Poor quality silencers threatening flying sites ?

[iqon]

I have just tried to quieten the noise of my engine - I have a dle 30 I bought the AGM wrap round silencer to replace the supplied one.......on the 4th flight it broke apart.........anybody thinking of getting that one ..try elsewhere.....wasn't even quieter, just a different tone to it....

[bert baker]

I have got a DLE 30 it was noisy with the standard exhaust, I made an extra silencer box from an old MC Culock strimmer. so in effect it now has two.

 

I am going to have a go at making the Sid King silencers for some of my G 38's.

I have been unable to get the size of box metal required,  Table  frame box section size would probably do if only I could find some.

Edited By bert baker on 26/09/2015 20:17:07

Edited By bert baker on 26/09/2015 20:17:44

[Area 51]

Posted by iqon on 26/09/2015 19:54:34:

I have just tried to quieten the noise of my engine - I have a dle 30 I bought the AGM wrap round silencer to replace the supplied one.......on the 4th flight it broke apart.........anybody thinking of getting that one ..try elsewhere.....wasn't even quieter, just a different tone to it....

Sorry to read that iqon; I'm following the thread with interest and a solution is really needed .. the manufacturers need to step up their game here.. big time.. and not just see it as a niche to provide a costly solution..

I'm not understanding this theory of needing to buy a silencer the same or more than the engine to get it quiet enough!.. Seems a crazy solution.. We could do with hobbyking getting their factories on on this one.. help the sales of petrol motors no end!

[Allan Bennett]

Poor quality silencers threatening flying sites ?

No, it's the flyers who ignore the established noise limits that threaten flying sites, isn't it? Agreed, some silencers seem to be only for show, but it's up to their owners to change them for a proper one if they can't get within the decibel limit.

I had an OS120 4-stroke which didn't meet our club's decibel limit, so changed it for an OS120AX which did. A club mate bought a petrol engine a year or so back, which also didn't meet the limit. The vendor agreed the silencer was rubbish and supplied him with one that did the job.

[Simon Wright]

Well today we did some testing of a selection of models. first, WOT 4 ARTF, EVO10GX petrol, Bolly 12 x 6.5 standard silencer with silicone extender, 78 dba max.. I would have sworn it was louder.  Changed to a 13 x 7 APC 79db max (prop noise?)

Next my Pilot RC Extra 35%, DLE111 with JMB cans, and 28x10 chinese carbon prop, loudest from front, ripping at full throttle. 93db

Changed to Mejzlik 27 x 12 TH DB dropped to 90, still ripping. adjusted throttle to stop ripping, now 86dba. flew nice smooth aeros on the reduced output, barely made a noise at low throttle settings used through 95% of the flight. Was lacking punch in 3D flight.

DLE55 in Sukhoi, chinese noise diverter 94 dba....

 

Edited By Simon Wright on 26/09/2015 22:25:04

[Simon Wright]

PS... what agreed noise limits? I thought that the COP cop carried no legal weight and is therefore nothing more than a guide.

Edited By Simon Wright on 26/09/2015 22:22:48

[Bob Cotsford]

I'm seriously amazed at the Evo Gx10 result, mine is fitted with an ASP52 quiet silencer and to get the same noise level needs to be running a 13*8. With the supplied Evolution silencer and a 13*6 it recorded 83dBa on the clubs official calibrated meter.

As for OS 120 four strokes, my Surpass III is 80dBa running a 14*7 three bladed prop.

[Simon Wright]

Bob, I was shocked too, have to admit that my expectation was more in the order of 84? may have been an operator error thing but at least gives figures for comparison. the EVO silencer has a pepperpot drilled baffle 2 or 3mm holes? and is large volume, the ASP IIRC has a reflector cone with a large bore of around 10mm?  Perhaps the glow muffler isnt as good as the petrol one?

we took a ride over to a field next to one of our neighbours and it was interesting to note that the noise of our models flying was clearly audible even though the meter showed no variation in the ambient noise 40-43 db.

