"Mortimer Schnerd, RN" wrote

You want bigger blades; not shorter. The rasping noise the Red Barons
make is
the blade tips going supersonic.

Close. It is the air over the blades being accelerated to supersonic
speeds.

Shorter blades go even faster.

Shorter blades turned at the same RPM would not have supersonic airflow.

Personally, I find that rasp is like music.

I don't mind a certain amount of rap. Theirs is too much. IMHO
--
Jim in NC