Large heavy plastic USAF navigation computer, 8" dia. Basic Type R-1 computer (speed, range, time, drift) with two thin plastic overlays titled:"B II Celestial Computer/Designed by Maj. P.H. Barber - 376th Bomb Wing" The R-1 has a contract serial number AF-52-5771. The 376th Bomb Wing flew B-29s, B-47E, and ED-47L while active from 1951 to 1965 as part of our Strategic Defense Forces. Likely this was used on B-47s during this Cold War period. About Good+, light soiling and marks from use.