# US 8,541,091 B2 · Composite leg for landing gear assembly

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- Number: US 8,541,091 B2
- Document ID: US8541091B2
- Status: Granted
- Kind: B2
- Application number: 13/429,630
- Filed: 2012-03-26
- Published: 2012-09-20
- Granted: 2013-09-24
- Earliest claimed: 2005-03-31
- Assignees: The Boeing Company
- Applicants: Max U. Kismarton
- Inventors: Max U. Kismarton
- Web page: https://patentgrep.com/patent/US8541091B2

## CPC

- B64C 25/06: fixed
- B64C 2025/325: {specially adapted for helicopters}
- Y10T 428/24124: Fibers
- B64C: AEROPLANES; HELICOPTERS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A composite leg for a landing gear assembly includes a composite compression cap including reinforcing fibers that provide strength in compression, and a tension cap including reinforcing fibers that provide strength in tension. At least some of the fibers are oriented at +α and −α with respect to a longitudinal axis of the leg, where α is between 2 and 8 degrees.

## Claims

### Claim 1

A composite leg for a landing gear assembly, the composite leg comprising:
a composite compression cap including reinforcing fibers that provide strength in compression; and
a composite tension cap including reinforcing fibers that provide strength in tension;
wherein at least some of the fibers are oriented at +α and −α with respect to a longitudinal axis of the leg, where α is between 2 and 8 degrees.

### Claim 2 (depends on 1)

The composite leg of claim 1, further comprising a torque box for providing torsional rigidity of the leg and carrying shear flow between the caps.

### Claim 3 (depends on 2)

The composite leg of claim 2, wherein plies of reinforcing fibers in the torque box are interleaved with plies of the fibers in the caps.

### Claim 4 (depends on 3)

The composite leg of claim 3, wherein the reinforcing fibers in the torque box have a lower strain of compression than the fibers that provide the strength in compression and a lower strain of tension than the fibers that provide strength in tension.

### Claim 5 (depends on 1)

The composite leg of claim 1, wherein the fibers providing the strength in compression include glass fibers and wherein the fibers providing strength in tension include plastic fibers.

### Claim 6 (depends on 1)

The composite leg of claim 1, wherein the fibers providing strength in compression and tension both include glass fibers.

### Claim 7 (depends on 1)

The composite leg of claim 1, wherein the compression cap is 20-40% thicker than the tension cap.

### Claim 8 (depends on 1)

The composite leg of claim 1, wherein the compression cap and the tension cap have the same thickness.

### Claim 9 (depends on 1)

The composite leg of claim 1, wherein the leg has holes for receiving attachment members, and wherein the leg further includes thickened pads of carbon fibers are around the holes.

### Claim 10 (depends on 1)

A landing gear assembly comprising at least one composite leg of claim 1.

### Claim 11 (depends on 1)

An aerospace vehicle comprising:
a fuselage; and
a landing gear assembly coupled to the fuselage, the landing gear assembly including at least one composite leg of claim 1.

### Claim 12 (depends on 1)

The composite leg of claim 1, further comprising a torque box for providing torsional rigidity of the leg and carrying shear flow between the caps.

### Claim 13 (depends on 12)

The composite leg of claim 12, wherein the torque box includes plies of reinforcing fibers that are interleaved with plies of the fibers in the caps.

### Claim 14 (depends on 13)

The composite leg of claim 13, wherein the reinforcing fibers in the torque box have a lower strain of compression than the fibers in the compression cap and a lower strain of tension than the fibers in the tension cap.

### Claim 15 (depends on 13)

The composite leg of claim 13, wherein the reinforcing fibers in the torque box include carbon fibers, the fibers in the composite compression cap include glass fibers, and the fibers in the composite tension cap include plastic fibers.

### Claim 16

A landing gear assembly leg comprising:
a composite compression cap including reinforcing fibers oriented at +α and −α with respect to a longitudinal axis of the leg; and
a composite tension cap including reinforcing fibers oriented at +α and −α with respect to the longitudinal axis of the leg;
where α is between 2 and 8 degrees.

### Claim 17 (depends on 16)

The composite leg of claim 16, wherein the compression cap and the tension cap have the same thickness.

### Claim 18 (depends on 16)

The composite leg of claim 16, wherein the leg has holes for receiving attachment members, and wherein the leg further includes thickened pads of carbon fibers are around the holes.

### Claim 19 (depends on 16)

A landing gear assembly comprising at least one composite leg of claim 16.

### Claim 20 (depends on 16)

An aerospace vehicle comprising:
a fuselage; and
a landing gear assembly coupled to the fuselage, the landing gear assembly including at least one composite leg of claim 16.