RE: U Can Do 3D as a trainer?
NBCGUY-
Can it be a trainer? No. It won't be a trainer no matter what because of its flight characteristics. Could it be used successfully as a first plane? Possibly.
I "learned" to fly 15 yrs ago on an Andrews Aeromaster biplane with a Veco .50. That was the plane I had available at the time. I had an experienced pilot helping me take off and land, and was able to handle the rest relatively easily. I say "learned" because I flew for a few summers, always with the supervision of an instructor and then got out of the hobby until now. Although I could take off, fly fine, and do quite a bit in the way of aerobatics, I never really mastered landing on my own, as I recall. I am now getting back in the hobby.
Was this the best course? Probably not, but I inherited the plane from my brother and did the best I could. Like the Aeromaster, the U Can Do has a light wing loading and probably a relatively low stall speed. I'm sure your friend could fly it with some assistance, but it still is not a trainer. The engine choice makes no sense, however.
When I decided to start flying again, I made another semi-poor choice. Instead of getting a real trainer, I bought a GP .60 size Cub with a Saito .91. I am having a ball building the kit and am almost done, but I will still need to hone my flying skills with our local club's loaner trainer.
-Scott