was a form of ammunition: a World War II-era combined shrapnel and incendiary anti-aircraft round used by the Imperial Japanese Navy. The type of layered construction of the warheads were generically referred to as Beehive rounds. The shells were intended to put up a barrage of flame through which any aircraft attempting to attack would have to navigate. However, U.S. pilots considered these shells to be more of a pyrotechnics display than an effective anti-aircraft weapon. The Sanshiki anti-aircraft shell was designed for several gun calibers, including the 46 cm (18.1-inch) guns of the Yamato-class battleships. Specifications 46 cm (18.1 in) The 46 cm (18.1 in) Sanshiki Model 13 round weighed 1,360 kg (2,998 lb) and was filled with 900 incendiary tubes and 600 steel stays. The round was equipped with a delay fuze set before firing that detonated the shell at the set altitude; on explosion, the steel stays and the incendiary tubes were ejected in a 20-degree cone forward, with the shell fragments from the explosion itself further increasing the amount of debris. The incendiary tubes ignited about a half-second later and burned for five seconds with long flames. Each of the incendiary tubes was a long, diameter hollow steel cylinder, filled with rubber thermite (phosphorus, vulcanized rubber, natural rubber, stearic acid, sulphur and barium nitrate) and ignited through holes on both sides. The rounds were similar to conventional shells, except for their wood-filled ogive and several layers of assembled fragments. 41 cm (16.1 in) The 41 cm (16.1 in) round contained 1,200 incendiary tubes and on explosion burst into 2,527 fragments. By contrast a 46 cm round burst into 2,846 fragments. 20.3 cm (8 in) The 20.3 cm (8 in) round weighed and contained 255 incendiary tubes and a burst charge in its base. It used the 91 Shiki delay fuze. Its maximum altitude was . The burst charge scattered the fragments in a 12 degree cone. The maximum effective distance from the shell burst was about , where the fragments reached dispersion diameter of . 12.7 cm (5 in) A 12.7 cm (5 in) round contained 66 incendiary tubes and had a 10 degree dispersion angle with dispersion diameter of . Operational history The Sanshiki anti-aircraft shells were used for shore bombardment during the Battle for Henderson Field. On 13 October 1942, in order to help protect the transit of an important supply convoy to Guadalcanal