You can't get everything in just one package. There was no .15 from any US brand in 1952, when the Ringmster Jr was new, just the OKCub 0.14, with about the same power as a Black Widow .049. The original kit was best suited to an .09 of some sort, with its 190 square inch wing, but balanced just fine with the first few loop-scavenged .15s, when those appeared (K&BGH, Fox 15X, OSMax I .15, etc.

Those were light in weight, but more power than needed. An 8-4 was the usual prop to use with them. The Enya you are using came later, although if I'm recalling correctly, wasn't much bigger or heavier than the older .15s. Modern Schneurle ported 15s can generate power equal to the best of the 19s and 20s from the old days of loop scavenged porting, however, they are heavier by far, so not usually a good match for doing aerobatics with on any planes as comparatively small as this design.

The Schneurle ported engines are more economical, as you've discovered. Even a modern 0.10 is a lot of power for a small plane the Ring Jr's size (of course, when it was a new kit, I built several with 19s on them, with the noses cut short, and the tanks inside the wing . . )


Kiwi