The SD2 submunition was an 8-centimetre (3.1 in) long cylinder of cast iron, which was slightly smaller in diameter before its wings deployed. A steel cable 15 cm long was attached via a spindle to an aluminium fuze screwed into the fuze pocket in the side of the bomblet. The outer shell was hinged and would flip open as two half-cylinders when it was dropped. Additionally, spring-loaded wings at the ends would flip out. The wings at the end were canted at an angle to the airflow, which turned the spindle (connected to the fuze) anti-clockwise as the bomblet fell. After the spindle had revolved approximately 10 times (partially unscrewing itself from the bomb) it released a spring-loaded pin inside the fuze, which fully armed the SD2 bomb. The wings and arming spindle remained attached to the bomb after the fuze had armed itself, as the bomb descended towards the ground. Butterfly bombs contained 225 grams of TNT. They were generally lethal to anyone within a radius of 10 metres (33 ft) and could inflict serious shrapnel injuries (e.g. penetrating eye wounds) as far away as 100 metres (330 ft). Butterfly bombs were usually painted dark green. A dull yellow colour scheme was sometimes used, either for use in the middle east, or when dropped on grain crops at harvest time to kill farm-workers. ~ Wiki

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