Anything light enough to be safe to fly in a park should not be powered by a glow engine. Not only are they loud and annoying, they're also much more dangerous than a small electric motor.

Parkflyers generally weigh in the 10 to 20 ounce range, ready to fly! (even a small Norvel comes close to that by itself.) Anything larger, heavier, or more powerful does not belong in a park.
Dennis-