[NSRCA-discussion] Noise rules

[Ed Alt]

FYI, our club slapped the IMAC noise rule into effect for all models and 
it's basically a license to make about as much noise as you can.  One of the 
problems with how measurements are made is that the height above the ground 
of the exhaust and prop arc is not specified.  So you take a small, high RPM 
glow model with an industry standard noise vectoring nozzle.  You run it up 
on a grass surface, just a few inches above nature's muffler.  Man, what a 
nice reading you get.  Doesn't even register on the meter at 25' if it's 
close enough to the grass.  Pick that little buzz saw up a foot or so and 
it's an entirely different story.  Effectively, what our club unwittingly 
did was hand a permission slip to everyone to drown out anyone who makes a 
serious attempt at quieting the airplane down.  No one pays much attention 
to these things until a field is threatened.  When you can't here your 
DA-150 in flight, you know you have a problem.

The point is, the science doesn't seem to be easy to boil down into an easy 
to follow recipe.  IMAC did attempt that with their sound committee a few 
years back, but the results weren't as good as hoped for.

Ed

----- Original Message ----- 
From: "Joe Lachowski" <jlachow at hotmail.com>
To: <nsrca-discussion at lists.nsrca.org>
Sent: Thursday, June 22, 2006 7:54 AM
Subject: Re: [NSRCA-discussion] Noise rules


> >From what I measured a quite a while ago, I believe the equivalent at 25 
> >ft
> to that at 10ft is about a 7db difference.
>
>
>>From: "Lance Van Nostrand" <patterndude at comcast.net>
>>Reply-To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
>>To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
>>Subject: Re: [NSRCA-discussion] Noise rules
>>Date: Wed, 21 Jun 2006 22:53:36 -0500
>>
>>I'm not sure if there may be a perception that measuring at 25 feet is
>>somehow more palatable than at 10 ft.  If this is the feeling in your club
>>then go for it.  However, I know from experience that all influences on 
>>the
>>measured result (wind, hard/grass, fences, proximity to a covered pit echo
>>chamber, cars, etc) are exponentially amplified with distance.  I measured
>>the same Extra330 with a large gas engine in every way possible and found
>>the results varied from 101-105 db.  This is a huge variation.
>>Upwind/downwind in about 10 mph winds is worth 2-3 db.  At 10 ft the
>>variation was from 102-103 db.  If you have a guy with a plane near the
>>limit he may argue your measurement result.  If you say the lmit is the
>>highest value measured then you are really restricting some guys with loud
>>planes to less than the nominal. If you provide leeway, then your limit is
>>effectively raised.  It opens a can of worms.
>>
>>Lance
>>   ----- Original Message -----
>>   From: Glen Watson
>>   To: 'NSRCA Mailing List'
>>   Sent: Monday, June 19, 2006 10:52 PM
>>   Subject: Re: [NSRCA-discussion] Noise rules
>>
>>
>>   Links below are to a RC club in the Houston market who implemented a
>>noise standard..  My club has adopted the same standard.  In 2004 we had
>>complaints from a nearby neighbor regarding noise.  Since implementing 
>>this
>>noise standard we've had zero complaints.
>>
>>
>>
>>   http://fortbendrc.com/
>>
>>
>>
>>   http://fortbendrc.com/Field/Field%20Noiselevel.htm
>>
>>
>>
>>   Regards,
>>
>>
>>
>>   ~Glen
>>
>>
>>
>>
>>
>>
>>
>>
>>------------------------------------------------------------------------------
>>
>>   From: nsrca-discussion-bounces at lists.nsrca.org
>>[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of John 
>>Ferrell
>>   Sent: Monday, June 19, 2006 8:09 PM
>>   To: NSRCA Mailing List
>>   Subject: [NSRCA-discussion] Noise rules
>>
>>
>>
>>   If someone out there has a set of noise rules for a general purpose RC
>>club? Especially a set that works.
>>
>>
>>
>>   I cannot expect the masses to conform to pattern numbers, but I need
>>something to start with. "Reasonable" does not seem to mean the same thing
>>to every one.
>>
>>
>>
>>
>>
>>   John Ferrell    W8CCW
>>   "My Competition is not my enemy"
>>   http://DixieNC.US
>>
>>
>>
>>------------------------------------------------------------------------------
>>
>>
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>
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