This document discusses gyroscopic instruments and their principles of operation. It explains that a gyroscope will maintain its orientation in space due to its high-speed rotation and angular momentum. It can rotate about perpendicular axes, with any change in its axis of rotation called precession. It describes different types of gyroscopes like attitude gyros and rate gyros, and errors they may experience like drift, wander, gimbal lock, and gimbal error. It also briefly discusses directional gyros, gyro horizons, and fuel quantity indication systems using sight glasses, mechanical floats, electrical resistance transmitters, and electronic capacitance sensors.

1. GYROSCOPIC INSTRUMENTS

2. Gyro Theory
• Symmetrical rotor
• High speed rotation
• Free to rotate about one or more perpendicular axis

3. Rigidity
• Gyro will remain in the same posn in space regardless of the way the
mount is turned
• Constant velocity and constant angular momentum
• Law of conservation of momentum
• First Law of Gyro Dynamics
• Attitude gyros

4. Precession
• Change in orientation of the rotational axis of a rotating body
• Rate gyros

5. • Wander
• Mov of momentum axis away from ref frame
• Real wander (Real Drift)
• Imperfections in gyros
• Better engineering
• Apparent wander (Apparent Drift)
• Earth rotation and mov of veh
• Dir updated periodically
• 15 deg/hr
• Drift
• Mov of spin axis in horizontal plane
• Topple
• Mov of spin axis in vertical plane

6. • Gimbal Lock
• Spin axis becomes coincident with axis of freedom
• Gyro loses one of its DoF
• Also called toppling
• Gimbal Error
• Steep turns, pitching & rolling
• Changing relationships b/w two gimbal result in indication error or drift

7. Attitude Gyros
• Directional Gyro
• Gyro frame vertical to ac
• Circular ring with 360 deg
• Gyro Horizon
• Frame along longitudinal axis

9. Fuel Qty Indication System
• Sight Glass
• Direct reading gauges
• Mechanical type
• Float on surface of fuel
• Gauge usually on the tank
• Electrical (Resistance)
• Transmitter and indicator
• Warning mechanism
• Electronic (Capacitance)
• No moving parts
• Servo motor in indicator
• More reliable