Noise levels Model and Engine selection

[colin watson]

As my local club has a stringent noise level of 80db to be adhered to. when chosing both models and engines even exhausts and prop combinations it can prove quite costly if you can't get the model within the set db range. iam sure that other clubs or flyers have also come across this from time to time. Maybe we could start a thread that lists model combo's i.e airframe, engine exhauts used and prop used also any other modifications to quieten the model and the achieved db rating it would help modlers with noise restrictions at their club sites purchase models that can be within their noise restrictions. even help stop restrictions being placed on other clubs or loss of flying site due to noise problems. all model combos and db rating even if high db help us not purchasing the wrong model.

[Biggles' Elder Brother - Moderator]

Good idea Colin.

 

As you probably know I fly mainly scale-ish models usually with OS 4-strokes on board. Being scale I tend to go for props at the larger diameter range for the engine. I don't wish to sound smug but I think my models are among the quietest in the club! I often have trouble hearing my engines over the sound of other models I'm flying alongside.

 

Recently I was going through a spate of loosing exhausts on one engine an OS91 - even with the muffler hanging off it was still quieter than many others!

 

BEB

[Stephen Grigg]

Show oiff BEB,weve recently had complaints from a neighbour 600 metres away and due to this our models are tested stringently.On Friday our club cnairman arrived at the field at 5.00pm,asking who had been flying in the last hour ,where they had been flying and what models.The complainent had telephoned him telling him a noisy model was flying directly over her house.Its not practical to go neae her house its to far away and noone had been in that area because we have been told not to.The only model flying at the time was ASegull Jumper with an OS 40 FP with a noise level of 79db.We have been changing props mainly to get the sound level down,and some people have needed to purchase better silencers at upto £100 a time.So even if the club that is doing everything correctly 1 person can start stirring things up.In the last 2 weeks I have been approached by a gamekeeper complainig about models flying behind the pit area where they encourage pheasents to stay around by feeding them so in the shooting season,so they can be available for the shooting season.We are not permitted to fly in that area because of safety.His point was that the pheasants see a model aircraft fly over and they think its a bird of prey hunting them.I asked how he knew what pheasants think and his head blew up He informed me he would be reporting us to the council for scaring pheasants .

[colin watson]

it's because of people like the ones making complaints Stephen that we have an 80db limit. we were also accused of flying over property beyond our flying limits even a house that is 400m behind our pits a no fly zone. we have jumped through hoops to gain planning permision and had the enviroment agency take noise readings to prove we aren't making excessive noise. the club gets each model noise tested and logged these show the model and engine and prop etc. i think by using these logs we can help all of us from losing flying sites and save money on our purchases.

[Lazygit]

Posted by Stephen Grigg on 17/09/2011 22:20:31:

.I asked how he knew what pheasants think and his head blew up He informed me he would be reporting us to the council for scaring pheasants .

Brilliant move , another nail in the coffin..............

[Olly Giles]

even the cheapest and most chinese of motors can be quitened significantly with the right prop. A club member and i were experimenting with his SC 35 which was really loud on the recomended 10x6 Master Airscrew, we switched it for an APC 11x4 which was in his box and it was alot quieter, without much reduction in power. The make and size of prop makes a huge difference, not the make of your engine. Personally i find APC and Bolly to be the best.

[Bob Cotsford]

48 - 52 4 st - baffled exhaust, 13* 6 or 7

90 4St - baffled exhaust 14*6 or standard exhaust 14*7

90 2 st - Genesis pipe, 14*8 (13*8 marginal)

60 2 st Pitts muffler * twin expansion deflectors (Just Engines devices) 13*6

120 4St - 180 size exhaust 15*8

All with APC or GSonic props.

All these are within my club's 80dB limit, and the magic number seems to be 10k rpm.

 

One thing I've found in the past is that some airframes seem to amplify the engine noise, some strategically placed thin foam stuck to the inside of the fuselage sides can move the resonant frequency enough to make a definite difference.

Worn engine bearings can make as much noise as the exhaust or prop - found that out with a second-hand Magnum 4 st from the Redditch bring'n'buy - yes it was in such good condition wasn't it!

Edited By Bob Cotsford on 18/09/2011 11:15:28

[Peter Miller]

I used to mount my engines on nylon mounts supported on those rubber pillars. That made a huge difference. The engine might wobble for a moment at lower rpm but they worked really well.

