| 主权项 |
1. A noise reduced and performance improved rotor blade for a helicopter, comprising three aerodynamic sections along a blade span between a leading edge and a trailing edge, with an inner rectangular or tapered section, a blade root for connecting the blade to a rotor hub rotating about a rotor axis of the helicopter, a middle section adjacent to the inner section and opposed to the blade root, the leading edge of the middle section being forward swept over a distance along the blade span and the trailing edge of the middle section being forward swept over a distance along a corresponding span of the blade, and an outer section between the middle section and a blade tip, the outer section being back swept along a further part of the span of the blade, the inner section extending from radii R0 to R1, R0 being in a range from R0=0.29·R−14%·R to R0=0.29·R+4%·R and R1 being in a range from R1=0.8·R+10%·R to R1=0.8·R−14%·R, the middle section extending from the R1 to R2 with R2 being in a range from R2=0.875·R+10%·R to R2=0.875·R−10%·R, the outer section extending to the blade tip with a distance R from the rotor axis, the middle section and outer section having a twist decreasing in a multi-linear or non-linear progression along the span of the rotor blade, wherein R2 corresponds to a most forward-swept portion of the blade and the trailing edge throughout the outer section is linear. |
