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'[OT] Acoustic damping of vehicle exhaust noise'
2004\12\13@233539 by Russell McMahon

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To solve a problem with sound levels from race cars at a local track I
propose the following. Any comments welcome.

A fluid (preferably water) is pumped into the vehicle exhaust stream at a
point that suits specific conditions either before, at or after the exhaust
exit point. Most probable arrangement is just after the end of the pipe.
Water would be produced in a range of droplet sizes plus could be atomised
finely. Preferred arrangement is a moderately divided spray of droplets with
enough water linking them in finer form as to provide a continuous curtain
but other arrangements would be variably effective. Object is to provide
effective reduction in noise (sound pressure level) to meet local regulatory
requirements. This concept is an extension of that used by many rocket
launchers to absorb acoustic energy to prevent it damaging the rocket. In
that application mechanical energy reduction is the  main aim rather than
reducing perceived acoustic noise. Other fluids than water may be used.
Initial application is for race cars but extension to other vehicles and non
vehicular applications would be possible. Fluid flow could be held at
maximum requisite level or adjusted to match engine output as it varied.

In the specific instance concerned, all other known avenues have been tried
and there is a real risk of racing being shut down if regulatory
requirements keep not being met. Whether an oval of "Stanley Steamers" is
acceptable remains to be seen.




       Russell McMahon





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2004\12\14@012835 by Hopkins

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Just a thought :-)

How about using audio feedback in anti phase to cancel noise output from
cars.

Would require either an amplifier or can a mechanical method be used to
direct the noise back onto itself out of phase?

The water droplets sounds interesting.

_______________________________________
Roy
Tauranga
New Zealand
_______________________________________



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2004\12\14@041425 by Morgan Olsson

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My grand father invented a heater/boiler designed like a pulse jet variant.
In one designe the pulse pipe ended a couple mm over water in a bucket.
The bucket also contained pipes to dissipate heat from the water.
When operated the sond level was really damped, heat transfer to water magnificient, and we cold also catch sulfur from the oil in the water and neutralize, so it also rinsed the exhaust gas, bla,bla,... :)

Hopkins 07:28 2004-12-14:
>How about using audio feedback in anti phase to cancel noise output from
>cars.

Practically impossible due to sound level, and the irregular sound form.

It worked somewhat on the pulse heater though, but too expensive.

...

A better idea i saw discussed in a newspaper, was to get rid of theese in my and many other people ridiculous racing where the only thing matter is peak power.  Often limitid to only use the old ancient Otto engine with cold cylinder that never have and never will work neither efficiently or quiet.

Ther could be lots of other racing:
Oter clases of motors.  Limited fuel use.  Wood/hydrogen/battery powered.  Ultra low weight.  Etc, etc.  Much more interesting, and more demanding on engineers and driver.
And it would prabably have some good impact on vehicle development.

Mine -and just not mine- cents.
/Morgan

--
Morgan Olsson, Kivik, Sweden

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2004\12\14@042909 by Alan B. Pearce

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>In the specific instance concerned, all other known
>avenues have been tried and there is a real risk of
>racing being shut down if regulatory requirements
>keep not being met. Whether an oval of "Stanley
>Steamers" is acceptable remains to be seen.

Oh, you going stock car racing at Western Springs now?


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2004\12\14@053013 by Russell McMahon

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> >In the specific instance concerned, all other known
>>avenues have been tried and there is a real risk of
>>racing being shut down if regulatory requirements
>>keep not being met. Whether an oval of "Stanley
>>Steamers" is acceptable remains to be seen.

> Oh, you going stock car racing at Western Springs now?

No. But that's the venue that's under threat. It's been used for midgets and
similar for 75 years but the local resident's association is complaining
about the noise. Needless to say, they ALL bought houses in the area knowing
there was a speedway there.



       RM


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2004\12\14@062928 by Michael Rigby-Jones

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{Quote hidden}

We have simmilar situations in the UK, and as a motorsport fan this
NIMBY attitude really bugs me.  IMO there should be zero comeback if you
knowingly buy a property next to a motorsport venue.  

I'm not convinced that injecting water into the exhaust would be ideal,
even if it does reduce the noise levels.  There may be issues with
having the cars windscreen splattered in sooty water (and if they are
single seaters then it will be very unpleasant!) and grip levels may be
impacted during the race as more water gets put down on the surface.

Regards

Mike

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____________________________________________

2004\12\14@071422 by Jinx

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> We have similar situations in the UK, and as a motorsport fan
> this NIMBY attitude really bugs me.  IMO there should be zero
> comeback if you knowingly buy a property next to a motorsport
> venue

There's a fair bit of social baggage to this venue (which is also an
outdoor concert stadium)

A referendum has been suggested to sort this out, and have the
matter settled by majority voice, not the small minority of a few
complainers who may be motivated by more than their alleged
dislike of speedway noise

- a large stand of trees was cut down, removing a natural sound
barrier, but no one has explained why. It's been suggested that some
sort of fence be erected, as is done next to motorways

- a small group of residents have made it their goal to shut it down
come hell or high water (as detailed in minutes of resident's assoc
meetings from last year)

- some PC-leaning elements in the new (and some would say for
other reasons too) anti-blue-collar sport council are behind them. It's
the same kind of council that would "tone down" Christmas so as not
to offend anyone, but actually ruin it for the vast majority of people

