AC Electric Gyros and Rotating Magnetic Fields

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Questions and Answers

What is the typical voltage and frequency used in an AC electric gyro?

115-V, 400-Hz (correct)

115-V, 60-Hz

230-V, 50-Hz

230-V, 60-Hz

What is the purpose of the current induced in the rotor bars in an AC electric gyro?

To interact with the stator's rotating field and cause the rotor to turn (correct)

To switch the power supply off

To generate a rotating magnetic field

To erect the gyro

How is the failure of the power supply indicated in an AC electric gyro?

By a flashing light

By a shutdown of the torque motors

By a flag marked 'off' and actuated by a solenoid (correct)

By a warning buzzer

What is an advantage of DC gyro systems?

Rugged, light-weight instrument Signup and view all the answers

What is the typical speed range of the rotor in an AC electric gyro?

20 000–23 000 rpm Signup and view all the answers

What is the purpose of regularly caging and resetting the directional gyroscope during flight?

To ensure correct alignment with the compass heading Signup and view all the answers

Approximately how many rpm does an air-driven directional gyroscope spin?

12 000 to 15 000 Signup and view all the answers

What is the function of the torque generated by the rotor exhaust air in the directional gyroscope?

To maintain the inner gimbal erect Signup and view all the answers

What is indicated by the compass card in the directional gyroscope?

Aircraft heading Signup and view all the answers

What is the name of the indicator that provides a more intuitive presentation of the aircraft heading?

Horizontal situation indicator Signup and view all the answers

What is the purpose of the lubber line in the directional gyroscope?

To indicate the direction of the aircraft nose Signup and view all the answers

What is the purpose of the erection system in an artificial horizon?

To re-align the gyro with respect to gravity Signup and view all the answers

What is the main function of an artificial horizon in an aircraft?

To indicate the aircraft's pitch and roll attitude Signup and view all the answers

Why is the gyro spin axis maintained in a vertical position or horizontal plane of rotation?

To provide a reference point for the aircraft's movement Signup and view all the answers

What is the purpose of electrical or dynamic braking in electrically driven gyros?

To slow the gyro rotor very quickly once power is removed Signup and view all the answers

What is the reference point used to measure the movement of an aircraft in an artificial horizon?

The gyro rotor Signup and view all the answers

What is the purpose of the gimbals in an artificial horizon?

To measure the movement of the aircraft around the gyro Signup and view all the answers

What is the primary function of the rate gyro in a turn-and-slip indicator?

To detect the rate of turn Signup and view all the answers

What type of aircraft is the turn component of the indicator still commonly used in?

Light aircraft Signup and view all the answers

What is the primary component of the slip indicator in a turn-and-slip indicator?

A ball in a curved liquid-filled tube Signup and view all the answers

What is the purpose of the pointer in a rate gyro?

To align with a zero rate turn mark on the dial Signup and view all the answers

What is the purpose of the caging button on a vacuum direction gyro?

To lock the two gimbals together and align the needle with the compass heading Signup and view all the answers

What is the axis of spin of the gyro rotor in a rate gyro?

Lateral axis of the aircraft Signup and view all the answers

How does the readout on a heading indicator differ from that of a direction gyro?

The heading indicator shows the correct direction of turn Signup and view all the answers

What is the typical location of the slip indicator in modern aircraft?

Incorporated into the attitude director indicator Signup and view all the answers

On a direction gyro, what is the direction of 330° relative to north?

To the right of north Signup and view all the answers

What is the benefit of the heading indicator compared to the direction gyro?

It removes the confusion from the display Signup and view all the answers

What is the result of caging the direction gyro?

The two gimbals are locked together Signup and view all the answers

What is the horizontal spin axis directional gyro remotely mounted from?

The Horizontal Situation Indicator (HSI) Signup and view all the answers

Study Notes

AC Electric Gyro Specifications

Typical voltage for AC electric gyros is generally 115 volts.
Common frequency used is 400 Hz.
Rotor spins at approximately 5,000 to 20,000 RPM.

Induction and Failure Indicators

Current induced in rotor bars creates a magnetic field, contributing to gyroscopic stability and accuracy.
Power supply failure is indicated by a decrease or loss of signal to the gyro, often accompanied by warning lights or alarms.

Advantages and Functions of Gyros

DC gyro systems offer simpler construction and less sensitivity to ambient conditions compared to AC systems.
Regular caging and resetting of the directional gyroscope during flight ensures accurate alignment and prevents drift.

Directional Gyro Characteristics

Air-driven directional gyroscopes typically spin at about 15,000 RPM.
Torque from rotor exhaust air provides stabilization and helps maintain accurate orientation.

Compass and Indicators

The compass card in a directional gyroscope indicates the aircraft’s heading.
A heading indicator provides a more intuitive presentation of the aircraft's orientation compared to a traditional direction gyro.

Erection Systems and Functionality

The lubber line in a directional gyroscope serves as a reference for pilots to align the aircraft's heading with the indicated direction.
The erection system in an artificial horizon maintains correct positioning of the gyro during flight.
The artificial horizon's main function is to provide pilots with visual orientation relative to the earth's surface.

Gyro Orientation and Braking

Maintaining the gyro spin axis in a vertical orientation or horizontal plane ensures accurate readings of pitch and bank angles.
Electrical or dynamic braking in electrically driven gyros allows for controlled stopping or speed adjustments.

Movement Measurement and Gimbals

Movement in an artificial horizon is measured relative to the horizon line, aiding pilot navigation.
Gimbals provide the structural support allowing free movement of the gyro, minimizing the effect of aircraft movements.

Rate Gyro and Turn Indicators

The primary function of a rate gyro in a turn-and-slip indicator is to detect angular velocity and assist in understanding the turn rate.
The turn component of the indicator remains relevant in general aviation aircraft for maneuverability assessment.
The primary component of the slip indicator is a ball that reflects the aircraft's coordination during a turn.

Caging Buttons and Axis of Spin

The pointer in a rate gyro indicates the rate of turn, assisting in understanding horizontal flight dynamics.
The caging button on a vacuum direction gyro allows for temporary deactivation of the gyro for adjustments or resets.
The axis of spin in a rate gyro is perpendicular to the plane of rotation, essential for accurate readings.

Heading Indicators vs. Direction Gyros

Readout on a heading indicator remains continuous and typically calibrated in degrees, whereas a direction gyro may require manual adjustments.
The slip indicator is usually located on the instrument panel in modern aircraft to assist pilots in maintaining coordinated flight.
A direction of 330° on a direction gyro indicates the aircraft is heading northwest relative to north.

Benefits and Results of Caging

The heading indicator provides immediate context and ease of understanding compared to a direction gyro’s numeric display.
Caging the direction gyro re-aligns it to magnetic north, preventing drift and ensuring accurate orientation.
The horizontal spin axis directional gyro may be remotely mounted from the cockpit but still provides critical flight data.

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Description

This quiz covers the basics of AC electric gyros, including their power supply, stator and rotor operation, and the principles of rotating magnetic fields. Test your knowledge of these fundamental concepts and see how well you understand the inner workings of AC electric gyros.