Blockbuster Bomb - Design

Design

The bombs then called Blockbusters were the RAF's 4,000-pound (1,800 kg)—also known as a cookie—8,000 and 12,000 lb (1,800, 3,600 and 5,400 kg) HC (High Capacity) bombs. These bombs had especially thin casings that allowed them to contain approximately three-quarters of their weight in explosive, with the 4,000 pounder containing over 3,000 lb (1,360 kg) of Amatol. Most "normal" bombs (termed Medium Capacity—or MC—by the RAF) contained 50% explosive by weight, the rest being made up of the fragmentation bomb casing. Typically, three impact fuzes were fitted to a blockbuster in order to guarantee detonation.

In 1947 Alfred Brooks of Stourbridge was awarded the Order of the British Empire, for creating the Blockbuster. The local newspaper referred to him as "Blockbuster Brooks".

Blockbusters got larger as the war progressed from the original 4,000 lb version, up to 12,000 lb (1,800 to 5,400 kg). The initial 4,000 lb version was 30 in (76 cm) diameter. The larger 8,000 lb version was constructed from two 4,000 lb sections, however these sections were of a larger 38 in (97 cm) diameter. A 12,000 lb version was created by adding a third 4,000 lb section.

The 4,000 high capacity design was little more than a cylinder full of explosives—it was unaerodynamic and did not have fins. When fitted with a nose spoiler and a drum tail the bomb fell straight. These bombs were designed for their blast effect, to cause damage to buildings, specifically to blow roof tiles off, so that the smaller 4 lb (1.8 kg) incendiary bombs could reach the building interiors. These high capacity bombs were only used by the RAF, being too big to fit in the bomb bays of other countries' aircraft.