AviationBanter - View Single Post

**Mxsmanic** · April 5th 07, 06:22 AM posted to rec.aviation.student,rec.aviation.piloting

writes:

You are talking about a gyro compass.

No, I'm not.

A gyro compass is huge, expensive and heavy.

But there is none inside an inertial reference platform. An IRS uses laser
gyros.

They can take hours to settle on a usable reading.

An IRS can find true north in a few minutes, depending on latitude.

An INS system has to be initialized with it's current position and just
tells you where you have moved relative to the starting position.

But it also finds true north on its own, without any need for external data.
It simply detects the rotation of the Earth, and that gives it an east-west
reference, to which true north is perpendicular.

You have no idea what you are talking about.

Google for it. You'll be surprised.

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