- which would happen to the overall spectacle of speedway

- there's more than a hint of the intention being to raise house prices
in the area. It's said that some properties were bought cheap (perhaps
intentionally) because of the venue, now some individuals are trying to
profit

- immediate neighbours have had support banners on their fences. Some
whingers are actually a long way off. One wuss is from the NEXT suburb,
a couple of km away. He lives further away than I used to and can't say
speedway noise ever bothered me. Not for just 4 hours on 16 Saturday
evenings

- talkback logs reveal total support for speedway, not one pro-resident

I've no strong feelings either way for speedway (although a big fan of other
motor sports), but it's an infuriating example of babies whining for their
rattles. I hope they go rattle-less, there's little enough simple
entertainment
as it is

____________________________________________

2004\12\14@083703 by Edward Gisske

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The out-of-phase audio technique was accomplished by a Ford subsidiary
called Digisonix in Madison, WI in the late 80's. I believe they closed in
the mid-90's. I think the technology worked, but was difficult to make live
in a muffler.
Edward Gisske, P.E.
Gisske Engineering
608-523-1900
gisskespamKILLspamoffex.com

{Original Message removed}

2004\12\14@085059 by Walter Banks

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Russell McMahon wrote:

> To solve a problem with sound levels from race cars at a local track I
> propose the following. Any comments welcome.
>
> In the specific instance concerned, all other known avenues have been tried
> and there is a real risk of racing being shut down if regulatory
> requirements keep not being met.

It isn't clear that the noise reduction is for the drivers and spectators or the surrounding neighbourhood. I have a friend that is an acoustic expert who usually does design for the acoustics of concert halls and old refurbished abby's. A couple years
ago I asked what his current project was. He had just completed a noise reduction project at a quarry by surrounding it with some big blocks that broke up the sound and by making multiple sound paths damped the transient nature of quarry hammering.

Most expressways in cities in  Canada  and the US now have sound barriers that consist, physical barriers, walls with rough surfaces, strategic hills and mounds and/or dense vegetation which absorb sound (and eat COO for breakfast)

w..




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2004\12\14@102442 by redtock8

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Gee Russell that must have been a lot of work
for you to personally ask ALL those people
if they knew about the race track. About 15 miles
from where I live hundreds of people bought new homes
in the country only to find out there is a machine gun
range next to them.
Al
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2004\12\14@111347 by J. Gromlich

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About 16 years I and my wife bought a house built on the top of
a small mountain. We spent a lot of time up there before we
bought it - the place was empty and we would go up there and
enjoy the view ( 10 miles across the valley to the next mountain)
and the peace & quiet ( several herds of cows mooing down
along the valley floor).

After we had lived there for a bit over a year the RACE TRACK
across the valley re-opened -- it had been closed down by a
state/federal lawsuit over noise and property damage.  Of course
it had been closed and silent the entire year we were planning to
buy the property, and no one had told us it would be reopening.
Of course, the locals thought it was a great thing, so wouldn't
have known to tell us about it if we had asked.

After they opened,  the house became uninhabitable on weekends,
with the "thunder cars" rattling the windows AND doors from 6 PM
to 1 or 2 AM on Saturday and Sunday of every weekend during the
Spring, Summer & Fall.

We survived that for a few years - we don't live there anymore.

Moral (if any) - buyers might not know such a thing was there, or
that it was allowed to be such a public terror.

RJG

> {Original Message removed}

2004\12\14@134335 by Mike Hord

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> After they opened,  the house became uninhabitable on weekends,
> with the "thunder cars" rattling the windows AND doors from 6 PM
> to 1 or 2 AM on Saturday and Sunday of every weekend during the
> Spring, Summer & Fall.

It seems to me that a simple solution would be to limit racing times
to between 10 a.m. and 8 p.m., or a similar time frame.  There are
generally laws about noise after a certain time of evening, and I see
no reason motor racing should be exempt from them.

Mike H.
____________________________________________

2004\12\14@151228 by J. Gromlich

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Indeed, a reasonable person would think that a logical solution.

However, that wouldn't seem so to the "Thunder Car" types
because they WANT these to run after dark so the straight
exhaust pipes sticking out of the engine, belching superheated
exhaust gas, are clearly visible.  Needs to be dark to get
the required effect.  Also, you can't start the races before 6PM
or so because people aren't free to get there until then. Finally,
since the smaller and slightly quieter cars have already run people
are already almost deaf (and usually pretty drunk), and it takes a
lot more noise to get their attention.

And NO, I am not making this up - the editor of the town
paper told me this to my face.

Finally, as to legislation, the town Mayor and the Police Chief
were strong supporters of the race track, as being good
wholesome family entertainment. After all, there were only two
or three good punch-ups per race, and most of the drunks
just slept it off in the fields overnight after the race.  

This is a lifestyle issue - not a chance of legal help there.
The locals complained bitterly because of the EPA-ordered
shutdown.

