sound meter

[Xavier Mouraux]

Hello guys,

I am trying to have my club using some sort of noise rules. I would like to
know what level and what procedure are used in your clubs. Is there a
non-quantitative way of doing this in a club without creating troubles ?
Also, how do we calibrate the tester ?

Thanks

Xavier



----- Original Message ----- 
From: "David Lockhart" <DaveL322 at comcast.net>
To: <discussion at nsrca.org>
Sent: Monday, April 26, 2004 9:54 PM
Subject: Re: sound meter


> To me, the bottom line on the current noise rule (largely unchanged since
> introduced) is that we no longer have 105 db planes that offend the
> neighbors.  And from my experience over the past 15 years working with
> "quiet" setups - an honest 94 db on pavement is not that difficult to
> achieve.
>
> In practice, application of the noise rule is not without problems - but
it
> is not that difficult to copy setups that are known to be quiet, and
> following some basic rules of thumb will keep the noise under the limit -
> and avoid noise test failures at major contests.
>
> The last thing I would want to see is a shift from a quantitative noise
> measurement to a qualitative noise measurement - I'd hate to see placement
> in a contest determined by a bonus or penalty assigned by a judge to a
plane
> that sounded "nice" or "loud" - especially considering the relatively
> uncontrolled background noise present at most contests (other planes in
air,
> engines running in the pits, etc).
>
> Regards,
>
> Dave Lockhart
> DaveL322 at comcast.net
>
>
>
>
> ----- Original Message -----
> From: "Adam Glatt" <adam.g at sasktel.net>
> To: <discussion at nsrca.org>
> Sent: Monday, April 26, 2004 3:44 PM
> Subject: Re: sound meter
>
>
> > Earl Haury wrote:
> >
> > > Generally even the sound meter calibrators are +- 0.5 dB. Makes the
> > > flight zero for >94 (F3A) really a tough rule (even flying behind the
> > > flight line only zero's the maneuver)! Albeit, a fail isn't official
> > > until verified by a second meter - but generally both are calibrated
> > > with the same device, so the calibrator offset will be present at both
> > > meters. Calibrator equipment itself should be re-certified pretty
> > > often (yearly), want to bet when the Nats equipment was last
certified?
> > >
> > > The only way to be sure is to use known accuracy equipment and target
> > > a number that allows for equipment variance. The air density at the
> > > time you make measurements will vary the results also, both from an
> > > engine output (more/less rpm) and a sound transmission standpoint.
> > > This can amount to a couple of dB, and the Muncie site is usually
> > > better air density than soggy Houston - so the noise measured is
> > > higher in Muncie. Again, allow for this in your noise plan.
> > >
> > > The good news is that the Nats meters seem to be on the liberal side
> > > and the display is analog - making it difficult to discern the
> > > difference between 94 and 94.xx. Also the 96 dB AMA limit is much
> > > easier to attain and the penalty for missing a little not too bad.
> > >
> > > Earl
> >
> > Good idea, but terrible rule.  They should give a 5% score penalty to
> > the noisiest 10% of planes in a class (either by ear or by sound meter),
> > imo.  Measuring a plane on the ground, with someone holding it, people
> > standing around, wind blowing, and the prop a few inches from the
> > ground, and from a distance that doesn't represent the problem of noise
> > (i.e. Shulman's electric being one of the loudest planes on the meter
> > due to low clearance and gear box noise, but one of the quietest in the
> > air) is a dumb way to do it.  The only noise that matters is what we
> > hear while the plane is in the air.
> >
> > It was obvious in Poland the FAI officials knew the sound rule was
> > implemented wrong, as well.
> > =====================================
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> > and follow the instructions.
> >
>
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