Luftwaffe 'DR 3 Tp' Flight Navigation Computer (Dreieckrechner). The Luftwaffe used two different models of manual flight navigation computers which were basically circular slide rulers to assist in navigation calculations. This is the 'DR3 Tp' type which is having a hole in the center so it could be used as a protractor (Transporteur in German) as well. The flight navigation computer is having a diameter of 15cms and the computer is nicely maker marked by the company 'Dennert & Pape' in Hamburg-Altona and dated Juli 1943. Rare original 'DR 3 Tp' example in very good condition!