In rec.aviation.piloting Mxsmanic wrote:
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.
You are talking about a gyro compass.
A gyro compass is huge, expensive and heavy.
They can take hours to settle on a usable reading.
They don't work if they are moving much faster than a slow ship, and not
at all at aircraft speeds.
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.
Wrap some smarts around it with a built in map and it shows you where
you are.
Since real gyros in the real world precess, you have to update the
calculated position to the true position on a regular basis.
You have no idea what you are talking about.
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.
Theoretically you could do that, but no such thing is available for GA
aircraft.
INS is too big and expensive for GA aircraft.
That's one reason why I often like to fly big aircraft.
You don't fly anything, ever.
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.
You don't fly anything. You sit on your ass and watch a computer monitor.
Lots of real airplanes don't have electrical systems.
--
Jim Pennino
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