Jim,
Since you have ridiculed and made fun of my stating APC props will dependably run over 20,000 rpm on at least a half dozen occasions.

Here is a video of a APC prop wrung out at over 20,000.

So you can let all your rocket science buddies that you listed that think the same thing they are wrong like yourself and that it does work perfectly.

We have yet to throw a blade off a APC prop and several of us have been running these props on our test stands for 3-4 years without a single failure.

Carbon Props are not a requirement whatsoever for making a test stand that is functional over 20,000 rpm dependably.

If you think that a very brief period of time at 20, 200 RPM is the same thing as running an engine over the 21,000 RPM number you quoted, keep doing this. I hope you & "we" will be honest enough to tell everyone when the prop blows up!

Jim Allen

LOL !

Right. I promise I will post the pictures of the carnage.

That day may come when one lets loose, no doubt definitely could happen. We are certainly well about the recommended rpm for one of these props. You think 21,000 might be the magic number ? Certainly above where the engine is safe at. Lol.