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Old 08-25-2011, 03:39 AM   #1
Danny-II
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Default Trying to silencing a dle-30 muffler

Hi all,

Just wondering if anyone has tried this in the past years and how good/bad was it?

Problem: Muffler to noisy on a dle-30, muffler is a pitts wrap around.

Idea: Is to place 2 or 3 stainless steel scouring pads inside the chamber.

I know this might decrease engine performance, (I can live with that) but wouldn't this decrease the noise?

Also overtime, would the stainless steel breakup and end backup inside the cylinder chamber itself on
the down stroke of the piston?

I don't want to use a silencer or can at this stage.

Feedback welcomed.

Cheer Danny-II

Scouring pad image below.
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Old 08-25-2011, 05:18 AM   #2
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My concern would be the steel particles breaking up and blowing around in the can and going the wrong way during the intake stroke. Have you seen these? I don't know if they would fit the pitts muffler. http://www.troybuiltmodels.com/blog/...nes-silencers/
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Old 08-25-2011, 05:49 AM   #3
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There's no substitute for volume and baffles.
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Old 08-25-2011, 06:14 AM   #4
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a lot of motorcycle shops carry glassfiber wadding for re packing muffs you could try that
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Old 08-25-2011, 08:14 AM   #5
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In the 12+ years my family has owned JTEC I have seen lots of theories on what will make a muffler quiet, there are a few things I can tell you that do not work. You really do not want to put stainless steel mesh, the fiberglass wadding, or actually put anything inside of a muffler. Things like that are way to restrictive in a rc muffler, they may work on motorcycles or cars but not everything translates back to rc. Ultimately you will be replacing a piston, cylinder, rings and bearings so it just is not worth it.

As mode 1 said there is no substitute for volume (again in rc you will not find baffles like in a car or motorcycle, drilling a couple holes in a exhaust tube is not a baffle). The other things you need to look at are prop, airframe and even carb noise. The first thing to do is make sure you are running a good prop, if you can take the tips of the prop and bend them then you are getting flex which translates to inefficiency and mainly noise. Also, depending on your db level you may have to look at a three blade. Also, make sure you balance the prop, even if they say prebalanced.

As for the airframe, open airframes with built up wings and open structure in general can be louder, what you really want to do is make sure all of your covering is tight so harmonics don't go through the airframe.

As for the carb, the carb itself makes noise just like when a classic car runs without a filter on the carb or even in a new car when someone puts a cold air intake on it, you hear that sucking noise. Realistically you are not going to do much with the carb or a carb filter but realize that is may be 1 to 2 db.
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Old 08-25-2011, 08:18 AM   #6
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Quote: Originally Posted by Danny-II
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Hi all,

Just wondering if anyone has tried this in the past years and how good/bad was it?

Problem: Muffler to noisy on a dle-30, muffler is a pitts wrap around.

Idea: Is to place 2 or 3 stainless steel scouring pads inside the chamber.

I know this might decrease engine performance, (I can live with that) but wouldn't this decrease the noise?

Also overtime, would the stainless steel breakup and end backup inside the cylinder chamber itself on
the down stroke of the piston?

I don't want to use a silencer or can at this stage.

Feedback welcomed.

Cheer Danny-II

Scouring pad image below.
Prop it down. With the wrong prop any engine can be loud. I also have a ESM warbird with dle30 and propped correctly It is not loud at all
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Old 08-25-2011, 08:57 AM   #7
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Quote: Originally Posted by Show871
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Prop it down. With the wrong prop any engine can be loud. I also have a ESM warbird with dle30 and propped correctly It is not loud at all
What is on there 18x6?
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Old 08-25-2011, 09:13 AM   #8
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I make my own exhausts sometimes and I add a disc or several with holes in it if the muffler is large enough. Coupled with a small stinger it reduces the noise quite a bit. Without them they can 'ping' quite loudly even on tick over.

There's a company in the UK that makes custom exhausts that does the same thing.
http://www.justengines.unseen.org/ac...xhausts._.html

Last edited by MODE 1; 09-03-2011 at 11:46 AM.
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Old 08-25-2011, 03:54 PM   #9
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Thanks cap232tain, they might be the way to go, cheap enough, so wont hurt the bank.

Thanks again, Danny-ii

Quote: Originally Posted by cap232tain
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My concern would be the steel particles breaking up and blowing around in the can and going the wrong way during the intake stroke. Have you seen these? I don't know if they would fit the pitts muffler. http://www.troybuiltmodels.com/blog/...nes-silencers/
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Old 08-25-2011, 04:01 PM   #10
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The prop is as follows.

16x8 Carbon Fibre Propeller
High Performance , Factory balanced
Almost the same airfoil as JXF Laminated Props
High Gloss epoxy Resin, Gel coated 3K Black Woven carbon fibre.
Solid Hub, hollow blades.

Cheers Danny-ii

Quote: Originally Posted by pryor808
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What is on there 18x6?
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Old 08-25-2011, 04:30 PM   #11
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Hope they work for you!
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Old 08-25-2011, 05:53 PM   #12
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noise is a byproduct of engine rpm, prop, etc.

the items that troy built sell basically work by restricting the muffler and reducing engine rpm, there description even tells you that you will see an rpm loss. You can achieve the same thing by limiting your full throttle endpoint on your radio.
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Old 08-26-2011, 09:22 AM   #13
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Danny i reccomend you do not put anything inside the muffler as it has the potentual to get sucked into the motor also by restricting the flow in the muffler can cause a motr to get hot, I would recommend if possible cut a hole in the fuselage under the firewall and behind the motorbox and see if you can fit a canister in there or another option is to see if you can get a pitts style canister that mounts direct to the firewall i know they do them for the 55 so may be worth resurching if they have them for the 30.
regards Bill
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Old 08-26-2011, 09:30 AM   #14
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Quote: Originally Posted by Danny-II
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The prop is as follows.

16x8 Carbon Fibre Propeller
High Performance , Factory balanced
Almost the same airfoil as JXF Laminated Props
High Gloss epoxy Resin, Gel coated 3K Black Woven carbon fibre.
Solid Hub, hollow blades.

Cheers Danny-ii
I am running a 18x10 xoar laminate. IMO 16x8 is not even close to enough prop for the dle30. a 18x10 or something closer to that load range would be substantially quieter. I suggest a laminate also they are stouter than beachwood which may also help a tiny bit in the noise dept.

Good luck, I just electrified my ESM retracts cant wait to try them
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Old 08-26-2011, 08:05 PM   #15
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Danny i take it that the 16 x 8 is a 3 blade? if not 16 x 8 2blade is way too small for a dle30 also them carbon fibre props you are using need to be ballenced i have had a few of them now and only had 1 that was in ballence all the rest were way out.l
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