The increase in the recess depth T and in the shoulder depth B also results in an increase in the height of the blade root
26. Lengthening the blade root
26 necessarily also increases the blade weight, which would lead to increased centrifugal forces and thus to increased mechanical loads on the rotor
20. It is therefore particularly advantageous for at least a portion of the weight increase which is caused by the extension to be counteracted again by suitable measures. The measures comprise material being cut away on the rotor blade
25 in the area of the blade root
26 by the provision of cutouts at points which are not critical to the mechanical strength. A first preferred type of cutout is an elongated hole
19, which passes through the blade root
26 in the circumferential direction and extends in the radial direction. The elongated hole
19 is in this case arranged in the thin section of the blade root
26, and is located in the centre, between the two shoulders
24. A second preferred type of cutout is rounded depressions
29, at the edge, on the lower face of the lower part
27 of the blade root
26. Both types of cutouts
19,
29 may optionally be implemented individually or may be combined with one another, in order to achieve the desired reduction in weight by reducing the amount of material.