RE: Bragging about the .55 AX
It sounds like the general consensus is that the OS engines are definitely top quality, and they are, start easy, and they do, and break in very well, which they also do.
As for operating RPM is concerned, those numbers are so far off base, it's not funny. They are like gas mileage numbers you see on a new car. And, as the manufacturers say, for comparison use only. So, let's lie and everyone will swear by it, but expect much less in reality.
For the optimum prop on a given engine, that will give you the best performance in both accelleration, vertical power, and noise, well, the best RPM will usually be found by trial and error, but will never equal what they say it will be in the specs.
So, use those numbers "for comparison only" but experiment with props to give you the best performance based on your needs. And remember... noise does NOT equal power.
CGr.