Ross,


The K&B .65 Sportster is not a particularly powerful engine... The OS.65LA is more like it.

For a 70" span bipe, the recommended engines are [link=http://www2.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=biplane&FVPCODE=RF&search3=Go]larger in general[/link]. From a .90 to a whooping 1.60.

I guess it depends on the way you intend to fly this plane.

A .60 size engine, perhaps even a bit smaller, will carry this model for basic flight, but for aerobatics and strong vertical performance, neither engine; certainly not the Sportster, is among those I would recommend.