Pooleys BC-1 for Balloonists

The BC-1 is a comprehensive instrument designed for use with 1:250,000 Topographical and 1:50.000 Ordinance Survey Charts. Measuring 205mm x 155mm in clear plastic with an opaque circular scale. Enables easy transportation of Aeronautical Information onto Ordinance Survey Charts. The calculation of average and actual Balloon Ground Speed, plus conversion of temperatures and heights are all easily achieved.
The BC-1 incorporates a protractor, roamers, scales, balloon loading chart with lift calculator for standard balloon sizes circular cut outs and facilities for drawing various larger commonly used circles. Civil and Military Traffic Zones (including Stubs) are easily positioned and marked onto 1:50.000 Scale Ordinance Survey Charts.