Patent ID: 9475578
Filing Date: 2016-10-25
CPC Classification: B64C

Claim Text:
1. A rotary wing aircraft with a fuselage and a vertical midplane in an x-z plane through said fuselage, said fuselage having a width (w a main rotor mounted on top of said fuselage, a tail boom mounted on a rear end of said fuselage, a tail rotor in a rotor duct of a shroud mounted to a rear end of said tail boom, a vertical fin projecting from an upper transition region of said shroud essentially along the x-z plane towards the top, said upper transition region having a left hand and a right hand upper transition edge between respectively a left hand and a right hand annular surface around the rotor duct of the shroud and the vertical fin, a bumper projecting from a lower transition region of said shroud essentially along the x-z plane opposite to the top, said lower transition region having a left hand and a right hand lower transition edge between respectively the left hand and the right hand annular surface around the rotor duct of the shroud and the bumper, and upper leading edges of said vertical fin and of said shroud and left hand and right hand trailing edges of said shroud, wherein a projection of the upper transition edge to the x-z plane is defined by a spline curve through points Pi (i=1 . . . 5) defined by their coordinates (xi, zi) relative to a Fenestron-Rotor's centre according to the following table: where for all the points Pi (i=1 . . . 5) the following constraints must be fulfilled: x1<x2<x3<x4<x5; z1≦z2≦z3; and z5≦z4≦z3.