# US 2022/0274692 A1 · Spherical bearing centrifugal force retention link

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- Number: US 2022/0274692 A1
- Document ID: US20220274692A1
- Status: Published application
- Kind: A1
- Application number: 17/188,785
- Filed: 2021-03-01
- Published: 2022-09-01
- Earliest claimed: 2021-03-01
- Assignees: Bell Textron Inc.
- Applicants: Bell Textron Inc.
- Inventors: Andrew Paul HALDEMAN; Paul Wayne WOOLBRIGHT; Timothy McClellan MOSIG; George Matthew THOMPSON
- Web page: https://patentgrep.com/patent/US20220274692A1

## 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 at position 5

-6. (canceled)

### Claim 7 (depends on 10)

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

### Claim 8 (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 9 (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 10 (depends on 9)

The rotor blade assembly of claim 9, wherein the inboard spherical bearing and the outboard spherical bearing react a centrifugal force radially.

### Claim 11 (depends on 10)

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

### Claim 12

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 13 (depends on 12)

The rotorcraft of claim 12, wherein the rotor is located in a duct.

### Claim 14 (depends on 12)

The rotorcraft of claim 12, wherein the rotor is an anti-torque rotor.

### Claim 15 (depends on 12)

The rotorcraft of claim 12, wherein the rotor blade pitch range is between 70 and 85 degrees.

### Claim 16 (depends on 12)

The rotorcraft of claim 12, wherein the rotor is a ducted anti-torque rotor; and
the rotor blade pitch range is between 70 and 85 degrees.

### Claim 17

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 18 (depends on 17)

The ducted fan of claim 17, 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 19 (depends on 17)

The ducted fan of claim 17, wherein the rotor blade pitch range is between 70 and 85 degrees.

### Claim 20 (depends on 19)

The ducted fan of claim 19, 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 21 (depends on 17)

The ducted fan of claim 17, wherein the rotor blade pitch range is between 50 to 85 degrees.

### Claim 22 (depends on 12)

The rotorcraft of claim 12, wherein the rotor blade pitch range is between 50 to 85 degrees.