Hi Stig,
Double Command seems very likely based on this post from theaerodrome which is very good on Sopwith 1 tail markings generally
https://www.theaerodrome.com/forum/s...t=31768&page=3
However, I note that the photo at the bottom of the page has different markings again,retaining the 1-B-2 at the top of the rudder,with the D2 seperate and lower down. I also note that the machine I posted has a single cockpit,whereas the aerodrome has the usual two seperate cockpits. I wonder if 4180 was perhaps built as a 1D2 whereas the other machine is a conversion?
I also wonder why the Nieuport 80 with dual control are still, according to Davilla and Soltan E2, rather than D2. Puzzling. Also odd that there existed seperately 1E2 with seperate cockpits as well as the 1B2 D2
https://www.alamy.com/aviation-milit...560782756.html
A lot more questions than answers following a search for the 1D2. Bearing in mind that my best reference on the Sopwith 1 is Davilla and Soltan and that it dates from the C.20th (but then so do we
) I've decided to order Le Fana de l'Aviation 636 which has an article by David
Méchin which may help,though I suspect not. Still if it helps with questions about the 1D2 I'll post it here.
Regards,
Clint