The clipped wing T-Craft was an aerobatic plane. And it has short wings and a stubby, chunky fuselage that creates a lot of drag. If yours came out to 15lbs, a 30cc like my Wolf Predator swinging a 19x8 would perform fine, with limited aerobatics. The Wolf is about the same power as a G38 but the weight of a G26. I have 2 of them and I'm definitely saving one of them for a 1/4 scale cub eventually.

However, if you expect your T-Craft to be heavier and/or you really want to add smoke, etc, and have greater aerobatic potential, then a 40cc or so with a 20x10 would be a good bet and provide good reserve power when needed.