Helicopter rotor

1. A rotor for a helicopter, comprising:

a hub rotating about a first axis, the hub comprising a radially inner cylindrical body and a radially outer tubular portion;

a number of blades projecting from said hub in respective longitudinal directions lying in a plane crosswise to said first axis, each of said number of blades being connected to said hub so as to be movable at least about a second axis crosswise to said first axis and to one of said respective longitudinal directions; and

a number of damping devices for damping vibration of said helicopter, and each interposed between one blade and said tubular portion of said hub;

characterized in that each said number of damping devices comprises a separate plate member fixed, on one side, to said hub, and connected, on an opposite side, to said blade by elastic means; and in that said separate plate member, during movement of said blade, is flexible about a third axis parallel to said second axis and located close to the second axis;

each said plate member being V-shaped, and comprising:

a tip connected to the relative said blade;

two diverging lateral branches originating from said tip; and

an end, opposite to said tip, the tip being defined by free ends of said lateral branches and being connected to said tubular portion of said hub;

said lateral branches of each said plate member being spaced from each other and defining together with said tip a cavity for receiving part of said tubular portion of said hub.

2. A rotor as claimed in claim 1 , characterized in that said third axis is coaxial with said second axis.

3. A rotor as claimed in claim 2 characterized in that said hub remains substantially unbent about said second axes and third axes, during movement of each said blade and each said plate member respectively about respective said second and third axis.

4. A rotor as claimed in claim 1 , characterized in that said plate member is connected to said elastic means by an articulated connection.

5. A rotor as claimed in claim 4 characterized in that said hub remains substantially unbent about said second axes and third axes, during movement of each said blade and each said plate member respectively about respective said second and third axis.

6. A rotor as claimed in claim 1 , characterized in that said plate member is V-shaped, the tip of which is connected to the relative said blade, and the end of which, opposite said tip, is connected to said hub.

7. A rotor as claimed in claim 6 , characterized in that said plate member is fixed peripherally to said hub, and defines a cavity for receiving part of the hub.

8. A rotor as claimed in claim 7 characterized in that said hub remains substantially unbent about said second axes and third axes, during movement of each said blade and each said plate member respectively about respective said second and third axis.

9. A rotor as claimed in claim 6 characterized in that said hub remains substantially unbent about said second axes and third axes, during movement of each said blade and each said plate member respectively about respective said second and third axis.

10. A rotor as claimed in claim 1 , characterized in that said blade comprises, close to said hub, a frame-like portion defining a seat for housing a relative said damping device.

11. A rotor as claimed in claim 10 characterized in that said hub remains substantially unbent about said second axes and third axes, during movement of each said blade and each said plate member respectively about respective said second and third axis.

12. A rotor as claimed in claim 1 characterized in that said hub remains substantially unbent about said second axes and third axes, during movement of each said blade and each said plate member respectively about respective said second and third axis.

13. A rotor for a helicopter, comprising:

a hub rotating about a first axis, the hub comprising a radially inner cylindrical body and a radially outer tubular portion;

a number of blades projecting from said hub in respective longitudinal directions lying in a plane crosswise to said first axis, each said blade being connected to said hub so as to be movable at least about a second axis crosswise to said first axis and to the relative said longitudinal direction; and

a number of damping devices for damping vibration of said helicopter, and each interposed between a respective said blade and said tubular portion of said hub;

characterized in that each said damping device comprises a separate plate member fixed, on one side, to said hub, and connected, on the opposite side, to the relative said blade by elastic means; in that said plate member, during movement of said blade, is flexible about a third axis parallel to said second axis and located close to the second axis; and in that said hub remains substantially unbent about said second axes and third axes, during movement of each said blade and each said plate member respectively about respective said second and third axis;

each said plate member being V-shaped, and comprising:

a tip connected to the relative said blade;

two diverging lateral branches originating from said tip; and

an end, opposite to said tip, the tip being defined by free ends of said lateral branches and being connected to said tubular portion of said hub;

said lateral branches of each said plate member being spaced from each other and defining together with said tip a cavity for receiving part of said tubular portion of said hub.