Owing to many technical details, I think the correct datation is about 1935 - but before 1936, when the official denomination was changed, the 12 Ycrs becoming 12 Y 31.....
Owing to many technical details, I think the correct datation is about 1935 - but before 1936, when the official denomination was changed, the 12 Ycrs becoming 12 Y 31.....
Thanks for this. I have broader information on the 12Y, but there are some fine details of differences among the early models there. The performance graphs are particularly valuable (assuming that they're accurate--they could always be brochure BS, or they could be understated to keep military secrets!).
Thanks for this. I have broader information on the 12Y, but there are some fine details of differences among the early models there. The performance graphs are particularly valuable (assuming that they're accurate--they could always be brochure BS, or they could be understated to keep military secrets!).