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The science of the Dam Busters

This week marks the 70th anniversary of the iconic ‘Dam Busters’ raid on German dams. The strategic impact of the raids is still a matter of debate, but that doesn’t detract from the technical innovation of Barnes Wallis’ ‘bouncing bombs’ and the bravery of RAF 617 Squadron

ON THE EVENING OF MAY 16, 1943, 19 modified Lancaster bombers set out from RAF Scampton to attack the dams of the industrial Ruhr region in Germany.

The planes of the newly-formed 617 squadron were carrying a very special ‘bouncing bomb’ that, although it would have very little impact on the outcome of the war, would ensure the aircrew that deployed it and the man who designed it would be forever remembered as the Dambusters.

At the height of World War II, Bomber Command was tasked with destroying as much of Germany’s industry as possible.

They had tried targeting factories but these were quickly rebuilt so they turned their attention to targeting the power sources that supplied them – coal mines, oil fields and hydroelectric dams.

Coal mines were too easily repaired and the oil fields were too far away, so the dams, which supplied both power and water to industry, became the target. Unfortunately, aircrews faced two problems: first, dams are (damn) difficult to destroy – after all they are strong enough to hold millions of tonnes of water at bay. Only a very large bomb, or an underwater torpedo strike would do the job.

Second, Hitler was aware of the importance of his dams, so they were well defended by submerged anti-torpedo defences.

The large bomb idea was abandoned because the RAF lacked an aircraft big enough to carry it, so it had to be the underwater option. But how would the crews get past the defences?

Enter engineer Barnes Wallis. He had an idea that, rather than trying to breach the anti-torpedo nets, you could bypass them by ‘bouncing’ a bomb across the surface of the water, in the same way that you might skim a stone across a lake. The difference being that his ‘stone’ was a four-tonne cylinder full of explosives.

The final bomb, called Upkeep, was a masterpiece of innovation and improvisation and, when it was deployed on the evening of May 16, it performed (almost) flawlessly.

Of the three dams targeted during Operation Chastise, the Möhne and Edersee were breached, flooding the Ruhr valley and villages in the Eder valley. The third, the Sorpe, was only lightly damaged.

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