Home made mufflers

[Gary Anderson]

Hi guys, how many of you make your own muffler? I wanted a muffler that has several small tube coming out the sides. I wanted it to look like one of the real plane that has  a header a long side of the engine compartment. So, I made one today, it has three 1/4 inch tubes cut at a 45 degree angle coming out of each side. Looks funny seeing caster smoke coming out these tubes. I can't wait to get her in the air. I'm building a plane that has a strega wing, kind of a shark 45 fuseage, stab and elevator something weird. The tail and rudder close to being a shark's. I'm using a enya 60, model 7032 for power. I haven't timed how much fuel is needed but I made a 8 ounce tank. Controls, used all ball joint. I'm using the strega landing gear setup. Don't know what to call her, arf/enya? Have a great day, Gary

[mike mullis]

we wanna see pictures!!!!!  sounds neatto!!! love to see what you got goin on there...thanks...Mike

[Will Hinton]

Not only pictures, but what materials and adhesives, if any, you used.  You may force me to build another stunt ship yet this year!!
Blessings,
Will

[Randy Ryan]

I start out making wooden forms the shape of the exhaust stack, these are for the McCoy .29-.36 Super Stunt. there is an inner and outter form


The inner form shapes the .062" stiffback (the "T" shaped pieces of aluminum). These provide a stop against the stack and a doubler to hold the rivets that hold it all together


Next 2 pictures are the stiffbacks being shaped on the wood forms, I just hold it against the ply in the drill press vice and roll it over



Fresh off the form it is checked against the stack



Now the shell is formed on the outter form, this is .032" aluminum


Checked for fit on the stack


Here you see the stiffback in the muffler and how it forms the stop to go against the stack


Trial fit on an engine after being drilled and riveted, I make rivets from 1/16" aluminum welding rod, sorry, no pics of that


The fabed up end plate is 2 laters of .062 aluminum riveted together and dimpled to accept the .046" music wire bail to hold it on the engine.



Ready to go flying, notice the bail, it doglegs to match up with the gap between the fins, The ends provide spring tension to retain it when running. This installation will not distort the case like most of the clampons do, and its quite light and clean looking.

[Chris Edinger]

Wow... great looking muffler... love the construction....  I built a Sig Super Chipmunk back in the 70's and didnt want to cut a hole in that plastic cowl... so I improvised.... was great for about 2 flights..   took two pieces of thin wall copper tubing... and diligently bent them from exhaust port down to exit at the bottom of the cowl... but how to attach them... so i made a plate to fit the exhaust and then soldered them all together.. Of course i thought it was the koolest thing I''d ever done.. untill it fell apart on the second flight...  oh well.. how to build a better mouse trap... .. yours is great... was going to insert a picture..but cant seem to get it done..thanks for the great tutorial..

[Chris Edinger]

think maybe i have it...
on the side view if you notice the slight copper glint at the bottem rear of the cowl.. is the pipes...

   

[Chris Edinger]

LOL.. Ty... yep... it was a 70's kinda thing... today.... Flames... 

[Terry Bolin]

Very Very nice job and good look to on the muffler. How well does the spring clip work on keeping everything in place?
Keep up the good work!
Terry B.

[Randy Ryan]

Very Very nice job and good look to on the muffler. How well does the spring clip work on keeping everything in place?
Keep up the good work!
Terry B.

It works fine, but don't go smaller then .046 on anything larger then a .35

[don Burke]

Very clean design.
I assumed that the strip perpendicular to the exhaust stack is a joiner plate that connects the two sides of the the outer shell and it is riveted to both sides.  The rivets look like they are flush head on both sides, is this correct?

I recently found some nice 1/16 button head alum rivets from MICROFASTENERS.  Not really necessary to buy them just convenient. A rivet is manufactured by upsetting the end of alum wire anyhow.

[Gary Anderson]

Hi guys, how many of you make your own muffler? I wanted a muffler that has several small tube coming out the sides. I wanted it to look like one of the real plane that has a header a long side of the engine compartment. So, I made one today, it has three 1/4 inch tubes cut at a 45 degree angle coming out of each side. Looks funny seeing caster smoke coming out these tubes. I can't wait to get her in the air. I'm building a plane that has a strega wing, kind of a shark 45 fuseage, stab and elevator something weird. The tail and rudder close to being a shark's. I'm using a enya 60, model 7032 for power. I haven't timed how much fuel is needed but I made a 8 ounce tank. Controls, used all ball joint. I'm using the strega landing gear setup. Don't know what to call her, arf/enya? Have a great day, Gary

Hi guys, I ran her today, checked r's against different type mufflers, including no muffler. Engine seems to like the muffler I made. Plane looks cool going through the air with the pipes out the side. I try to get some pictures, just to give everyone a laugh. I used brass plate and tubing for test run. I'll make the next one out of thin stainless. I believe the stainless will be stronger and look prettier. The brass muffler weighs out at 3 ounces and is 10 1/2 inches long. Tip to tip of 1/4 inch tube is 4 1/4 inches. The header tube is 11/32 that inters the collector box. The collector box is 4 inches long x 1 1/2 wide x 3/4 inches thick. With thin material I didn't make a mold just layed it out on the material and bend it with vise grips using 3/4 inch metal strips for support. Made end cap from brass plate. Just having fun, have a great day. Thanks for all the comments, Gary

[fernando torres]

How does one rivet?

