Roddie's muffler vid

roddie Fri Apr 21, 2023 3:30 pm

This is a vid that shows my muffler design in use on a Cox .049 Babe Bee engine.. and the ease in which the muffler installs, as well as uninstalls. I'm using a single/fully-open header-pipe in this vid. I didn't actually take any sound level readings, but there is a distinct difference in the "tone" when the muffler is installed.

The engine cylinder has the "slit-type" exhaust ports. I can't find a cylinder ID number anywhere on it. It doesn't appear to have SPI (Sub Port Induction). The glow head is a standard one and has X1 gasket installed. The reed is a copper/star-shaped one. The 5cc tank-bowl has been bypassed to allow for an external fuel-delivery. The needle-valve "spring" has been removed and a short piece of silicone fuel line installed in its place to prevent air-leakage; greatly improving mixture-control.

Note that I'm using a flywheel rather than a propeller to allow installing the muffler while the engine is running, which makes it easier to hear the difference in the resolution of the exhaust tone.

I'm also using an Ace (Ralph Cooney designed) throttle consisting of a tapered-plunger that enters the air-intake/venturi at the rear of the engine after removal of the little mesh-screen. I have a polyurethane air-filter in between the engine and the engine-mount. My custom engine mount has a center-bore (guide) to accept the Ace throttle plunger.

It should also be noted that I'm using Sig Champion "25" glow fuel from the early 1990's.. Shocked

(edit-add) One of my recently-built electric starters gives me trouble at around 02:35:00 on the counter.. Rolling Eyes

I need to file a "flat" on the motor-shaft for the grub-screw.

HalfaDave Fri Apr 21, 2023 8:35 pm

Hi roddie,
Thanks,
I did Db tests back in the day.
RadioShack Db meter, versus an average or tuned pipe .60
Any 1/2A was less noise.
You results,
Will confirm,
Dave

balogh Sat Apr 22, 2023 12:31 am

Great experiment and muffler, Roddie, it indeed muffles the engine noise, and I did not hear sizeable drop in rpm...I could audiotach the engine video if longer engine runs with and without the muffler, maybe without the throttle, would be recorded..of course then cooling the engine without a prop maybe an issue.

My slit cylinders are non-SPI, if yours is SPI, that should come from a later - but not the latest - Killer Bee, the only SPI split cylinder, if my memory serves me right...see also Cylinder Identification sheet, Slit cylinders table, link on the left of this page..

getback Sat Apr 22, 2023 6:30 am

Good video roddie , sounds to me like it rattling but I don't hear so well maybe just not hearing the prop noise LOL This Site Rocks!

rsv1cox Sat Apr 22, 2023 7:41 am

I enjoyed your video too roddie. I'm always amazed at the throttle range that you guys can achieve with these just by using simple measures. Some muffling but it's not going to keep the school yard police away. Not many do.

roddie Sat Apr 22, 2023 7:54 am

HalfaDave wrote:Hi roddie,
Thanks,
I did Db tests back in the day.
RadioShack Db meter, versus an average or tuned pipe .60
Any 1/2A was less noise.
You results,
Will confirm,
Dave

Thanks for your interest Dave. I'll be testing some other pipes with smaller (graduated) holes drilled in them. We'll see if those make any difference.

Ken Cook Sat Apr 22, 2023 8:18 am

Recently, a meter was brought to the field I fly at. Personally, I would've rather punched the guy in the mouth as I don't really need to know what the DB levels are. The signage says upon entrance, THIS IS A MODEL AIRPLANE FLYING FIELD. So, now that we know it's not a library I really don't give two hoots what the noise levels are, I feel most can interpret the signage and know what to expect. So he was persistent in doing whatever he felt he was trying to prove, I don't know what that was. I get it, many fly electric. I can't really say they're a enjoyable quiet either. Some of those electrics had a helluva a high pitch whine that I feel was more annoying than my 1/2A's.

On initial starting of 1/2A engines, this was considerably peaking the meter until the engine was running. I'm not certain as to why, possibly the sound waves are more like shock waves due to the initial rap the engines offer until running.

