Double gimbal describes what?

• A. A single-axis mount used for the gyro in an attitude instrument.
• B. A type of mount used for the gyro in an attitude instrument; the axes of the two gimbals are at right angles to the spin axis of the gyro, allowing free motion in two planes around the gyro.
• C. A support structure that prevents gyro motion.
• D. A solid-state alternative to a gyro.

Answer: (B)

Two-axis freedom in the gyro’s mounting is what this term describes. A double gimbal means the gyro is mounted on two gimbals, with their pivots perpendicular to the gyro’s spin axis. This arrangement lets the gyro tilt in two independent planes around the gyro, typically corresponding to roll and pitch, so the instrument can maintain a stable reference even as the aircraft attitudes change. If there were only a single axis, it could move in only one plane; if the mount prevented motion entirely, the gyro wouldn’t sense attitude changes; and a solid-state gyro isn’t a mechanical gimbal setup at all. So the two-gimbal mounting that allows rotation in two planes around the spin axis is what defines a double gimbal.