Pe, I had to laugh at your comment about Americans and RPM, its so true! I have the MVVS 58 Prosport and it turns a NX 24x8 at 6300 RPM on a pitts muffler. I used to think RPM was the "Holly Grail" , however, over time ,I have found that with practice I can do more with less. I think my 58 is better suited for a 24x10, less static rpm, but overall it provided better performance in my current 30% YAK. I was told to try and prop the 58 for around 6100 rpm static. I dont know if this is a proven rule, but it seems to work fine for me.

I learned from flying electric that sometimes there is no set rule. You have to match the best diameter and pitch to both your motor and air frame through trial and error. The solution is to purchase more than one propeller and fly them all to see which one best suits your model airplane and motor. Some times the propeller that yields less than the desired rpm on the ground offers the best overall performance in flight.

Barry