A 12,000lb HC blockbuster pictured in the factory minus-tail unit.
A 12,000lb HC blockbuster being dropped.
'Blockbuster' bombs, also known as cookies, got their name from the press during the Second World War through their ability to destroy entire blocks.
They typically weighed either 4,000, 8000 or 12,000lbs and usually contained 50 per cent explosive by weight.
Their primary was use was in causing extensive damage to buildings so that smaller 1.8kg incendiary bombs could reach their interiors.
In 1943, 25,000 blockbusters were used. This increased to 38,000 the following year, before returning to 25,000 in 1945.
A safe height for unleashing the 4,000lb blockbuster was said to be around 5,000ft - any lower and the aircraft risked being caught in the blast.
During the Blitz the Germans created improvised blockbuster by attaching naval mines dropped on parachutes.
Bomb disposal experts in the German city of Koblenz have successfully defused two bombs from World War II found in the riverbed of the Rhine.
The bigger of the two bombs weighed 1.8 tonnes and was dropped by the Royal Air Force between 1943 and 1945.
Nearly half the city's population - 45,000 - has been evacuated, including the inhabitants of two hospitals, seven nursing homes and a prison.
It is the biggest bomb disposal operation in Germany since 1945.
The smaller of the two bombs - weighing 125kg (275lb) - was dropped by US forces. Experts said it was the more dangerous of the two.
Both bombs have now been made safe in a three-hour operation.
A smoke grenade canister found at the same site was blown up in a controlled explosion.
The BBC's Stephen Evans, in Berlin, says more bombs are expected to be discovered because of the low water levels in the Rhine.
About 600 tonnes of unexploded ordnance are discovered in Germany every year, our correspondent says.
Everyone living within a 2km (1.25 mile) radius of the bomb site was ordered to leave the area.
Shelters with 12,000 beds were set up in schools to accommodate those with no other place to go.
However, only 500 people were reported to have made use of them. Most residents went to stay with friends or relatives.
River drained Hundreds of sandbags were laid around the site of the bombs, and water pumped out from the surrounding area. Only once the bomb site was dry could work to defuse the explosives begin.
Wartime bombs are frequently found in Germany - but this is believed to be one of the biggest ever.
In July 2010, three people were killed in the central German town of Goettingen when a 500kg World War II bomb unearthed during the construction of a sports stadium exploded.
The RAF bomb in the Rhine - discovered on 20 November - is one of the so-called block-busters designed to cause maximum damage to buildings.
More than 250 bombs of the block-buster type were dropped on Koblenz between 1943 and 1945, Ronald Eppleheim of the city's fire department told the BBC. Some still lie undiscovered.
If the bomb had gone off, Mr Eppleheim said it would have sent "shrapnel flying through the air in and around 1.5km".
There would also have been a "big, big air blast that would crash into the walls and the houses and put the windows out, or the doors," he said.
The newspaper Die Welt quoted one woman who said her elderly relative in one of the care homes was distressed by the evacuation.
"She lived through nights of bombing in World War II, and now it is all coming back to her," the woman said.
Trains were not stopping at the main railway station in Koblenz, and access roads into the city were closed.
The city authorities began distributing leaflets on Tuesday, advising residents to close up their properties and pull down shutters where possible.