Topic: Club noise levels?

I was completely wrong, its a JMB... my excuse is that Duncan bought it not me!

http://www.iadmodeldesigns.co.uk/

CM

Good link. Excellent range of stuff.

Silencers can improve running. We tried an experiment with my Acrowot with an Irvine 46 some years ago, measured it and it was just on the limit. Fitted a silencer add-on which was on sale in the nineties but has now been discontinued, the 'Quiet Silencer', as fitted to the Q engines from Irvine, it was much quieter AND 100rpm more!

perhaps that is what I need to do...fit an add-on, what say? half the size of what`s fitted?

chaz@2b

perhaps that is what I need to do...fit an add-on, what say? half the size of what`s fitted?

chaz@2b

I would say larger! The gases need to expand, which reduces the noise and lowers the note. On a 50cc petrol, the trick of two Camping Gaz cylinders soldered back to back with holes drilled in the concave bases (not aligned with each other) is very effective. (Connect with Bendy pipe) This can usually be hidden in the fuselage, with an outlet at the bottom. The silencers I referred to were made by Martin Forrest, who has since given up the trade. You took the rear part off an Irvine or OS silencer and replaced it with his bit, with baffles inside, and it worked a treat.

as a flier of solely petrol motors these days can i just say that these engines are no noisier than glow motors, the problem, and i,m no scientist here, is frequency, low frequency noise (petrol engines) travels much further than high frequency sound,(ask a whale ) so the same people 1km away will poss not hear the buzzing glow, but will hear the low drone of a petrol, also don't forget prop noise, the only time we have had a noise complaint from our nearest neighbour was due to some large aerobatic aircraft with very effective, expensive, silencers with carbon props howling away being heard for miles,

  cj

as a flier of solely petrol motors these days can i just say that these engines are no noisier than glow motors, the problem, and i,m no scientist here, is frequency, low frequency noise (petrol engines) travels much further than high frequency sound,(ask a whale ) so the same people 1km away will poss not hear the buzzing glow, but will hear the low drone of a petrol, also don't forget prop noise, the only time we have had a noise complaint from our nearest neighbour was due to some large aerobatic aircraft with very effective, expensive, silencers with carbon props howling away being heard for miles,

  cj

Hmm- I thought that carbons were quieter? But I agree, low notes travel much further. (but are not so obnoxious as a small glow)

Hmm- I thought that carbons were quieter? But I agree, low notes travel much further. (but are not so obnoxious as a small glow)

Depends how fast they are turning.
MIke

Just an interjection from one of the Colonials here, but our club in Burlington, Ontario, Canada, the Burlington Radio Control Modelers has a noise limit in our rules.  We have two airfield within the city limits, and we try to be proactive to reduce any noise polution to protect our flying fields.  Below is copied from our field rules:

4.No aircraft shall exceed a noise level of 85 db at 7 meters.

If anyone is interested, our club website is
 http://www.brcm.org
and we list the club flying rules on our website, following closely the guidelines of MAAC (Model Aeronautics Association of Canada), our governing body for modeling in Canada

Just my 2 cents worth from off shore in the New World.

Bill
MAAC 47841L
IMAA 31638
Burlingnton Radio Control Modelers

Hi Bill - always good to get the non-UK-centric view on things! 

We often perceive Americans and Canadians as having loads of space and flying miles from anywhere.  I'm sure that's true in some instances, but many clubs "over there" must fly, like we do, not too far from noise-sensitive neighbours.  Interesting that your limit is 85 db at 7 metres, in contrast with the typical 82db at 7 metres over here.

I thought the 82d was a guideline and not a limit as such. 

Ok, 82db comes, I think, from some government agency and you're right it is a guideline rather than some hard and fast limit.  But it's the figure that a lot of clubs have adopted.

And I did say "in contrast with the typical 82db at 7 metres over here."

85 dba is also approximately twice as loud as 82dba...  It should be very easy to get most models through at 85dBA

CM

85 dba is also approximately twice as loud as 82dba...  It should be very easy to get most models through at 85dBA

It's twice as much sound energy, yes. But it doesn't sound twice as loud because our ears have a logarithmic response curve too. That's why dBs are useful for measuring volume...

For those new to trying to  understand the noise element of our hobby, Andy Ellison has an article on the subject (to be included as a series in future issues)  in the Autumn 2011 RCM&E special. It`s a very good read, also good for those who cannot spend a long time viewing computer screens. Take it along with you to the airfield and discuss with other flyers, the article also includes a propeller tip speed calculator..even just as a topic of conversation it has value......

...."can I have my commission now...."

just my £4.99`s worth

chaz@2b

I thought the 82d was a guideline and not a limit as such. 

It's a figure from the Dept Of Environment (though I think they are now DEFRA), and is used by the BMFA etc as a guideline. It is also the figure you will be judged on if a noise abatement officer has cause to attend your field following a complaint.

Our rules state the 82dB @ 7m limit is adopted, and we have a couple of very quiet 50cc models, acheived with padding the cowls (often a big contributer, especially with the H9 Carden Yak) and using oversized cans. IIRC one has a JMB 80cc can, no lack in performance.

As others have noted, noise is very subjective. I fly all electric, and the 50cc electrics are very loud on the ground, all prop noise, but whisper quiet in the air. My EDF models 'sound' louder, and a 400 sized brushless delta like a Funjet can be really quite objectionable.

Our last noise complaint was 10+ years ago, after which the 82dB limit was enforced. We have had no complaints since, and since the area affected is now beyond some very tall and bushy trees, don't expect another

What material was used for the `padding`?

chaz@2b

Foam, like you'd wrap your Rx in, stuck to the inside of the cowl.

Foam, like you'd wrap your Rx in, stuck to the inside of the cowl.

You can also get 'sound deadening' material from Halfords etc., intended to stop car door panels resonating with powerful stereos, but it's very heavy. Which could be good if it means you can replace some lead with something actually doing a job!

or nip down the scrap yard and whip some of the lining out of a bonnet or from under the front carpets...

S'funny but this weekend at the field - out of all the models flying around the only ones you couldnt hear youself think was the three little glow's buzzing around like angry nat's.

The jets / petrols and even the electrics were all nosy up close but much - much quieter in the air.

Maybe the valid test would be a greater distance ?

Chris

Hi all, read this through with interest cos my club has gone from a very strict noise regime (totally objective) to a mixed response. We now have;
All ic tested as per bmfa recommendations.
Most electric not tested.
Ic helis not tested as it was felt to be inappropriate, but if it sounds loud on the ear, words will be had.
Any fw over .90 size flown only after consultation with, and a demo to, the committee.

Points of note are that We also found that that some of the larger electrics fail the bmfa test but sound very quiet in the air.

It may sound obvious but it is important for club officials to lead the way by ensuring their own models are reasonably quiet !  Accurate noise measurement is not easy and since a 3Db (a ) increase doubles the noise level " What it sounds like " is just as important as the actual reading obtained.
It is important to remember that the maximum noise reading is mostly a measurement of the noisiest element . If this happens to be the prop then fitting a quieter prop may make the exhaust the noisiest element - after that it might be the induction system. So you have to keep chipping away at different elements until you achieve a satisfactory result.
It is a bit like listening to a brass band with one instrument out of tune - that instrument is the only one you hear ! When that is silenced the next " worst "instrument becomes predominant, and so on.