Hi,
I've received some informations on the P-39 in Finnish museum from Jan Vihonen:
Sorry for the delay but I have finally got the information from Harri Huopainen, my friend who's working as an aircraft conservator at the Central Finland Aviation Museum. This is what he told me:
He has checked the files in the museum and also contacted his predecessor. The fin is from Norway and came to Finland already conserved and primed. Aluminium colour is based both on the research done by the then director of the Museum, Dr. Hannu Valtonen, and remains of the aluminium colour in the original fin fairing. It remains uncertain, though, whether the fin fairing is originally from the tactical number (aluminium) 26.
After the war there were remains of at least three Airacobras stored in Finland, but at some time most of them were scrapped and only the main components for one a/c were kept, along with a pile of smaller, unsorted parts. The pieces in worse condition were destroyed and the ones in better shape were kept, which means in this case that the wings and the fuselage are from different aircraft altogether.
Colouration was studied at the time, but, as usual, no certainties were established. In the old Red Stars vol. I there is a photo of Airacobra 24, apparently from the same unit, which has only the rudder painted in aluminium.
So there, I hope this was of help to you. If you're citing this anywhere, the info is to be credited to the Central Finland Aviation Museum (and if you want to be more specific, to Harri). I'm only acting as a messenger here.
Regards
Massimo