Most annoying noise from close on 600m was screaming electrics- Funjets and pusher wing whistle was clearly audible, no way this is silent flight!

 

Edited By Simon Wright on 27/09/2015 08:04:23

[cymaz]

Perhaps modellers should look at the noise problem from another angle. If modellers sent of emails and contacted the engine manufactures explaining the reasons for not buying their product is due to poor silencing, would that change things? Possibly not, I live in hope.

We want cheap good quality gear. That means in some areas material is reduced. As in the silencer wall thickness and design.

Going electric does not necessarily mean a quiet plane! It's convinience and cleanliness I guess. Maybe as one of our club noise testers we should adopt the policy of testing electrics too. For the record our limit is 84dB @ 7m.

Edited By cymaz on 27/09/2015 08:25:43

[Rich too]

Posted by Allan Bennett on 26/09/2015 21:27:36:

Poor quality silencers threatening flying sites ?

No, it's the flyers who ignore the established noise limits that threaten flying sites, isn't it? Agreed, some silencers seem to be only for show, but it's up to their owners to change them for a proper one if they can't get within the decibel limit.

I had an OS120 4-stroke which didn't meet our club's decibel limit, so changed it for an OS120AX which did. A club mate bought a petrol engine a year or so back, which also didn't meet the limit. The vendor agreed the silencer was rubbish and supplied him with one that did the job.

Surely it's the clubs that control noise limits? So I don't see why there should be a problem - if you don't meet noise limits you don't fly!

I don't have to worry about noise limits where I fly 😜

[Allan Bennett]

Posted by Simon Wright on 26/09/2015 22:18:00:

PS... what agreed noise limits? I thought that the COP cop carried no legal weight and is therefore nothing more than a guide.

Yes, it is a guide, but it's mandatory at our club because we've made it a club rule. Our local council is satisfied that it's a reasonable guide, and a few years back dismissed a noise complaint against us because we were able to demonstrate that we were enforcing our rule by testing and documenting each model.

As with so many other things, adherence to a nationally accepted guide -- even if it isn't "the law" -- always puts you in a good position if someone complains.

Also, maybe you're not aware, there's a BS Code of Practice on Noise from Model Aircraft which also mentions the 82dB figure.  I'm not sure if it's still in force, but it adds weight to one's defence if one is seen to be abiding by it.

Edited By Allan Bennett on 27/09/2015 08:50:35

[cymaz]

Posted by Allan Bennett on 27/09/2015 08:43:18:

Posted by Simon Wright on 26/09/2015 22:18:00:

PS... what agreed noise limits? I thought that the COP cop carried no legal weight and is therefore nothing more than a guide.

Yes, it is a guide, but it's mandatory at our club because we've made it a club rule. Our local council is satisfied that it's a reasonable guide, and a few years back dismissed a noise complaint against us because we were able to demonstrate that we were enforcing our rule by testing and documenting each model.

As with so many other things, adherence to a nationally accepted guide -- even if it isn't "the law" -- always puts you in a good position if someone complains.

The exact same thing happened to our club some years ago. The noise measurements are entered into a log book, along with calibration dates of the equipment.

[Simon Wright]

Thanks Allan, have to agree with that as a perfectly reasonable argument, and something that I too would sign up too if it offered a level of security. There are loopholes though, various competition classes, un-silenced control line & free flight, Noisy electric models and turbines are excluded despite being prolific noise generators. It is after all the noise that causes nuisance and complaint rather than the powersource.

Unfortunately councils are not required to comply with the COP and can therefore impose all sorts of irrational restrictions based on the planning officers mood or whim and clubs still lose their sites when it goes to court even when operating below the limit.

Continuing the reasonable use of guidelines argument , and apologies if it is slightly off topic but how many clubs maintain a safe separation of 30 to 50m between models and spectators? Difficult to argue a reduced safe distance when guidelines are in the handbook from our governing body.