Many of the r/c guys are flying .40 size racers. This isn't exactly quiet either. Nonetheless, on the meter, they were certainly showing less DB's than the 1/2A's. Due to the 1/2A's being in closer proximity of the ground and to where the meter was could've certainly been a factor. But, one thing that was certainly obvious was that the 1/2 A engine sound wasn't carrying as far as a distance as the r/c engines. The r/c engines were certainly lower pitched growlers but they were more detectable at the opposing end of the field. The 1/2A engines with their in and out oscillation were still recognizable. Up close, ( within 50 yds ) the 1/2A's were not quieter in DB's. They were off the hook compared to the larger stuff. What makes it worse is when you have a back drop such as a school and the plane is passing by the building cause HUGE reverberation. Now the noise is extremely magnified and it's not just for a second or two at a time, it's constant. So yes, I can see why people get ticked off. I find bouncing basketballs annoying so I can understand the whine of engine going round and round being a problem.

I don't want to muffle my engines, I've never ever found it to be beneficial. Running a engine on the bench using a muffler and trying to determine if a muffler does what's asked of it is one thing. Flying a plane with one is another. It critically starves the engine of power. Now some may suggest oh it's so little it doesn't matter. When you start into consecutive maneuvering, the entire issue changes. This may or may not impact a r/c flyer. I can't answer that because I don't fly r/c. Control line is dealing with a lot of drag and it takes little to nothing to limit your planes ability to fly correctly.

roddie Sat Apr 22, 2023 8:20 am

balogh wrote:Great experiment and muffler, Roddie, it indeed muffles the engine noise, and I did not hear sizeable drop in rpm...I could audiotach the engine video if longer engine runs with and without the muffler, maybe without the throttle, would be recorded..of course then cooling the engine without a prop maybe an issue.

My slit cylinders are non-SPI, if yours is SPI, that should come from a later - but not the latest - Killer Bee, the only SPI split cylinder, if my memory serves me right...see also Cylinder Identification sheet, Slit cylinders table, link on the left of this page..

Thanks Andras, Yes.. the ear-piercing tone of running "open-face" is definitely augmented when the muffler is installed. I'd usually have a heat-sink (Cox Sandblaster type) installed when running a flywheel.. but wanted to be able to install/remove the muffler while the engine was running.. (toggling) where you can clearly hear the difference in tone. I use the throttle to guard against rpm run-away while I'm needling.. and always try to keep the mixture on the "rich" side.. to help keep things cool and well lubricated.

Regarding the engine's slit type exhaust-ported cylinder; I'm fairly certain that it's a "plain-Jane".. and not of the Killer Bee type.. Laughing

roddie Sat Apr 22, 2023 8:28 am

getback wrote:Good video roddie , sounds to me like it rattling but I don't hear so well maybe just not hearing the prop noise LOL

Hey Buddy! Thanks for your interest. Yes; you can definitely hear more of the engine "alone" running.. without the additional noise created by a spinning air-screw.

roddie Sat Apr 22, 2023 8:30 am

rsv1cox wrote:I enjoyed your video too roddie. I'm always amazed at the throttle range that you guys can achieve with these just by using simple measures. Some muffling but it's not going to keep the school yard police away. Not many do.

Thanks for watching my vid Robert. Thumbs Up

I'll be doing some more testing.. so stay tuned!

roddie Sat Apr 22, 2023 8:54 am

Ken Cook wrote: partial quote Recently, a meter was brought to the field I fly at. Personally, I would've rather punched the guy in the mouth as I don't really need to know what the DB levels are. The signage says upon entrance, THIS IS A MODEL AIRPLANE FLYING FIELD. So, now that we know it's not a library I really don't give two hoots what the noise levels are, I feel most can interpret the signage and know what to expect. So he was persistent in doing whatever he felt he was trying to prove, I don't know what that was. I get it, many fly electric. I can't really say they're a enjoyable quiet either. Some of those electrics had a helluva a high pitch whine that I feel was more annoying than my 1/2A's.

I don't want to muffle my engines, I've never ever found it to be beneficial. Running a engine on the bench using a muffler and trying to determine if a muffler does what's asked of it is one thing. Flying a plane with one is another. It critically starves the engine of power. Now some may suggest oh it's so little it doesn't matter. When you start into consecutive maneuvering, the entire issue changes. This may or may not impact a r/c flyer. I can't answer that because I don't fly r/c. Control line is dealing with a lot of drag and it takes little to nothing to limit your planes ability to fly correctly.

Remind me to never even show you a photo of a sound-meter.. Curious if you watched the vid.. as you did not comment on it. This muffler design of mine actually has another significant benefit in that it can be used to divert exhaust-wastes (oil mist in particular) away from the engine/model.. making for less clean-up as well as less oil-soaking.

