Patent ID: 8056851

Claim:
A helicopter antitorque tail rotor ( 3 ), comprising a shaft ( 5 ) rotating about a rotation axis (A), at least two blades ( 6 ) extending along relative longitudinal axes (B) crosswise to said rotation axis (A), and a hub ( 7 ) for connecting said shaft ( 5 ) to said blades ( 6 ); each blade ( 6 ) comprising, in turn,: a leading edge ( 8 ) and a trailing edge ( 9 ) opposite each other and elongated along relative longitudinal axis (B); said trailing edge ( 9 ), in use, interacting with the air current after said leading edge ( 8 ); a first and a second surface ( 12 , 13 ) opposite each other and extending between said leading edge ( 8 ) and said trailing edge ( 9 ); a radially inner first end ( 10 ) with respect to a rotation axis (A) of said blade ( 6 ); a radially outer second end ( 11 ) opposite to said radially inner first end ( 10 ); and a root portion ( 14 a ) comprising said radially inner first end ( 10 ) and spaced from said outer second end ( 11 ) along said longitudinal direction (B); said root portion ( 14 a ), when sectioned in a plane perpendicular to said leading edge ( 8 ) or said trailing edge ( 9 ), comprising a profile (G) asymmetrical with respect to a chord (P) joining said leading edge and said trailing edge ( 8 , 9 ) in said plane; characterized in that the points of first ends ( 10 ) of said blades ( 6 ) are located at a distance from said rotation axis (A) ranging between 10 and 25% of the maximum distance between said rotation axis (A) and the points of said second ends ( 11 ) of said blades ( 6 ).