Flyingmonk wrote:
In addition, Glen Ryerson, who built and flown the CH-7 "Miss Nina" in
PA, didn't have any trouble tracking and balancing his blades.

Good ol'Glen. He used to be a Mini-500 supporter too, even had a pic on
his site of Fetters sitting in Miss Nina. And then the big picture
started to emerge.

I found this comment in the Mini-500 owners list:
"I am working on further improving the airflow in the engine compartment
for cooling, this is a still a problem."