Blockbuster bomb Blockbuster or " cookie " was the name given to several of the largest conventional bomb s 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 an entire city block . Design . The bombs then called " Blockbusters " were the RAF ' s HC ( " High Capacity " ) bombs . These bombs had especially thin casings that allowed them to contain approximately three - quarters of their weight in explosive , with a 4 , 000 pound bomb containing over of Amatol . Most General - purpose bomb s ( termed " Medium Capacity " — or MC — by the RAF ) contained 50 % explosive by weight , the rest being made up of the fragmentation bomb casing . Blockbusters got larger as the war progressed , from the original version , up to . The Mark 1 4000 lb bomb was a welded , cylindrical shell , made of thick steel . The body of the bomb was in diameter and long . The nose of the bomb was conical and a long cylindrical tail was fitted ( a lightweight , empty cylinder with a closed end ) . A T - section steel beam was welded to the inner surface of the bomb to strengthen it . Subsequent Mark II and Mark III HC bombs differed in detail ; the conical nose was replaced with a domed nose and the number of fuze s was increased from one to three , in order to guarantee detonation . The Mark IV bomb did not have the T - section beam . The Mark V and Mark VI bombs were versions manufactured in the United States . The larger 8 , 000 lb bomb was constructed from two 4 , 000 lb sections that fitted together with bolts , although 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 lb 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 tile s off , so that the smaller 4 lb ( 1 . 8 kg ) incendiary bomb s could reach the building interiors . These high capacity bombs were only used by the RAF , being too big to fit in the bomb bay s of other countries ' aircraft . 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 " . Operational use . The first type of aircraft to carry cookies operationally was the Wellington , but they later became part of the standard bomb load of the RAF ' s heavy night bombers , as well as that of the Mosquitoes of the Light Night Strike Force , whose aircraft would sometimes visit Berlin twice in one night carrying " cookies " , flown by two different crews . 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 . First use of the 8 , 000 lb was by 15 Squadron Lancasters against Berlin on 2 December 1943 . Bad weather and other factors meant their effectiveness was not noted . 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 , i . e . , jettisoned , in a supposedly " safe " unarmed state . Safety height above ground for dropping the 4 , 000 lb " cookie " was 6 , 000 ft ; any lower and the dropping aircraft risked being damaged by the explosion : " We were flying at 6 , 000 feet which was the minimum height to drop the 4 , 000 pounder . We dropped it in the middle of town [ Koblenz ] , which gave the aircraft a hell of a belt , lifted it up and blew an escape hatch from out of the top " . Post - war unexploded ordnance . An unusual dry period led to low river levels in the Rhine in December 2011 exposing a 4 , 000 lb ( 1 , 800 kg ) blockbuster in the riverbed near Koblenz . A radius of 2 km ( 1 . 25 miles ) around the bomb site ( containing about 45 , 000 people ) was evacuated while the bomb was defused . Bombs . 4000 lb HC bomb . In 1943 , 25 , 000 of these were used , this rose to 38 , 000 in 1944 . In 1945 up to the end of the war a further 25 , 000 were used . Other uses . Air mines . During The Blitz the Germans used naval mine s dropped with parachute s as improvised blockbusters . They exploded on contact with a hard surface ; as the bomb was not in a crater , the force of the blast would disperse laterally , causing extensive damage . The large raid on Coventry on November 14 / November 15 , 1940 included the use of 50 parachute naval mines , which caused extensive blast damage . The British called these devices " air - mines " , a cognate for the German term Luftmine , their own name for these ordnance items . These types were used also during air raids on Malta , especially on its harbour areas .