RE: Which airplane for US 40cc ?
I am thinking about war birds for this engine.
Since we won't do 3d or pattern flight with them, as long as weight and power match, I think that would be a good candidate.
I am watching the specs of World Model Spirfire G.S. With the wing span of 80" and 13 lb weight, looks like it's gonna work.
I think the challenge will come for fitting the engine inside the cowl.