A unique, fuel flexible engine is being developed. It is a true rotary engine in that the motion of the rotors is truly rotational and does not have any reciprocating or epitroichoidal motion. The engine has an external precombustion chamber with main combustion occurring in the engine itself - this makes the engine fuel flexible. A physical working model has been constructed, run on compressed air and has demonstrated successfully the design concepts. In this paper the engine design, physical working model construction and operation as well as the results of computed engine performance are presented.