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Home Made Canister Mufflers?

Old 08-29-2006, 02:56 PM
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mmattockx
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Default Home Made Canister Mufflers?

Has anyone made their own canisters? I have searched around this forum, but came up with nothing much. I would like to try making a canister myself before I spend the $100 or so it will take to get a 40cc sized one commercially. Bob Pastorello did his own pattern exhaust and it looks like a reasonable start on a gasser exhaust as well.

http://www.rcaerobats.net/Making_Quiet.htm



Thanks,
Mark
Old 08-29-2006, 03:07 PM
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F1race79
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Default RE: Home Made Canister Mufflers?

On another site they are making them out of a Budlight can that looks like a long neck bottle.
Old 08-29-2006, 03:57 PM
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rmh
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Default RE: Home Made Canister Mufflers?

I did some -all worked well -I did muffled only -- muffled tuned and non muffled tuned
best can is all steel paint and pressure cans - braze with silver solder -the other things required are KS tubing/adapters of proper size
Old 08-29-2006, 04:00 PM
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mmattockx
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Default RE: Home Made Canister Mufflers?

Any tips, hints, dimensions to shoot for?


Mark
Old 08-29-2006, 05:45 PM
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Rcpilot
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Default RE: Home Made Canister Mufflers?

I was just talking to a guy at our field last weekend about cannisters on his DA-100. He told me that the 50cc canisters would actually cause a loss of power, but were superbly quiet. He bought the 75cc canisters for the DA-150 and installed them on his DA-100, He claims a 150--200RPM increase and says it sounds cool as all get out. I think his plane sounds cool. It has a very constant and smooth throttle response. Low drone. Not loud at all, but you can still hear it.

Going by that info--I'd make my cannister volume minimum 25% up to 50% larger than the cylinder volume.

Edit:
Just for clarification

When I said 50cc cannisters--I meant that EACH cannister is 50cc in volume. Thats what DA sells for the DA-100. 50cc cylinder--50cc cannister.

He bought the cannisters for the DA-150 which are 75cc in volume to match the 75cc cylinders on the DA-150.

But, he put those bigger cannisters on the DA-100. That way, he's running a 75cc cannister on each cylinder that is 50cc.
Old 08-29-2006, 06:57 PM
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blkbird68
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Default RE: Home Made Canister Mufflers?

ORIGINAL: dick Hanson

I did some -all worked well -I did muffled only -- muffled tuned and non muffled tuned
best can is all steel paint and pressure cans - braze with silver solder -the other things required are KS tubing/adapters of proper size
Dick,

How did you calculate volume needed to achieve a "tuned" design?



I have been experimenting with a home-made can for my G26. I stumbled upon a "design" that works pretty good (10100RPM on an 18x6 Skorepa) first attempt yielded 9400rpm one minor change got me to 10100. I stumbled on the design of my can totally by lucky guess work. I would love to know how to do it correctly
Old 08-29-2006, 07:22 PM
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rmh
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Default RE: Home Made Canister Mufflers?

much of the calculated info is NWAS.
why?
because it does not include full throttlability required
Plus NONE of the BS (Facts about tuned pipes)I have read ever included pressure readings and without that - it is a crapshoot .
Your gues if it works and is smoothe with no flatspots - beats all the calulated crap.
How to do it right ?
really takes experimentation as the rpm is a prime factor
Do this first
establish a rpm baseline with NO exhaust system - wide open tuned for full power (don't overheat it
Decide if you want a severe noise reduction with no power losses or good noise reduction with a little power increase.
look at the pictures attached -these designs work but they must be sized close to correctly and there needs be about 1/2psi in main chamber at full power
a paint can can be used a steel paint can is a good one to use - and tubing for stinger - just KSbrass hobby shop tubing
The larger the better -within reason
small touch up cans for under 26cc and slim to std paint cans on 50 60cc.
You must try carefullysqueezing off the stinger to see how it affects overall performance. this changes pressure
The muffled only setup can run a very short header but can should be quite large - NOTE it is the drawing with the tube stopping way short of a baffle
these are blatent copies of existing commercial mufflers -cans - I have no pride
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Old 08-29-2006, 08:47 PM
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mmattockx
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Default RE: Home Made Canister Mufflers?

Dick,

Thanks for the sketches, that is exactly what I was looking for as a starting point.

Just a note on muffling, for effective silencing on motorcycle 4 stroke single cylinder engines, the smallest muffler considered reasonable is 10x the cylinder volume. A bit smaller for 2 strokes, but you can see how much bigger a lot of this stuff should be for truly effective sound reduction.

I will have to go look for some old spray bombs or hair spray cans now.


Mark
Old 08-29-2006, 09:09 PM
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Bob Pastorello
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Default RE: Home Made Canister Mufflers?

Mark - most of what I learned, I learned from Dick Hanson, and did my own experimenting. After I wrote that article on my webpage, I became compulsively lazy. If I can't buy what I need, I won't need it....anymore.

