AviationBanter - View Single Post

**Mxsmanic** · April 5th 07, 03:23 AM posted to rec.aviation.student,rec.aviation.piloting

writes:

INS has to be initialized from something known and updated because
gyros in the real world precess.

No, not for true north. An INS determines true north by sensing the rotation
of the Earth. It doesn't require any data input to do this.

GPS can tell you which direction you are going, but can not tell you
where the nose of the airplane is pointing.

If you are moving, it can tell you your ground track. If you have more than
one receiver on different parts of the aircraft, you can also determine which
way the nose is pointing.

INS is too big and expensive for GA aircraft.

That's one reason why I often like to fly big aircraft.

Not all real airplanes have electrical systems.

True, and some are powered by rubber bands as well, but there's a lower
threshold below which I don't bother.

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