Grand Slam Bomb

Grand Slam Bomb Kelham Island Museum

The Grand Slam Bomb was designed by Sir Barnes Wallis during the Second World War.

Barnes Wallis, a British Aeronautical Engineer, is most famous for the Bouncing Bomb and the Dambuster’s Raid. He also developed the Tallboy bomb which weighed 12,000lbs before designing the Grand Slam Bomb which weighed almost twice as much and was officially known as the 'Bomb, Medium Capacity, 22,000 lb'.

It was used by RAF Bomber Command against strategic targets such as bridges and viaducts, railways and U-boat shelters. The bombs were produced by Vickers & Co, Sheffield, at their River Don Works, however only 30 to 40 of the bombs were ever actually made and they were only used during 1945, the last year of the war.

The Grand Slam Bomb is in the Guinness Book of World Records as the heaviest bomb in the world. It weighs 10 tonnes (22,000lbs) - hence it's nickname Ten Ton Tess - and the complete bomb with its tail fin was 7.75 metres long. The bombs were carried by Lancaster Bomber planes which were specially adapted to carry the weight.

The Grand Slam Bomb was also known as the earthquake bomb because of the effect it had on the ground. It was designed to go up to 24 metres into the earth before exploding, undermining the foundations of structures and causing them to collapse.

An example of the main portion of the Grand Slam Bomb, without the lightweight tail, can be seen at the museum.