You probably know that I'm using spent .22 cal. (long) shell-casings with the primer-end drilled-out for my header-pipe(s). I've obtained some silicone tubing that fits tightly on the pipe and can be run outside of a cowling.. down a gear-strut and attached with a zip-tie.

Below is a photo of the tubing.. and an oil-sump that made to try out.

aspeed Sat Apr 22, 2023 8:57 am

Seems more tolerable. Maybe try one with the front folded over so it can clear the TD carb?

roddie Sat Apr 22, 2023 10:19 am

aspeed wrote:Seems more tolerable. Maybe try one with the front folded over so it can clear the TD carb?

Hi Alan, Thanks for watching my vid. Yea.... I hope to be able to fit this design to the Tee Dee .049/.051.. but I need to run some cylinders that have SPI.. to see if it's worth the effort.

Here's a couple photos of non-Cox FRV .049 engines where "folding-over" does work on one of them (the DC Wasp). The other is an OK Cub.

In contrast.. The Norvel, Brodak, Wen-Mac and Testors FRV .049 engines (just to name a few).. have their venturi's "too close" in proximity to the cylinder, for my design to work on those engines.

Here's a couple more photos that show my muffler design "deconstructed"..

The inner-chamber (1" aluminum tubing)

with dual-pipe arrangement..

Lots of pipes!!

The outer-chamber (bicycle tire inner-tube/butyl rubber) two circular pieces..

stapled together.. and center-punched for a snug fit around the engine-cylinder.

Pipe extensions can be made from 3/16" ID X 5/16" OD silicone tubing.

It's really easy to make this muffler.. and it only weighs .25 oz.

aspeed Sat Apr 22, 2023 10:32 am

Oh, I did not know about the 1" dia. spacer. Thought the rubber was just stapled over the shell casings. Funny how things are made up from things around the house. I would have trouble getting shell casings here. We don't have the right to bear arms without giving $ to the government. I could likely machine something up if I had to, or had some clever idea?

roddie Sat Apr 22, 2023 10:40 am

aspeed wrote:Oh, I did not know about the 1" dia. spacer. Thought the rubber was just stapled over the shell casings. Funny how things are made up from things around the house. I would have trouble getting shell casings here. We don't have the right to bear arms without giving $ to the government. I could likely machine something up if I had to, or had some clever idea?

If you have a shooting-range/Rod & Gun Club nearby, you might find the spent shell-casings there. Here in the US, it's against the law to reload the .22 cal. casing.. so most people just throw them in the trash can.

aspeed Sat Apr 22, 2023 10:52 am

Oddly enough I was a member of the Waterloo Rod and Gun club for a few years. Had to join it because of an agreement with the model airplane club. Was nice to have a bar at the field. I only lived a block away so never got a beer there, or owned a real gun for that matter. Couple pellet guns. The pellets are good for plugging up bladders. The club was one of the better stops on the snowmobile trail.

rdw777 Sat Apr 22, 2023 10:58 am

You’re muffler is a very innovative design Roddie…. I like the quick mount aspect of it, Might help with quick fixes at the field…. I think that’s the neat thing about these little engines….. There’s lots of room to experiment to try new and different things Very Happy

roddie Sun Apr 23, 2023 7:23 pm

rdw777 wrote:You’re muffler is a very innovative design Roddie…. I like the quick mount aspect of it, Might help with quick fixes at the field…. I think that’s the neat thing about these little engines….. There’s lots of room to experiment to try new and different things

Thanks Rob, It's been rainy here over the last day or so.. otherwise I'd have tried running some other pipes having smaller diameters and also swapping out the current "non-SPI" cylinder for a known SPI type. The OEM Cox muffler is known to hamper the performance of an engine equipped with a cylinder having Sub Port Induction by eliminating the entry of "fresh air" into the crankcase via the exhaust-ports as the piston reaches TDC. I'm curious to know how my muffler will affect the SPI performance. My design is highly customizable.. where flow is concerned.

Here's a photo I took tonight.. that shows a "smaller" version installed on one of my oldest 1/2A C/L airplanes. The single-outlet muffler has a "full-flow" header-pipe installed on a Cox .049 product-type engine having an external wedge-tank.. and an outboard/horizontal cylinder-orientation. I attached some 5/16" (OD) silicone tubing to the header-pipe.. and cut the length to fit down against the LG strut where I secured it with a zip-tie.

