Helicopter rotor comprising elastomer joints

A helicopter rotor (1) comprising elastomer joints, which comprises a main shaft (2) provided upperly with a hub (5) in the form of a flat polygonal member extending radially outwards from said main shaft (2) and rigid therewith, said hub (5) comprising a plurality of through apertures (40) closed outwardly by a transverse arm (41) and supporting, at each of said apertures (40), a blade (6) extending outwards in a substantially radial direction and connected to said hub (5) by means of a yoke (42) extending through the relative said aperture (40) and connected to the relative said arm (41) by means of an elastomer joint (43);

• lever means (76) being rigidly connected to each of said yokes (42) and to each of said blades (6) in order to vary the pitch thereof;
• characterised in that said yoke (42) is constituted by a single substantially U-shaped piece comprising an intermediate curved portion (45) extending through the relative said aperture (40) and disposed with its concavity facing the relative said arm (41), first and second connection means (58-60, 66-67) being provided for connecting each of said elastomer joints (43) to the relative said intermediate curved portion (45) and to the relative said arm (41) respectively;
• and in that said lever means (76) define, between two opposing arms (44) of the relative said yoke (42) and together with said second connection means (66, 67), a chamber (91) housing a device (92) for controlling the flapping movements of the relative said blade (6);
• said control device (92) comprising two rocker members (95, 105) supported by said lever means (76) and rotatable, against the action of resilient means (110) about a substantially horizontal axis (93) perpendicular to the axis of the relative blade (6);
• each of said rocker members (95, 105) being arranged to cooperate with a relative first stop surface (71) carried by said second connection means and a second stop surface (74) carried by said lever means.