RE: Electric motor for SPAD SPADET-40
I'm not familiar with the construction of the SPADet is in general, but you can eliminate a lot of weight by using 2mil Coroplast for the top surface of the wing, and using a folded Coroplast tube instead of gutter pipe for the fuselage. Using these techniques, my Coro-trainer weighs about the same as a standard balsa trainer.
One of my next projects is to fold up a slightly smaller version of my own-design Coro-trainer and put a 400 Watt system on it.