Patent ID: 9061758
Filing Date: 2015-06-23
Classification: B64C

Abstract:
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 R 0 to R 1 , R 0 being in a range from R 0 =0.29·R−14%·R to R 0 =0.29·R+4%·R and R 1 being in a range from R 1 =0.8·R+10%·R to R 1 =0.8·R−14%·R, the middle section extending from the R 1 to R 2 with R 2 being in a range from R 2 =0.875·R+10%·R to R 2 =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 R 2 corresponds to a most forward-swept portion of the blade and the trailing edge throughout the outer section is linear.