I'm afraid I will have to differ with this otherwise very good Russian publication...
The Model H type that is shown in the plan (the one with the enclosed cockpit) is NOT the H-7.
The H-7 was the little-known Super America, a type that has sadly been overlooked by most Curtiss books, and even U. S. Coast Guard history books despite the fact it was the very first aircraft to ever be evaluated by that service in 1916. It was an open cockpit design.
The enclosed cockpit variant is the earlier H-4 America, as designed and built by Curtiss and financed by Rodney Wanamaker, for the botched 1914 attempt at crossing the Atlantic. It was arguably the most advanced aircraft design of its time when it left the drawing board. A full-scale flying replica was built a couple of years ago and it is absolutely stunning.
The document that was falsely labeled as the "Bartini DLR" depicts two very similar profiles, one with the open cockpit and the other one with the enclosed one. Although I have never found a plan of the H-7 (I only have a couple of photos) I don't think it was just an H-4 without a cockpit... There were notable structural differences.
Without access to original company documents for the Russian variant (which I believe are long gone now), we can only speculate. However, having studied these types in much detail a few years ago for a unpublished project, and given the timeline, I would suggest that the Russian boats came after the H-4 and before the H-7. An "H-6" designation was quoted once as an undocumented variant. I'm NOT saying the open cockpit America could be this, but it certainly is a possibility.
The other possibility (more likely) is that Russia actually ordered the H-7 type and Petrov's book illustrated the article with the wrong images (both the photo and plan are H-4).
