Ducted open rotor apparatus and method

A structure for shrouding a propeller of a turboprop engine used with a mobile platform, the structure comprising:

• a propeller duct having a tapering aerodynamic shape that forms a shroud for said engine;
• a circumferential ring supported within said propeller duct so as to closely circumscribe a plurality of outermost tips of said propeller;
• said circumferential ring including a surface, with said surface including sound attenuating material secured thereto for attenuating noise generated by vortices created at said outermost tips of said propeller during operation of said engine;
• and
• a plurality of circumferentially spaced apart structural mounts for supporting said propeller duct from a portion of said mobile platform, wherein at least a pair of said structural mounts is adapted to directly couple to at least one spar of a mobile platform wing.

A method for attenuating noise generated by a plurality of blades of a propeller of a turboprop engine, comprising:

• forming an aerodynamic duct that encloses said propeller;
• within said aerodynamic duct, fixedly supporting a circumferential ring having a sound attenuating quality that closely surrounds outermost tips of said propeller blades, to attenuate noise associated with vortices created at the outermost tips of said propeller,
• the circumferential ring having a plurality of laterally spaced structural mounts adapted to secure the circumferential ring to at least one spar with a wing of a mobile platform;
• and
• coupling said structural elements to the at least one spar of the wing.