I have had a 21cc Echo on a 60 size Edge. Just consider the wing and what type of flying you will be doing when choosing your engine. The 30cc would fly a 4 star 120 just fine but would probably not be real strong in a 120 size Extra or Edge. Again it boils down to the flying style. I am building an 80 plus inch wing GTM Fokker DVIII now and will be using a 31cc Honda 4 stroke in it. Should be an ideal combination, however that engine in a mild to high performance plane would be a dog at best.