It is in the nature of CL combat that small, very sharply made, direction changes are the way to collect multiple cuts per attacking pass, if the target is unable to jink away in as equally quick a manner. This puts a heavier model in a serious disadvantage. While any IC engine is the typical rule, the majority (in my experience) are from the .15 to .25 glow engine class, weighing from 4 1/2 to 7 1/2 Ounces, plus the fuel system, which typically is a bladder in a thin walled tube, filled with 3 1/2 Ounces of fuel that weighs about an Ounce per Ounce.
I would imagine the combination of batteries and motor for an electric that could go 75 would be heavier than that. I may be wrong, of course, won't be the first time.