Connection joint for attaching an airfoil blade to a helicopter's bearingless main rotor

Patent metadata

Field	Value
Publication number	US-9714579-B2
Application number	US-201313804732-A
Country	US
Kind code	B2
Filing date	Mar 14, 2013
Priority date	Apr 18, 2012
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

An airfoil blade ( 2 ) of a bearingless rotor of a helicopter. Said airfoil blade ( 2 ) has a pitch axis from a tip end to a root end and said root end is provided with junction means for a separable junction arrangement of said airfoil blade ( 2 ) with a flexbeam head ( 13 ), and a control cuff ( 4, 22 ). Said junction arrangement is mechanical with removable fasteners respectively removable connecting said root end of said airfoil blade ( 2 ) to said control cuff ( 4, 22 ) and said flexbeam head ( 13 ). Said root end comprises at least two openings ( 7, 8 ) being asymmetric with regard to said pitch axis.

First claim

What is claimed is:

1. An airfoil blade comprising:
a root end;
a tip end; and
a body extending between the root end and the tip end with a pitch axis extending from the root end to the tip end, wherein the root end defines a chordwise axis extending perpendicular to the pitch axis and includes a first fastener hole and a second fastener hole aligned along the chordwise axis, the first and second fastener holes extending through the root end of the airfoil blade from a top surface of the root end of the airfoil blade to a bottom surface of the root end of the airfoil blade, the first and second fastener holes being configured to receive first and second fasteners, respectively, to couple the root end to a control cuff and a flexbeam head, the first fastener hole having a first diameter and being spaced a first distance from the pitch axis, the second fastener hole having a second diameter and being spaced a second distance from the pitch axis, the first distance being different from the second distance, the first diameter being larger than the second diameter, wherein the first fastener hole is between the leading edge and second fastener hole.

2. The airfoil blade of claim 1 , wherein the pitch axis passes through the root end at 25% of the chord length from a leading edge.

3. The airfoil blade of claim 1 , wherein the first fastener hole passes through the root end at between 10% and 30% of the chord length from a leading edge.

4. The airfoil blade of claim 3 , wherein the first diameter is greater than the second diameter.

5. The airfoil blade of claim 3 , wherein the second fastener hole passes through the root end at between 50% and 90% of the chord length from the leading edge.

6. The airfoil blade of claim 1 , wherein the distance from the first fastener hole to the second fastener hole is between 40% and 80% of the chord length.

7. The airfoil blade of claim 1 , wherein the root end is fork-shaped to accommodate a flexbeam head.

8. A rotorcraft comprising:
a rotor head;
a flexbeam having a flexbeam root and a flexbeam head, the flexbeam root being coupled to the rotor head;
a control cuff extending about a portion of the flexbeam, the control cuff having a first control cuff hole and a second control cuff hole;
a rotor blade having a blade root, a blade tip, and a body extending therebetween with a pitch axis extending from the blade root to the blade tip, the blade root defining a chordwise axis extending perpendicular to the pitch axis, the blade root having a first fastener hole and a second fastener hole aligned along the chordwise axis, the first fastener hole coaxial with the first control cuff hole, the first fastener hole having a first diameter and being spaced a first distance from the pitch axis, the second fastener hole coaxial with the second control cuff hole, the second fastener hole having a second diameter and being spaced a second distance from the pitch axis, the first distance being different from the second distance, the first diameter being different from the second diameter;
a first fastener disposed within the first control cuff hole and the first fastener hole; and
a second fastener disposed within the second control cuff hole and the second fastener hole.

9. The rotorcraft of claim 8 , wherein the pitch axis passes through the blade root at 25% of the chord length from a leading edge.

10. The rotorcraft of claim 8 , wherein the first fastener hole passes through the blade root at between 10% and 30% of the chord length from a leading edge.

11. The rotorcraft of claim 10 , wherein the first diameter is greater than the second diameter.

12. The rotorcraft of claim 10 , wherein the second fastener hole passes through the blade root at between 50% and 90% of the chord length from the leading edge.

13. The rotorcraft of claim 8 , wherein the distance from the first fastener hole to the second fastener hole is between 40% and 80% of the chord length.

14. The rotorcraft of claim 8 , wherein the blade root is fork-shaped to accommodate the flexbeam head.

15. The rotorcraft of claim 8 , wherein the first control cuff hole has a first control cuff hole diameter and the second control cuff hole has a second control cuff hole diameter, the first control cuff hole diameter being different from the second control cuff hole diameter.

16. An airfoil blade of a bearingless rotor of a helicopter comprising:
the airfoil blade being integrally formed and having a tip end and a root end forming opposite ends thereof and having a pitch axis from the tip end to the root end;
the root end being provided with removable fasteners, each fastener removable connecting the root end of the airfoil blade to a control cuff and a flexbeam head, the root end of the airfoil blade defining a chordwise axis extending perpendicular to the pitch axis, the root end comprising at least two openings aligned along the chordwise axis and being asymmetric with regard to the pitch axis, the two asymmetric openings including a main opening and a supporting opening, the main opening having a greater diameter than the supporting opening, the main opening being located at 10-30% chord length of the airfoil blade from a leading edge of a profile section, and the supporting opening being located at 50-90% chord length of the airfoil blade from the leading edge.

17. The airfoil blade according to claim 16 , wherein the main opening is arranged in front of the axis towards the leading edge.

18. The airfoil blade according to claim 16 , wherein the root end is fork shaped to accommodate the flexbeam head.

19. The airfoil blade according to claim 16 , wherein the supporting opening of the root end is prepared for connecting the flexbeam head to the root end.

20. The airfoil blade of claim 16 , wherein the main opening and the supporting opening are both spaced away from the pitch axis.

Assignees

• Airbus Helicopters Deutschland GmbH

Inventors

• Kuntze-Fechner Gerald
• Bauer Markus
• Ortner Martin

Classifications

• B64C11/04

  Blade mountings · CPC title

• B64C27/50 Primary

  Blades foldable to facilitate stowage of aircraft · CPC title

• B64C27/54

  Mechanisms for controlling blade adjustment or movement relative to rotor head, e.g. lag-lead movement · CPC title

• F01D5/30 Primary

  Fixing blades to rotors; Blade roots {; Blade spacers} · CPC title

• B64C27/33

  having flexing arms · CPC title