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Esprit Model . Thunder Power RC . Mikado Modellhubschrauber

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Gasser Model RC Helicopters > zimmerman muffler
 
 
rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

My Posts This: Topic  Forum		I don't think so

Quote 
With regards to the rear mount muffler causing the rear A frame to crack, is it possible that this would have happened anyways just due to aging of the airframe? Also, where exactly did you notice the cracking

I believe it cracked because the muffler is fixed to the upper half and the inlet is fixed to the lower half (engine) which stresses the A-frame when the top half tries to flex in flight in relation to the bottom half. My coupler was very stiff (I used the Vario black coupler) and it could have been a cause for it as well. If I was you I'd use the flexible coupler to make the two halves less rigid.

A frames can crack from age or vibrations - I look for them now. I found someone else's A frame cracked at the Hurlock funfly in May so it can happen though in my experience with my machines I only cracked mine when I put on the rear zimmerman. In any case just because I had that issue doesn't mean everyone else will. Mine cracked at the thinnest point where its relieved for the spark plug cable.

-=>Raja.

1005 Xcell Gas, G26 3D Max, 2195+ flights
Spectra-g, G26 3D Max, 855+ flights
06-24-2009 02:41 AM
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jrockstuart
Elite Veteran
Location: Allen, Texas

My Posts This: Topic  Forum		Thanks Raja. I think we all need to keep an eye on these A-frames regardless of the muffler we're using.

MinAir Spectra-G
Trex 450Pro V-bar /Scorpion /JR
Wally Motors/New England Heli/DL Canopies
06-24-2009 03:55 AM
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Jarno
Veteran
Location: Finland

My Posts This: Topic  Forum		I look forward to your findings of that Zimmermann side mount muffler Raja. I used to have one of them on my Cuatro in the past and it cracked just near where the flange starts from. After some re-welding job it still serves very well with the guy that I sold my Cuatro.

Here is one more choice of Zimmermann mufflers that will not crack.
The name of it actually gives a bit wrong information: Gas Pipe. It actually works as a muffler but mounts like a pipe with a header.



Jarno
06-29-2009 07:37 PM
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TaleGunner
Elite Veteran
Location: Deer Park WA

My Posts This: Topic  Forum		I have now tried 2 different ways to put second mount point on the V-4
and although the bolts did not come loose this weekend it still started leaking from the gasket. even with hi-temp gasket sealer it starts to leak after a few flights.

CRASH! GLUE! REPEAT!
06-29-2009 09:56 PM
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chilibean
Heliman
Location: cape may,n.j.usa

My Posts This: Topic  Forum		broken A-frame

I own the heli that Raja fouund to have broken A-frame. It also has Zimmerman rear mount muffler but I don't think that is the cause of the cracking. My engine was badly out of balance and the crank was .004 out of true. That caused serious vibration. My rear A-frame was completely broken and the front one had stress cracks. I replaced both and sent the engine to Hanson. He turned the engine into a pro-plus. Best money I've spent since I've owned this heli. Now it is incredibly smooth.
As to the muffler, it has small leaks at corners of the mounting flanges. Otherwise I'm very happy with it.
Thanks to Raja for looking at my heli and advising me.
Paul
06-29-2009 09:58 PM
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Billme
Elite Veteran
Location: MS

My Posts This: Topic  Forum		You may have to drill the holes out a little on the V 4 for better alignment...I had to...

Face the muffler flange with stick on sand paper on glass, or a good straight edge till flat..Clean the threads with acetone, making sure everything is super clean..

Do not use any gaskets or sealer...I use automotive Goop on the threads.. You must move quick since the goop tends to get sticky quick.
Push the bolts through the muffler so the threads are showing, and then put the goop on keeping the muffler from raking off the goop as you mount it.. I dab some in the holes too...

Tighten hard at room temp...Don't touch it there after. Don't worry about the excess getting on the flange..Mine has never leaked or come loose...

Bill
06-30-2009 05:24 AM
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jimboflies
Elite Veteran
Location: Beaumont, Texas;

My Posts This: Topic  Forum		Billme , I`m sorry for sounding dumb ,but what is "automotive Goop"??

EP8 EX twinring frame
Quick of Japan
EP8v2 EX
EP9
Quick World Wide Bat 26cc gasser
06-30-2009 11:51 AM
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TaleGunner
Elite Veteran
Location: Deer Park WA

My Posts This: Topic  Forum
Quote 
it has small leaks at corners of the mounting flanges. Otherwise I'm very happy with it.

That is the same place as Raja had cracks in his. that is cracks from metal fatigue it will continue to crack.

Billme what is the brand name anf type on your goop?

CRASH! GLUE! REPEAT!
06-30-2009 12:49 PM
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Billme
Elite Veteran
Location: MS

My Posts This: Topic  Forum		Walmart, and Advance auto sells it..Its in a red squeeze tube with automotive GOOP written on it....

Goop it a type glue used to repair stuff...they have plummers goop, and also shoe goop...I think they are all the same IMO..

If you need to take the muffler off, it will ting or snap with a little effort and come right on off...

Great way to keep the muffler on...If it comes loose using this stuff, you have problems, or you didn't clean the bolt holes, and thread
06-30-2009 02:47 PM
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Billme
Elite Veteran
Location: MS

My Posts This: Topic  Forum		Zimmerman mufflers have to be stressed relieved when mounting...This means you may not be square on the mount in order for the pipes to line up when you finally bolt them on. If you force it square, it will crack every time. its the nature of the material...
This means one side of the bolt on muffler holes may have to cocked over on one side in order for the pipes to align when bolted...
06-30-2009 02:52 PM
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rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

My Posts This: Topic  Forum		New zimmerman

The new zimmerman from Quick Worldwide has been reinforced with extra welding and an additional plate to make the weld joint stronger.

