Hey Ed - I have a Fox 40 R/C BB from the early 80's. I think it'd be perfect for this aircraft as it doesn't weigh much more than a typical 25BB. This may be the airplane that get my fox 40 in the air - good thought! I like the Fox's since it's something different at the airfield. I flew a couple of seasons with a Fox-74 on an Ultrastick-60 recently. had a heak of a time running it until it hit about 2 gallons, then it ran great.