Whenever I drop by DA to get a prop for the 50 it seems they give me a 22-10 or 8. The recommendation for the DA-50R is 22-8 to 22-12 or 23-8 to 23-10. For the bigger props they use carbon fiber props since they are thinner but more efficient.

The chinese 40s and 26 I have used need a lot of break-in. I don't start seeing the power I would like out of them until around three gallons of fuel. So lately I built a giant big stick to break-in these engines. I might as well have some fun while they are breaking in.

I am not too much of a fan of 50CC on 1.60 sized aircraft. I have two that are done that way. They fly heavier with a higher landing speed. The 540 with the OS 160 is a really sweet flying plane.