I have a Ringmaster with an OS FP 25 on it, my buddy flies his with an older Fox .25 (4 bolt backplate). Both fly very nicely on 60' X .018. You can use .015 on the .25 powered ships but our flying areas are "Improvised" and usually include weeds, rocks, sand etc. So we stick with the .018 lines for durability.

Both planes are stock from kits, not especially light, and still needed tailweight to balance. The Fox .35 that it was designed for is a pretty light engine, modern engines with mufflers almost always make the older Sterling Profile series designs noseheavy. Even with a couple extra ounces of lead bolted to the tailend my O.S. 25 powered RM is a good sport flier, does decent loops, wingovers, and 8's. Follow the advice posted previously and keep the elevator travel down to about 1/2 -3/4 inch up and down. Too much travel and it acts more like an air brake than a control surface. Get a handle you can adjust the line spacing on and start out with 2 1/2 to 3''. You can go wider after a few flights if you think it is not responsive enough.

The Ringmaster is not as good a flier as my ARF Flite Streak was with the same engine, but the Flite Streak is a pile of broken peices from a crash that the Ringmaster might have broken the prop on. They are fairly tough, easy to repair, easy to fly. Have fum