Reinforced blade

1. A propeller blade comprising:

a root;

a tip, distal from the root;

a trailing edge extending from the root to the tip;

a structural spar;

a trailing edge insert arranged between the structural spar and the trailing edge;

a shell forming an outer surface of the propeller blade, wherein the shell is a glass fiber resin shell or a carbon fiber resin shell; and

a plurality of stitches of yarn extending through two opposing parts of the shell adjacent the trailing edge, wherein the yarns do not extend through the trailing edge insert.

2. The propeller blade of claim 1 , wherein the stitches of yarn are formed from at least one yarn extending through the opposing parts of the shell at more than one point along the span (S) of the blade.

3. The propeller blade of claim 1 , comprising a row of stitches of yarn extending along a portion of the span (S) of the blade from the tip thereof.

4. The propeller blade of claim 3 , comprising at least two rows of stitches of yarn extending along the portion of the span of the blade.

5. The propeller blade of claim 3 , wherein said portion extends along less than 70% of the span (S) from the tip and more than 20% of the span (S) of the blade from the tip.

6. The propeller blade of claim 1 , further comprising a laminate sheet of composite material extending from the structural spar of the propeller blade towards the trailing edge and extending between the opposing parts of the shell, wherein the stitches of yarn also extend through the laminate sheet.

7. The propeller blade of claim 1 , wherein the yarn is formed from carbon or glass.

8. The propeller blade of claim 1 , wherein the trailing edge insert is a foam insert.

9. The propeller blade of claim 1 , wherein the structural spar comprises:

a spar foam material;

a central structural member surrounding the spar foam material; and

an outer structural material surrounding the central structural member.

10. The propeller of claim 9 , wherein the central structural member comprises a laminate sheet of composite material and the outer structural material is in the form of a braided layer.

11. A method of manufacturing a propeller blade comprising:

arranging a trailing edge insert adjacent a trailing edge of a structural spar;

surrounding the trailing edge insert and structural spar with a shell such that the trailing edge insert is arranged between the structural spar and a trailing edge of the propeller blade, wherein the shell is a glass fiber resin shell or a carbon fiber resin shell; and

threading a yarn through the shell adjacent the trailing edge of the propeller blade such that the yarn extends through two opposing parts of the shell but does not extend through the trailing edge insert.

12. The method of claim 11 , wherein the threading is performed before surrounding the insert and structural spar with the shell.

13. The method of claim 11 , wherein the shell includes at least two layers surrounding the blade and the yarn is threaded through two parts of each of said at least two layers, the method further comprising cutting an outer layer of the at least two layers after the threading.

14. The method of claim 11 , wherein the threading is performed with a vibrating needle.

15. The method of claim 11 , wherein the threading is performed by tufting.

16. The method of claim 11 , wherein the threading includes forming at least one row of stitches extending along a portion of the span (S) of the blade from a tip thereof, the portion extending along less than 70% of the span (S) from the tip and more than 20% of the span (S) of the blade from the tip.

17. The method of claim 11 , further comprising bonding a laminate sheet to the structural spar and threading the yarn through the laminate sheet.

18. The method of claim 11 , wherein the yarn is formed from carbon or glass.

19. The method of claim 11 , wherein the trailing edge insert is a foam insert.