 

Other types of rubber mounts were slightly less effective but still helped.

 

Going up a size in props doesn't reduce the power too much but does make them quieter.

[Del Wheatley]

the old noise issue ay.

The prob with this is we can never please the complainers.You could set a 50db limit and still the same people would complain.

I only know this because of my summer persuit of motorcross.

i use a practice track thats between a motorway and an airport,the bikes comply to the FIM sound limits and the sound levels set by the local planning dept.

The track is open wed/sat and sun yet the owner and the council still receive complaints of our tyres apparently screaching on mud on a monday/tuesday etc.

the council are now trying to close the track based on these bogus any noise must be the thing i don't like style complaints.

[Alan Randall]

Posted by Stephen Grigg on 17/09/2011 22:20:31:

.I asked how he knew what pheasants think and his head blew up He informed me he would be reporting us to the council for scaring pheasants .

 

Doesn't he scare the pheasants with the noise of his gun when he shoots at them?

 

What a weird view point

 

Edited By Alan Randall on 13/12/2011 16:42:42

[Mondeoman]

Posted by Del Wheatley on 13/12/2011 16:28:13:

the old noise issue ay.

The prob with this is we can never please the complainers.You could set a 50db limit and still the same people would complain.

I only know this because of my summer persuit of motorcross.

i use a practice track thats between a motorway and an airport,the bikes comply to the FIM sound limits and the sound levels set by the local planning dept.

The track is open wed/sat and sun yet the owner and the council still receive complaints of our tyres apparently screaching on mud on a monday/tuesday etc.

the council are now trying to close the track based on these bogus any noise must be the thing i don't like style complaints.

Quite right Del. A ludicrouly low db limit won't stop the moaners!!, an earlier post of mine on this issue quoted that a club I was in had regular complaints of noise, the club WAS ALL ELECTRIC!!!! they simply DON'T WANT YOU THERE.

[Andrew Bourne]

Hi Guys,

 

Interesting thread but not a single reference to noise measuring meters/equipment or calibration of these.

I wonder any fliers or clubs with experience shed any light on "approved" meters or where these can be calibrated and against which standards?

 

Many thanks

[Andy Symons]

Posted by Andrew Bourne on 05/02/2012 18:19:58:

Hi Guys,

 

Interesting thread but not a single reference to noise measuring meters/equipment or calibration of these.

I wonder any fliers or clubs with experience shed any light on "approved" meters or where these can be calibrated and against which standards?

 

Many thanks

Noise meters need to be in accordance with BSEN 61672-1, was BSEN60651 and use the "A" weighted response set to "slow".

[Josip Vrandecic -Mes]

I often think that there is a Movement for complaints in all geographic longitude and latitude.  very sad.

Thanks

Jo

Edited By Josip Vrandecic -Mes on 05/02/2012 21:27:03

[colin watson]

well the guy making all the noise (i mean complaints) has started again. even after the planners approved our 80 db limit. the other week a small crosser being riden without a baffled silencer on the field next to his house no complaint. its in his head but we are the ones who ultimateley lose out.

[Tony Richardson]

Jo I agree, noise is not really the issue something deeper is responsible, case in point ( and this will get Andy E hot under the collar ) a couple of years ago my wife and I drove to San Francisco from Victoria taking the coast road ( scenic route ) with various stops along the way, at one fairly remote hotel on the Oregon coast we went for an evening walk along the cliffs overlooking the Pacific and noticed some glider guiders with their models, now being ever on the lookout for model aircraft in the air I was on this like a wippet on a rabbit, wall we stood and watched, chatted for a while with those who were not flying when up the trail comes a police car? now remember this is not private land and there are no engines or electric motors gliders only: one of the officers approaches and says " guys when have had a complajnt from one of the locals that somebody is flying model aircraft on the cliffs and making a lot of noise.

After standing around and shooting the breeze with the flyers for a while he says while leaving "someone will complain even when there is nothing to complain about most likely don't like to see people having fun" just got in his cruiser and left. My wife and I were astounded anybody would complain at all, even if one of the models crashed it would have done so into the ocean and most likely been lost, noise meter or not this person would have complained why? maybe they thought this spot was their own maybe they had an issue with aircraft who knows, some people will complain simply because they can.

 

 

Tony.................