RJG

> {Original Message removed}

2004\12\14@161054 by Richard.Prosser

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Re the water injection idea.
I used to own a small runabout boat that used this method. (Pleanty of
water available). The motor cooling water ejected directly into the open
exhaust pipe. Apart from leaving a trial of steam  behind and getting a
salty taste in the mouth of the water skier it seemed to work quite well.
Killed the higher frequency noise & what was left was not unpleasent. The
motor was an old Dodge flathead six FWIW.  Salt water got  to it in the end
I think, despite flushing out after each use. (The oil used to get water
mixed with it -  could have been a cracked block or corroded water jacket)
Used to go like stink though - 40mph at a time most local outboards could
only just manage 30.

How much water do you think they would need to carry.?

I've been following the Western Springs saga with interest as I used to
have a flatmate that raced there. Also, I've had similar experience of
being asked to sign a petition regarding a noise complaint despite knowing
the noise was there when I moved into the area.
I didn't sign.

If Wigram aerodrome ever opens up for proper use again I expect I'll be
asked to sign another one! (And I'll again refuse).

Richard P

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2004\12\14@184041 by Russell McMahon

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> Gee Russell that must have been a lot of work
> for you to personally ask ALL those people
> if they knew about the race track.

Due diligence / caveat emptor / common sense / NZ's best known speedway and
world famous for dirt track motorcycle racing.

Anyone buying a house in the relevant area and not knowing about Western
Springs Speedway doesn't know enough about house buying and should have
taken far better advice from all the sources that offer it, free or paid.
Odds are they have far worse problems with the house that they also don't
know about. I sympathise with people who are mislead by shonky sellers, but
there are some things that you can easily find out and should.



       Russell McMahon


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2004\12\14@193951 by Nate Duehr

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Roy J. Gromlich wrote:

[snipped long story about race track noise and the world's perfect house...]

> Moral (if any) - buyers might not know such a thing was there, or
> that it was allowed to be such a public terror.

Which was there first, the race track or the house?

I absolutely hate it when people whine about one of my favorite places
to go: Airports.

Why?  Because almost invariably the airport was there FIRST and had been
there for years before idiots encroached on it and then start
complaining about the airplane noise.

Absolute freakin' idiots.

If your house was there first, I can feel sorry for ya.  If the race
track was there first... see above.

Nate
____________________________________________

2004\12\14@195139 by redtock8

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What planet do you live on?
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{Original Message removed}

2004\12\14@205756 by Bob Axtell

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Russell McMahon wrote:

>> Gee Russell that must have been a lot of work
>> for you to personally ask ALL those people
>> if they knew about the race track.
>
>
> Due diligence / caveat emptor / common sense / NZ's best known
> speedway and world famous for dirt track motorcycle racing.
>
> Anyone buying a house in the relevant area and not knowing about
> Western Springs Speedway doesn't know enough about house buying and
> should have taken far better advice from all the sources that offer
> it, free or paid. Odds are they have far worse problems with the house
> that they also don't know about. I sympathise with people who are
> mislead by shonky sellers, but there are some things that you can
> easily find out and should.  


OK, Russell. Now, hear MY due diligence story.

Once upon a time there was a young engineer who lived in Texas, and
LOVED the Texas Gulf Coast, especially the Port Aransas area. He'd made
a killing on Datapoint stock and wanted to invest into a business that
would make a few $. He decided he wanted to invest on the seacoast, so
that he could check his investment and the drive to the investment was
deductible, and at the same time be near his ocean.

With his nose to the ground, one day he got a tip that the Dairy Queen
on the beach needed an investor, because the owner's wife needed surgery
and the owner needed to raise quick cash. The young engineer quickly
checked out the investment; $10K would have gotten 25% of that
restaurant. The Dairy Queen was right at the start of the island
highway, located in a good position, one mile from a favorite fishing
spot just down the road.

This young engineer was smart; he took a day off to research it in the
public records, and found out that alas, the freeway was to be cut and
rerouted to another spot.  Quick thinking and careful research had saved
the day. The investment was NOT made, and the young engineer saved his
money for the usual: song and women, not necessarily in that order (he
didn't drink).

Advance two years, and another visit to the beach. Indeed, the freeway
had been cutoff. But at that good fishing spot was  now a long, LONG
public fishing pier, allowing hundreds of people to fish on a
24hr-basis. The Dairy Queen restaurant was thereafter the highest
grossing Dairy
Queen in the state of Texas, over $5M per yr. As far as I know, it still is

I know this story well.   _I_ was that young engineer.

--Bob

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2004\12\14@211753 by Russell McMahon

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>> Due diligence / caveat emptor / common sense / NZ's best known speedway
>> and world famous for dirt track motorcycle racing.

> What planet do you live on?

I take it that's a reference to my comment on "world famous".

SO

Answer: The same one that the 10,000 odd NON-New Zealand sites are on that
you get when you google using

   +"western springs" +"new zealand"

ie a lot of people know about it worldwide, but you'll still have no
difficulty finding people on a NZ street who don't know what major event
finds it's home in Indianapolis. In NZ "The Springs" or "Western Springs" is
probably almost as well known as the concept "The Superbowl" is in a certain
other country.



       RM


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2004\12\14@213536 by Jinx

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> I know this story well.   _I_ was that young engineer.

Aw ;-((((  Would you like sighs with that ?

