Mystery for Now 2

Here was 1.  As a warm up, let’s start with some land models, and easy ones given the clues.  About 4000 of these were built,

about 2000 of these,  and

half a million of these, but of the same era and intended for the watery parts of the planet, there was only

one of these.  Can you identify her?

All fotos by Will Van Dorp, in the past month.