Thanks for your comments, JP.

That's what I like in electric. Almost everything can be measured and quantified and yet, the complete system (the flying model) is far from trivial to master and we still have large room for personal preferences and optimisation.

Having tried a few props for my setup, I didn't find yet a prop that loads the motor to its maximum power (about 350W out of 550W). would you agree that it would be best (in terms of performance) to enlarge the prop (diameter and pitch) until it is close to (say) 500W on a static test?

Yoav