Beehive (ammunition)

Beehive is an anti-personnel round fired from an artillery gun. The round is packed with metal flechettes which are ejected from the shell during flight by a mechanical time fuze. It is so called because of the 'buzzing' sound the darts make when flying through the air. It is intended for use in direct fire against enemy troops.

The first round actually termed "beehive" was first fired in combat in 1966 and was thereafter used extensively in the Vietnam War, though the later development of the Killer Junior air burst technique provided an alternative to beehive in some situations. The primary beehive round for this purpose was the M546 anti-personnel tracer (APERS-T) shell which projected 8000 flechettes and was direct fired from a near horizontally leveled 105 mm howitzer. Beehive rounds were also created for recoilless anti-tank weapons including 90 mm, 106 mm, Ontoses and M48 tanks.

Subsequently it was reported that the USSR had developed similar rounds for 122 mm and 152 mm artillery for use in indirect fire.

Beehive rounds became less popular in the United States following Vietnam, with low-angle airburst techniques such as Killer Junior supplanting the use of beehive.

Sanshiki (anti-aircraft)
The term Beehive may also refer to Sanshiki, San-Shiki or sanshikidan (lit. "type 3") ammunition, a combined shrapnel and incendiary round for anti-aircraft use, used by the Imperial Japanese Navy in World War II. The shell was designed for several gun calibers, including the 18-inch (460 mm) guns of the Yamato-class battleships.

The 460 mm (18 in) round weighed 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 16-foot long flames. Each of the incendiary tubes was a 90 mm long, 25 mm 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.

The blast of the main guns turned out to disrupt the fire of the smaller antiaircraft guns, so the 460 mm rounds were not successful. The copper drive bands of the rounds were poorly machined, and constant rapid fire was damaging to the gun rifling.

The 406 mm (16 in) round contained 1,200 incendiary tubes and on explosion burst into 2,527 fragments. By contrast a 460 mm round burst into 2,846 fragments.

The 203 mm (8 in) round weighed 125.86 kg and contained 255 incendiary tubes and a 2 kg burst charge in its base. It used the 91 Shiki delay fuze. Its maximum altitude was 10,000 m and it was reached after 55 seconds of flight. The burst charge scattered the fragments in a 12 degree cone. The maximum effective distance from the shell burst was about 1,000 meters, where the fragments reached dispersion diameter of 100 meters.

A 127 mm (5 in) round contained 66 incendiary tubes and had a 10 degree dispersion angle with dispersion diameter of 54 meters.