Luftwaffe 'DR 2' 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. 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 October 1939. Nice original example in good used condition!