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A film still of a bouncing bomb trial (Photo: BAE Systems/SSPL)
Film stills of a bouncing bomb trial, signed by Barnes Wallis (Photo: BAE Systems/SSPL)
The bouncing bomb rig (Photo: BAE Systems/SSPL)
Wallis arrived at the idea of a bouncing bomb when thinking about how he, as an engineer, might help shorten World War II. His idea was that a bomb dropped from an aircraft could be made to bounce along the surface of a river before striking a dam where it would sink and detonate. The bouncing would allow evasion of anti-torpedo nets placed in the river to protect the dams, and allow the bomb to explode right next to the dam, where it would be most effective, and potentially breach. Numerous tests were carried out before arriving at the dustbin-shaped Upkeep bomb design, and determining optimal backspin and drop height. On May 16, 1943, 19 modified Lancaster Bombers left on their mission to destroy the Möhne, Eder and Sorpe Dams in an effort to disrupt Nazi supply lines. After several attempts, the Möhne and Eder Dams were breached, though the Sorpe Dam obtained less damage. Eight aircraft were lost, with 53 of the 56 crew aboard them killed. The mission is thought to have resulted in more than 1,300 causalities on the ground, many of whom were overseas workers. The mission did strike the Nazi war machine, however, destroying 25 bridges, 11 factories, and various other mines and infrastructure, and damaging many more.
Barnes Wallis' sketch outlining his bouncing bomb concept (Photo: BAE Systems/SSPL)
The geodetic airframe devised by Wallis in the 1930s is a basketwork structure which describes the aerodynamic form of the aircraft, as opposed to being an aerodynamic skin supported by a beam. By crossing geodesic members on a curved surface, the torsional loads on each are cancelled out, accounting for its great strength. The geodetic principle was used in the gasbag of the Vickers R100 airship, the design of which Wallis led. Geodetic design was subsequently applied to the Wellington Bomber. Though this construction method took longer than monocoque
techniques, they resulted in robust aircraft. There are several accounts of Wellingtons returning safely, though rather less than intact, following raids on Germany, such as that pictured above, heavily damaged by anti-aircraft fire during a raid on Duisburg in 1943.
After the war, Wallis turned to the question of supersonic flight, and developed concepts for a number of such aircraft, which he called aerodynes. His Wild Goose concept was notable for the position of the wings to the rear of the aircraft. This was to counteract the rotational forces experience be a solid body moving in air at an angle – an issue he was alerted to thanks to his experience designing airships. The wings would pivot to steer the craft, and sweep back to attain greater speeds. Wild Goose proved successful as a model, but was cancelled in the early 1950s before a piloted version was completed. His subsequent Swallow concept, pictured above, also employed a swing-wing, but in a delta configuration. After promising early test flights, the loss of a test model followed by military cuts did for the development of the aircraft. His work was built on in the United States, though without the involvement of Wallis or Vickers. (Image: rp-one.net
Here, Nahum is referring to Blockhaus d'Éperlecques
(pictured under construction in 1944), sometimes called Watten after a nearby town, which was subjected to numerous raids during the war, including by Tallboy bombs. The Tallboy raid was reportedly influenced by Sir Malcolm McAlpine, who advised that the attack should be made before the concrete had set. However, Gizmag is as yet unable to verify this for certain.
It's seventy years to the day since No. 617 Squadron of the Royal Air Force returned from Operation Chastise, in which specially designed bouncing bombs were dropped in an attack on the Möhne, Sorpe and Eder Dams in Germany during World War II. Though the bouncing bomb is without doubt the invention for which Barnes Wallis is most renowned (thanks in no small part to its depiction in the film Dambusters) Wallis' other work before, during, and after World War II was of great importance, and in some cases, far ahead of its time. Gizmag spoke to Dr. Andrew Nahum, Principal Curator of Technology at the Science Museum where many of Wallis' papers are archived, about swing-wing aircraft, earthquake bombs, improbable mathematics lessons, and the geodetic Wellington Bomber.
Read the full article: Dambusters 70 years on: Barnes Wallis – an engineer ahead of his time
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