Overview
The theoretical advantage is that there is no high-speed contact area with the engine walls, unlike in the Wankel engine in which edge wear is a problem. However, the combustion chambers are divided by blades which do have contact with both the walls and the rotor, and are said to have been difficult to seal due to the perpendicular intersection with the moving impeller.
Sarich worked on the concept for a number of years without ever producing a production engine. A prototype was demonstrated, running on the bench with no load. The engine, which produces very high revs, has only one moving part. It can supposedly be powered by compressed air or steam and can be run as a pump.
Read more about this topic: Orbital Engine