A broker friend talked me out of putting a lot of money
into gold at the end of the 70s. At the time it was ~ $200
and not long after shot up to $850. Bastard ;-)

http://www.kitco.com/charts/historicalgold.html

Tick boxes for Yearly Gold Charts 78, 79, 80. Didn't
like reminding myself at all

____________________________________________

2004\12\14@214856 by jrem

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--- Bob Axtell <engineerspamspam_OUTcotse.net> wrote:

{Quote hidden}

hindsight is 20/20, we all have stories like that.  




               
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2004\12\14@214959 by jrem

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--- Bob Axtell <@spam@engineerKILLspamspamcotse.net> wrote:

{Quote hidden}

hindsight is 20/20, we all have stories like that.  




               
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2004\12\14@215257 by redtock8

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I am 60 years old and have lived and worked from one end of the US
to the other and I have never been to a sporting event
and I do not know where of the stadiums or race tracks are so
by your standards I guess I deserve to take it in the rear
when I by another house only to find out that someone
down the street is a thoughtless SOB and runs their dirt bikes and ATV's
all day and most all night spring thru fall. I should knock on each and
every door
for 20 miles around and hope that the people would tell me about all the
problems in the immediate area before I buy. Yea right. Misery loves
company!
And yes it's possible to buy a home and not know that there is a race track
or what ever just a few miles away. I'm sorry to say that I am of the
working class
and after putting in 60 to 70 hours a week I am pretty tired and
it is difficult to cover all the bases when looking for a house.
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2004\12\14@232220 by Russell McMahon

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> I know this story well.   _I_ was that young engineer.

Can I sell you  a nice house by The Springs? :-)


       RM

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2004\12\15@003941 by Russell McMahon

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I'm sorry if I've sounded heartless. I certainly didn't mean to suggest that
people should be disturbed unreasonably by people who know the rules and
break them, or by substantial changes to an area that only benefit a special
interest group, or changes that aren't carried out in accordance with rules
that apply to all involved. All that works both ways of course. There are
always individuals who will seek to take advantage of the majority or to
walk into an existing situation and expect things to be changed to
accommodate them, regardless of the cost to others.

In that context -

> ... so by your standards I guess I deserve to take it in the rear
> when I by another house only to find out that someone
> down the street is a thoughtless SOB and runs their dirt bikes and ATV's
> all day and most all night spring thru fall. I should knock on each and
> every door for 20 miles around and hope that the people would tell me
> about all the
> problems in the immediate area before I buy. ...

Absolutely not. There's not much that can be done to stop a person moving in
who has scant disregard for the law. And there's no official means of
finding out where they are before you buy. What I was talking about was an
officially sanctioned activity that has been being carried out for 75 years.
It's something akin to buying a house somewhere near the Indianapolis race
track

> And yes it's possible to buy a home and not know that there is a race
> track
> or what ever just a few miles away.

It is. But that was my point about due diligence and using resources
available for free or for money when buying a house. No system is perfect,
but there are so many traps when house buying that, if you know you are not
an expert, it would be extremely unwise to invest in something as major as a
house without taking expert advice. Even a drive around a neighbourhood and
a look at a city map can work wonders. In the case of "Western Springs",
even a look at the track from a nearby high level road would give you a very
good idea of its function.

It certainly is possible to do due diligence and use common sense and still
get caught out, but most of the complainants (perhaps all) in this case are
liable to have been very aware of the existence of the speedway when they
bought in the area.

> I'm sorry to say that I am of the working class
> and after putting in 60 to 70 hours a week

You only work 70 hours a week ? :)

> I am pretty tired and it is difficult to cover all the bases when looking
> for a house.

Understood. But the magnitude of the investment means an essential part of
it is to either have an even tireder week, or to add a relatively small
amount to the cost by getting a report from people who do that sort of
thing for a living. Failure to do that may see you ending up next to someone
like me :-)


       Russell McMahon





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2004\12\15@003946 by Russell McMahon

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> Which was there first, the race track or the house?

Track has been there for 75 years.
The carpetbaggers rather less in almost all cases.
I have no great axe to grind for speedway - I haven't been for years. But
there is no doubt that the large majority of complainants here are
attempting to better themselves after knowing what they were letting
themselves in for. See Jinx's erudite prior synopsis.


       RM

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2004\12\15@091933 by Howard Winter

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Russell,

On Tue, 14 Dec 2004 23:08:58 +1300, Russell McMahon wrote:

> It's been used for midgets and similar for 75 years but the local resident's association is complaining
> about the noise. Needless to say, they ALL bought houses in the area knowing there was a speedway there.

Similar things happen here - a local aerodrome has been there since 1927, and local residents are complaining
about aricraft noise.  They really should have noticed it was there when they were looking at the houses!  One
of the complainants is a famous TV celebrity, and his house actually faces the field, across a 15' wide road.  
*No* chance he could have missed it.  He's a magician, so newspaper headlines about "...tries to make airfield
disappear" abound...

Cheers,



____________________________________________

2004\12\15@093143 by Howard Winter

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On Tue, 14 Dec 2004 07:38:55 -0600, Edward Gisske wrote:

> The out-of-phase audio technique was accomplished by a Ford subsidiary
> called Digisonix in Madison, WI in the late 80's. I believe they closed in
> the mid-90's. I think the technology worked, but was difficult to make live
> in a muffler.

