Rotorcraft blade provided with a radial segment and with at least one forwardly- and/or rearwardly-swept segment

1. A rotorcraft blade provided in succession, along a pitch axis of the blade going from a root of the blade fastened to a rotorcraft rotor hub towards a free end of the blade remote from said hub, the rotorcraft blade comprising a radial segment followed by a swept segment, said swept segment being provided with at least one of a forwardly-swept segment and a rearwardly-swept segment said blade having a single spar extending from said blade root, said radial and swept segments each having a respective leading edge and trailing edge, and also a top skin and a bottom skin, wherein said single spar has a radial spar in the radial segment, and then divides where the radial segment becomes the swept segment so as to form in said swept segment both a primary spar and a secondary spar.

2. A blade according to claim 1 , wherein said single spar is made up of unidirectional inorganic fibers.

3. A blade according to claim 2 , wherein said radial spar and the secondary spar comprise unidirectional inorganic fibers extending along the pitch axis.

4. A blade according to claim 2 , wherein said primary spar comprises unidirectional inorganic fibers directed parallel to the leading edge of said swept segment.

5. A blade according to claim 1 , wherein the radial spar is arranged in the leading edge of the radial segment.

6. A blade according to claim 1 , wherein said primary spar is arranged in the leading edge of the swept segment.

7. A blade according to claim 1 , wherein said secondary spar is arranged in a central portion of the swept segment, said central portion extending between the leading edge and the trailing edge of said swept segment.

8. A blade according to claim 1 , wherein said secondary spar is an elongate element of height extending from the bottom skin to the top skin of the swept segment.

9. A blade according to claim 1 , wherein said secondary spar comprises a top secondary spar disposed flat against the top skin of said swept segment.

10. A blade according to claim 1 , wherein said secondary spar comprises a bottom secondary spar disposed flat against the bottom skin of said swept segment.

11. A blade according to claim 1 , wherein said secondary spar is arranged in alignment with said radial spar.

12. A blade according to claim 1 , wherein said secondary spar is arranged in alignment with the leading edge of the radial portion.

13. A blade according to claim 1 , wherein for a portion of the single spar being made up of the radial spar extended by said secondary spar, said portion has a length (L 2 ) lying in the range 90% to 95% of the total length (L 1 ) of the blade (P).

14. A blade according to claim 1 , wherein said single spar includes first reinforcement reinforcing at least part of the top skin of the blade (P) between said primary spar and said secondary spar.

15. A blade according to claim 14 , wherein said first reinforcement is made of fabric constituted essentially by unidirectional inorganic fibers directed along said pitch axis (A).

16. A blade according to claim 1 , wherein said single spar includes second reinforcement reinforcing at least part of the bottom skin of the blade (P) between said primary spar and said secondary spar.

17. A blade according to claim 16 , wherein said second reinforcement is made of fabric constituted essentially by unidirectional inorganic fibers directed along said pitch axis (A).

18. A blade according to claim 1 , wherein the swept segment comprises in succession a forwardly-swept segment and a rearwardly-swept segment.