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noise reduction on gas engines planes.

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Old 01-26-2013, 01:19 PM
  #26
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Default RE: noise reduction on gas engines planes.


Quote:
ORIGINAL: oneaew@msn.com

I MUST BE HARD HEARING MY GAS ENGINES DONT MAKE AS MUCH NOISE AS A NITRO ENGINE I HAVE 3 ZENOAH 20 CC>>1 RCGF 15 CC
U must be talking 2 strokes .... 4 stroks make the same DB but at a lower Frequency that is not as annoying as any 2 stroke.
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Old 01-26-2013, 01:22 PM
  #27
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Default RE: noise reduction on gas engines planes.


Quote:
ORIGINAL: tailskid

It works....and it only costs $20

http://www.troybuiltmodels.com/items...0SILENCER.html
TailSkid have U hand te opertunity to actully DB the motor both ways to see the actual noise drop?
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Old 01-26-2013, 01:22 PM
  #28
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Default RE: noise reduction on gas engines planes.

4 strokes a the way to go for reducing the noise.
but i totall agree on the fact that its the frequency of the strokes thats making em so annoying to hear
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Old 01-26-2013, 01:25 PM
  #29
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Default RE: noise reduction on gas engines planes.

my is 89 db with a 16/6 xoar at 8300 rpm with the stock muffler. the stibger muffler changed the tone of no db's cut here.

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Old 01-26-2013, 01:35 PM
  #30
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Default RE: noise reduction on gas engines planes.

It dropped about 4 Db but I forgot the actual numbers....the best part is that it took out the 'sting' of bark. I also changed to a three-bladed prop and it flys quieter than most nitros!

Check out this video... http://www.troybuiltmodels.com/items...0SILENCER.html
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Old 01-26-2013, 03:57 PM
  #31
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Default RE: noise reduction on gas engines planes.

What are the noise limits where you fly? There must be an excessive noise notation in the zoning laws. Some places can make excessive noise for no more than 10 or 15 minutes before anyone can squawk. That should work for some flying sites. Check it out where you live. There are always 4 strokes too.
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Old 01-26-2013, 05:04 PM
  #32
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Default RE: noise reduction on gas engines planes.

AMA Sound/Noise Abatement Recommendations
http://www.modelaircraft.org/files/927.pdf
Pretty well says it all
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Old 01-26-2013, 05:26 PM
  #33
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Default RE: noise reduction on gas engines planes.

Inreply to all-Blessed are the big open pastures with no houses around
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Old 01-26-2013, 07:04 PM
  #34
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Default RE: noise reduction on gas engines planes.

+1our clubs in the middle of the country too. I have the DLE and Idon't think it's any moe noisy than a 2 stroke nitro. Try stuffing some course still wool into the can through the down pipes. I have heard that helps.
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Old 01-26-2013, 07:10 PM
  #35
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Default RE: noise reduction on gas engines planes.

I don't know much about the DLE20CC, but I think I would try a 15X8 prop to cut the rpms down to reduce the tip noise. You should have the power you need and the rpms might drop to 8,000 to reduce the noise....


Good luck,
Larry
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Old 01-26-2013, 07:36 PM
  #36
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Default RE: noise reduction on gas engines planes.

For the DLE20 the biggest cause of noise is the propeller. The easiest fix is larger prop (16x10 two blade) or a three blade at last resort, the exhaust baffle that that zipties to the exhaust pipe, or an exhaust header and stinger or perhaps as some have suggested the Bisson muffler (I dont have a Bisson). A combination of the first two really drops the dbs and are doable in just about any application, whereas the stinger and muffler options my not work with your airplane. My engine runs right up there at 98dbs with any 15" or smaller prop on it, but drops a good 2-3 dbs with an additional inch of prop and keeps it under the AMA recommended noise limits. You can also mechanically limit top end at the throttle arm and therefore limit dbs but that is really counter to where this engine produces power which is at the top end. Good luck!
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Old 01-26-2013, 10:31 PM
  #37
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Default RE: noise reduction on gas engines planes.


Quote:
ORIGINAL: speedracerntrixie

I would think that with the DLE 20 you could use a full tuned pipe. This would be better then the stock muffler and most airplanes that one would want to put the 20 into may not have room for a canister. The use of a soft mount would be high on my list of things to quiet the airplane. When one gets up to this size and larger, wood props seem to be the loudest.
SRT hit it on the head. I've been developing quiet gasoline set-ups in a little larger sizeenginesgoing on 4 years.

An engine mounted on a soft rubber isolation mount that'spiped and proppedcorrectly is extremely quiet. Here's a video of an OS GT33 mounted in an original design Pattern model
which is turning a 20x10.5 apc prop
http://www.youtube.com/watch?v=iAd8d...ature=youtu.be

I have several threads in the Pattern Forum mostly, where I discuss in detail what I've been doing and what works. The set-up I show in the vid has asound output of about 92 Db at 10 feet over grass. It develops a little more than 4 HP which is about double whatthe DLE20 will develop. It is MUCH easier to quiet a smaller, less powerfulengine, believe me!

I tried a 3 bladed 18x10 Mezjlik carbon and it didn't reduce the noise much. Have not been able to find an 18x11 or 12 3 blader which should drive noise downsome more. But I think that for most places, the noise my model produces is acceptable..............YMMV

Noise reduction is not cheap. The pipe was 210$ and header another 90$. It can cost almost as much as the engine and that's because I build my own rubber isolation mounts for small gas engines up to 60cc. If I had to buy a mount that's another 200$. These added costs are possibly well outside the pocket of many folks.

But I think you can get some of the benefits with a lined canister on the exhaust. That means the canister (Mile High RC has an aluminum unit that isn't too expensive) will need to be opened and lined with coarse fiberglass, then put back together with screws. The best 2 blade props are APC for noise suppression. No wood prop even comes close. The problem is the hubs are usually too narrow for all them screwy screws. Carbon props in the sizes required are a better way to go but are also 50-80$ depending......AS ALWAYS....YMMV

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Old 01-27-2013, 04:53 AM
  #38
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Default RE: noise reduction on gas engines planes.

The steel mufflers on the Zen G-20s are quieter than the DLE 20.
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