Compass, Aperiodic, US Military Aircraft, Pioneer 1811-1-D C-45 The design of the mounts

The design of the mounts of aircraft instruments evolved during early WWII from the dog-ear-style as seen on this instrument to a more robust integral design that was less vulnerable to breaking on a hard landing

Complete face with controls is 5 1/2" rectangular and 15" deep

but could probably be recalibrated with the compensator screws

5 inch deep

indicates the manufacturing year 1944

Compass, Aperiodic, US Military Aircraft, Pioneer 1811-1-D C-45 The design of the mountsThis appears to be a post WWII Direct Reading Aperiodic Compass used at the navigators station in US military aircraft. Made by Bendix, part number 1811 1 D. It appears to have never been put into service judging from its superb condition. An aperiodic compass, after being deflected, returns by one direct movement to its proper reading, without oscillation. It is similar to a WWII era D 12 compass, which was typically mounted on the navigator's desk.