Artillery Firing Calculator, USSR, 1944 Northrop The B-20 Compass design is

The B-20 Compass design is unique in that it contains a magnetic horizontal float suspended in damping fluid that engages the directional pointer on a vertical compass card to display direction

Two of these indicators appeared on the B-50's engineer's instrument panel (see photo)

or release it for use during flight

This instrument is stamped with a service date of June 1961 while serviced at SMAMA

indicates 1942 year of manufacture for an order from the Air Force US Army

Artillery Firing Calculator, USSR, 1944 Northrop The B-20 Compass design isTrue, this is not aviation in nature, but it is an exceptional artifact from WWII. This is an original Soviet Army Artillery Firing Calculator, used in determining proper elevation and deflection (direction) when operating field artillery weapons. It was carried in the map document case worn by a Soviet artillery officer. The calculator contains diagrams and a graph, with rotating wheels and tabs, and made of material which permits writing in