Where I fly, I am fortunate to not have ANY noise issues, ever, as we are less than 1/4 mi. from a VERY loud dirt bike/quad runner track, and they are FAR, FAR louder than my pretty-loud Brillelli 60....and they are 1/4mi away. It's all in the frequencies and duration, I guess.

Anyway - the VERY best source of canisters is in the "beauty aids" aisle at Wally world... take a magnet with you, so you can select the tin containers.... and have a blast (no pun intended). ALSO - be ready to make a LOT and throw away a LOT of work effort before you find "just right".

I'm not trying to be pessimistic about it - just telling you to be on the lookout for burnout. You can chase a helluva lot of stuff off the shelves and putz around for DAYS, or WEEKS in your workshop and find something that goes "BOOM" on first run.

Or = you can buy a ready-made canister, purpose built, and performance-proven. KS is SUPER stuff, their website works FINE, and so does Desert Aircraft....
Old 08-29-2006, 09:20 PM
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mmattockx
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Default RE: Home Made Canister Mufflers?


ORIGINAL: aerobob

I'm not trying to be pessimistic about it - just telling you to be on the lookout for burnout. You can chase a helluva lot of stuff off the shelves and putz around for DAYS, or WEEKS in your workshop and find something that goes "BOOM" on first run.

Or = you can buy a ready-made canister, purpose built, and performance-proven. KS is SUPER stuff, their website works FINE, and so does Desert Aircraft....
Bob, you're not being pessimistic, you're being REALISTIC. I fully understand the risks in what I am looking at, but the price for a simple muffler is enough to make me take a shot at it. If it works out, great. If not, I will break down and buy what I need. I like the looks of the JMB cans on RCS and would probably go for their 50cc can if I buy one. But I have to see for myself how well I can make one in my garage...


Mark
Old 08-29-2006, 09:27 PM
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Bob Pastorello
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Default RE: Home Made Canister Mufflers?

And good luck to you! If I can help (although I think Dick already gave you everything but the brazing rod!!! ), don't hesitate to holler! Remember - roughly 10-12:1 ratios....50cc motor - about 500cc volume chamber...
Old 08-29-2006, 09:45 PM
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mmattockx
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Default RE: Home Made Canister Mufflers?


ORIGINAL: aerobob

And good luck to you! If I can help (although I think Dick already gave you everything but the brazing rod!!! ), don't hesitate to holler! Remember - roughly 10-12:1 ratios....50cc motor - about 500cc volume chamber...
I'm not sure about that, those sketches ARE pretty rough...

I will see how it goes and post some results if/when they are presentable.


Mark
Old 08-29-2006, 10:31 PM
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blkbird68
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Default RE: Home Made Canister Mufflers?

Your gues if it works and is smoothe with no flatspots - beats all the calulated crap.
Must have been luckier than I thought.. Throttle response is great. open header RPM was 9400..10100 was an absolute peak rpm on the ground with the can....I backed off to 9800-9900 to fly and so far it is working great. My can is a more simple design than you show. But I did the construction the hard way (alum. tube, tig welded)

I used all .035 wall alum. tube. 2" OD tube 8" long. .75" OD inlet, .625" OD outlet. It is a front inlet/front outlet can. I ran an .035" thick plate down the center 6". The inlet extends into the can 1" as does the outlet. The inlet is against the top of the can and the outlet comes straight out the front at the bottom of the can and then bends down 90 degrees. I haven't measured the header length I ended up with. I just kept cutting until it did'nt pick up rpm's anymore.
Old 08-30-2006, 01:44 AM
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Default RE: Home Made Canister Mufflers?

take a look at this post:


http://www.rcuniverse.com/forum/m_42...tm.htm#4250935

Cesar
Old 08-30-2006, 08:20 AM
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ben beyer
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Default RE: Home Made Canister Mufflers?

http://www.flyinggiants.com/forums/s...ead.php?t=6322
Old 08-30-2006, 08:43 AM
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rmh
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Default RE: Home Made Canister Mufflers?

For those who are really serious about trying to make a
more quiet setup
or
a more powerful setup:
for a quieter setup you must expand and change direction of the fast moving gasses
this slows them- look a a really good modern car muffler
the noise you are trying to stop is the "pop"of the exhaust port opening under high pressure --often called the the champagne cork effect -
to add power:
the exhaust rushing out the pipe creates a low pressure behind it - and this allows intake charge to rush in and fill th chamber .
If-- you control that outrush --speed it up- then abruptly stop it -at the right time you will effectively allow more fuel charge to rush into the engine . air/fuel has weight - and once it gets in motion - it tends to keep on moving - this is where the "tuned " in "tuned" system comes in.
If the in n out are set up in a rhythmic pull n stop n pull n stop pattern ---which match precisely the rpm of the engine--- - NO MATTER HOW YOU DO IT- the incoming charge will match the pattern and fill the combustion chamber with a larger charge and the abrupt stop of the exhaust pulse will stop it all from flowing out with the burned mix.
The critical nature of this "wave" is just like blowing across a bottle top and finally getting a resonant sound to come from the bottle - it all has to match volume -pressure and speed.
The beer bottle setup can work!-if the length and pressure are correct -
- don't expect miracles- try stuff -if it works - examine WHY it works.

