I will have my instrument stage check soon, and I will have to be able to explain every instrument as far as to how it functions.
A question I have that nobody has been able to explain to me well is why the directional gyro (heading indicator, if you prefer) needs to have a double gimbal? AFAIK, the gyro only needs to sense yaw, so I don't really get why the need for the other gimbal. I have acces to decomissioned and opened instruments at school to see the internal working if that helps.
BTW, I'm talking for a vacuum driven heading indicator, found in late model C172s.
Thanks for answering