I think the plane would "fly" with the 10 cc engine, but it would not be much fun and power would be marginal. A cub has a lot of drag and if the plane is built with the long wing, it may fly close to the edge of the stall speed, which will take a lot of concentration. It would be a little better with the clipped-wing configuration. A 15 cc engine would be about right and a 20 cc engine would give plenty of reserve power.