It's a big bulky ringed engine and a Kraft 61 clone...except for carb. I flew a Kraft 61 in rc for years and it had a great life until the front bearing cage let go and trashed the head, piston and liner. Subsquently, I bought the RJL K61 and flew it for years too...still have it but don't fly rc any more. If you are ok with the weight of a Fox 60 Eagle III or IV then the RJL would do for CL. As mentioned already, the K&B 61 is lighter (but not as powerful). I had one of those in rc too.