[Erfolg]

Simon

I am not certain that I fully understand your position, possibly i also mis-understand your argument.

The clubs which I am a member, do not distinguish between any form of power system which breaches the 82 decibel reading. In the case of one of the clubs all IC engines were banned, on the basis that many IC engines were very close to 82 decibels, measured at some distance on a particular scale.

At the time measurements were taken on what was thought to be the noisiest electric model, a Zagi. In its case it was produced substantially lower level of noise, however the model was orientated. To further reduce the impact of noise, all modellers are encouraged to move the propeller away from trailing edges etc.

Jets are not permitted on not only the basis of noise, just as importantly the consequences of a crash on cultivated farmland and other safety related issues. Although many do not seem to be as noisy as some IC engines. As far as I know, no attempt has been made to measure jet noise at the club.

I cannot but agree very strongly with the proposition that noise can cost us sites. That is from any model type.

It does seem that some larger petrol motors can be a little to noisy.

I think that the view taken by one of my clubs, that the 82 decibels is not seen as everything is OK if we operate at up to the limit. The objective is not to be seen as a noisy activity, rather to operate a much lower level, to stay below the radar of potential objectors.

[Owdlad]

Strange title this one.

Because in all honesty it's not the silencer that's the problem.........its the end user that's the problem simply because they know the engine is noisy and over the limit but still persist in flying the model at all costs.

This is the real problem and not the cheapo silencer.......just my opinion

[Simon Wright]

Posted by Owdlad on 27/09/2015 17:18:48:

Strange title this one.

Because in all honesty it's not the silencer that's the problem.........its the end user that's the problem simply because they know the engine is noisy and over the limit but still persist in flying the model at all costs.

This is the real problem and not the cheapo silencer.......just my opinion

Good post.

[Area 51]

Posted by Owdlad on 27/09/2015 17:18:48:

Strange title this one.

Because in all honesty it's not the silencer that's the problem.........its the end user that's the problem simply because they know the engine is noisy and over the limit but still persist in flying the model at all costs.

This is the real problem and not the cheapo silencer.......just my opinion

Totally agree.. and the exact reason we lost a field a couple years back.. one flyer and user of petrol flown very very poorly.. their first and only petrol and we lost the site!

[Former Member]

[This posting has been removed]

[Area 51]

Posted by Percy Verance on 28/09/2015 12:52:35:

Which is exactly why we don't have them on our site.................

Helicopters are (for us at least) another no no. They're almost always flat out all the time

Yes Percy, they are a nuisance the frequency of the noise they make is high and being flat out I suspect more of a problem.. We have had some new members recently at our club, from a defunct local heli club, and its all aggresive aerobatics/3D stuff, the noise is really localised in one spot and high pitch.. a noise, which I suspect, travels more than a selection of airplanes being flown with an operational throttle...!

No wonder their last site was lost....

I'm petrol watching the petrol thread with interest as I am going that way, but only when its quiet enough to match the 4 strokes and draw no attention too itself..

[john stones 1 - Moderator]

Noise is noise whatever it's attached to, yep heli's are in idle up a lot and flown close, so they can get on your wick, BUT mine had a Zimmerman exhaust fitted and it made far less noise than some of the 40's fitted to trainers also the tone was much softer and carried much less, comes down to same thing effective silencing and will the pilot make the effort and spend the money.

John

[Erfolg]

It is so reassuring to read that it is apparently universally acknowledged that noise can very easily cost sites.

i think the one unfortunate trait many of us flyers have, is the liking for IC engines. It is all to easy to convince yourself, my motor is perhaps near to being noisy to others. But hey, it is a Diesel, or a nice 4 stoke, this is my very first Glo motor, or more recently, it is a 50cc petrol, the self same that powers chainsaws, brush cutter or even a lawn mower.

