"1/2 A" & "1/8 A" airplanes These are the small ones...more popular now than ever.

cox mufflers

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Old 02-24-2014, 05:35 AM
  #1
jdwardus
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Default cox mufflers

is there any plans for cox 049 mufflers. i have mill and lathe with the knowledge to use. im sure i can come up with somthing. plans would be nice tho
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Old 02-24-2014, 05:37 AM
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another one of my hobbies is metal casting i wounder if this would work better casting it from aluminum the machining it to fit
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Old 02-24-2014, 08:06 AM
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Default Cox muffler

I like these.. Hard to come by of late.
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Old 02-24-2014, 06:08 PM
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this would be easy to make. now to put a muffler on the end of it with out it weighing more than the engine. make a cast with mounting base on the end of the exhaust. use a aluminum tube for the muffler. how solid is this type of muffler mounted to the engine. would it support a muffler made of thin wall aluminum tubing
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Old 03-30-2014, 12:41 AM
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Humm pic didnt come out very clear but you get the idea 9 different mufflers for cox engines.
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Old 03-30-2014, 06:57 AM
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I wish I could fly my 1/2 A .049 Cox powered RC planes at the Club Field. But, I need to muffle them first.
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Old 03-30-2014, 10:32 AM
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The one like Skaliwag has looks like a good candidate to make. I think it would quiet it down a bit on it's own. Some of the Cox ones interfere with the carb on the TD motors, and most of them suck a bit of extra power because of the SPI. There is always the piece of silicon tubing with a hole punched in the middle to go over the exhaust too.
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Old 03-30-2014, 10:59 AM
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One can quite easily make something that will quiet them down, here is one I made as a kid;

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Old 03-30-2014, 02:38 PM
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Is that just regular solder and a silicon bead on the tank to case? I have seen an older .049 from many years ago that used a piece of aluminum tubing wrapped around the cylinder then machining a hole the size of the O/D of the cyl. with a nut and bolt holding it tight.
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Old 03-30-2014, 07:36 PM
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I scanned a few mufflers for a extreme high res view = )
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Old 03-31-2014, 10:37 AM
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You do know you can buy one from Cox International. Right?
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Old 03-31-2014, 11:22 AM
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Pond Skipper,

Have you ever tried using the Hiscott muffler you have on your Space Hopper the "right way" - mounted on a Medallion or TD as a muffled throttle setup?

I've never run one but the Hiscott throttle accessory looks very well designed and made, and appears to me to have the potential to be as good or better than anything else that was ever offered.



jdwardus, if you're looking for a machining project, making a copy of a Hiscott would keep you busy for a little awhile...
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Old 03-31-2014, 12:28 PM
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The best breathing more typical type muffler is the Cox RC the second best is the Tatone due to the bolts being in the way it doesn't quite make first the Hiscott all be it sexy looking and very well made has two drilled 2.5mm est. holes in which the exhaust escapes towards the can portion of the muffler design and has the brass piece for choking down the exhaust in the way to boot the loses are too great. I plan to gut the throttle part and bore out the area for better flow if I put a RC carb on the hopper for now it suits this engine set up with no SPI.

The best breathing muffler shown would be the new cox made muffler without the exhaust pipe unmounted to a engine. It just has a hole to breath, you can bore out further or I recommend you match the hole size opposing and align the two in front of the engines cylinder exhaust ports for some SPI function.

I have not tried these on Medallions.
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Old 04-01-2014, 07:42 AM
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Sport Pilot - No I did not know. I had ask via their forum right after they were open for business as "International" and the reply from the owner was not encorraging so I never checked again ...
Thanks,
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Old 04-03-2014, 08:45 AM
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Keep 'em light, eh? I keep looking at the little aerosol "puffer" canisters (i.e., bronchdilators for asthma) as candidates for 1/2A mousse can style mufflers. I did drill into the top of one and found a fair bit of plastic paraphenalia inside. I thought opening up the passages in one of the cast diverters (like in skaliwag's post #3 above) and shortening it would turn it into a useable header section. Maybe a cigar tube with Al cap would be lighter.
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Old 04-03-2014, 10:06 AM
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I think most clubs either have a muffler exemption for .049's if the members are old enough to remember them. I checked a TD once and it wasn't that loud. It was just on the threshold at 15 feet. I have no access to the decibel meter now at the new club. Even with a stock muffler things could be drilled out to get just at the threshold, if there is access to a meter. I am sure the Fora and more high performance ones are much over the 85 or whatever limit. Sometimes just the effort of putting a muffler on is good enough. It would be nice to get an improvement in performance at the same time for all the effort. I think there is a meter on an I phone app. for those with those luxuries.

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Old 04-03-2014, 11:31 AM
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Speaking of apps I have a new free audio tach app its icon shown - that is within 30rpm of a photocell or laser tach. Its neat to use in real time on the ground but more so in the air or on water. Has settings for 2 and 4 stroke engines mine is set to 50k rpm if I recall it goes higher.
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Old 04-03-2014, 01:34 PM
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I use a pitch pipe, the old kind from music class, and a digital guitar tuner with a chart. It is pretty close too. Maybe a couple of hundred rpm. It is good for air rpm or if you are at the field and wonder everyone elses rpm hehe.
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Old 04-04-2014, 06:33 AM
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Being a trumpet player for nearly 40 years, I love taching by ear.. you can get very close indeed. It is a good way to weed out BS at the field or on Youtube videos, for example KMD 2.5 diesel team race engines turning 8-4 props at 24k and the like.

I have an Excel chart I keep posting somewhere. It's easy - A above middle C is 440 Hz = 440*60 = 26,400 rpm. Multiply by the 12th root of 2 to go one semitone higher, divide to go one step lower, and just build a table from A=440 down. (or up too if you need).
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Old 04-04-2014, 11:58 AM
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I like your methods tried and true.
I use a Radar Gun for mph and now the Audio Tach app for field in motion observations. Its
On the ground if the field box is on had I will use a photocell tach and the laser tach stays at home.
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