BARNES WALLIS – The Dams, the Theory, the Weapon

The Dams Raid was conceived in the brilliant mind of Barnes Wallis, an experienced aircraft designer. Wallis had designed the very successful Wellington bomber that had been operational since the beginning of the war and, in his spare time, he searched for weaknesses in the enemy’s industrial infrastructure. The hydroelectric dams of the highly Ruhr Valley became his focus.

He devised a cylindrical, 9500 pound weapon that could be dropped at low level while rotating backwards at 500 rpm. Released from a height of 60 feet, about 450 yards from the dam, and at a speed of 230 miles per hour, the weapon would then skip along the water (and over any torpedo nets) until it struck the dam wall, the spinning maintaining the weapon’s stability and slowing it down.

The backward rotation would then cause the cylinder to roll down the dam wall where it would explode at a predetermined depth. The wall would be weakened and the great weight of water would cause the dam to collapse.

[ Rikyu Watanabe ]

The Lancaster, designed by Roy Chadwick, was the only aircraft capable of delivering the weapon. The mid-upper gun turret and bomb bay doors were removed and the mounting and spin-motor for the weapon were installed. As well two lamps were fitted on the bottom of the fuselage and oriented so that their beams intersected at an altitude of sixty feet.

The idea was not immediately accepted. However, Wallis’s concept, backed by his extensive testing, had reached the highest levels and at the end of February, 1943, Winston Churchill himself ordered that a raid on the German Dams be prepared. Time was of the essence, as the attack had to be launched during the full moon in May, when the water level in the reservoirs was at its highest.

“This is tripe of the wildest description. There are so many if’s and and’s that there is not the smallest chance of it working.”
– AVM Arthur Harris (Officer Commanding Bomber Command)

“It seemed incongruous that this kindly and quietly-spoken, white haired man should be involved with devastation.”
– Sgt. Jim Clay (P/O Rice’s bomb aimer)

“I shall always remember this particular operation as an example of how the engineers of this country have contributed substantially towards the defeat of our enemies.”
– Roy Chadwick (Designer of the Lancaster Bomber)