Aerodynamic, blunt aft body

摘要

An aerodynamic blunt aft body (10) of a helicopter fuselage with two strakes (7, 8) along an aft surface (9) and/or respective left hand and right hand side fuselage surfaces (5, 6). Each strake (7, 8) is defined by first and second intersection lines (3, 4) resulting from intersections of horizontal planes (z) with the surface of the aft surface (9) or the respective left hand and right hand side fuselage surfaces (7, 8). The strakes are defined by a two or three dimensional spline (12) from the surface (2) towards the aft surface (9) inside said first and second intersection lines (3, 4) and inside the bounding box (15).

主权项

1. An aerodynamic blunt aft body of a helicopter fuselage with a longitudinal middle plane, the helicopter fuselage comprising left hand and right hand side fuselage surfaces essentially parallel to the longitudinal middle plane,
an aft surface between the left hand and right hand fuselage surfaces with an essentially normal alignment of the aft surface to the longitudinal middle plane, and at least two stakes provided along the aft surface and/or the respective left hand and right hand side fuselage surfaces as an essentially mirrored image of each other with respect to the longitudinal middle plane, wherein each respective strake is defined by:
an upper plane normal to the longitudinal middle plane and passing through a junction between the aft surface and a tail boom,a lower plane normal to the longitudinal middle plane and being placed at 10% of the helicopter width above the lowest horizontal station of the fuselage,a first intersection line defined by a respective first set of points between the upper plane and the lower plane, wherein at the respective first set of points, local tangents to the respective surface lying in a horizontal plane are inclined at an angle of 15° relative to the central plane; anda second intersection line defined by a respective second set of points between the upper plane and the lower plane, wherein at the respective second set of points, local tangents to the respective surface lying in a horizontal plane are inclined at an angle of 60° relative to the central plane; each respective strake being defined within a respective bounding box with a height of 13% (+/−7%) offset relative to the fuselage width with a two or three dimensional spline towards the aft surface inside the first and second intersection lines.