Return-Path: Sender: (Marvin Kaye) To: lml Date: Fri, 19 Jul 2002 07:58:33 -0400 Message-ID: X-Original-Return-Path: Received: from pop3.olsusa.com ([63.150.212.2] verified) by logan.com (CommuniGate Pro SMTP 4.0b5) with ESMTP id 1641699 for lml@lancaironline.net; Thu, 18 Jul 2002 22:54:24 -0400 Received: from granger.mail.mindspring.net ([207.69.200.148]) by pop3.olsusa.com (Post.Office MTA v3.5.3 release 223 ID# 0-71866U8000L800S0V35) with ESMTP id com for ; Thu, 18 Jul 2002 22:47:50 -0400 Received: from 1cust177.tnt1.port-townsend.wa.da.uu.net ([67.250.16.177] helo=rossann) by granger.mail.mindspring.net with smtp (Exim 3.33 #1) id 17VNuO-0002Wy-00 for lancair.list@olsusa.com; Thu, 18 Jul 2002 22:54:20 -0400 X-Original-Message-ID: <001101c22ecf$b60b5860$b110fa43@olympus.net> From: "Ross W. Colebrook" X-Original-To: "Lancair List" Subject: Noise Control X-Original-Date: Thu, 18 Jul 2002 19:54:07 -0700 MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_NextPart_000_000B_01C22E94.E0398A20" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2919.6600 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2919.6600 This is a multi-part message in MIME format. ------=_NextPart_000_000B_01C22E94.E0398A20 Content-Type: multipart/alternative; boundary="----=_NextPart_001_000C_01C22E94.E0398A20" ------=_NextPart_001_000C_01C22E94.E0398A20 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable for you who are sweating noise control stuff: Here is an article (HTML Document format) from Boeing on light weight = ACTIVE noise control material. It is very interesting but the material is probably not really = available. My experience with PASSIVE noise absorption material is that weight is = the first order gauge of effectiveness. That is, a pound of lead, a pound of bricks or a pound of chicken feathers has the same sound reduction effectiveness within 10 percent. Noise is also perceived = logarithmically, which means a 10% change is completely trivial. Therefore it makes no difference what material is used. Chose the material for convenience = of installation and cost. Exotic high cost "miracle" stuff does not really perform. But the biggest item is to close all the cracks and holes between you = and the noise source and it also makes no difference what you use to close = the holes and cracks. This is the biggest control. There can also be resonant vibrations of panels but usually these are = not a factor for compound curved epoxy reinforced panels. It is more of a = problem on RVs and spam cans. Ross W. Colebrook 235 N7828 ------=_NextPart_001_000C_01C22E94.E0398A20 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable for you who are sweating noise control = stuff:
Here is=20 an article (HTML Document format) from Boeing on light weight ACTIVE = noise=20 control
material. It is very interesting but the material is probably = not=20 really available.

My experience with PASSIVE noise absorption = material is=20 that weight is the
first order gauge of  effectiveness.  = That is, a=20 pound of lead, a pound
of bricks or a pound of chicken feathers has = the same=20 sound reduction
effectiveness within 10 percent.  Noise is also=20 perceived logarithmically,
which means a 10% change is completely = trivial.=20 Therefore it makes no
difference what material  is used.  = Chose the=20 material  for convenience of
installation and cost.  Exotic = high=20 cost "miracle" stuff does not really
perform.

But the biggest = item is=20 to close all the cracks and holes between you and
the noise source = and it=20 also makes no difference what you use to close the
holes and = cracks. =20 This is the biggest control.

There can also be resonant = vibrations of=20 panels but usually these are not a
factor for compound curved epoxy=20 reinforced panels. It is more of a problem
on RVs and spam = cans.

Ross=20 W. Colebrook 235 N7828


------=_NextPart_001_000C_01C22E94.E0398A20-- ------=_NextPart_000_000B_01C22E94.E0398A20 Content-Type: text/html; name="Noise control.htm" Content-Transfer-Encoding: quoted-printable Content-Disposition: attachment; filename="Noise control.htm" Boeing Feature Release: A Soundproof Idea to Block = Noise
3D"Boeing
 

A Soundproof Idea to Block=20 Noise
Boeing Scientists = Developing=20 a 'Wallpaper' With Potential for Use Across the Aerospace=20 Industry

by William Cole
 

Imagine a high-tech "wallpaper" that uses compressed air to = block=20 outside noise on an airplane, protect sound-emitting military = equipment=20 from detection in the field, or shield sensitive satellites from = deafening=20 rocket sounds. Such a solution is not so off-the-wall.

