Ok Thanks for the help so far. The Airplane I’ve planning to but the 3 blade props on is a Grumman goose which is 250 cm in wingspan, and I think the weight on the plane is approximately 7 -9 kg. The props I use now are 14 x 7 2-bladed.

Another thing I been wondering about is the relation between the material the prop is made of and the performance it carries out. How big an impact on that performance does this have?