# US 12,179,928 B2 · Aircraft with arm having eigenmodes in disjunct frequency ranges

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- Number: US 12,179,928 B2
- Document ID: US12179928B2
- Status: Granted
- Kind: B2
- Application number: 17/216,739
- Filed: 2021-03-30
- Published: 2021-12-02
- Granted: 2024-12-31
- Earliest claimed: 2020-04-03
- Assignees: Dr. Ing. h.c. F. Porsche Aktiengesellschaft
- Applicants: Dr. Ing. h.c. F. Porsche Aktiengesellschaft
- Inventors: Martin Hoffmeister
- Web page: https://patentgrep.com/patent/US12179928B2

## CPC

- B64C 29/0025: {the propellers being fixed relative to the fuselage}
- B64D 27/34: All-electric aircraft
- B64D 27/402: {comprising box like supporting frames, e.g. pylons or arrangements for embracing the power plant}
- Y02T 50/50: On board measures aiming to increase energy efficiency
- Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft
- B64C: AEROPLANES; HELICOPTERS
- B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An aircraft includes: a body with an arm. The arm carries a lifting rotor. The arm has a cavity. The aircraft may include at least one of: the arm being made of sheet metal, and the cavity includes an embossment or a corrugation in the sheet metal. The cavity may contain cables and the cables run from the body along the arm to the lifting rotor.

## Claims

### Claim 1

An aircraft, comprising:
a body with an arm,
wherein the arm carries a lifting rotor,
wherein an underside of the arm has an externally facing concave cavity extending along an axial length of the arm and along a center of the underside of the arm,
wherein the cavity has a first axial end and a second axial end, the first axial end being proximal to the body and the second axial end being distal to the body,
wherein the arm includes a point of attachment by which the arm is configured to be attached to the body,
wherein the first axial end of the cavity is axially offset from the point of attachment along the axial length of the arm, and
wherein a width of the cavity at the second axial end is greater than a width of the cavity at the first axial end.

### Claim 2 (depends on 1)

The aircraft of claim 1, wherein:
the arm comprises sheet metal, and
the cavity comprises an embossment or a corrugation in the sheet metal.

### Claim 3 (depends on 1)

The aircraft of claim 1, wherein the cavity contains cables, and
wherein the cables run from the body along the arm to the lifting rotor.

### Claim 4 (depends on 3)

The aircraft of claim 3, wherein the cables enclose control lines.

### Claim 5 (depends on 1)

The aircraft of claim 1, wherein the arm has eigenmodes in disjunct frequency ranges.

### Claim 6 (depends on 1)

The aircraft of claim 1, wherein the arm has a closed hollow cross section.

### Claim 7 (depends on 1)

The aircraft of claim 1, wherein the arm is arranged at a nose end of the body.

### Claim 8 (depends on 1)

The aircraft of claim 1, wherein the cavity extends more than halfway along the axial length of the arm.

### Claim 9 (depends on 1)

The aircraft of claim 1, wherein the cavity has a varying width from the first axial end to the second axial end.

### Claim 10 (depends on 9)

The aircraft of claim 9, wherein along at least part of an axial extent of the cavity from the first axial end to the second axial end, the cavity gradually narrows.

### Claim 11 (depends on 10)

The aircraft of claim 10, wherein along at least part of the axial extent of the cavity from the first axial end to the second axial end, the cavity also gradually widens.

### Claim 12

An aircraft, comprising:
a body;
an arm; and
a lifting rotor,
wherein the arm is attached to the body and carries a lifting rotor,
wherein an underside of the arm has an externally facing concave cavity extending along an axial length of the arm and along a center of the underside of the arm,
wherein the cavity has a first axial end and a second axial end, the first axial end being proximal to the body relative to the second axial end from a point of attachment of the arm to the body and the second axial end being distal to the body relative to the first axial end from the point of attachment of the arm to the body,
wherein the first axial end of the cavity is axially offset from the point of attachment along the axial length of the arm, and
wherein a width of the cavity at the second axial end is greater than a width of the cavity at the first axial end.