High performance blade for helicopter rotor

A high performance blade for a helicopter rotor having a hub, comprising:

• an end profile at one end of said blade disposed perpendicularly to the leading edge of the blade and a root profile located between said end profile and the other end of said blade,
• said end profile and said root profile defining along the major part of the length of the blade an aerodynamic surface produced by profiles of substantially constant chord,
• each profile having a maximum radius of curvature Ro at the leading edge defined approximately by the expression Ro=1.7 C.e.sup.2.sub.max', in which C represents the chord and e.sub.max the maximum relative thickness of the profile and a point of minimum curvature positioned on the lower surface at a distance from the leading edge approximately equal to 20% of the length of the chord,
• said aerodynamic surface having an aerodynamic twist which increases linearly from the end profile to a maximum at said root profile, said twist then being reversed to become zero at said other end,
• the angle of twist formed by a zero lift chord of a profile of said aerodynamic surface and a plane of reference passing through the centre of the hub of the rotor is, for the end profile, approximately equal to 0.2 degrees,
• said end profile having a maximum relative thickness equal to about 7% of the length of its chord, and a difference of twist with respect to the root profile equal to about 7.degree.,
• the distance separating said end profile from said root profile being approximately equal to 80.degree. of the length of the span of the blade, and
• the maximum relative thickness of the roof profile being approximately equal to 12% of the length of its chord, said relative thickness being maintained constant over a distance approximately equal to 57% of the length of the blade, and decreasing thereafter linearly towards the end profile.