On Sun, 5 Oct 2008 21:05:32 +0000 (UTC), Bertie the Bunyip
wrote:

Tman x@x wrote in :

OK, I get that the thing has a gyro in it which remains rigid as the
airplane banks and pitches around it. But how does it get "reset" to
the correct orientation?

Is it dependent upon gravity to orient it when it spools up, and the
plane is on the ground?

Conversation started when I was talking to a pilot on a dual-vacuum pump
powered 172. One vac pump is shot, and it did not build up sufficient
vacuum to spool up the gyros until airborne.

Well he was VFR only, but still...


Yeah, it references to gravity and averages it al out. If you maintain a
gentle turn for a long long time it will eventually settle on the bank you
maintain as being level flight.. That's acomplished by a couple of little
doors hung around the enge of the wheel in the gyro that are arranged so
that when the gyro isn;t aligned the doors open and a little puff of air
comes out and applies a precessional force to right the gyro. Since nobody
flies in circles all the time it pretty much averages itself out.
Electric ones have a simlar electronic pendulum.

Bertie
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I've flown vacuum gyros that if they had not erected by time for take
off you could pull a knob on instrument and manually erect the gyro.

Bertie may have time and place of those gyros?

Haven't see one for years.

Big John