# US 11,440,651 B1 · Spherical bearing centrifugal force retention link

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- Number: US 11,440,651 B1
- Document ID: US11440651B1
- Status: Granted
- Kind: B1
- Application number: 17/188,785
- Filed: 2021-03-01
- Published: 2022-09-01
- Granted: 2022-09-13
- Earliest claimed: 2021-03-01
- Assignees: Textron Innovations Inc.
- Applicants: Bell Textron Inc.
- Inventors: Andrew Paul Haldeman; Paul Wayne Woolbright; Timothy McClellan Mosig; George Matthew Thompson
- Web page: https://patentgrep.com/patent/US11440651B1

## CPC

- B64C 27/35: having elastomeric joints
- B64C 27/48: Root attachment to rotor head
- B64C 27/82: characterised by the provision of an auxiliary rotor or fluid-jet device for counter-balancing lifting rotor torque or changing direction of rotorcraft
- B64C 2027/8254: {Shrouded tail rotors, e.g. "Fenestron" fans}
- B64C: AEROPLANES; HELICOPTERS

## Abstract

A spherical bearing centrifugal force retention link includes an inboard spherical bearing to attach to a rotor hub and an outboard spherical bearing to attach to a rotor blade. In use, the inboard spherical bearing and the outboard spherical bearing react centrifugal force radially and a torsional moment of the centrifugal force link is substantially constant throughout the rotor blade pitch range.

## Claims

### Claim 1

A rotor blade assembly, comprising:
a hub rotatable about a rotational axis;
a rotor blade extending radially from the hub along a pitch axis and having a rotor blade pitch range; and
a centrifugal force (CF) link having an inboard spherical bearing attached to the hub and an outboard spherical bearing attached to the rotor blade and a torsional moment of the CF link is constant throughout the rotor blade pitch range.

### Claim 2 (depends on 1)

The rotor blade assembly of claim 1, wherein the CF link comprises a beam between the inboard spherical bearing and the outboard spherical bearing.

### Claim 3 (depends on 1)

The rotor blade assembly of claim 1, wherein the rotor blade pitch range is between 70 and 85 degrees.

### Claim 4 (depends on 1)

The rotor blade assembly of claim 1, wherein the rotor blade pitch range is 50 to 85 degrees.

### Claim 5 (depends on 1)

The rotor blade assembly of claim 1, wherein the inboard spherical bearing and the outboard spherical bearing react a centrifugal force radially.

### Claim 6 (depends on 1)

The rotor blade assembly of claim 1, further comprising a blade grip having an inboard end connected to the outboard spherical bearing and a first blade grip portion rotationally coupled to the hub outboard of the inboard end.

### Claim 7 (depends on 6)

The rotor blade assembly of claim 6, wherein the inboard spherical bearing and the outboard spherical bearing react a centrifugal force radially.

### Claim 8 (depends on 7)

The rotor blade assembly of claim 7, wherein the rotor blade pitch range is 50 to 85 degrees.

### Claim 9 (depends on 7)

The rotor blade assembly of claim 7, wherein the rotor blade pitch range is between 70 and 85 degrees.

### Claim 10

A rotorcraft, comprising:
a rotor comprising a hub rotatable about a rotational axis;
a rotor blade extending radially from the hub along a pitch axis and having a rotor blade pitch range; and
a centrifugal force (CF) link having an inboard spherical bearing attached to the hub and an outboard spherical bearing attached to the rotor blade, wherein the inboard spherical bearing and the outboard spherical bearing react centrifugal force radially, and a torsional moment of the CF link is constant throughout the rotor blade pitch range.

### Claim 11 (depends on 10)

The rotorcraft of claim 10, wherein the rotor is located in a duct.

### Claim 12 (depends on 10)

The rotorcraft of claim 10, wherein the rotor is an anti-torque rotor.

### Claim 13 (depends on 10)

The rotorcraft of claim 10, wherein the rotor blade pitch range is between 70 and 85 degrees.

### Claim 14 (depends on 10)

The rotorcraft of claim 10, wherein the rotor is a ducted anti-torque rotor; and
the rotor blade pitch range is between 70 and 85 degrees.

### Claim 15 (depends on 10)

The rotorcraft of claim 10, wherein the rotor blade pitch range is between 50 to 85 degrees.

### Claim 16

A ducted fan, comprising:
a duct having a central axis;
a rotor assembly located in the duct, the rotor assembly comprising:
a hub rotatable about a rotational axis coaxial with the central axis;
a rotor blade extending radially from the hub along a pitch axis and having a rotor blade pitch range; and
a centrifugal force (CF) link having an inboard spherical bearing attached to the hub and an outboard spherical bearing attached to the rotor blade, wherein the inboard spherical bearing and the outboard spherical bearing react centrifugal force radially, and a torsional moment of the CF link is constant throughout the rotor blade pitch range.

### Claim 17 (depends on 16)

The ducted fan of claim 16, further comprising a blade grip having an inboard end connected to the outboard spherical bearing and a first blade grip portion rotationally coupled to the hub outboard of the inboard end.

### Claim 18 (depends on 16)

The ducted fan of claim 16, wherein the rotor blade pitch range is between 70 and 85 degrees.

### Claim 19 (depends on 18)

The ducted fan of claim 18, further comprising a blade grip having an inboard end connected to the outboard spherical bearing and a first blade grip portion rotationally coupled to the hub outboard of the inboard end.

### Claim 20 (depends on 16)

The ducted fan of claim 16, wherein the rotor blade pitch range is between 50 to 85 degrees.