It was used by British Gas to remove the low frequency components from the noise of a stationary jet engine
(an RR Olympus, as used in Vulcan, Concorde, and Type 42 destroyers, I believe) which drives a gas pump.  They
found that high frequencies could be filtered out by accoustic muffling, but the low frequencies were hard to
stop.  The anti-sound system works fine, apparently!

Not sure it would be any good at the scale we're talking about, though.

Cheers,



Howard Winter
St.Albans, England


____________________________________________

2004\12\15@152129 by Nate Duehr

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Russell McMahon wrote:

>> Which was there first, the race track or the house?
>
>
> Track has been there for 75 years.
> The carpetbaggers rather less in almost all cases.
> I have no great axe to grind for speedway - I haven't been for years.
> But there is no doubt that the large majority of complainants here are
> attempting to better themselves after knowing what they were letting
> themselves in for. See Jinx's erudite prior synopsis.

Yeah, understood.  I liked your reply -- no one here is heartless, but
the business of buying real-estate is.  Many many many people don't put
enough time and energy into their real-estate purchases or hire the
appropriate professionals to help them.  It's the largest single
transaction many of us will make in our lives -- barring us becoming
fabulously wealthy or running medium to large-sized businesses of our
own... and yet many of us buy real-estate like we buy automobiles.

An interesting twist developed near my house about ten years ago... the
local airport was being encroached on by housing and neighborhoods, and
the usual noise complaints started.  No mention of the fact that the
airport had both been there twice as long as the houses and was also out
in the middle of an empty field for ten years prior to the development
of the area.

The FAA, trying to "help" the situation opened a "complaint line"... an
answering machine local homeowners could call to complain about aircraft
not following the voluntary noise-abatement procedures.  Since the FAA
had paid for well-over half the runway environment, it seemed prudent
that they assist with the perceived "problem".

One of the more militant pilot's organizations filed a Freedom of
Information Act request to get all names and numbers of people
complaining, and then filed "Defective Property" notices against the
homeowners in the local county court.  Our State is a "disclosure"
State, meaning that if there's something wrong with the property the
owner hasn't disclosed to the buyer, the original owner is liable for
damages.

It was ugly, but it got the point across... the local judges eventually
forced the FAA to close down the complaint line because their dockets
were clogged with cases they had to hear about tens of "Defective
Property" hearings.  The homeowners and the FAA had accidentally created
a direct way for the local pilot's group to instantly lower complainer's
property values.

Luckily the airport is *extremely* busy and home to a number of very
successful businesses in the area, or there may have been a bigger
battle... eventually it all pretty-much blew over, pilots were trained
on how to fly near the airport but not over the affected neighborhoods,
and generally the neighbors and the airport live peaceably in the same
space now... but if the houses had never encroached on the airport, the
whole problem wouldn't have happened.  There was PLENTY of open space
East and South of the airport with adequate major road access that was
later developed that any of the complaining neighborhoods could have
been built in.  But the developers got the land cheap, the people got
the houses cheap, and then complained...

Certainly was interesting to watch the fireworks that ensued, and the
lack of reason once people on both sides started letting their anger get
the better of them.

Nate
____________________________________________

2004\12\15@171636 by Bob J

picon face
> An interesting twist developed near my house about ten years ago... the
> local airport was being encroached on by housing and neighborhoods, and
> the usual noise complaints started.  No mention of the fact that the
> airport had both been there twice as long as the houses and was also out
> in the middle of an empty field for ten years prior to the development
> of the area.

I live on out in the sticks on a residential airpark that became a
public airport in 1967, and between myself and one of my neighbors we
a create quite a racket once or twice a week when practicing our
aerobatic routines.  Fortunately for us, the neighbors nearby love it,
they have called the office asking when the next airshow is.  They
know we're good neighbors who are respectful of them, so they don't
mind the occasional noise.  But the day is coming as more and more
housing tracts are built around us, when some chump that comes along
who buys a cheap, poorly-constructed vinyl village home near our
airport will decide that airplane noise bugs them more than the daily
noise of their neighbor's harley-davidson.  Of course since they've
solved all of society's other problems they have energy to devote to
such activities.  I've seen this happen too many times.  The FAA guys
have to investigate all complaints, and it turns out that something
like 99.9999% of the complaints are unfounded or unenforcable.  All it
ends up doing is creating is a lot animosity.

Regards,
Bob
____________________________________________

2004\12\15@173512 by Support - KF4HAZ

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Within 20mi. of me there is a housing development that has a very
unusual "restriction clause", to meet the requirements to live there
at least one member of the household MUST hold a valid pilots license.
They have a taxi-way from each house to the hangar and the runway.
Interesting sight, planes parked at homes for lunch, then back up they go.

KF4HAZ - Lonnie

----- From: "Bob J" <rocketbob@

{Quote hidden}

____________________________________________

2004\12\15@195253 by Robert Rolf

picon face
Is there some reason that these racers just don't use a
'PROPER' muffler to solve their noise problem? I have heard
big luxury cars under full power acceleration and they
are very quiet compared to small 'sport' cars which have less
power.

There was also an article in Popular Science a decade ago,
on a siliastic rubber muffler used on small 4 cycle engines
(like lawn mowers). Apparently it made this motor MUCH quieter
and cost only a few 10s of dollars to retrofit. For some reason
it never caught on.

