"San Shiki" (the Beehive) Model 13 - Japan's Most Unusual Anti-Aircraft Shell
This remarkable anti-aircraft shell was designed to be fired from the 18-inch guns of the super battleship Yammamoto. The idea was pursued as Japanese capital ships could almost never count on friendly air cover and were forced to provide their own defense against allied aircraft. Called "San Shiki" (the Beehive) Model 13 the round weighed 2,998lb (kg) and was filled with 900 incendiary tubes (of rubber thermite) and 600 steel stays. A time fuze was set before firing that went off at a predetermined altitude causing the explosive and metal contents to burst in a cone extending 20 degrees forward, towards the oncoming aircraft. Instantly after detonating, the shell itself was destroyed by a bursting charge, increasing the quantity of steel splinters. The incendiary tubes ignited about half a second later and burned for five seconds at 3000 degrees C, producing a flame about 16ft (m) long.
Although quite impressive the weapon when used was a failure ruining several of the battleship's main guns and barely effecting the swarm of attacking allied aircraft