Drs Mary Ryan and Amy Cruickshank are in a race against time to save the last remaining intact Flying Pencil
During the Battle of Britain, a German light Bomber – a Dornier Do-17 – crash landed in the Goodwin Sands, just off the Kent Coast. For 70 years, the aircraft – also known as The Flying Pencil – lay submerged, but shifting sands have uncovered the wreckage, exposing it to the corrosive effects of seawater and threatening to destroy it entirely.
Mary Ryan and Amy Cruickshank are one of many teams working to save the historic relic, which will be raised later in the year, cleaned and displayed in the Royal Air Force Museum.
We visited Mary’s lab at Imperial College London to find out more about their preservation efforts.
How did you get involved in this project?
The museum was looking for some technical help and they got in touch with a colleague of mine they’d worked with before and he said “Well, the person you need to speak to is Mary”. We just thought this was a really interesting project – it’s such a historical issue and there’s a lot of interesting science so we’re very happy that they came to us and to be involved in this project.
So what does the project actually involve: what are you working on?
There’s a lot of different work going on that the museum are coordinating, but one of the big issues is that when they raise the aircraft – the plan is to bring it up as whole as possible in the Spring – how do you make sure that you stabilise it against corrosion, how do you clean up all the marine deposits and do it in a way that conserves any historical information?
You have to treat in a very different way than you would any other engineering problem – you can’t just dip it in a strong acid or sandblast it; you have to do it very gently. Because its aluminium, it’s very sensitive to corrosion – aluminium is a very reactive metal, and one of the things about aluminium and sea water is that it’s particularly prone to localised corrosion damage by any chloride left on the surface. If you just bought it up and washed it quickly and put it on display in the museum, you’d probably have chlorides left and then over time you’d have further degradation.
So really for us, it’s to try and work out simple, inexpensive methodology to effectively get rid of all the sea deposits and all of the chloride, and we know that will help to stabilise the aircraft. So that’s the first end point – how do we know how to clean the aircraft properly so that it’s structure will be stable?
Going forward, we’ll actually help the museum with the conservation and placing it the museum. They do have a conservation department but they deal with the bigger picture of the space and the environment, so I guess our connection is more technical as we have access to equipment that can more sensitively analyse what’s happening on the surface and understand the mechanisms a bit better.
What are you doing to preserve the parts of the aircraft that have already been raised?
It’s actually in remarkably good condition. When they came to me and said there’s an aeroplane that’s been in the sea for 60, 70 years I was almost convinced there would be virtually nothing left, but it’s been buried under the sand for a large part of that time and that has protected it somewhat. It’s got a lot of sea life growing on it now and I think that’s also helping to stabilise it – it’s forming a natural barrier on the surface.
These are very small pieces we’re working on, but we are not doing a big effort on them – we are just using them to test our methodology and protocols.
There is a large piece that’s just been bought up that was detached from the main fuselage when it landed so were hoping to bring that here soon and use it as a test case for the procedures.
What methods of cleaning and preservation have you tried so far?
One of the issues is that most of the artefacts that have been salvaged from the sea are not made of aluminium – so there’s not a lot of history or literature – it’s mostly gone!
There are different suggestions about what you can do for things that are iron-based, but there is only one case of a similar aluminium artefact which is in Australia in the National War Memorial. The conditions are slightly different, but they did a lot of complicated treatments and the question here is how necessary was that? So we tested some of their protocols versus a more simple reducing solution with slight acidity and we’re just playing with the chemistry of the bath really to get the best cleaning but without going too far or causing extra corrosion.
And you’ve chosen to work with citric acid?
Yes, that’s not uncommon in heritage circles as it’s a weak acid and so you want to start with something delicate, but it’s also very environmentally friendly so if you need to use a lot of it, you don’t have to have a lot of health and safety precautions. Logistically it makes it easier and quite a bit cheaper.
How long do you think it will actually take to clean the whole aircraft?
Some of the questions at the beginning was do we just build a big tank and put the whole thing but we didn’t want to have to do that, so the initial thing is getting as much seawater off as quickly as possible, and then starting the longer process. It just depends on how many people there are and what kind of space and equipment we have.
The small pieces salvaged so far have been treated in solution for three days, but the thing is we want this to be a quick process as we need to get this stuff off as quickly as we can. I’d prefer it to be weeks, rather than months. It’s a difficult problem and there are a lot of difficult logistics on how exactly to do it. We are also looking at simple tests that can be applied on site will tell us when
it’s clean, and correlating this to more sensitive measures of surface chemistry
here at Imperial.
Will you also be involved in determining the best conditions for the aircraft to be displayed in?
We’re going to work with the conservation department on that so initially the plan is to have a temporary home with an enclosed environment where everything is controlled. I guess the question is how stable is it? And we’re going to do some electrochemical tests here to get an idea of the sensitivity of the materials and find out if we need to coat it or control the humidity. We don’t want to have to do that because that put a big constraint on the museum – I know that they want to have it displayed in the entrance hall and so we’ll be seeing what’s possible.
There’s got to be a balance – which is partly why this is so interesting – but also why it’s so difficult, we have to have a compromise between preserving and displaying the material in a way that is sensitive and the engineering aspect where you want to do your absolute best to preserve it.
But this isn’t all you do at the university – what’s your day job?
I am in the Materials Department and the London Centre for Nanotechnology and there is a lot of interdisciplinary science here; I’m interested in the interface between solid and liquid phases. This project is basically electrochemistry, and I’ve done a lot of corrosion related work in the past; now we also work on corrosion of materials in different and perhaps unusual situations such as in nuclear waste storage, or the corrosion of nanoparticles in physiological conditions and how that relates to their toxicity, and what they do in the body. We also do a lot of electrodeposition and Amy is involved in electrodepositing structures for photovoltaics for energy harvesting; we have a lot of work on making nanomaterials from solution for functional devices.
History of the Flying Pencil
The fate of this Dornier Do-17 was sealed at midday on 26th August 1940 during the Battle of Britain. The bomber was part of a German formation heading to attack airfields in Essex. However, the plane – which was loaded with 2,000lb of bombs – was intercepted by RAF aircraft.
It sustained heavy damage and crash landed in the shallows of Goodwin Sands. It was carrying a crew of four: pilot Sergeant Effermert and Corporal Ritzel managed to escape the wreckage, but were later captured, becoming prisoners of war. The other crew members – Sergeant Reinhardt and Aircraftman Huhn – were killed. Their bodies were recovered and laid to rest in military cemeteries.