Four rotors on one e-shaft seems to be the upper limit.
600 HP for a normally aspirated (NA) four rotor is doable.
Higher HP if turbo charged. Up to 1600 HP. Cooling is critical.
I recommend buying this book. http://www.rotaryeng.net/cooling.html

Thanks - I'll order the book.

Is cooling the barrier to greater than four rotors? Can one link complete
four rotor engines together in series through an interlink shaft?

For certified rotaries see http://www.mistral-engines.com/

I will contact Mistral and see what they can do in terms of additional turbo
charging. Their 360 turbo puts out 280 Hp (from their chart) at 25,000 ft.
An extrapolation of the power output line puts it at 200 Hp at somewhere
around 35,000 ft (assuming a linear extrapolation?) or 66% of the baseline
300 Hp normally aspirated engine on which it is based.

A further extrapolation is just about 105 Hp at 50,000 ft or 35% of the
baseline. Very close to our minimum needs for that altitude.

If one adds a second turbo, presumably larger, and does so in series,
properly waste gated for low altitudes, is this a necessarily difficult
technical and costly challenge?

Cheers,
Brian
--------------------

Brian Feeney
DreamSpace and The da Vinci Project
bfeeney@davinciproject.com
http://www.davinciproject.com

Not in series as the torque from the rear engine must be transmitted through
the front engine e-shaft as well as its own torque. Nothing to do with cooling.

Mistral is not in the biz of custom engines. You are going to need to hire
your own well qualified engineers to do this kind of work. IMHO you will need at least three series turbos to reach 50,000 feet. Not an easy project. My wild ass
guess it will take close to $500,000 U.S.. A good engineer cost a lot of money.
Plus a high altitude dyno chamber is not available as far as I know. It is for jet engines but not shaft driven engines.

Paul Lamar