The Futaba S3010 servos are really overkill for that size Cub. Futaba S3004 servos are more than powerful enough for that size J-3 Cub especially with a 6.0 volt on board battery. Give or take, you will pay about $25 ea. for the 3010 servo and $15 ea. for the 3004 servo. That will save you about $50 on this plane. As a long time Cub flyer in all sizes I would use the 3004's in this plane and spend that extra $50 somewhere else.