Thierry,
You might want to direct your question to Jerry Crandall at Eagle Editions. I usually don't volunteer other people as a source of info because you never know, they might not want to be bothered. But in Jerry's case he is always willing to discuss his "baby". Also, a new Modellers Eye has been published on the Dora, and includes great restoration pictures of the D-13 (with correct wings from the D-9 at the USAFM). HTH, Larry S.