Helicopter provided with a plurality of lift elements each provided with a respective tab for controlling the angles of incidence of its blades

1. A helicopter is provided with a main rotor ( 1 ) having at least two blades ( 10 , 20 ), each blade ( 10 , 20 ) being provided with attachment means ( 11 , 21 ) attaching it to a hub ( 2 ) of the rotor ( 1 ), wherein the helicopter is provided with one lift element ( 12 , 22 ) per blade ( 10 , 20 ), said lift element being provided with a tiltable tab ( 19 , 29 ), each lift element ( 12 , 22 ) being mechanically connected to a single blade ( 10 , 20 ) to vary the pitch of said single blade ( 10 , 20 ).

2. A helicopter according to claim 1 , wherein each lift element ( 12 , 22 ) is constrained to pivot with the blade ( 10 , 20 ) with which it is mechanically connected about a first longitudinal axis ( 13 , 23 ) for varying the pitch of said blade ( 10 , 20 ).

3. A helicopter according to claim 1 , wherein each lift element ( 12 , 22 ) is mechanically connected to a single blade ( 10 , 20 ) by a mechanical connection ( 14 , 24 ) that is independent of the hub ( 2 ) of the rotor ( 1 ), said mechanical connection ( 14 , 24 ) includes a first end (EX 1 ) that is secured to an attachment zone ( 200 ) of the blade ( 10 ), and said lift element ( 12 , 22 ) is secured to a second end (EX 2 ) of the mechanical connection ( 14 , 24 ) to enable the lift element ( 12 , 22 ) and the mechanical connection ( 14 , 24 ) to be constrained to pivot together about a flapping axis ( 303 ) of said lift element ( 12 , 22 ).

4. A helicopter according to claim 3 , wherein the root ( 12 ′) of each lift element ( 12 , 22 ) passes through an orifice in said second end of the mechanical connection to be attached to a rotary unit via an attachment ( 305 ) of a first type having one or two degrees of freedom.

5. A helicopter according to claim 1 , wherein each lift element ( 12 , 22 ) is mechanically attached to a single blade ( 10 , 20 ) by a mechanical connection ( 14 , 24 ), said mechanical connection ( 14 , 24 ) includes a first end (EX 1 ) secured to the attachment means ( 11 , 21 ) of the blade ( 10 , 20 ), and said lift element ( 12 , 22 ) is constrained to pivot about the flapping axis ( 303 ) of said lift element ( 12 , 22 ) with a second end (EX 2 ) of the mechanical connection ( 14 , 24 ) via a pitch hinge ( 16 , 26 ) enabling the lift element ( 12 , 22 ) to perform pivoting movement about a second longitudinal axis ( 17 , 27 ) for varying the pitch of the lift element ( 12 , 22 ).

6. A helicopter according to claim 5 , wherein the root ( 12 ′) of each lift element ( 12 , 22 ) passes through an orifice in said second end of the mechanical connection to be attached to a rotary unit via said pitch hinge ( 16 , 26 ).

7. A helicopter according to claim 3 , wherein said attachment zone ( 200 ) includes the attachment means ( 11 , 21 ) of the blade ( 10 ) and a segment of said blade, and said first end (EX 1 ) is secured to said attachment means ( 11 , 21 ).

8. A helicopter according to claim 3 , wherein said attachment zone ( 200 ) includes the attachment means ( 11 , 21 ) of the blade ( 10 ) and a segment of said blade, and said first end (EX 1 ) is secured to said segment.

9. A helicopter according to claim 3 , wherein said mechanical connection ( 14 , 24 ) is a bent bar.

10. A helicopter according to claim 3 , wherein said mechanical connection ( 14 ) comprises a bent bar ( 15 ) hinged to an intermediate link ( 100 ), the first end (EX 1 ) of the mechanical connection ( 14 ) corresponding to the first end zone ( 15 ′) of the bent bar ( 15 ) that is not connected to the intermediate link ( 100 ), the second end (EX 2 ) of the mechanical connection ( 100 ) being represented by the free end ( 100 ′) of the intermediate link ( 100 ) that is not connected to the bent bar ( 15 ).

