lat)
8
Q
What is the purpose of the Latitude Nut and how does it work?
A
- The counters the Earth Rotation drift
- Uses the principle of precession
9
Q
What provides vertical erection of an electric Directional Gyro?
A
Torque motor
