Sig used to sell .008 stranded cables for 1/2A flying. They are a lot easier to handle than solid .008 lines at 35 to 42 feet. Most Cox, Norvel, Wasp .049 to .061 engine sizes would be fine with those lines when using a nominal sport power setting on a trainer like model. I always liked the Carl Goldberg Lil' Wizard and Sig 1/2A Skyray for 1/2A trainers, they have a nice size wing area and lots of tip weight.
Chris...