Remember I'm talking about pattern planes, sport or trainers where you can fit a 6oz tank, battery and ignition box up front where normally you would put a 12 or 14oz tank this engine will work ok. the motor makes good power in my aeromaster bipe with a vess 12X7 prop it was to fast and vertical out of site, weight 7.5#.What I mean by "not worth it" is if you replace a glow engine you fly a lot the difference in the price of fuel will make it worth it. I just take my classic planes out 8 or 9 times a year $200.00 for the engine I could have had 10 gallons of fuel. But there are lots of other things to consider. I think what i'm saying is don't let me talk you out of it I'm just giving my experience for your information. Hope I'm not confusing you.