i fly the great planes patty wagstaff extra 300 with a moki 2.10. i believe it's 26% scale or so i've been told. it is the most durable arf plane flown at our field. the other PW extra 300's at our field fly with 48-50 cc gasser engines. their's have a bit more vertical although mine will climb until i feel like getting the crick out of my neck.