The Soviet Reds continued the last Czars' established practice of buying foreign-built subs, and/or design rights, for domestic construction - and the West continued to sell to them, even as they were trying to derail their Revolution.

We've already seen how their '30s-vintage S-class subs were a Dutch design (I think they were built in Russia) - and their D-class looks quite a bit like the Dutch K-class (which apparently evolved from the American S-boats - that's a whole 'nother story). And I know that - just like the Dutch - the Russians bought several American subs/designs from John Holland - and especially from Simon Lake, whom they patronized a lot better than the US did - and definitely better than the Germans, who essentially just ripped him off, as I understand it. Lake's pioneering sub designs were cutting-edge, and definitely gave the Kaiser's WWI-vintage subs a leg-up on the early competition.

From the look of the later, German Type IX, vs the Dutch S-class design, it would seem the Germans also ripped off the Dutch - though that, too, could well have been by mutual agreement, seeing as how the Dutch let the young Nazis use their sub development program as a cover for Hitler's rearmament.

Quite a bunch of whores, all-around - particularly in those days! Anyway, the (good) upshot of it today is, we appear to have yet more potentially great options for kitbashing WWII-era subs...

Cheers,

-Matty