What about an air-cooled rotary?

I think this would be a great solution to aircraft propulsion as it has the opportunity to be:
1.  Lighter
2.  Less cooling drag
3.  Simpler – no water pump or water radiator.
4.  More reliable - With cast rotors and aluminum/magnesium housings, it should be immune to the excessive thermal expansion issues of an air cooled piston engine.

I would image rotor housings with cooling fins similar to air-cooled cylinders and no water jackets.  The front, center, and rear housing would also be covered with cooling fins.  The center housing would likely have air cooling passages from top to bottom, and maybe a larger space between the front and rear rotors to allow more cooling air flow.

The engine would have baffles around it to keep cooling air traveling through the fins.

The engine metal temperature would likely be higher than water cooled.  This may force the use gaskets instead of “O” rings between the rotor housings and the front/middle/rear housings.

Oil Cooling duty would likely be increased with the higher metal temps.

So who has a foundry and the investment castings….

mitch...back to lurker mode...