RE: U-Can-Do 3D .46 with OS .46 2-stroke
A .46 will be okay for sport flying but not for serious 3D. I would not even put a .55 in it. I would be thinking OS .75 or Saito .82? I am not a 4 stroker. The wing loading is ridiculus low - the .75 would be fine.
I had an OS-50sx-H heli engine in mine and it really lacked pull out.