Electric Attitude Indicator Erection Mechanism


Well-Known Member
Does anyone know how electric attitude indicators erect themselves and correct for precession effects? Vacuum AIs use the pendulous veins, and I think the electric ones use magnetic induction, but can anyone explain how the magnets are arranged and what the field looks like?

A common answer is that they use a simple weight, but that won't work due to precession.
I wonder if Electric AIs work somewhat the same way as HSIs equipped with remote gyros? If so, I'd assume there is someplace on the plane with an actual, physical gyro sending information to the AI. If this is true, then I'm certain the gyro uses pendelous vanes too.

Just a guess.
I think he's refering to a mechanical AI but one that uses electrically powere/spun Gyros as opposed to the more common vacuum driven gyros.

And I have no idea how one of these would deal with precession.
We had one for backup in a 182 that I used to fly. It wasn't self-erecting, you had to do it manually. As far as precession, I don't honestly know. I think that because its electric, its less susceptible to precession since it spins at a higher speed.
The old Instrument Flying Handbook has pictures of an erection mechanism for an electric AI. The gyro is connected to a vertical shaft that spins at the same rate as the gyro. It has a magnet on its top and rotates in a steel sleve, causing the sleve to rotate at about 44-48 rpm. The sleve has a bearing race around the outside and 2 ball bearings roll around on the top. If the gyro tips, then the ball bearings roll to the low side and the precession force they generate cause the gyro to erect. It is alot simpler to look at the picture. Get a copy of the book if you can. The new Instrument Flying Handbook really sucks compared to the old one.
It wasn't self-erecting, you had to do it manually.

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Naw, ain't goin there...

Actually "Electric Attitude Indicator Erection Mechanism" sounds like something you'd buy in a store that has cheezy 70's wa-wa music playing in the background, but I liked your post even better.....