Flux Gate Gyro Master Compass Indicator, AN5752-2, WWII B-17, B-24, B-29
The Master Compass Indicator AN5752-2 was an integral component of the WWII era Bendix Gyro Flux Gate Compass System used in aircraft such as the B-17, B-24, and B-29. The 7-component Flux Gate Compass system was designed to provide accurate navigational guidance using the earth's magnetic forces by minimizing interference from the systems of the aircraft, such as its turrets, guns, and engines. A flux gate gyro transmitter typically located within the wing would send signals to the Master Compass Indicator normally located in the navigator's compartment, which in turn would transmit these signals to smaller repeater indicators located at other positions such as the pilots instrument panel. See photos in the gallery describing the system in greater detail.
The knob at the top of the indicator is actually a hex key used to adjust deviations in readings on the Master Compass. Once turned and removed, the perimeter face plate is removed, revealing set screws around the face. These set screws may then be used to correct the reading of the indicator. The knob at the bottom is used to adjust variation, but is frozen in position in this specimen and may be able to be repaired. The interior of the glass requires cleaning. The housing looks to have been repainted at some point in its history. The serial number prefix, "AF-42", indicates 1942 year of manufacture for an order from the Air Force US Army. It is in decent condition given its age. Measures 6 inches diameter by ~8 inches deep.