Hi Steve,

the Ringmaster Jr was manufactured a long time ago when the .19 engine displacement was standard and plentiful. But today's engines are much more powerful than the ones of the past. Actually this airplane will fly quite well with the OS .15 C/L ...as well as a new .19 of 40 years ago. With the .15 up front, I would suggest you keep your flying lines around 48 feet in length to start. Try to keep your lap times in the 5-6 second range; that way you won't screw yourself into the ground. Once you're comfortable with that you will want to fly something like a Flite Streak with a .25 up front. Still one of the best all around C/L flyers is the combination of the original Ringmaster and a Fox .35 Stunt engine. So you see, you have lots of things to experience. Good luck.

Mudduck