However.......

Just as modelers who fly 4cycle engines would be well advised to purchase and learn to use tachometers,
modelers who fly electric would benefit tremendously from using an amp meter or watt meter for checking the performance of their power system (prop, motor, esc, and battery).

Just recently, a couple of us helped out with the maiden of a new plane. One check was to plug a wattmeter into the sucker and do some runs with a handful of props. All of them were the same diameter and pitch as it turned out. Also as it turned out, one of the props was rejected for overloading the system and one was rejected for not even loading the system worth spit. Could any one of us "hear" those rejects rpms and thrust? Nope

We wound up selecting the first prop to use for the flight tests from it's matchup to the factory specs that came with the motor. The testing of that handful of props took very little time. Removing a prop and placing the next one on takes how long? Running them up takes seconds. Writing down the numbers takes longer than the couple of seconds each runup takes.

Of course there were 3 of us doing the testing, so it took longer. (Ever hear the old saw, "If one programmer takes one day to code the program, it will take 3 programmers 3 days to code the program." That how lots of things work in real life.)

What we got out of that was one guy being amazed that a handful "of the same props" performed so differently and another guy who now does that test on every new plane in his vast collection, and who is also going back to test his "old" ones.

Beginners would probably learn a bunch from doing the same testing just once. Get more than one prop to use and borrow a watt meter if needbe. It's amazing what one can learn from doing and how little you get from just asking "what's the best prop for that motor." Which seems to be what everyone does. I guess they don't want to spend the money to buy more than one prop.