11. A helicopter according to claim 1 , wherein the blades ( 10 , 20 ) being contained in a first plane (P 1 ) when they are not flapping, and the lift elements ( 12 , 22 ) mechanically linked to said blades ( 10 , 20 ) being contained in a second plane (P 2 ) when they are not flapping, said first and second planes (P 1 , P 2 ) coinciding.

12. A helicopter according to claim 1 , wherein the blades ( 10 , 20 ) being contained in a first plane (P 1 ) when they are not flapping, and the lift elements ( 12 , 22 ) mechanically linked to said blades ( 10 , 20 ) are contained in a second plane (P 2 ) when they are not flapping, said first and second planes (P 1 , P 2 ) being mutually parallel.

13. A helicopter according to claim 1 , wherein said rotor ( 1 ) includes stop means ( 30 ) for limiting the flapping of each lift element ( 12 ).

14. A helicopter according to claim 13 , wherein said stop means ( 30 ) is provided with a top plate ( 31 ) lying over a top portion ( 3 ) of the hub ( 2 ) of the rotor ( 1 ), at least in part, said top portion ( 3 ) being situated on the side of the hub ( 2 ) that is remote from a fuselage of the helicopter.

15. A helicopter according to claim 14 , wherein each lift element ( 12 ) is mechanically connected to a blade ( 10 ), said stop means ( 30 ) includes one actuator ( 32 ) per lift element ( 12 ), each actuator ( 32 ) being arranged between said top plate ( 31 ) and a corresponding lift element in order to limit the flapping of that lift element ( 12 ).

16. A helicopter according to claim 14 , wherein said stop means ( 30 ) are provided with a bottom plate ( 33 ) covering a bottom portion ( 4 ) of the hub ( 2 ) of the rotor ( 1 ), at least in part, said bottom portion ( 4 ) being situated on the side of the hub ( 2 ) that faces the fuselage of the helicopter.

17. A helicopter according to claim 1 , wherein said main rotor ( 2 ) includes a pitch control swashplate ( 50 ) having a rotary plate ( 51 ) and a non-rotary plate ( 52 ), each tab ( 19 , 29 ) being connected to said rotary plate ( 51 ) by a main rod ( 40 ).

18. A helicopter according to claim 1 , wherein said rotor ( 1 ) has at least one actuator ( 70 ) per tab ( 19 , 29 ) arranged on the associated lift element in order to adjust the tilt of the tab ( 19 , 29 ) relative to the lift element to which it is attached.

19. A helicopter according to claim 16 , wherein said actuator ( 70 ) is powered electrically by slip rings ( 71 ) arranged on a rotary mast ( 5 ) of the rotor ( 2 ).

20. A helicopter according to claim 18 , wherein said actuator ( 70 ) is powered electrically via an electricity generator comprising a stator arranged inside a rotary mast ( 5 ) of the rotor ( 2 ).

21. A helicopter according to claim 18 , wherein said actuator ( 70 ) is controlled by wireless transmission means.

22. A helicopter according to claim 18 , wherein said actuator ( 70 ) is a piezoelectric actuator generating angular movement.

23. A helicopter according to claim 1 , wherein each lift element ( 12 , 22 ) is managed in functionally and mechanically independent manner so as to vary the pitch of a single blade individually.

24. A method of varying the pitch of a blade of a helicopter rotor having at least two blades, wherein a lift element ( 12 , 22 ) provided with a tab ( 19 , 29 ) that is connected solely to said blade ( 10 , 20 ), and the lift generated by said lift element ( 12 , 22 ) is adjusted by tilting the tab ( 19 , 29 ) relative to the lift element so that the lift element ( 12 , 22 ) performs a flapping movement to entrain the blade ( 10 , 20 ) to which it is connected in pivoting about a first longitudinal axis ( 13 , 23 ) for varying the pitch of said blade ( 10 , 20 ).