Bouncing bomb

The bouncing bomb was a kind of bomb designed by Barnes Wallis of Vickers-Armstrong at Brooklands, Surrey. It was used in the famous Dambusters raid to attack major dams in Germany's industrial Ruhr Valley during World War II.

Barnes Wallis first began to think of producing a bouncing bomb in 1941. He was aware that in the 19th century the British Navy had bounced cannonballs on water to increase their range. Initially his work on the device was to attack battleships. The bomb could be released away from the ships; the bomb would skip over anti-torpedo defenses, and when it struck would roll down the hull to below the waterline, where a battleship would be least protected. This version of the bomb, which was sphere-shaped and dimpled like a golf-ball, was codenamed Highball.

The dam targets were largely immune to conventional attack because of their size. An immense amount of explosive would be required to breach them, and the cushioning effect of the water meant that a near miss would be ineffective. However a bomb placed right by the dam would be effective because the water would direct the explosion onto the dam, instead of protecting it, and greatly reduce the explosive power required. Current techniques would not allow the placing of a large bomb with that much accuracy. The Germans had guarded against attack by torpedo by placing nets upstream of the dams.

The version of the bomb required to destroy the dams was codenamed Upkeep. It weighed 9,250lb including 6,600 of RDX explosive. It was cylindrical in shape, 60in in length and 56in in diameter. The bomb was designed to be spun at high velocity (500rpm) before being released. It would then literally bounce over the water (avoiding the torpedo nets) in the same way that a spinning stone will skip. However to achieve this effect the bomb must be released from a very low level (60ft), at a very precise height and at 240-250mph, 400-500ft from the target. On striking the dam the bomb would sink to a prescribed 30ft depth before being detonated by hydrostatic fuse. A time fuse would detonate the bomb if the hydrostatic fuse failed.

The bombs were successfully deployed by Royal Air Force Squadron No. 617, led by Wing Commander Guy Gibson using Avro Lancasters under the codename Operation Chastise, on May 16-17, 1943. For loss-of life and other reasons, the bomb project was discontinued.

A 850 pound version of the bouncing bomb was also attempted by the Luftwaffe. Designed for use against British shipping, it was given the codename Kurt, and was built at the Luftwaffe Experimental Centre in Travemunde. In trials, it proved to be dangerous to the delivering planes as the bomb matched the speed at which it was dropped. Attempts to rectify this with booster rockets were ultimately a failure, and the project was discontinued in 1944.

External links

• Memories of an apprentice who worked on the bouncing bomb prototypes (http://www.bbc.co.uk/dna/ww2/A2163827)
• Technical description of the bomb (http://www.chm.bris.ac.uk/webprojects2001/moorcraft/The%20Bouncing%20Bomb.htm)