British engineers are helping to save a Second World War German bomber being retrieved from the English Channel.
The researchers from Imperial College London are working with the Royal Air Force Museum to clean the Dornier Do-17, known as The Flying Pencil (Fliegender Bleistift), and prevent further corrosion once it is removed from the water.
In 2010, shifting sands uncovered the aircraft, which lies off the Kent coast and was previously protected by layers of sediment, exposing it to the corrosive effects of seawater and threatening to destroy the aircraft entirely.
Dr Mary Ryan from Imperial’s Department of Materials, who is working on the project, said: ‘This is the last remaining intact Flying Pencil of its kind in the entire world, so the significance of this project to our history cannot be underestimated.
‘We have been analysing fragments already brought to the surface and it is absolutely fascinating to see how this bomber, which crash landed more than 70 years ago, has been so well preserved by the layers of sand.’
One of the challenges for the Imperial team is devising a method for cleaning and removing the corroded layers from the Flying Pencil’s aluminium fuselage, which contains large amounts of the corrosive agent chloride from the seawater.
The researchers are currently testing a solution based on citric acid, which is found in high concentrations in citrus fruit, to remove the surface layers of corrosion and sea deposits such as crustaceans from small pieces of wreckage already retrieved.
The aim is to develop a solution that is powerful enough to clean the bomber, but not so powerful that it damages any remaining paint and markings on the aircraft, which are of historical significance. Any remaining chloride on the metal surface could lead to further attacks of corrosion when the plane is on display.
’We think this old bomber has one last scrap left in her – the battle against corrosion’
Ian Thirsk, Royal Air Force Museum
The Imperial team will also help to work out the best environmental conditions for displaying the bomber in the museum. For example, too much humidity in the air could lead to condensation on the metal, which would activate further corrosion.
Once the research is complete, a team from the museum, working with specialist underwater archaeologists and recovery experts, will use a lifting cradle to support the weight of the fragile aircraft as it is brought to the surface, currently planned for spring 2012.
The Flying Pencil was brought down by the RAF on 26 August 1940, during the height of the Battle of Britain while en route to attack airfields in Essex with a large German formation.
It crashed into the shallows off Goodwin Sands killing two of the crew members, who were later recovered and buried in a military cemetery. The other two crewmen were taken prisoner.
Ian Thirsk, head of collections from the Royal Air Force Museum, said: ‘At the moment, we are attempting to trace the relatives of the crew members who survived this fateful mission, in order to help engage visitors to the museum about the human story behind this episode of the war.
‘As the last surviving example of the Dornier Do-17, this aircraft is truly unique. We think this old bomber has one last scrap left in her — the battle against corrosion.’
Once the aircraft is lifted from the seabed, it will then be transferred to the museum’s conservation facility at Cosford, and then placed on display in the planned Battle of Britain Beacon Wing at the museum’s London site.