3D"BBJ  
New technology is = being=20 developed called "fluidic wallpaper" that has many potential = applications for protection, privacy and stealth. This = Boeing=20 Business Jet, for instance, could take advantage of the new=20 lightweight sound-stealthy wallpaper to provide an even = quieter=20 atmosphere for in-flight meetings and improve en route = productivity=20 in the on-board conference rooms, executive offices and = individual=20 work spaces.  

Scientists at Boeing are working on a technology that could = actively=20 suppress unwanted sound inside airplanes and even make life more=20 comfortable for astronauts in space. The technology, called = "fluidic=20 wallpaper," has many potential applications for protection, = privacy and=20 stealth, and is being developed by Phantom Works, the research and = development unit of The Boeing Company where advanced = technologies,=20 processes and systems are developed.

Anders Andersson, a Phantom Works Technical Fellow in Seattle, = said the=20 system promises to be "a breakthrough in acoustics = technology."

The wallpaper is an active-control system using "smart" = materials and=20 will be about a quarter-inch thick. It will employ compressed air = to=20 counterbalance oscillating pressures that make up low-frequency = noise.=20 Low-frequency sound is emitted by such commonplace systems as = propellers,=20 jet engines, and heavy-duty diesel engines, and is easily = transmitted=20 through walls and windows.

Reducing sound has traditionally commanded heavyweight = solutions -=20 layers of sound-suppression materials that give the vehicles = unwanted=20 pounds and cost. Fluidic wallpaper would weigh much less than = traditional=20 materials, take up less space and be produced inexpensively. The=20 compressed air used within the wallpaper could be generated by = aircraft=20 engines or air conditioning and would not require electrical = power. The=20 wallpaper is projected to be unmatched by any other concept in its = low-frequency noise performance, according to Andersson.

"We're still in the early development stages and there's a lot = of=20 testing to be done," Andersson said.

Unwanted sound currently is controlled by various methods. The = first=20 strategy Boeing uses is to design systems that are quiet in the = first=20 place. When necessary, however, noise treatment measures must be=20 developed. A few current treatments include:

  • Acoustic panels in the engine enclosure=20
  • Insulation and vibration-damping materials in the fuselage = walls=20
  • Vibration isolation mounts for mechanical equipment=20
  • Mufflers in the air conditioning and Auxiliary Power Unit = systems=20

"Although we already take a lot of steps to make modern = airplane cabins=20 quiet, there's always room for improvement," said Larry Craig, = chief=20 engineer in Noise and Emissions Engineering at Boeing Commercial=20 Airplanes. "And, an added advantage of this new 'fluidic = wallpaper' is=20 that it promises to be inexpensive and very lightweight compared = to many=20 other sound treatment measures."

Andersson foresees plenty of applications for fluidic = wallpaper.

It could be used, for example, as wall trim in commercial = airplanes,=20 and in executive airplanes and military transports to satisfy = command-post=20 communication and stealth requirements. It could muffle the noise = of=20 armored vehicles and improve communication and the quality of life = for=20 astronauts aboard the International Space Station. The system = could be=20 built into equipment tarps that would shield the outside world = from noisy=20 generators and other equipment and prevent their detection in = military=20 operations. Rocket fairings could be lined with it to protect = sensitive=20 satellite payloads from the effects of noise generated by a = launch.

"There is potential for building a whole industry around this = concept,"=20 Andersson noted.

###

Contact: Kathleen Hanser 206-766-2911

Image is available for editorial use by news media on boeing= media.com

   
  =
=20
Contact Us = | Site=20 Map | Sit= e=20 Terms | Privac= y |=20 Copyright=20 =A9 2002
The Boeing Company. All = rights reserved.=20
------=_NextPart_000_000B_01C22E94.E0398A20--