[thedoc (OP)]

Björn Fahller asked the Naked Scientists:
   
In 2001 I got my flight certificate as private pilot. One thing that's bugged me since then, and has never been satisfactorily answered by instructors, regards gyroscopes.

Most airplanes have two major gyroscopic instruments. An artificial horizon helping you know what's up and down when in clouds, and a directional gyro that bounces less than a compass.

Pretty much through the 20th century those where mechanical gyroscopes.

Disregarding mechanical imperfections the directional gyro drifts with the earth's rotation meaning no drift at all by the equator and 15°/h at the poles.

The explanation is that the gyro points to the same location in space while the earth rotates.

But... Why does the artificial horizon gyro not make a slow roll through 24 hours, but instead continues to point to the earth's centre?

What do you think?

[syhprum]

Proper gyroscopes with frictionless bearings do not be behave same way by precessing that toy ones do