Original Item: Only One Available. The gyroscopic autopilot was a type of autopilot system developed primarily for aviation uses in the early 20th century. Since then, the principles of this autopilot has been the basis of many different aircraft control systems, both military and civilian.

The U.S. Army Air Corps and the U.S. Navy experimented with autopilots on military aircraft before and during World War II. Straight and level flight had become a necessity for new level bombing techniques that were being developed at the time. The Sperry Gyroscope Company developed many autopilot systems for use on military aircraft. When the Boeing B-17 Flying Fortress was delivered in the late 1930s, it came equipped a commercial Sperry A-3 Autopilot. The A-3 was a simple autopilot and only corrected angular deviations in the aircraft's straight and level course. It utilized pneumatic hydraulic servos, which had a tendency to react slowly to inputs, and this often led to overcompensation of the aircraft's corrected course. This caused navigation and control issues when pilots were flying in poor weather or rough air.

This Bank Climbing Gyro was utilized on the Sperry Mark 4 Autopilot System. This autopilot system was used in versions of the WWII medium bomber B-25 Mitchell, patrol bomber PBY Catalina, fighter P-61 Black Widow, and transports C-46, C-47, and C-45, as well as in multi-engine trainers and others.

The Gyro provided visual cues to the pilot regarding the attitude of the aircraft, i.e., banked port or starboard (and by how many degrees) and diving or climbing. The caging knob at the top right corner would either capture the gyro in a fixed position i.e., caged, when encountering turbulent motion which could tumble the gyro, or release it for use during flight. The gyro is vacuum-powered, receiving its suction from either an engine-powered vacuum pump or externally-mounted power venturi tube.

The center small knob adjusts the center 'airplane' silhouette up/down. This corrects for the height of the seated pilot by aligning his line of sight with the silhouette and the tilting horizon marking behind it while in level flight. Otherwise, a tall pilot might want to climb his aircraft that is actually in level flight, since he would view the silhouette as being positioned below the horizon and think he is in a dive. The left and right knobs are for the Aileron and Elevation.

The condition is good and the gyro appears to be functional, however, we cannot guarantee the functionality of this instrument and it is being sold only as a novelty/display item.

Comes more than ready for further research and display.