Boomerang1

For a model like the Solution I'd start with a balsa/plywood box to carry the wing/tail/engine/undercarriage.
No need to make the box narrower at the bottom like the Solution's basic frame. The box provides all the rigging
angles for the important bits.

Then 'puff out' the box with white foam carving it & sanding it down like a big log. If weight's a factor I lightly
glue the foam on so I can remove it easily & hollow it out to a wall thickness of, say, half an inch leaving areas
touching the central box for support where required.

The trick is to make the foam a little smaller than the final shape, the difference is made up by stringers glued
onto the foam in the required, scale position. Once finished & sanded cover as normal.

Advantages? Much faster than adding little quarter formers, notching for stringers, adusting slots to make the
stringers straight - you know the story. The stringers are supported along their entire length so much, much
more resistant to bumping & breaking them. For the same reason the stringers don't get the 'starved horse'
look as the model ages.

Disadvantages? It may/may not be a little heavier. You may have to use a little imagination to fake the cockpit
interior as this will be a little smaller & look a little different. You may have a guilty concience about doing the job a
quicker, easier, more durable, less traditional way.

I know it works for me. - John.