Seems to me that the solution is to use an appropriate muffler,
rather than to reinvent the wheel.

Robert

Howard Winter wrote:

{Quote hidden}

____________________________________________

2004\12\15@205750 by Richard.Prosser

flavicon
face

According to the TV reports they have put a reasonable amount of work into
trying different mufflers but I do wonder how much of that is window
dressing to try and get the local council to make some sort of concession.
Pictures were shown of them fitting & evaluating a variety of different
commercial & modified systems.They also tryed to evaluate how many cars
they could run before exceeding the noise limit - it tuned out to be about
7 & not considered enough for a "proper race".
However, how much noise is generated by their induction systems and how
much directly radiated from the motor etc. was not covered. I agree that
commercial mufflers seem to be able to reduce the noise level to a very
large extent and marine systems using water injection appear to take it
even futher.
I'm sure people go there not just for the racing, but the whole experiance
- the smoke and the smell and the noise being a large part of it so I
suspect they are trying to find out just how close to the "acceptable"
noise level they can get rather than going all out to reduce it to a
minimum.

RP



Is there some reason that these racers just don't use a
'PROPER' muffler to solve their noise problem? I have heard
big luxury cars under full power acceleration and they
are very quiet compared to small 'sport' cars which have less
power.

There was also an article in Popular Science a decade ago,
on a siliastic rubber muffler used on small 4 cycle engines
(like lawn mowers). Apparently it made this motor MUCH quieter
and cost only a few 10s of dollars to retrofit. For some reason
it never caught on.

Seems to me that the solution is to use an appropriate muffler,
rather than to reinvent the wheel.

Robert





____________________________________________

2004\12\15@225709 by Roy J. Gromlich

picon face
There are several  reasons they don't / won't use a "proper" muffler.

First, they will tell you that there is some power loss due to back
pressure and flow resistance in even the best muffler.  Car racing
- especially super car racing - is about squeezing every last drop
of torque out of the engine.  This is the same reason motorcycle
owners of a certain sort insist on straight-thru pipes.

Secondly, these are what are called "thunder cars" -- the name
should suggest that one of the "features" of these machines is the
fantastic amount of sound pressure they can produce. It definitely
reaches the threshold of pain, and probably there is enough energy
to cause permanent physical damage to the ear.  But that, apparently
is part of the ":thrill".

Finally, some of the people who enjoy this "sport" just love the idea
that people 5 miles away know that they are out having a good time
with their expensive toys.

RJG

{Original Message removed}

2004\12\16@121523 by Peter L. Peres

picon face

On Wed, 15 Dec 2004, Roy J. Gromlich wrote:

> Secondly, these are what are called "thunder cars" -- the name
> should suggest that one of the "features" of these machines is the
> fantastic amount of sound pressure they can produce. It definitely
> reaches the threshold of pain, and probably there is enough energy
> to cause permanent physical damage to the ear.  But that, apparently
> is part of the ":thrill".

No, it's a part of the supercharging the engine using resonating exhaust
pipes.

Peter
____________________________________________

2004\12\16@121600 by Peter L. Peres

picon face

On Wed, 15 Dec 2004, Robert Rolf wrote:

> Is there some reason that these racers just don't use a
> 'PROPER' muffler to solve their noise problem? I have heard
> big luxury cars under full power acceleration and they
> are very quiet compared to small 'sport' cars which have less
> power.

A big luxury car under full acceleration is under full control of its
ECU that limits torque and hp and acceleration rate. Otherwise calculate
for yourself what happens to a Merc that weighs under 1 ton and has
~550hp and more torque than the average diesel tractor in 1st gear.

> There was also an article in Popular Science a decade ago,
> on a siliastic rubber muffler used on small 4 cycle engines
> (like lawn mowers). Apparently it made this motor MUCH quieter
> and cost only a few 10s of dollars to retrofit. For some reason
> it never caught on.
>
> Seems to me that the solution is to use an appropriate muffler,
> rather than to reinvent the wheel.

Mufflers eat horsepower by gas friction/back pressure, and they prevent
the operation of tuned (resonating) exhaust stacks, which costs more hp.
They are also very bulky to be efficient on race engines and there is no
place to put them on the car. I have read somewhere that a properly
designed exhaust system for a car has 1/4 to 1/2 of the volume of the
engine (total volume not cylinder capacity). Also on a race engine the
air intake manifold can make more noise than the exhaust under certain
conditions.

Peter
____________________________________________

2004\12\16@121601 by Peter L. Peres

picon face

On Thu, 16 Dec 2004 RemoveMERichard.ProsserTakeThisOuTspamPowerware.com wrote:

> However, how much noise is generated by their induction systems and how
> much directly radiated from the motor etc. was not covered. I agree that
> commercial mufflers seem to be able to reduce the noise level to a very
> large extent and marine systems using water injection appear to take it
> even futher.

I'm pretty sure that the water spray into the exhaust system on marine
engines is not a noise-related device. Exhaust plumbing on a boat can
run hot enough to ignite fuel vapor in closed compartments and the water
injection prevents this.

