ORIGINAL: Espresso-Outfitters
From the experts I've discussed this with, some of which have 30+ years in the "real" aircraft design field, only 20% of any prop at best is actually doing anything, the rest is waste.
Maybe we are not talking about exactly the same thing here, but according to some formulas I have played with from design books, and converted to software, efficiency factors tend to be in the 70% to 80% range when filled with real-world performance data. That refers to the amount of engine horsepower that is converted to thrust. I'm not arguing here. Perhaps you could specify in more detail what your statement means? Are you talking about efficiency, or how much of the span of the blade is moving fast enough to produce a lot of thrust?