# US 7,407,131 B1 · Method for creating an aeronautic sound shield having gas distributors arranged on the engines, wings, and nose of an aircraft

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- Number: US 7,407,131 B1
- Document ID: US7407131B1
- Status: Granted
- Kind: B1
- Application number: 11/288,052
- Filed: 2005-11-14
- Granted: 2008-08-05
- Earliest claimed: 2005-11-14
- Assignees: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
- Inventors: Stephen Corda; Mark Stephen Smith; David Daniel Myre
- Web page: https://patentgrep.com/patent/US7407131B1

## CPC

- B64C 23/005: {by other means not covered by groups B64C23/02 - B64C23/08, e.g. by electric charges, magnetic panels, piezoelectric elements, static charges or ultrasounds}
- B64C 2220/00: Active noise reduction systems
- B64C 2230/16: by blowing other fluids over the surface than air, e.g. He, H, O2 or exhaust gases
- Y02T 50/10: Drag reduction
- B64C: AEROPLANES; HELICOPTERS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

The present invention blocks and/or attenuates the upstream travel of acoustic disturbances or sound waves from a flight vehicle or components of a flight vehicle traveling at subsonic speed using a local injection of a high molecular weight gas. Additional benefit may also be obtained by lowering the temperature of the gas. Preferably, the invention has a means of distributing the high molecular weight gas from the nose, wing, component, or other structure of the flight vehicle into the upstream or surrounding air flow. Two techniques for distribution are direct gas injection and sublimation of the high molecular weight solid material from the vehicle surface. The high molecular weight and low temperature of the gas significantly decreases the local speed of sound such that a localized region of supersonic flow and possibly shock waves are formed, preventing the upstream travel of sound waves from the flight vehicle.

## Claims

### Claim 1

A method for creating a noise attenuating shield comprising the steps of:
providing an aircraft comprising at least a jet engine attached to each main wing of the aircraft;
providing at least a gas distributor positioned on each jet engine attached to each main wing;
providing a high molecular weight gas, the gas comprising at least a molecular weight above one hundred, operationally associated with the gas distributor;
flying the aircraft at subsonic speeds wherein the gas distributor distributes gas into airflow adjacent to and upstream of each engine attached to each main wing and each main wing of the aircraft flying at subsonic speeds; and creating a local area of decreased speed of sound upstream and adjacent to each engine attached to each main wing and each main wing of the aircraft.

### Claim 2 (depends on 1)

The method of claim 1, wherein the gas distributor comprises a gas injection system.

### Claim 3 (depends on 1)

The method of claim 1, wherein the high molecular weight gas comprises a temperature below ambient.

### Claim 4 (depends on 1)

The method of claim 1, wherein the high molecular weight gas comprises a molecular weight above 120.

### Claim 5 (depends on 1)

The method of claim 1, wherein the high molecular weight gas comprises a molecular weight above 140.

### Claim 6 (depends on 1)

The method of claim 1, wherein the high molecular weight gas is selected from the group of sulfur hexafluoride, xenon based gases, polyatomic n-perfluorobutane, tetrafluoroethane (R134A), pentafluoroethane (R125), and combinations thereof.

### Claim 7 (depends on 2)

The method of claim 2 wherein the gas injection system comprises a direct gas injection system positioned on at least each wing of the aircraft and positioned on a nose of the aircraft.