Peter
____________________________________________

2004\12\16@135807 by Robert Rolf

picon face
Peter L. Peres wrote:
> On Wed, 15 Dec 2004, Robert Rolf wrote:
>
>> Is there some reason that these racers just don't use a
>> 'PROPER' muffler to solve their noise problem? I have heard
>> big luxury cars under full power acceleration and they
>> are very quiet compared to small 'sport' cars which have less
>> power.
...
> Mufflers eat horsepower by gas friction/back pressure, and they prevent
> the operation of tuned (resonating) exhaust stacks, which costs more hp.
> They are also very bulky to be efficient on race engines and there is no
> place to put them on the car. I have read somewhere that a properly
> designed exhaust system for a car has 1/4 to 1/2 of the volume of the
> engine (total volume not cylinder capacity). Also on a race engine the
> air intake manifold can make more noise than the exhaust under certain
> conditions.

OK.
So why can they not run baffles or ducts that would suppress
the noise of the turbocharger(?). Weight?

How much horsepower is being lost in noise generation?
How much HP are racers willing to give up to suppress noise
if the trade off is NO racing?

Can some of the exhaust gas be diverted down a 1/4 wave longer
pipe to achieve phase cancellation as it comes out
the end of the exhaust pipe? (given changing RPM this
would be a tricky problem).

Being naive on the subject, it just seems that if one draws
an electrical analogy, one needs impedance transformers to
allow for high impedance exhausts to be dumped into
low pass filters with minimal loading.
Or is part of the 'experience' of racing the gut pounding
noise?

And if vehicles are noisy because of the desire to have
free exhaust flow, doesn't injecting water into the tailpipe
defeat the point by impeding gas flow?

Robert

____________________________________________

2004\12\16@145921 by Howard Winter

face
flavicon
picon face
Peter,

On Thu, 16 Dec 2004 18:30:08 +0200 (IST), Peter L. Peres wrote:

> Otherwise calculate for yourself what happens to a Merc that weighs under 1 ton and has ~550hp and more
torque than the average diesel tractor in 1st gear.

Nothing happens, because half of it is missing!  I don't think you'll find any Merc, apart from possibly the
new "Smart" type shopping cars, that come anywhere near being under a ton - or even much under two!

Cheers,


Howard Winter
St.Albans, England


____________________________________________

2004\12\17@045236 by Michael Rigby-Jones

picon face


{Quote hidden}

Turbochargers make little noise, and in fact work as very efficient
silencers (mufflers) themselves as they slow down the pulses on the gas
and give a more even flow.  However, most track racing series don't have
turbocharged engines.

>How much horsepower is being lost in noise generation?

Very little, the noise generation is part of the mechanism that is used
to produce MORE horsepower.  Cams with very steep opening and closing
ramps are used to give the maximum possible valve curtain area, and also
produce very strong pressure waves that are utilised with tuned length
exhausts to provide improved cylinder scavenging.  Standard silencers
that use baffles and restrictions to reduce noise effectively stop this
mechanism from working and also increase pumping losses due to the
increased back pressure.  Absorbtive type silencers don't introduce
significant back pressure, but also are not as effective.

{Quote hidden}

It is a big part of the racing experience, but obviously it needs to be
regulated to reasonable levels.  The problem is, who defines what level
is reasonable, and also there is a practical issue.  The track in
question is for speedway, the cars are small and there is limited room
to install an effective silencing system.

Speedway in the UK is motorcycle racing around a dirt oval, the
reference to cars had me confused for a while!

Regards

Mike

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____________________________________________

2004\12\17@060347 by Russell McMahon

face
flavicon
face
> Speedway in the UK is motorcycle racing around a dirt oval, the
> reference to cars had me confused for a while!

At Western Springs it can be both cars and bikes.


       RM
____________________________________________

2004\12\17@070855 by Gerhard Fiedler

picon face
Michael Rigby-Jones wrote:

> It is a big part of the racing experience, but obviously it needs to be
> regulated to reasonable levels.  The problem is, who defines what level
> is reasonable, and also there is a practical issue.  The track in
> question is for speedway, the cars are small and there is limited room
> to install an effective silencing system.

Racing in all classes/formulas is already extremely regulated --
displacement volume, number of cylinders, size, weight, many technology
restrictions.

One could argue that the displacement volume restrictions do much more to
curb power than any sound restrictions could ever do -- most are in place
with the explicit objective to curb power. So if power is the real issue,
why not increase the maximum allowed displacement and reduce the maximum
allowed noise? This simple solution (and the fact that nobody seems to
think of it) seems to indicate that power loss in mufflers is not the
issue.

Why not add some restrictions that would actually be worthwhile? Maximum
noise level, maximum fuel consumption, you name it -- motor sport has been
a traditional venue for developing technology, so why not direct it to
where it's more directly useful? Get rid of the artificial restrictions of
displacement and aerodynamics and fuel injection, let the engineers
optimize the engines and cars as much as they want, but under restrictions
that actually make sense in the world as it is now.

What would not be exciting about a race track where cars run at 200 km/h
with engines that don't make more noise than 60 dB and don't consume more
than 10 l over a 200 km course? (Not sure all three of them are possible
with today's technology, but you get the drift...)

