http://youtu.be/pBA8bxQQhgQ
Link to JGM Designs PSRU test flight video.
Here he shows an MVVS 45 / Evolution engine turning a much larger 24in three blade prop at a ratio of 1.6:1. So again, high rpm motor with a reduction drive to turn a scale prop with authority. Normally this engine could not fly this plane nearly as well and would use a much smaller two blade prop.
Check out his other videos, pretty nice machined parts.