Method and apparatus for manufacturing a helicopter rotor fairing, and a fairing obtained thereby

1. A method of manufacturing a tail structure for a rotary wing aircraft, the structure comprising:

a tubular portion or duct having two ends and including two collars or flanges extending respectively from each of said two ends; and

two curved fairing side walls extending respectively around the two collars or flanges;

the two side walls are made of a composite material comprising an organic matrix and reinforcement,

said method comprising the steps of:

uniting the curved-fairing side walls by solidifying the matrix to form a one-piece shell configured for receiving the tubular portion upon solidification, and

connecting the shell to the tubular portion using the collars or flanges wherein one or two fairing side wall preforms are made, each preform having a side wall junction zone, the junction zone comprising said organic polymer matrix, and the two curved fairing side walls are united by solidifying or consolidating the matrix in the junction zone.

2. The method according to claim 1 , wherein said reinforcement is resin-preimpregnated reinforcement used to make at least one side wall preform.

3. The method according to claim 2 , in which the resin-preimpregnated reinforcement is put into place on a mold with pressure being applied.

4. The method according to claim 3 , in which the reinforcement is put into place mechanically.

5. The method according to claim 3 , in which the reinforcement is put into place manually.

6. The method according to claim 1 , in which the organic matrix of the side wall preform(s) is constituted by a thermosetting resin.

7. The method according to claim 1 , in which the organic matrix of the side wall preform(s) is constituted by a thermoplastic resin.

8. The method according to claim 1 , in which the preform(s) is/are prepared from fibers or a fiber fabric which is/are impregnated with a resin, and in which the preimpregnated fibers and/or fabric is/are deposited and oriented mechanically or manually on a projecting or recessed mold, and is/are pressed against an outside or an inside face, as appropriate, of the mold.

9. The method according to claim 1 , in which the two side walls are hardened together and are united via at least one peripheral junction portion.

10. The method according to claim 1 , in which, in addition to the fairing side wall preform(s), one or two composite wall preform(s) for a rudder or a fin is/are simultaneously united with the side wall preform(s) from which it/they extend.

11. The method according to claim 1 , in which, in addition to the fairing side wall preform(s), one or two composite wall preform(s) for connection to a tail boom is/are simultaneously united with the side wall preform(s) from which it/they extend.

12. The method according to claim 1 , in which one preform of composite material is made by placing preimpregnated fibers around a segmented core or mandrel to form both of said fairing side walls.

13. The method according to claim 12 , wherein a plurality of mandrel segments forming the segmented core or mandrel are separated, said segments being extracted from a cavity defined by the preform of the fairing side walls, via an opening provided in the side walls.

14. The method according to claim 13 , in which the preform is then transferred into a two-part recessed mold.

15. The method according to claim 13 , in which an expandable and/or shrinkable preform support structure is then inserted into said cavity, and the preform is solidified.

16. The method according to claim 15 , in which the preform is solidified in an autoclave.

17. The method according to claim 1 , in which two side preforms are made, each preform being made of composite material comprising a first portion for forming a fairing side wall, a second portion for forming a rudder side wall, and a third portion for forming a wall for connection with a tail boom.

18. The method according to claim 17 , in which each of the portions has at least one peripheral junction strip suitable for being folded and/or bent to overlie a peripheral junction strip of a corresponding portion of an opposing one of said preforms.

19. The method according to claim 17 , in which each of the preforms is obtained by placing resin-preimpregnated fibers under pressure on a projecting or recessed half-mold.

20. The method according to claim 19 , in which the fibers are placed mechanically.

21. The method according to claim 19 , in which both preforms are placed in respective recessed half-molds of appropriate shape, the respective peripheral junction strips of the two preforms then being put into mutual intimate contact in order to obtain good structural continuity of a finished part in said junction zone corresponding to a join plane of the half-molds, the half-molds together then being closed, and placed in an autoclave to cause the preforms of the finished part to set.