Ducted open rotor apparatus and method

A propulsor apparatus for a mobile platform, for example an aircraft is provided. The propulsor apparatus includes an aerodynamically shaped propeller duct that houses at least a portion of a turboprop engine, and fully houses a propeller driven by the engine. Inside the propeller duct is a circumferential ring that closely surrounds the propeller such that only a small clearance is provided between the outermost tips of the propeller blades and an inner surface of the circumferential ring. The circumferential ring includes sound deadening material that attenuates noise generated by the tip vortices created at the outermost tips of the propeller blades. The propeller duct and circumferential ring are supported by a plurality of structural rods that couple to structure of the mobile platform, for example to the spars within a wing of an aircraft. The apparatus and method significantly reduces the noise associated with a turboprop engine.