WWII Diagram of QF 3.7" anti aircraft shell, with trajectory chart. War Office. [n.d., c. 1940].
27 x 11 inches, tracing paper on backing paper, hand-coloured diagram of QF 3.7" anti-aircraft shell, with 20 x 19 inch printed trajectory chart ("O.C. Diagram No. 72"); a little toning, very good.
A scarce wartime survival. It appears that the diagram has been reproduced from an original on tracing paper, possibly by hand, and then backed; the colouring is certainly by hand. It shows, slightly smaller than life-size, a shell for the British QF 3.7inch AA gun, the country's foremost anti aircraft weapon from 1937 through to the 1950s. As the diagram shows, the shell could be fitted with either high explosives or shrapnel, and would be colour coded accordingly. It could be fitted with a number of timed fuzes. The trajectory chart is calibrated for use with the 199 fuze, which had a running time of 30 seconds and was used before 1942, placing these two diagrams at the beginning of the war.