Seventy years ago, in the early hours of the 17th May 1943, 8 Lancaster bombers flew back to RAF Scampton and into the history books as part of the daring Dambusters raid. The 617 squadron, formed only two months earlier, had successfully destroyed two dams (Mohne and Eder), and damaged a third (Sorpe) using the ingenius invention of Barnes Wallis – a four tonne bouncing bomb.
Shortly before he died, Wallis donated the bulk of his papers to the Science Museum, including design notes, photographs, correspondence and reports relating to his work. We’ve picked out a few images below to tell the story of the bouncing bomb.
Even before the war begin, the UK Government had identified the three German dams as potential targets, but had no suitable weapons to launch an attack. Wallis’ idea is simple to explain, but was far more complex to put into action: bounce a 4 tonne rotating bomb across 400m of water until it hits the dam, sinks and explodes.
Bouncing bombs allowed Wallis to completely avoid the torpedo nets protecting the dam. However, to get the bounce just right, the Lancaster bombers needed to approach the dams flying just 20m above the water while traveling at 230mph (more on how this was done can be read here).
At exactly 389 metres from the dam wall – calculated by triangulating with the dam’s towers – the bombs were released. Wallis calculated that backspin would stabilise the bombs in ‘flight’, help create the bounce and forced the bomb to cling to the face of the dam once it sank.
Even with practice runs, it took many attempts to bounce the bombs correctly, and trials with live ammunition were only conducted three days before the raids. To this day, the skill and bravery of the 617 squadron (113 men in total), who flew low over enemy territory under the cover of darkness, remains breathtaking.
After the war, Wallis continued his work on aircraft design (before WWII he was a pioneer of geodetic design, used to build the largest airship of its time, the R100), designing “swing wing” aircraft suited to hypersonic flight.
Our Senior Keeper, Andrew Nahum, was recently interviewed about Barnes Wallis, his bouncing bomb and other work. The full interview can be read here.