Old 08-30-2006, 08:58 AM
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mmattockx
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Default RE: Home Made Canister Mufflers?


ORIGINAL: dick Hanson

For those who are really serious about trying to make a
more quiet setup
or
a more powerful setup:
If you want to know more of WHY in 2 stroke exhaust design, check out:

"Design and Simulation of 2 Stroke Engines" by Gordon P. Blair
ISBN #1-56091-685-0

available from the SAE (www.sae.org) along with a host of software utilities and simulation packages.


For a decent simulation package for reasonable $$$, check out MOTA:

http://www.iwt.com.au/MOTA.HTM

I have an older version of this and it works pretty well for developing pipe geometry. Considering the cost of one tuned pipe setup, it is money well spent if you are looking to develop your own system.


Mark
Old 08-30-2006, 10:37 AM
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rmh
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Default RE: Home Made Canister Mufflers?

I looked at it downloaded it -- note they say it may not be good for small glo engines?
The trap in all of these published pipe/can setups -is they are for max power extraction -which for aerobatic flying at various throttle settings is not good.
But try em-- see for yourself .
Old 08-30-2006, 10:49 AM
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mmattockx
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Default RE: Home Made Canister Mufflers?


ORIGINAL: dick Hanson

I looked at it downloaded it -- note they say it may not be good for small glo engines?
The trap in all of these published pipe/can setups -is they are for max power extraction -which for aerobatic flying at various throttle settings is not good.
But try em-- see for yourself .
Dick,

It has been a few years since I bought it and the work I used it for was motorcycle related. Never thought to check for model engines at the time... I was thinking of use on our gas engines, which are similar to the motorcycle engines I used it for. I don't see why it wouldn't work for glow, although all of the various tuning factors will be different. Maybe the compression ignition messes up their analysis?

The motorcycle world is a decent place to look for pipe design info, because smooth power and a gentle transition onto the pipe are important for good rideability and best speed around a racetrack. Part throttle performance is very important in this application, just like aerobatics.


Mark
Old 08-30-2006, 11:12 AM
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rmh
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Default RE: Home Made Canister Mufflers?

Understand - the BIG difference is that motorcycles are setup with torque multipliers (gearboxes) and and this plus a whole lot better carburetor setup -really changes the game
Also the relatively small passage sizes we have- makes a lot of difference in flow
Technically it has to do with air attachment to the confining sizes ( tubes/passages ) so relative flow to size changes .
Once when I was learning about fluidic control systems (a very limited field) the setup information stated that I should use X diameter tubing for X number of valves (these valves simply switched paths by diverting the column from port A to B - then it stuck there ) and if this didn't work - double the size of the supply lines -- (cut with a lazer then trim with a chainsaw)
Old 09-09-2006, 07:18 PM
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Default RE: Home Made Canister Mufflers?

We are building them out of square or retangle auminum and welding covers and outlet pipes in them, we have had no problems with back pressure or anything . once in a while the end might pop open if it was not welded with good penatration. we have made round, square,rectanglur, what ever we needed to fit the plane. waterloged.
Old 03-01-2008, 03:21 PM
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davidf
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Default RE: Home Made Canister Mufflers?

almost had heart failure when i priced a canister for my da 85 . check these out , made these from budwiser alumiun bottles. the 1'' pole came from my neighbor awning . hope he doesn't miss it .
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Old 03-01-2008, 04:58 PM
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Default RE: Home Made Canister Mufflers?

I have always found that a big can on a short header works really good. All of this effort tends to get lost at full throttle if propeller speed is to high. Its very easy to make these large models sound like an F3A setup. Basic human factors prevent it from happening.
Old 03-01-2008, 05:23 PM
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Default RE: Home Made Canister Mufflers?


ORIGINAL: davidf

almost had heart failure when i priced a canister for my da 85 . check these out , made these from budwiser alumiun bottles. the 1'' pole came from my neighbor awning . hope he doesn't miss it .
Davidf,

That looks great to me. I have a couple of questions.

1---Did you make the piece that connects to the engine, i.e., the flange and tubing? Is the tubing aluminum? How did you bend it?

2---Where did you get the silicone tubing? It looks to be about 1" ID. I have not been able to find any that large.

Thanx Rich
Old 03-01-2008, 08:57 PM
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davidf
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Default RE: Home Made Canister Mufflers?

it's a macs header pipe it's about $ 35.00 for the 120 ax . www.macspro.com it comes with 3'' peice of silicone tubing and plastic ties .

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