Nestler Flugzeit 55 cm 22″ military airplane slide rule 1940 Germany

This is a seldom seen slide rule used for pilots and army purposes. It is meant for reconnaissance purposes determining airplane speed and or the time it will take to get closer or further from a target. It has beens made extra long to give the user more information and better change to make accurate calculations over large distances. It comes in the original very though black cardboard case that is still complete but has clear signs of storage. I am guestimating this rare rule is from ca. 1940. Everything is complete, no cracks, chips or dings and in working condition with noticeable signs of use and age, mostly wear. This rule has a wooden base and a unique flat pyramid like shape. It measures 55 cm or 22 inches wide. Check the attached video on how to work your vintage man tool : slide rule operation instructions!