I'd love to have a good tangential solution.  Mistral had developed one before they declared bankruptcy.  But, their engineer told me that they were loosing at least 5 HP with it.  So, if I am ignorant, I am happy to be corrected.

You could very well be right; but am I willing to give up 5 hp for a reliable compact way to a quiet engine? Yup! 

I presume that you have shared your design before?  Can I find in in the archives?  I am not a welder, so I have to hire any welding that needs to be done, so the cost of an Inconel device will be quite pricy, I presume.

Should be in the archives. If not, I think I’ve scanned my drawings and have them stored somewhere. You’ll need a good welder and some money. I think mine was $1950 for the 3-rotor; and it has a few details like internal vanes. The drawings will cost only $600 (ju-u-u-st kidding).

Al