FIELD: mechanical engineering; angular control of blades. SUBSTANCE: mounting portion of blade includes stem and projection at its end with partially spherical contact surface directed towards blade fin; locating area in hub bead with partially cylindrical contact surface directed radially towards center of hub; both surfaces are located in such position that they are engageable through linear contact, thus keeping the position of line constant irrespective of angular position of blade relative to hub. EFFECT: enhanced efficiency. 8 cl, 9 dwg
