The rotor blade (6) has a specific aerodynamic profile as a function of relative blade length with a blade chord and blade twist. The cross-sectional plane defined by the transition from the blade attachment to the blade tip is located in range between 0.8 and 0.98 of the blade length, while the blade chord in the cross-sectional plane of the tip is at least 60 percent of that in the cross sectional plane of the transition. The blade twist of the profile in the tip cross-sectional plane is greater than that in the transition cross-sectional plane.
