1 Axis Gyro. This is for rudder.

The 350 AVCS gyros are compact, lightweight and developed for airplanes. Mounted on ailerons, elevators and rudders, it strongly maintains flight attitude. The gyro corrects almost all bad tendencies peculiar to each aircraft which tend to appear during upright, inverted, upward, downward or knife-edge flight. These newest gyros not only enable stable takeoff and landing but also minimize the need for manual control during stunt or acrobatic flights.