Rotor hub fairing system for a counter-rotating, coaxial rotor system

• US 20060269411A1
• Filed: 05/31/2005
• Published: 11/30/2006
• Est. Priority Date: 05/31/2005
• Status: Active Grant

• Current Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Original Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Inventors: Bertolotti, Fabio P., Scott, Mark W., Wake, Brian E., McCormick, Duane C., Egolf, T. Alan
• Granted Patent: US 7,229,251 B2
• Time in Patent Office: Days
• US Class Current: 416/134.A
• CPC Class Codes: B64C 1/00 Fuselages; Constructional features common to fuselages, wings, stabilising surfaces or the like
• CPC Class Codes: B64C 27/04 Helicopters
• CPC Class Codes: B64C 27/10 arranged coaxially
• CPC Class Codes: B64C 27/12 Rotor drives
• CPC Class Codes: B64C 27/14 Direct drive between power plant and rotor hub
• CPC Class Codes: B64C 27/20 Rotorcraft characterised by having shrouded rotors, e.g. flying platforms
• CPC Class Codes: B64C 7/00 Structures or fairings not otherwise provided for

Abstract

A rotor hub fairing system includes an upper hub fairing, a lower hub fairing and a shaft fairing therebetween. The rotor hub fairing system is sized and configured to reduce the overall drag on a dual, counter-rotating, coaxial rotor system. Preferably, the rotor hub fairing is fully integrated. The shaft fairing preferably includes a minimal thickness at the midsection to reduce drag with an increasing thickness adjacent the upper and lower hub fairings to reduce the flow separation on the hub fairing surfaces without overly excessive drag. Other aerodynamic structures, such as a horizontal splitter and/or a plurality of turning vanes may be mounted to the shaft fairing to facilitate flow around the upper and lower hub fairings to reduce flow separation and drag.

Claims

1. A rotor hub fairing system for a coaxial rotor system comprising:

an upper hub fairing defined about an axis;

a lower hub fairing defined about said axis; and

a shaft faring between said upper hub fairing and said lower hub fairing, said shaft fairing contoured to reduce drag on the coaxial rotor system.

2. The rotor hub fairing system as recited in claim 1, wherein said shaft fairing is bearing mounted relative said upper hub fairing and said lower hub fairing.

3. The rotor hub fairing system as recited in claim 1, wherein said shaft fairing includes a pitching axis which extends through said upper hub fairing and said lower hub fairing, said pitching axis including an axis of rotation of the coaxial rotor system.

4. The rotor hub fairing system as recited in claim 2, wherein said pitching axis is generally parallel to said axis.

5. The rotor hub fairing system as recited in claim 1, wherein said pitching axis is defined at quarter chord, said pitching axis overlays said axis.

6. The rotor hub fairing system as recited in claim 1, wherein said shaft fairing is generally of an hour glass shape in cross section taken along said axis.

7. The rotor hub fairing system as recited in claim 1, wherein said shaft fairing includes a thickness distribution in which a minimal thickness occurs at least partially along said contoured midsection.

8. The rotor hub fairing system as recited in claim 1, wherein said shaft fairing includes a NACA 0028 airfoil along said midsection and an NACA0042 airfoil adjacent said upper hub fairing and said lower hub fairing.

9. The rotor hub fairing system as recited in claim 1, wherein a trailing edge of said shaft fairing extends beyond a periphery of said upper hub fairing and said lower hub fairing.

10. The rotor hub fairing system as recited in claim 1, further comprising a splitter airfoil transverse to said shaft fairing.

11. The rotor hub fairing system as recited in claim 10, wherein said splitter airfoil extends from a contoured midsection of said shaft fairing, said shaft fairing includes a thickness distribution in which a minimal thickness occurs at least partially along said contoured midsection.

12. The rotor hub fairing system as recited in claim 10, wherein a trailing edge of said splitter airfoil extends beyond a trailing edge of said shaft fairing.

13. The rotor hub fairing system as recited in claim 10, wherein said splitter airfoil defines a maximum thickness adjacent a mid-chord position.

14. The rotor hub fairing system as recited in claim 10, wherein said splitter airfoil includes a span which is less than a diameter of said upper hub fairing.

15. The rotor hub fairing system as recited in claim 1, further comprising a plurality of turning vanes.

16. The rotor hub fairing system as recited in claim 15, wherein said plurality of vanes includes an upper turning vane and a lower turning vane.

17. The rotor hub fairing system as recited in claim 15, wherein said upper turning vane and said lower turning vane are cambered toward said respective upper and lower hub fairing.

18. The rotor hub fairing system as recited in claim 1, wherein the upper hub fairing, the lower hub fairing, and the shaft fairing are integrated into a single element.

19. The rotor hub fairing system as recited in claim 1, wherein said fairing is contoured to have a reduced thickness at a center region thereof.

20. A rotor hub fairing system for a coaxial rotor system comprising:

an upper hub fairing;

a lower hub fairing; and

a shaft faring between said upper hub fairing and said lower hub fairing, said shaft fairing defining a shaft fairing chord to hub fairing diameter (c/D) between 0.90 D to 1.25 D.

21. The rotor hub fairing system as recited in claim 20, wherein said shaft faring defines a shaft fairing chord that is approximately between 110% to 120% chord to the hub fairing diameter.

22. A coaxial rotor system comprising:

an upper rotor system including an upper rotor hub which rotates about an axis of rotation;

an upper hub fairing which at least partially surrounds a portion of said upper rotor hub;

a lower rotor system including a lower rotor hub which rotates about said axis of rotation;

a lower hub fairing which at least partially surrounds a portion of said lower rotor hub; and

a shaft faring between said upper hub fairing and said lower hub fairing, said shaft faring having a pitching axis generally parallel to said axis of rotation.