Heavy bomber version of the bouncing bomb, was used to destroy the Mohne and Eder dams by Lancasters from the specially recruited and trained 617 Squadron, often known as the Dambusters, under Wing Commander Guy Gibson. In March and April 1945, as the war in Europe was ending, Lancasters dropped Grand Slams and Tallboys on U-boat pens and railway viaducts across north Germany. At Bielefeld more than of railway viaduct was destroyed by Grand Slams creating an earthquake effect, which shook the foundations. The Boeing B-29 Superfortress was a development of the Fortress, but a larger design with four Wright R-3350 Duplex-Cyclone
Victory Bomber role. The project was studied in detail, the bomber proceeding to wind tunnel testing while the earthquake bomb to equip it was tested on representative models. The Air Ministry chose not to proceed with development of the Victory Bomber, terminating it in May 1941. No prototypes were built, but the Avro Lancaster filled a similar role and was fitted with a similar armament array. The Lancaster used Wallis' Bouncing bomb during Operation Chastise to perform the famous "Dambusters" mission. During the early stages of the Second World War, Wallis performed extensive studies of the German war economy and industry, concluding