Gerhard
____________________________________________

2004\12\17@153950 by Peter L. Peres

picon face

On Thu, 16 Dec 2004, Robert Rolf wrote:

{Quote hidden}

Same reason as above. The intakes are *also* resonance tuned, and the
volume of a muffler that would shut it up without power penalty would
likely be half the size of the entire car.

> How much horsepower is being lost in noise generation?
> How much HP are racers willing to give up to suppress noise
> if the trade off is NO racing?

Look, you can always race bicycles, you know.

> Can some of the exhaust gas be diverted down a 1/4 wave longer
> pipe to achieve phase cancellation as it comes out
> the end of the exhaust pipe? (given changing RPM this
> would be a tricky problem).

In theory it should work and I know from hearsay that the exhaust
systems on some 60's and 70's cars were deliberately built like this
(not race cars) to obtain some specific exhaust sound, even with small
engines.

> Being naive on the subject, it just seems that if one draws an
> electrical analogy, one needs impedance transformers to allow for high
> impedance exhausts to be dumped into low pass filters with minimal
> loading. Or is part of the 'experience' of racing the gut pounding
> noise?

Again, the noise comes from an air column resonating in the exhaust and
intake manifolds. You *want* it to resonate. The noise is an unwanted
byproduct. 'Impedance' matching in the case of exhaust and intake piping
means flared apertures at the atmosphere side, and so they are.
Unfortunately this also maximises noise coupling. Tuned plumbing is
usually not flared (to give a good reflexion at the 'impedance
mismatch'.

> And if vehicles are noisy because of the desire to have
> free exhaust flow, doesn't injecting water into the tailpipe
> defeat the point by impeding gas flow?

The water mostly gets there to relax exhaust system requirements, like
heat and volume (water injection increases exhaust density by lowering
its temperature - this affects the speed of sound in it and with it the
required muffler size). If done right it should not impede gas flow, on
the contrary, the expansion of water into steam can be used to generate
more suction in the exhaust system (but I have never read about it used
for this).

It *is* possible to build and run large engines quietly, f.ex. see
commuter aircraft turboprop engines where the majority of the noise
comes from the propeller in despite of 3000+hp ratings.

Peter
____________________________________________

2004\12\17@155443 by Peter L. Peres

picon face


On Thu, 16 Dec 2004, Howard Winter wrote:

{Quote hidden}

Try a roadster. This is a start:

<http://www.fast-autos.net/mercedes/mercedessl65.html>

notice 'top speed 155mph electronically governed'

Peter
____________________________________________

2004\12\17@201136 by Howard Winter

face
flavicon
picon face
Peter,

On Fri, 17 Dec 2004 22:55:04 +0200 (IST), Peter L. Peres wrote:

{Quote hidden}

They don't give the weight - I'd be amazed if they can get a car with a V12 twin-turbo 6 litre engine to weigh
less than a ton!  Apart from anything else, getting 612bhp onto the road would be virtually impossible with
something that light, especially two-wheel drive.

> notice 'top speed 155mph electronically governed'

I also notice they don't give the price, or the mpg!  :-)

Cheers,



Howard Winter
St.Albans, England


____________________________________________

2004\12\20@051659 by Peter L. Peres

picon face


On Sat, 18 Dec 2004, Howard Winter wrote:

{Quote hidden}

The price was something like $45k and up, weight of the untuned roadster
is 3500lbs (afair) I think. With tuning they probably reduced it a
little. Technology reached 1hp/lb for engines around ww2, no ?

Peter
____________________________________________

2004\12\20@140434 by Andrew Warren

flavicon
face
Peter L. Peres <RemoveMEpiclistspamTakeThisOuTmit.edu> wrote:

> > > <www.fast-autos.net/mercedes/mercedessl65.html>
> ....
> The price was something like $45k and up, weight of the untuned
> roadster is 3500lbs (afair) I think. With tuning they probably
> reduced it a little.

   The price starts at around $180K in the USA.  Weight of the
   standard car (non-AMG SL600) is over 4400 pounds; since AMG's
   SL55 is a couple hundred pounds HEAVIER than the standard SL500,
   I would expect that their SL65 would also be heavier than the
   SL600.

   -Andy

=== Andrew Warren -- aiwEraseMEspam.....cypress.com
=== Principal Design Engineer
=== Cypress Semiconductor Corporation
===
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation

____________________________________________

2004\12\22@032958 by Peter L. Peres

picon face


On Mon, 20 Dec 2004, Andrew Warren wrote:

{Quote hidden}

Ok. I had compiled data from 3 different websites, thus some errors.
Strange that it is so heavy. I had expected it to be much lighter.

Peter
____________________________________________

2004\12\22@155726 by Andrew Warren

flavicon
face
Peter L. Peres <RemoveMEpiclistEraseMEspamEraseMEmit.edu> wrote:

> Strange that [the Mercedes/AMG SL65] is so heavy. I had expected
> it to be much lighter.

   The big SLs are boulevard cruisers, not sports cars; they've
   been "super light" in name only for decades.  Even the baby SLK
   weighs over 3100 pounds...

   -Andy

=== Andrew Warren -- RemoveMEaiwspam_OUTspamKILLspamcypress.com
=== Principal Design Engineer
=== Cypress Semiconductor Corporation
===
=== Opinions expressed above do not
=== necessarily represent those of
=== Cypress Semiconductor Corporation

____________________________________________

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