There won't be much oil to wipe-off that model after its flights.

rdw777 Mon Apr 24, 2023 6:03 am

Neat work Roddie, That combination looks like a good candidate for some school yard flying like we did in the past…. Another interesting side note of your project is that since the rubber is not melting, It hints a little bit toward the operating temp of the cylinder at that location….. Will be interested in your further tests Very Happy

Robert

roddie Mon Apr 24, 2023 6:21 pm

rdw777 wrote:Neat work Roddie, That combination looks like a good candidate for some school yard flying like we did in the past…. Another interesting side note of your project is that since the rubber is not melting, It hints a little bit toward the operating temp of the cylinder at that location….. Will be interested in your further tests

Robert

Interesting your mentioning the rubber not melting Rob. The Rubber is of the "Butyl" type (bicycle-tire inner-tube material) which can withstand temperatures up to 250 degrees F./121.1 degrees C. The silicone tubing can withstand temperatures up to 500 degrees F./250 degrees C.

I plan to source some sheet-silicone to replace the Butyl component in my design. I'm not sure how the Silicone sheet will hold-up as compared to the Butyl component. It will need to accept standard paper staples for securing the two halves.. and not "tear-out" when stretched-open for insertion of the aluminum inner-ring/chamber.

The Butyl has held-up to decades of oil-exposure.. which is another plus.

The aluminum-tube/inner-chamber of my design definitely sinks-off some of the heat that's coming directly out of the exhaust-ports. The OEM Cox muffler also sinks heat from that area. It would be interesting to record the static upper-cylinder running-temperatures of open-face vs. Cox OEM muffler installed vs. my design installed. Granted; my design can be set for max./min. flow.. but in all fairness; I need to conduct further testing in as much of a scientific manner as possible. I hope to improve in that area.. Embarassed

rsv1cox Mon Apr 24, 2023 6:35 pm

Love this picture roddie. Mr Spock report to the bridge.

You make a few, I'd love one for my display case. Trade for any engine maybe?

roddie Mon Apr 24, 2023 7:57 pm

rsv1cox wrote:Love this picture roddie. Mr Spock report to the bridge.

You make a few, I'd love one for my display case. Trade for any engine maybe?

PM sent.. I agree; my muffler is kinda' cool looking... whether it actually works or not. Laughing

I know that it works.......

Steel-wool.. or "glass-pack".. Cool

"Let's make Cox engines fun again"

aspeed Mon Apr 24, 2023 11:08 pm

The butyl rubber may stand up so far. You might try the dollar stores for some flat silicone baking sheets or kitchen gadgets. I was looking at the dollar stores for some squirt bottles for creams when flying on airlines or camping. They are about 2 oz. and made of silicone. Thought maybe a muffler for a .15 size motor. Around here the dollar stores are getting to be five dollaramas. Kind of like the old old 5 and dime stores. The Cox mufflers had a silicone sleeve around the outside of the exhaust ring. They lasted a while but would eventually get hard and brittle. Maybe your design would let the heat out faster and not be as hard on the rubber or silicone.

roddie Tue Apr 25, 2023 12:49 pm

aspeed wrote:The butyl rubber may stand up so far. You might try the dollar stores for some flat silicone baking sheets or kitchen gadgets. I was looking at the dollar stores for some squirt bottles for creams when flying on airlines or camping. They are about 2 oz. and made of silicone. Thought maybe a muffler for a .15 size motor. Around here the dollar stores are getting to be five dollaramas. Kind of like the old old 5 and dime stores. The Cox mufflers had a silicone sleeve around the outside of the exhaust ring. They lasted a while but would eventually get hard and brittle. Maybe your design would let the heat out faster and not be as hard on the rubber or silicone.

I never thought to check the dollar store for silicone baking sheets Alan. Just this morning I bought some silicone mat from Amazon. Granted; it was the thickness that I was looking for.. but was a LOT more $ than I would have paid at the dollar store. Here in my locale there is a chain of dollar stores where everything was $1 USD.. but since the pandemic and subsequent supply-chain issues... everything's now $1.25 USD.

Nothing lasts forever Alan.. although our little Cox engines seem to stand the tests of time. Small Cox Logo

aspeed Tue Apr 25, 2023 1:37 pm

Here is the tube thing that I thought might make a good flexible muffler for a .15. May not ruin the motor in a crash? Not that that ever happens? https://www.dollarama.com/en-CA/p-squeezable-silicone-travel-tube-assorted-colours/3051975 I found a few different sizes and shapes. Kind of a big opening that would need some sort of adapter.

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