Directional Gyroscope: Basics and Working Principles

This page covers the basics of a directional gyroscope, often simply called a directional gyro. It explains how a directional gyro works and also mentions some vendors who supply them.

The directional gyro is used to determine the direction of an aircraft, helping the pilot navigate and fly safely. It’s also commonly known as a heading indicator.

Directional Gyroscope

It might look like a compass, but it doesn’t rely on the Earth’s magnetic field. This makes it more accurate compared to a traditional compass. Figure 1, shown above, depicts a directional gyro.

Here are some key uses of a directional gyro:

• It displays the aircraft’s heading.
• It uses information from a magnetic compass.
• The pilot sets the magnetic compass heading into the directional gyro.

How Directional Gyro Works

Directional Gyro Inside

Here’s a breakdown of how a directional gyro operates:

• The Directional Gyroscope (DG) creates “rigidity in space.” This provides a stable heading reference.
• Bearing friction will cause the directional gyro to precess (drift).
• This precession leads to heading errors over time.
• An adjustment knob allows the pilot to reset the DG to the magnetic compass heading.
• A pneumatic vacuum pump creates a vacuum downstream from the DG gyro. This vacuum pulls air past the DG gyro vanes, spinning the gyro.
• The pneumatic vacuum pump is connected to the engine crankshaft, which turns it. This, in turn, creates the necessary vacuum.

Vendors of Directional Gyro or Directional Gyroscope

Here are some vendors that supply directional gyros:

• barnstormers.com
• Mid-Continent Instrument Co., Inc.
• Satair Group
• ALPINE AVIATION, CA
• Sigma Tek