Main rotor blade with integral cuff

1. A main rotor blade assembly comprising:

a main spar which comprises a root section and a main section, said root section forms an at least partially hollow integral cuff.

2. The main rotor blade assembly as recited in claim 1 , wherein the at least partially hollow integral cuff is formed together with the main spar.

3. The main rotor blade assembly as recited in claim 1 , wherein the at least partially hollow integral cuff is a monolithic structure together with the main section.

4. A main rotor blade assembly comprising:

a main spar which comprises a root section and a main section, said root section forms an integral cuff, wherein a lateral section through said integral cuff defines a first wall thickness and a lateral section through said main section defines a second wall thickness, said first wall thickness greater than said second wall thickness.

5. The main rotor blade assembly as recited in claim 4 , wherein said integral cuff defines a first chord and said main section defines a second chord, said first chord greater than said second chord.

6. The main rotor blade assembly as recited in claim 4 , wherein said root section defines a first hub mount aperture and a second hub mount aperture.

7. The main rotor blade assembly as recited in claim 4 , further comprising a tip spar mounted to said main spar in an overlap relationship.

8. The main rotor blade assembly as recited in claim 7 , wherein said overlap relationship extends between an inboard radial station of approximately eighty nine percent (89% x/R) and an outboard radial station of approximately ninety two percent (92% x/R).

9. The main rotor blade assembly as recited in claim 4 , wherein the root section, the main section, and the integral cuff are a single unitized structure.

10. A rotary wing aircraft comprising:

a rotor hub assembly;

a main spar which comprises a root section and a main section, said root section forms an integral cuff having a first wall and a second wall spaced from said first wall, said first wall providing a first hub mount aperture and a second hub mount aperture;

a first pin which passes through said first aperture to mount said main spar to said rotor hub assembly; and

a second pin which passes through said second aperture to mount said main spar to said rotor hub assembly.

11. The aircraft as recited in claim 10 , wherein the integral cuff is formed together with the remaining portions of the main spar.

12. A rotary wing aircraft comprising:

a rotor hub assembly;

a main spar which comprises a root section and a main section, said root section forms an integral cuff having a first hub mount aperture and a second hub mount aperture;

a first pin which passes through said first aperture to mount said main spar to said rotor hub assembly; and

a second pin which passes through said second aperture to mount said main spar to said rotor hub assembly, wherein a lateral section through said integral cuff defines a first wall thickness and a lateral section through said main section defines a second wall thickness, said first wall thickness greater than said second wall thickness.

13. The aircraft as recited in claim 12 , further comprising:

a tip spar attached to said main spar in an overlap relationship, said tip spar defining a non-straight form;

an upper blade skin adjacent to said main spar and said tip spar; and

a lower blade skin adjacent to said main spar and said tip spar.

14. The aircraft as recited in claim 13 , wherein said end section of said main spar comprises a reduced perimeter stepped section to receive said tip spar.

15. The aircraft as recited in claim 13 , wherein said tip spar defines a non-straight form.

16. The aircraft as recited in claim 13 , further comprising

a main core adjacent said main spar; and

a tip core adjacent said tip spar.

17. The aircraft as recited in claim 16 , wherein said tip core defines an anhedral form at an approximately ninety six percent a radial station (96% x/R).

18. The aircraft as recited in claim 16 , wherein said main core comprises a leading edge contour which generally matches a trailing edge of said main spar and said tip core comprises a leading edge contour which generally matches a trailing edge of said tip spar.

19. The aircraft as recited in claim 12 , further comprising:

a tip spar attached to said main spar in an overlap relationship, said tip spar defining a non-straight form;

a main core adjacent said main spar;

a tip core adjacent said tip spar, a core interface between said main core and said tip spar offset inboard from an inboard radial station of said overlap relationship.

20. The aircraft as recited in claim 19 , wherein said main core comprises a leading edge contour which generally matches a trailing edge of said main spar and said tip core comprises a leading edge contour which generally matches a trailing edge of said tip spar.

21. The aircraft as recited in claim 12 , wherein said integral cuff defines a first wall thickness and said main section defines a second wall thickness, said first wall thickness greater than said second wall thickness.

22. The aircraft as recited in claim 12 , wherein the root section, the main section, and the integral cuff are a single monolithic structure.

23. A method of mounting a main rotor blade assembly comprising:

forming an integral cuff into a root section of a hollow main spar; and

attaching the integral cuff directly to a rotor hub assembly.

24. A method as recited in claim 23 , wherein attaching the main spar directly to a rotor hub further comprising pinning the main spar to an integral hinge cuff of the rotor hub assembly.