"But what about the bomb bay? (now there is the steam-engine)...
...And these huge props? (the plane is only 4,30m high, so what about the Undercarriage)"
Good questions indeed and again no definite answer, just an assumption:
A prop diameter of 5,3m, as given on the tgplanes site, sems to be reasonable to me, as it
would give the a slightly greater prop disc area, as the four propos of 3,63m diameter each.
More ground clearance could be achieved either by moving the props further out on the wing,
or by higher on the wing. Additionally, the use of longer stroke oleos for the landing gear legs
should be possible, I think, and a combination of the abovementioned methods probably would
do the trick.
About the bomb-bay, I think, the boilers could have been fitted in the upper half of the fuselage
and the cut-away (from FlugRevue 8/1980) seems to show, that the bomb-bay only occupied the
lower part. Only suggestions, of course ... ???