Avro Lancaster {unmodified}

The Derwent Dams were used as flying practice for very low level bomb aiming techniques by the 617 R.A.F. Squadron during World War 2. The Derwent Dam and it's surrounding hills resembled that of some of the German Dams that were to become a target for this unique 'bouncing bomb' devised by Barnes Wallis.

19 modified Lancaster bombers left R.A.F. Scampton on 16th and 17th May 1943 heavily loaded with just one revolving bouncing bomb {code named 'Upkeep'} each. The Lancasters were powered by four Rolls Royce Merlin engines.

They flew night at 500ft until the enemy coast, after which they averaged just 100ft to avoid flak and fighter patrols. The Mohne and Eder Dams were eventually breached with The Sorpe Dam suffering slight damage. Operation 'Chastise' had been a success and Wallis's bomb proved successful amid previous doubts over its design.Aldis lamps were used which were set at the correct angle on the planes to give the correct release height indication of 60ft.

The Lancaster's had to align themselves up precisely prior to releasing their 'Upkeep'. They had to be 425-475yds away from the dam wall, traveling at 220mph, AND at a height of just 60ft. Only then could they release bomb which was back spinning at 500rpm. Each bomb weighed over 4 tons and contained 6600lbs of Torpex underwater explosive. Designed to explode at a depth of around 30ft or after 90 seconds of being released from the aircraft.

This 90 second timer feature would reduce the chances of The Germans obtaining an unexploded bomb for themselves. This feature totally demolished a power station after being dropped late by a badly damaged Lancaster prior to it crashing. The bomb bounced over the dam wall and landed on the power station in the valley below - 90seconds later the power station went up in a gigantic flash.

The first wave of three was led by Guy Gibson who set off at 2139 on 16th May and returned at 0415. Only 5 out of 9 aircraft returned in the first wave. 617 Dambuster Squadron Memorial is located just inside the gatehouse to the Western Tower of The Derwent Dam.

However 617 Squadron suffered heavy losses in what was to become one of the most difficult bombing raids ever carried out. The flying skill and bravery these men had shown was second to none, 8 aircraft and crew out of 16 {3 aborted or returned early} were lost, a total of 56 men.