'Bouncing Bomb' designer, Barnes Wallis.

Sir Barnes Neville Wallis CBE FRS RDI FRAeS (1887 - 1979), was an English scientist, engineer and inventor. He is best known for inventing the bouncing bomb used by the Royal Air Force in Operation Chastise (the "Dambusters" raid) to attack the dams of the Ruhr Valley during World War II. Among his other inventions were his version of the geodetic airframe and the earthquake bomb.

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In 1930 he designed the R100 Airship which incorporated the revolutionary geodetic construction. The Vickers Aircraft Factory used the system in the Wellington bomber. The Wellington had one of the most robust airframes ever developed, and pictures of its skeleton largely shot away, but still sound enough to bring its crew home safely, were impressive. The geodetic construction offered a light and strong airframe (compared to conventional designs. However the technique was not easily transferred to other aircraft manufacturers, nor was Vickers able to build other designs in factories tooled for the geodetic design.

An RCAF Wellington bomber, having flown back to England despite a direct anti-aircraft hit,

with exposed geodetic airframe construction

Early in 1942, Wallis began experimenting with skipping marbles over water tanks in his garden, leading to his April 1942 paper "Spherical Bomb - Surface Torpedo". The idea was that a bomb could skip over the water surface, avoiding torpedo nets, and sink directly next to a battleship or dam wall as a depth charge, with the surrounding water concentrating the force of the explosion on the target.

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A crucial innovation was the addition of backspin, which caused the bomb to trail behind the dropping aircraft (decreasing the chance of that aircraft being damaged by the force of the explosion below), increased the range of the bomb, and also prevented it from moving away from the target wall as it sank. After some initial scepticism, the Air Force accepted Wallis's bouncing bomb (codenamed Upkeep) for attacks on the Möhne, Eder and Sorpe dams in the Ruhr area.

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The raid on these dams in May 1943 (Operation Chastise) was immortalised in Paul Brickhill's 1951 book The Dam Busters and the 1955 film of the same name. The Möhne and Eder dams were successfully breached, causing damage to German factories and disrupting hydro-electric power.

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After the success of the bouncing bomb, Wallis was able to return to his huge bombs, producing first the Tallboy (6 tonnes) and then the Grand Slam (10 tonnes) deep-penetration earthquake bombs.

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Although there was still no aircraft capable of lifting these two bombs to their optimal release altitude, they could still be dropped from a lower height, entering the earth at supersonic speed and penetrating to a depth of 20 metres before exploding. They were used on strategic German targets such as V2 rocket launch sites, the V3 supergun bunker, submarine pens, and other reinforced structures, large civil constructions such as viaducts and bridges, as well as the German battleship Tirpitz.

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Source: Wikipedia