Tank indirect fire calculator army slide rule 1950 Netherlands

This is an early Dutch language indirect fire (no line of sight) calculating device made just after Worldwar II. It helps calculating shots in the range of 2000 – 8000 yards (or 1.8 – 7,3 KM). This is about the firing range of early tanks. After the Second World War in 1953, The Netherlands purchased close to 600 British Centurion tanks. The calculating slide rule (or in Dutch “Rekenplank” is all in the Dutch language and is double sided (not in Englands, but it uses yards instead of the Dutch KM).

A thick white plastic base with metal (brass) enforced edges and a brass nut on both sides. The nut is used to maneuver and turn the 2 thick perspex discs on both sides (5 layer in total). Producing this would only make sense if enough were to be used. No makers mark but it has probably been made by Alro from The Hague which also produced the “Military Rekenschijf” for the Dutch army in the same period. Many of the commission calculator Alro made are not signed with their company name, yet this calculator is not feature in the 2020 Alro Book. This one is large and measures 45 cm or 18 inches tall. It is completly working and in good condition with some signs of use and age (no case, short manual on the rule itself).