 

Edited By Tony Richardson on 05/02/2012 21:59:15

Edited By David Ashby - RCME Admin on 07/02/2012 06:53:36

[Josip Vrandecic -Mes]

Hi Tony,agree absolute...few year ago I was in Paris (Le Bourget Air Show)and I wonted to take a showers(Montmartre apartment)..My friend Al (Hi is from Cornwall),warned me that it can do it at noon ??!!..house rules !?

As you said Tony,...just they can.

Thanks for your time

Cheers

Jo.

[colin watson]

the big problem is they can make a complaint it costs them nothing, it has cost us hundreds countering the complaints so it is easy for them. we log every aircraft and its noise level it is only allowed to fly if below our 80db limit we have done every thing not to antaganise this one guy but we all know we will be the ones that ultimately lose out as our landlord is getting constant complaints and pressure. its not that our models are noisy or fly over his land he wants to stop others enjoyment this guy flew full size and used to have plerasure buzzing his neighbours to show his flying off.

[Stephen Grigg]

We have just successfully had change of use granted for our field for the same reason ,a complaint by 1 person after 26 years of flying.She is now complaining even more,even though we do not fly in the area of her home,but now we cannot be stopped as long as we abide by the club rules and fly in non sensitive air space.

[Del Wheatley]

Posted by Stephen Grigg on 06/02/2012 08:41:05:

We have just successfully had change of use granted for our field for the same reason ,a complaint by 1 person after 26 years of flying.She is now complaining even more,even though we do not fly in the area of her home,but now we cannot be stopped as long as we abide by the club rules and fly in non sensitive air space.

 

Don't be so sure you can't be stopped,only last week a track we use had permission removed to run.

They had a complaint of noise,the council investigated and found it to be running within the noise limits etc of their planning permission but still the council comitee voted to withdraw permission and order the track flattened.

[David Davis]

I have been peripherally involved with monitoring noise output at our club and, just to reinforce Bob Cotsford's point, we found that if engines peaked at about 10,000 rpm they would pass the noise test regardless of what type of engine mount, silencer or propeller was fitted. If they revved in excess of 10,000 rpm, they failed the test.

[Steve Hargreaves - Moderator]

Interesting thread.....

 

Our club is very lucky in that we don't have much trouble with noise/complaints so we don't have to apply a "noise test" to a model.....occasionally we get a noisy model & then the meter comes out.

 

I think a database of model/engine/prop/silencer against noise produced would be very handy although their are so many variables it might not be very useful. I'd be more than happy to set up such a database similar to the Electric Set Ups database I run.....at the very least it would give people a starting point.. I'm sure David Ashby would find space on the modelflying website for such a resource.....what do the members think??

 

For what its worth I agree with Davi Davies....revs are the key......get those down & exhaust/prop noise will reduce significantly....the type of noise is very significant too....electric flying wings with a tiny prop screaming away can be really loud......they even annoy me!!!!

[Bob Cotsford]

A lot does depend on the airframe Steve, a fibreglass fuselage can resonate and make things worse, cowlings can muffle induction noise and so on.

A spreadsheet would provide a valuable starting point though.

[Steve Hargreaves - Moderator]

Agreed Bob....we would need to take airframe construction into account.....foam core wings are often quieter than built up etc

 

What does everyone else think? Happy to compile & manage it if we think it will be useful....

 

Headings I've thought of...

 

Model

Contruction (Built up, foam wings etc)

Engine

Make of Silencer fitted (manufacturers own?)

Any deflector?

Prop size

Prop make

RPM if known

Measured noise level (this would need to be based on a common test to ensure a level playing field....the BMFA test seems the best to use)

 

Any database is only as good as the data in it & the more you have the better....

 

[Bob Cotsford]

so your starter for ten:

A sample -

Crescent Tornado

Balsa /foam

OS61SF

West Genesis pipe/manifold

No deflector

12*12

APC

9500rpm

78dBA

 

Ripmax Wot4 XL

Ply/Balsa

ASP120FS

JE 180 size baffled

No deflector

15*8

APC

9,700

80dBA

 

YT Dragon Lady

Balsa/rfoam

ASP120FS

JE 180 size baffled

No deflector

15*8

APC

9,700

78dBA

 

The last two show the difference between a built-up wing/ply fuselage (Wot4 XL) and foam wing/balsa fuselage (Dragon Lady)

 

 

Edited By Bob Cotsford on 06/02/2012 14:26:35