In a rotary-wing aircraft main rotor assembly, including a rotor hub carried on a rotor shaft and rotatable about a fixed axis of rotation and at least two rotor blades having each its root connected to said hub via mechanical attachment means including connecting joints allowing flapping movements of said corresponding blade for rotation in opposite directions in a substantially vertical plane, about a flapping axis, substantially perpendicular to an axial plane of symmetry of said corresponding blade at rest,
- a device for limiting said flapping movements of said rotor blades comprising
- for each blade, upper abutment means for limiting the upward rotary movement of said corresponding blade beyond a first predetermined position in said substantially vertical plane, said upper abutment means comprising:
- a bent lever rotatably mounted on a pivot secured to a top part of said rotor hub and having a first arm the free end of which forms an abutment part and a second arm the end of which carries a predetermined weight,
- a spring connecting said bent lever to said top part of said hub and being operable to normally rotate said bent lever in one direction and hold said bent lever in a predetermined position when the angular velocity of said rotor hub is below a predetermined value, said predetermined weight being operable to effect rotation of said bent lever in the opposite direct, beyond said predetermined position, when said angular velocity of said hub exceeds said predetermined value,
- and bearing means carried by one of the two elements comprising said corresponding blade root and said corresponding attachment means and being engageable with said abutment part of said corresponding bent lever when said bent lever is held in said predetermined position to thereby prevent the upward rotary movement of said blade beyond said first predetermined position in said substantially vertical plane wherein said corresponding pivot is parallel to said hub rotation axis near said blade axial plane of symmetry, and said first and second arms of said bent lever each rotates in a substantially horizontal plane, said first arm of said bent lever extending substantially parallel to said blade axial plane of symmetry when said bent lever is held in said predetermined position, and wherein said device also comprises lower abutment means for limiting the downward rotary movement of said corresponding blade beyond a second predetermined position in said substantially vertical plane, said upper abutment means comprising
- a reciprocal ring, common for all said rotor blade and slidably mounted around said rotor shaft in a plane perpendicular to said hub rotation axis,
- and for each rotor blade a bearing slide carried by one of said two elements, comprising said corresponding blade root and said corresponding attachment means, and being engageable with said reciprocal ring so that, when said corresponding blade is rotated downwards and said velocity is below said predetermined value, said corresponding blade tends to push inwards said reciprocal ring, which in turn tends to push upwards at least another of said rotor blades, at least one of said other blades being prevented from rotating upwards by its upper abutment means when said second predetermined position in said substantially vertical plane is reached by said corresponding blade.