RE: U-Can D0 engine
Once again, keep it light. Many are using the new Hype OS .50 on 30% Nitro and a 12X4 prop. I have a Magnum .52 on one now, running on 15% Nitro and a 12.25X3.75 APC prop and no limit on vertical and hover less than 3/4 throttle. I had tried a .91 mag 4 stroke, but the extra wing loading with that big engine hurt the 3D stuff more than you would imagine. My choice would be the .91 Saito, because it is about 4 oz. less than the competition and will swing a 15X4 APC wide blade pretty well.
Hope you enjoy yours as much as I have enjoyed mine. Just a really fun, relaxing, forgiving airplane, when you get it set up right.