The rear mount zimmerman is still of the un-reinforced variety and can crack much easier especially if you torque it bent while tightening the bolts like Bill says. On mine I tried to adjust things so that the muffler bolts went straight in with no friction into the exhaust port so the muffler isn't stressed but it didn't help. I think in the Spectra design the upper frame can bend slightly back and forth in heavy 3D flight which doens't help matters. Even with that being said my old 1005 zimmerman also leaked at the ears but I got it rewelded locally and its been holding good. Zimmerman did add a weld spot below the tube on the old 1005's as a v2 problem fix as the originals used to crack the pipe where it went into the can.

-=>Raja.

1005 Xcell Gas, G26 3D Max, 2195+ flights
Spectra-g, G26 3D Max, 855+ flights
06-30-2009 04:28 PM
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Paul-PJH
Senior Heliman
Location: The Netherlands

My Posts This: Topic  Forum		Hi,

Yesterday I was able to test my Spectra-G with the new side mounted Zimmermann. I was especially interested in the noice level with respect to the Century torpedo.

I measured 75 dB (!) with a headspeed of appr. 1600 revs. The sound reduction is 2 - 3 dB.

Grtz,

Paul
07-06-2009 10:09 AM
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chilibean
Heliman
Location: cape may,n.j.usa

My Posts This: Topic  Forum		mounting ear broke

I was feeling pretty good about this muffler. I have about eight hours on it and now one of the mounting ears broke right behind where it bolts to the frame. Prior to this it didn't show any signs of stress in that area. The crack opened about 1/16 inch. I flew four more tanks after and see no sign of cracking on the other tab but don't know if I should tust it.
...Paul
07-16-2009 03:06 AM
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jrockstuart
Elite Veteran
Location: Allen, Texas

My Posts This: Topic  Forum		Chilibean, is this the side mount or the rear mount you are referring to?

MinAir Spectra-G
Trex 450Pro V-bar /Scorpion /JR
Wally Motors/New England Heli/DL Canopies
07-16-2009 03:26 AM
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chilibean
Heliman
Location: cape may,n.j.usa

My Posts This: Topic  Forum		It's the rear mont muffler. The way it sepperated makes me think I might have drilled the holes slightly off.



...Paul
07-16-2009 04:19 PM
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jrockstuart
Elite Veteran
Location: Allen, Texas

My Posts This: Topic  Forum		Wow!! I've never seen one break like that. Better send it back for repair. Where did you buy it from?

MinAir Spectra-G
Trex 450Pro V-bar /Scorpion /JR
Wally Motors/New England Heli/DL Canopies
07-16-2009 07:53 PM
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imnxtc
Veteran
Location: Dawson

My Posts This: Topic  Forum
Quote 
I measured 75 dB (!) with a headspeed of appr. 1600 revs. The sound reduction is 2 - 3 dB.

Paul,

If you check on the relationship of sound pressure level and how the human ear precieves it, you will find that when doing an A/B test, most human ears could just barely detect a 3db difference in SPL's in the frequency bandwidth we work in here. And very few (mostly younger ears) could just barely detect a 2db difference.

So for all practicle purposes, a 2 to 3 db difference is not too relevant. But the difference to your pocket book would be much more noticeable, as would the differences in failure rates.

A study of the frequency spectrum at those SPL's, would be more significant to the relationship of preceived noise (what the average human ear preceives as a sound that is not desireable).

That is why one sound may read much higher on an SPL meter, yet be less objectionable to most human ears then another sound that reads far less on the same SPL meter.
07-16-2009 09:46 PM
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rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

My Posts This: Topic  Forum		Zimmerman update

So far so good on the side mount zimmerman. Logged another 4 flights today for a total of 22 flights or 5 1/2 hours run time.

Since I bolted it on it has not come loose nor have I had any exhaust leaks at the cylinder.

Weight wise it is lighter than the Century muffler by almost 4oz so between no leaks, weight, and sound its a winner all around for me so far. I'll definately keep you guys up to date as I log more flights on it.

So I still have the Century V4 I want to sell, but no takers on it. Its not so bad of a muffler, I used it for many flights (not this one but a v3) before going to the zimmerman. Any takers on it? How about you imnxtc, you're a Predator guy do you want it or know anyone who wants it?

Thanks guys,

-=>Raja.

1005 Xcell Gas, G26 3D Max, 2195+ flights
Spectra-g, G26 3D Max, 855+ flights
07-17-2009 12:05 AM
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Paul-PJH
Senior Heliman
Location: The Netherlands

My Posts This: Topic  Forum		Hi IMNXTC,

You are totaly right. Only thing is that local regulations don't allow a noice level above 78 dB. With the Century V3, I had problems to keep within limits! Next the sound is better (in my opinion). The Century V3 had a metalic high pitch sound.

Grtz. Paul
07-17-2009 01:43 PM
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imnxtc
Veteran
Location: Dawson

My Posts This: Topic  Forum		Hi Paul

Yes, I agree, you would find the V4 has a much nicer sound then the older V-3 (more like a big block V8) then the older V3 and it also seems quieter.

Wow - a 78db limit!!! what distance is that measured from etc.?
07-17-2009 05:07 PM
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Gasser Model RC Helicopters > zimmerman muffler
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