You don't seem to be getting any ideas here. You might try your proposal over in the "AERODYNAMICS" forum where scratch builders congregate. While I like the Buttercup and even remember the original article from years ago I don't think it would be that great of a design to upscale. You are going from a PeeWee .049 engine to a heavy weedeater engine? Maybe a 100 to 110 inch wing span? I could see maybe a 50 - 60 inch wing span with a .40 4 cycle?????