FTP, identify this type of engine named for its German discoverer.
It consists of a triangular rotor encased in an oval-shaped housing.  The rotor's three points are flush with the housing, and the three compartments created are where fuel is injected, ignited by a spark plug, and combusted to turn the rotor, which is connected to the main drive shaft.  It is useful as an alternative to traditional internal-combustion engine designs that use pistons, but it is limited by its low-fuel efficiency and high exhaust output.  FTP, identify this type of engine named for its German discoverer.
It consists of a triangular rotor encased in an oval-shaped housing.  
Wankel rotary engine (prompt on "rotary engine")