Blockbuster bomb

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A 4000lb Blockbuster or "Cookie" about to be loaded into a de Havilland Mosquito

Blockbuster was the name given to several of the largest conventional bombs used in World War II by the Royal Air Force (RAF). The term Blockbuster was originally a name coined by the press and referred to a bomb which had enough explosive power to destroy a city block.

During The Blitz the Germans used sea-mines dropped on parachute, as improvised blockbusters. They exploded on contact with a hard surface, as the bomb was not in a crater, the blast could go sideways causing a great deal of damage.[The Luftwaffe over the Bristol area - Luftwaffe weapons]Montague Trout comment in a [Collaborative Article: The Blitz by Mark E]The large raid on Coventry on November 14/November 15, 1940 included the use of 130 parachute sea-mines which caused extensive blast damage. [War in the West: Coventry November 14/15, 1940]

The bombs then called blockbusters were the RAF's 4,000 lb - 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, the 4,000 pounder containing over 3,000 lb (1,360 kg) of explosive filling. Most 'normal' bombs (termed Medium Capacity - MC - by the RAF) at that time contained only 50% explosive by weight, the rest being made up of the bomb casing.

The High Capacity design was little more than a cylinder full of explosive - it was unaerodynamic and didn't even have fins. Accuracy was not important - these bombs were designed for blowing the tiles off the roofs of buildings 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 country's aircraft.

The first type of aircraft to carry cookies operationally was the Wellington but they later became part of the standard bombload of the RAF's heavy night bombers, as well as that of the Mosquitoes of the Light Night Striking Force, whose aircraft would sometimes visit Berlin twice in one night carrying cookies, flown by two different crews. Blockbusters got larger as the war progressed from 4,000 to 12,000 lb (1,800 to 5,400 kg). These were essentially constructed by bolting two or three 4,000 lb bombs together. The 8,000 lb (3,600 kg) bomb, because of its large size, could only be carried by the Handley Page Halifax and Avro Lancaster and the 12,000 lb (5,400 kg) variant only by the Lancaster.

The 4,000 lb (1,800 kg) cookie was regarded as a particularly dangerous load to carry. Due to the airflow over the detonating pistols fitted in the nose, it would often explode even if dropped in a supposedly 'safe' unarmed state.

A blockbuster may also refer to a bomb designed to destroy a blockhouse. Bombs which can penetrate reinforced concrete of a blockhouse are also referred to as bunker busters. The two World War II bombs which best fit the description of bunker busters are the Tallboy bomb 12,000 lb (5,400 kg) MC and the Grand Slam bomb 22,000 (10,000 kg) MC both designed by Barnes Wallis for the RAF. The Tallboy and Grand Slam bombs had a thick skin to withstand the initial impact of hitting hardened targets and were therefore classified as Medium Capacity (MC) bombs.

See also

• RNEP
• Grand Slam bomb
• MOAB
• BLU-82
• T12

Further reading

• [World War II air power: Bombs Weapons Rockets Aircraft Ordnance] describes ordnance carried the RAF, Luftwaffe, and USAAF during World War II
• http://www.raf.mod.uk/history/line1941.html 1 Apr 1941 - During an attack on Emden in Germany, Wellingtons drop the first 4,000 lb (1,800 kg) Blockbuster bomb.
• http://www.raf.mod.uk/history/line1943.html 15/16 Sep 1943 - The 12,000 lb (5,400kg) Blockbuster bomb is used for the first time, when Lancasters of No. 617 Sqn make a low-level attack on the Dortmund-Ems Canal.
• http://www.constable.ca/bombs.jpg picture of English Bombs of WWII

Footnotes

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