Orbital engine

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Drawing of an orbital engine from Ralph Sarich's patent application
Drawing of an orbital engine from Ralph Sarich's patent application

The Sarich orbital engine is a type of internal combustion engine, featuring rotary rather than reciprocating motion of its internal parts. It differs from the conceptually similar Wankel engine by using a shaped rotor that rolls around the interior of the engine, rather than having a trilobular rotor that spins "in place".

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[edit] Overview

The advantage is that there is no high-speed contact area with the engine walls, unlike in the Wankel where 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.

The orbital engine was invented in 1972 by Ralph Sarich, an engineer from Perth, Australia, who worked on the concept for years without ever producing a production engine. A prototype was demonstrated, running on the bench with no load.

[edit] Technical problems

The Sarich Orbital engine has a number of fundamental, unsolved problems that have helped keep it from becoming a practical engine. Amongst these are key components that cannot be cooled and others that cannot readily be lubricated. It is very susceptible to overheating. At one press conference where Ralph Sarich presented the engine, automotive engineer Phil Irving (designer of the Vincent Motorcycle and Brabham Formula One engines) pointed out a number of technical reasons why the engine would not work (eg, excessive pressure in contact areas).

[edit] Political problems?

A conspiracy theory known to almost all mechanically-inclined Australians holds that the patent for the Sarich Orbital engine was exclusively licensed and then suppressed by Ford, perhaps in order to prevent a drop in oil prices, or simply to maintain the value of existing manufacturing facilities, should the highly efficient engine displace conventional piston engines.

More widely, the case is seen as a defining example of a syndrome of 'good invention, poor development' felt by many nations, with an unusually high number of good inventions becoming successful products only once they have been moved off-shore, and with economic returns on them not being returned to the nation's economy.

It needs to be noted that novel engine types are conceived in very great numbers, but overcoming the technical difficulties of producing an impressive prototype is exceedingly rare, even where investment substantially exceeds the cost of machining and assembling components. In other words, novel designs tend to be incomplete designs.

[edit] See also