Some also take a view, it is not the engine or motor that makes all the noise, it is the propeller. More recently some of these very fast small electric have been seen at one club. Although the propellers must be turning at +20,000 rev min-1 they are not even audible in the car park. Which is not the case for some lowish rev'd IC types.

I am not sure with respect to helicopters, either electric, IC or turbine, as long as they are below 82db. I have only seen them operated at a low level, a few hundred feet and then kept local. The operation of 3d types, do seem to emit sudden changes in noise type as they go through manoeuvres. AS long as there is no local people to annoy, I am not sure that they have the impact of RC planes which can cover a lot of area during there operation.

At the end of the day noise is noise, and all of us need to acknowledge, that we have to be responsible.

If this requires greater use of sound measuring devices, so be it. Although I support one of my clubs policy of, noise must be unobtrusive.

 

Edited By Erfolg on 28/09/2015 16:40:33

[MattyB]

I have been toying with the idea of a petrol model (which would be my first IC), so have been doing plenty of research as I don't want to be one of those noisy petrol types who lose us sites! Whilst doing so I found this thread - it's very interesting stuff, particularly the last few posts...

...Providing you have some efficient can on the motor and not just a Header, the order in which you should set about getting ANY gas model quiet is as follows. First isolate the engine from the airframe using a soft mounting and cover the iside of the cowl and open structure of the fuselage with thin sticky back foam. Second, silence the air intake by constructing a box fro which the air is taken into the motor. It not enough to stick on a car type foam or mesh filter. The reason for this is that during the cycle the exhaust gases are actually pushed out of the inlet. Third as already said most of the noise from this motor will be from the prop. Simply put once the tips of the prop get near or over the speed of sound your well over 90db. The best solution is a 3 blade well balanced wooden prop. This manufacturer is superb and one of the cheapest in the world. As a general rule go down one size in diameter and up 2 sizes in pitch. Finally you may have to wrap your can or add an extension pipe.. 

Extensive research and experimentation over many years has taught me that there is no simple answer to gas engine noise.  I have a 30% Glens CAP with a Zenoah 60 that is club legal at 84 db at 7 meters, a Greenley Tug with Zenoah 45 which is UK legal at 81db at 7 meters. The average spend on noise suppression on these 2 models is around £350. As an experienced LMA modeller told me years ago, what ever you spend on the motor expect to spend the same getting it quiet.

Ohh and the reason why changing the can first is wrong is because an efficient 3 or 4 chamber can will up the revs about 1500 at the top end making the prop go supersonic, you will then load the prop with a bigger 2 bladed prop, probably carbon cos the club genius told you to. This makes the cg move forward, the prop tips go even faster, top end performance is rubbish, and it's still screaming over 90 db. And you just spend £80 on a fix that didn't work.

In my extended experience I have never got a 60 plus gasser down to 82 db so if that's the club requirement, don't bother trying. Same for twin 30cc planes and most scale models with 40 plus motors.

Get a good sound meter and get it calibrated by your local environmental health dept, don't rely on your ears.

Edited By MattyB on 29/09/2015 10:30:22

[Erfolg]

I am somewhat surprised that some petrol engine users are besotted with not loosing power. My observations of petrol engines within our club is that do not suffer from a lack of power by my standards, that is they can prop hang with no apparent issues, transition to vertical flight from the hover without any apparent issues to this observer. For more normal flying, they seem to haul some quite large models about with ease.

it really would be sad to loose any flying sites due to noise levels, particularly when there is no apparent need to.

All of us modellers labour under the shadow of the perception that our models are noisy. Just one noisy model reinforces this perception.

[bert baker]

Where in th e UK can I purchase a Jtec Snuffler muffler 30cc size

[Alan Gorham_]

Seems like they have no UK distributor at present. I think Irvine Engines used to sell them in days past, but they don't exist anymore.

You could ask if JTEC will deal direct. I am sure they would.