[Mark Mc]

So, resurrecting an old thread.  I'm going to try this for a couple of engines, a McCoy Redhead .35 and an O.S. Max-II .15.  I have 3 questions:

1) How do I determine length?
2) How many holes do I drill?    \  or, what total area for outlet should I have?
3) How big do I drill the holes?  /


Mark

[Douglas Ames]

Excellent fab. job! Thanks for posting your technique.

[Terry Caron]

I'd also like to know about the riveting - what's used as a bucking bar?

Thanks

Terry

[Phil Krankowski]

Basic riveting:

Use 1 1/2 diameters of material to form a head.  Cut, file or sand the end square, then take the edge of the end off with a file or sandpaper to form a centered, truncated cone.  Support the work off the anvil 1 1/2 diameters and form 1 head, then place the work on the anvil and form the other.  So 3 diameters + grip length is the proper rod length prior to upsetting.

Using a suitable thickness plate with a suitable hole to preform one head is a good idea, as is buying pre-made rivets.

Using less material will form a smaller head, and may be easier.  Using more material will form a larger head, and risks bending or bursting of the metal.  The rivet can be filed or sanded at any point in the process to make an attractive head, or prevent bursting of the metal.

Practice on scrap metal first.  Bending the rivet requires it be removed and redone. 

Good common "anvil like objects" include large steel plates or bars, preferable at least 1 inch thick.  Hammer head held in a vise, or large hammer heads laying on a stout table.  Hardened steel is best, mild steel is good.  Work over table legs instead of in the middle of the table to reduce bouncing.

Phil

[Terry Caron]

Excellent overview Phil.
Randy - what procedure/tools do you use to rivet the parts of your muffler together.

Thanks.

Terry

[Avaiojet]

I have my RRSM, "Randy Ryan Style Muffler" almost completed.

I used aluminum sign stock. To date, all that is left is two features. The first is drilling the holes. I'll copy Randy's as I also did with the mufflers construction.

Second feature would be the way it's attached to the engine. Nothing wrong with the tempered wire clip that Randy devised, excellent method actually. In fact, hats off for the entire design. 

It was mentioned that someone drills and taps the center exhaust bar on the McCoy .35.

I would like to try this. Thing is, I cannot imagine the single bolt not comming loose? I'm looking for more info on that. Thread size and whatever?

Here I am to date.

[Randy Ryan]

Excellent overview Phil.
Randy - what procedure/tools do you use to rivet the parts of your muffler together.

Thanks.

Terry

Terry,

Like I said, I use 1/16 aluminum welding rod for rivets. I have a small steel block I use as a "cold heading " die, just a blind 1/16 hole countersunk to about a 3/32 diameter. I hold a piece of 1/4 X 1/2 steel in the vice, slide the muffler over it and that's how I buck the rivets. I use a small ball peen hammer to set them.

[Terry Caron]

Terry,

Like I said, I use 1/16 aluminum welding rod for rivets. I have a small steel block I use as a "cold heading " die, just a blind 1/16 hole countersunk to about a 3/32 diameter. I hold a piece of 1/4 X 1/2 steel in the vice, slide the muffler over it and that's how I buck the rivets. I use a small ball peen hammer to set them.

Gotcha - Thanks!!

Terry

[david beazley]

Randy, is it possible to post a pic of your cold heading die? Also, what holds the muffler end plate on?  Does the bail do that as well?
Thanks.

[L0U CRANE]

I was very fortunate to have a high school with an aero shop. We learned many things then useful for aero mechanics. Among them was formng dead soft aluminum 6SO and 56SO by hammering and tempering the stock for spinning or further hammering.

Most hardware store aluminum milled stock is dead soft. Sheet and tubes, particularly. It does work-harden and become brittle, so needs occasional tempering.

Sears, at one time, sold an aluminum brazing pack, wire and flux, usable with a propane torch. VERY fussy stuff, and aluminum simply drops away, disappears!, if it gets too hot. Nevertheless, with care, and some wastage, I've made several brazed aluminum mufflers. Some I hammered rounded at the front, where a flat cap could complete a "bullet nose." Others I hammered to a tapered wine-bottle rear form, like the Fox mufflers of the 1970's.

A lot of work! With some math about the contained volume, etc., my mufflers weighed about half  as much as similar looking commercial pieces, and did not cut power or cause heating problems. Too much work to offer to build one for anyone else, though...