Butterfly Bomb

A Butterfly Bomb, or (Spreng Dickwändig 2 kg or SD2) was a German 2 kilogram anti-personnel bomb dropped by the German Luftwaffe during the Second World War. It was named because the thin cylindrical metal outer shell hinged open when it was dropped and gave a superficial appearance of a large butterfly.

Before the vanes deployed, the bomb was a cylinder 80 millimetres long and slightly smaller in diameter. A steel cable 150 millimetres long was attached to the fuze screwed into the fuze pocket in the side of the bomb. When it was dropped, the outer shell would hinge open as two half-cylinders and spring-loaded vanes at the ends of them would also flip out. As the bomb fell these rotated the spindle, arming the fuze.

The bomb could be fitted with one of three fuses - the 41 fuse which detonated on impact, the 67 fuse which had a settable time delay of between 5 and 30 minutes, and the 70 fuse which detonated if the bomb was moved. It contained 225 grams of TNT. It was generally lethal to anyone standing unprotected within about 25 metres of it, and could injure people as far away as 150 metres. Defusing ones which had failed to detonate or equipped with the anti-handling fuse, was not practical and they were usually destroyed where they fell.

They were packed into canisters containing between 6 and 108 of the bombs, depending upon the canister type, and were released as the canister fell. These bombs were first used on 28 October 1940 against Grimsby & Cleethorpes - the ONLY towns to be raided in Great Britain, and subsequently used in the Middle East. The British kept secret all the damage and disruption caused by these bombs so as not to encourage Germany to use them elsewhere. The United States manufactured a copy of the bomb for use during the Korean War and Vietnam War, designating it the M83 bomb.

See also Thermos Bomb