13 Gyro Basics

Question 1

What does it mean when a Gyro is said to be:

• Horizontally Tide
• Vertically Tide

Answer 1

• Horizontally Tide means the axis of rotation is in the horizontal plane
• Vertically Tide means the axis of rotation is in the vertical plane

Question 2

Describe the two basic properties of a Gyro

Answer 2

• Rigidity: Resistance to a change of orientation

- Procession: A force applied to a gyro will ‘act’ 90 degrees in the direction of rotation

Question 3

Describe a Space Gyro

Answer 3

• Supported such that it can retain orientation regardless of how it is moved
• Two degrees of freedom (i.e. two gimbals)

Question 4

What are the requirements for a Gyro’s Rigidity?

Answer 4

• Dense material (high mass)
• Mass Biased to the outer rim
• High RPM

Question 5

What are the factors effecting a Gyro’s Rigidity?

Answer 5

• Amount of mass
• RPM
• Distribution of mass
• The radius of rotation

Question 6

What is Gimbal Lock and what causes it?

Answer 6

• Where gimbals become stuck, usually where two gimbals become aligned
• Caused by Extreme Manoeuvres

Question 7

Describe a displacement Gyro

Answer 7

• Displacement gyro has 2 degrees of freedom

- Used as a datum from which to measure angular displacement

Question 8

What are the two directions of Gyro Wander?

Answer 8

• Topple: motion in the vertical plane

- Drift: motion in the horizontal plane

Question 9

What are the two main types of Gyro Wander?

Answer 9

• Apparent Wander: ‘imaginary’ movement of the gyro caused by the rotation of the Earth and/or flying from A to B
• Real Wander: actual movement of the gyro caused by mechanical imperfections or by intentional means

Question 10

What are the two types of Gyroscopic Apparent Wander?

Answer 10

• Transport Wander (TW): movement caused by moving the AC from point A to point B
• Earth Rotation (ER): movement caused by the rotation of the Earth

Question 11

For a Vertically Tide Gyro what can be said about Topple and Drift at the:

• Equator
• Poles

Answer 11

• Equator: Maximum Topple, Zero Drift

- Poles: Zero Drift, Zero Topple

Question 12

For a Horizontally Tide Gyro what can be said about Topple and Drift for:

• An East aligned gyro at the Equator
• An East aligned gyro at the Pole
• A North aligned gyro at the Equator

Answer 12

• East aligned at Equator: Max Topple, Zero Drift
• North aligned at Equator: No Topple, No Drift
• North aligned at Poles: Max Drift, Zero Topple

Question 13

What are the two types of Gyroscopic Real Wander?

Answer 13

• Random Wander: caused by mechanical imperfections

- Latitude Compensation: Intentional wander introduced to compensate for latitude changes

Question 14

Describe the different powers sources which can power a Gyro

Answer 14

• Pneumatic Power source: Jet of air blown onto the edge of the rotor causing the spin
• Electric Power source: Spin is generated through the use of a DC motor

Question 15

What is rate of the Earth’s rotation?

Answer 15

15.04 degrees per hour

Question 16

Describe a Rate Gyro

Answer 16

• A gyro which has one degree of freedom

- Provides a datum from which the rate of change can be measured