Sir Barnes Neville Wallis

Wallis was born in Ripley, Derbyshire. He was the second in a family raised by Charles Wallis, a doctor, and his wife, Edith Ashby, whose parents had run schools. From 1891, the family lived in south London, where illness left Barnes' father disabled. In 1900, Barnes entered Christ's Hospital School, leaving in 1904 for an apprenticeship with Thames Engineering at Blackheath. In late 1907, he moved to the shipbuilders J. Samuel White in Cowes, Isle of Wight, gaining practical experience upon which he looked back with gratitude.

In 1913, Wallis was recruited to Vickers' airship department. Within 7 years, he had become lead designer, architect of the elegant R80 airship. In 1924, Wallis was engaged by the Airship Guarantee Company to design R100, one of two intercontinental airships to be separately developed and then compared under a UK national programme. R100 was successful, but disaster befell R101 and the programme was closed.

Wallis returned to Vickers, now to collaborate on designs for heavier-than-air aircraft that progressed from the Wellesley bomber to the outstanding Wellington, both of which relied on a geodetic construction system of Wallis' devising.

In 1940 to 1941, Wallis argued for new, large bombs that would destroy coal mines, oil storage complexes and hydro-electric plants. Energy sources, he said, were unlike factories in that they could not be dispersed or hidden, and without them industry could not function. This idea was never put to the test, but discussion of it led to the weapon used to attack the Ruhr dams, and the deep penetration bombs that were subsequently used against V-weapon launch and storage sites, E-boat pens, transport targets and the battleship Tirpitz.

From 1945, Wallis turned to ways of spanning the world at supersonic speeds by developing an aeroplane in which the tail empennage and aileron control were eliminated in favour of independently-moving wings. Withdrawal of government support left his vision unfulfilled, although one aspect of it - variable geometry- has passed into wider use.

While in personal outlook Wallis bore the stamp of his late Victorian upbringing, as an engineer he looked ahead. In his eighties he evolved plans for an aircraft that would fly at many thousands of miles an hour on the edge of space. Alongside aeronautical work he contributed to projects such as bridges, a telescope mount, prosthetics, a new kind of submarine, and worked for charitable causes and the betterment of education.

Wallis was appointed CBE in 1943, elected a Fellow of the Royal Society in 1945 and knighted in 1968. For the public, following Michael Redgrave's portrayal of a slightly abstracted, self-effacing genius in the 1955 film The Dam Busters, he became a hero who stood for creativity and imaginative daring in the face of bureaucratic caution. For the Science Museum on the centenary of his birth, Wallis was one of the most celebrated inventors and aeronautical engineers of the twentieth century.

The Road Research Laboratories tests at Harmondsworth

In October 1940, Barnes Wallis began to consider ways to attack sources of enemy industrial power. These included dams that held back supplies of water required to produce steel and armaments. Wallis enlisted the help of the Road Research Laboratories in experiments to find out how much explosive would be needed to break such dams, and how it should best be placed.

After initial tests at the Building Research Establishment at Garston, work was transferred to Harmondsworth in early 1941. 1/50th scale models of the Mohne Dam were built to test Barnes Wallis's original idea that a 10 ton bomb, dropped close to the dam from 40,000 feet would do the job. The results of these early model dam trials were disappointing, and by May 1941 the Air Ministry had rejected this concept.

Wallis was undeterred. Further tests were carried out during the summer and autumn of 1941, during which time Dr. Collins and his team acquired the nickname of the "Dam Blasters". In November, two 1/5th scale models were built in layered mortar representing a small disused dam at Nant-y-Gro in Wales that Wallis hoped to destroy as a larger scale experiment. Tests were conducted in an attempt to find a combination of explosive type, weight and distance from the wall that was both effective and practical. Results were far from conclusive. A test against the actual Nant-y-Gro dam likewise proved disappointing.

During the first months of 1942, an idea began to form in Wallis' mind. What size charge was required if it exploded directly in contact with the dam wall? How might it be placed there? He thought he had a solution to the latter.

Further research continued with the models. In late February or early March 1942, Collins carried out an unscheduled test, using a damaged model from a previous test. A charge placed directly in contact with the wall breached the dam in spectacular fashion. The test was successfully replicated, on a larger scale, in July 1942 against the Nant-y-Gro dam. In August 1942 Collins published a paper stating that a charge of 7,500 lbs detonated 30 feet beneath the surface of the water in contact with the dam wall could cause a breach 50 feet deep.

The results gave Wallis added impetus to perfect his design. A spherical weapon with backspin, dropped at the right height and speed from an aircraft could be made to bounce across the water in diminishing leaps until it struck the dam. The backspin kept the bomb in contact with the dam wall as it sank, until a hydrostatic pistol detonated the charge just as Collins had calculated. For his final design, shortage of materials meant that Wallis had to resort to a cylindrical weapon, but the principle remained the same.

The technicians who built and experimented with these models have long since passed on. Changes to the landscape and local economy have removed all traces of the vital work they carried out. Now, finally after over 70 years and almost as the Dams Raid fades from living memory, due recognition has been accorded to the critical role played by this small, dedicated team of engineers and their series of experiments. Without their work, Wallis's weapon and the legend of No. 617 Squadron, "The Dambusters" would never have been born