LDM

My Feedback: (15)

Has anyone out there tried simple coppoer light weight plumming supplies from home depo for scale exaust??? would this work ?

khodges

My Feedback: (1)

It works just fine; you can use the flexible copper tubing, bend it as desired, solder as needed; standard plumbing joints and pipe also works. The biggest drawbacks are the weight of the stuff compared to the same thing in aluminum, and its heat conductivity. It is also rather soft, so it will deform easily when stressed. Actually aluminum is has a greater ductility per weight than copper, so weight is the greater issue.

Brass (alloy of copper/zinc) tubing is better if you can find the sizes you need. It's a bit less malleable, but still has a high heat conductivity and weight is similar.

nashtm

Hi

I have used some thin walled plumbing joints that come in 90 deg etc and have silver soldered them totogether - have about one hour running so far.
The gentleman that gave me the idea has been using it for a long time and the only reported problem is work harding - a long copper exhaust in plane with vibration may/will crack
at some stage.

I used it to build an in cowl exhaust for a Pacific Aeromodels 120 Tiger Moth and put a washer at the end to provide restriction for back pressure and I am very happy.

Tim

nhblacksmith

Copper will work harden but if you can remove the pipe you can heat it with a torch or in a forge and then quench it in cold water and it will be like new-soft and pliable. I once participated in a big blacksmithing group project building a copper water fountain and we were cold hammering the pieces. Every ten or 15 minutes it would harden up so we reheated and quenched it. Never had a piece split.

Neal

jaka

Hi!
It's heavy!
Use thin wall stainless steel tubing from Krumscheid in Germany instead.

SoCalSal

My Feedback: (16)

I second this idea. It is a bit pricey..but it is the best way to go. Here is the web link http://www.krumscheid-metallwaren.de...op.php?lang=EN

You may find some of this product at Desert Aircraft.look under the "exhaust" section on their web-site to see if they have the parts you need.

LDM

My Feedback: (15)

Yes , K& S responded to me with a suggestion to the G26ei , but I lost the link and could not find the part number for the G26ei .

As far as weight the copper I found was very very light , that is what I found so interesting , I was planning on a hobby after market muffler then attaching the copper to the after market muffler in a scale manner .

even if weight is a issues vs staneless , the Fw190 can afford a littel weight on the nose , but more important I need the system to work as far as duribility over the long haul , I am not looking for a cool factor that I am fixing every weekend .

voyager_663rd

I also use copper cold water pipe for my OS91 4s exhaust. Bit too big on the diameter for the muffler exhaust exit so I cut a slit in it/re-bent it to shrink the diameter around the exhaust on the muffler and pinned it on. No problems at all.

LDM

My Feedback: (15)

Pinned it on , can you explane ?

voyager_663rd

Because the copper tube was still too large, I just drilled a tiny hole through the pipe/muffler exhaust "nipple" (don't know what it's called)/pipe then put a piece of thin piano wire (such as you might get for a control rod, but never use, in an smallish arf) through it and bend the ends at 90o to each other so it wouldn't slip out of the holes. Kind of like a Z-bend. I had tried using zip ties but could never get it tight enough.

It's all hidden inside the cowl so it doesn't show. It doesn't weaken any part and does not impede the exhaust gases.

One thing I should add: normally, rpms/compression/whatever, power tends to drop if an extention is added. In my particular case, I actually got better performance with the 4" copper pipe added on. It had fallen off once (in the air) and I couldn't understand why I wasn't getting the power I had just a few minutes b4.

Put a new pipe on and all power was restored. Counter-intuitive I know but that's my story and I'm sticking to it.

LDM

My Feedback: (15)

Thanks great info looks like I will try this menthod

nashtm

Hi Neal

The problem is that it work hardens during use - thinner copper more so.
However if your exhast is not overly long and flexible itwill be fine.

Interestingly my plain copper exhaust consisting of 2 elbows and about 1 inch straight sounds more pleasant than the factory muffler on a 125 Saito.

Also the thin 1/4 inch (I think) fittings I am using are very light !

Tim

LDM

My Feedback: (15)

I am passing on this idea simply based on medal to medal - non sodered possible vibration problem + gas engine = radio interferance . I love the idea and the pipe I purchased would make a nice scale exaust when attached to my slimline muffler but its a problem waiting to happen

Kmot

My Feedback: (24)

I know this isn't what you are looking for as far as scale exhaust for an airplane. But over 20 years ago I made a few 'real' mufflers out of copper fittings for my gas buggies. Some of them I made with inner baffles and perforated tubes and the idea was to make a quiet muffler without losing performance and I succeeded completely. But the mufflers are indeed pretty heavy.

However, on a gas buggy they take a beating like an airplane would never see unless you re-kitted it. So for durability, I say yes copper is plenty durable.

The pictures are from when I took them out of a storage box recently.

LDM

My Feedback: (15)

Kmot , thanks for the pics and the shop advice said that today many car guys make there mufflers from copper for scale effect .
My issues is how to keep it together , I dont know if silver solder will hold up to the temps of a gas engine and if not radio interferance will be 100% a factor from medal to medal vibration .
I can tell you that Lowes sells great light weight copper tubeing , very similir to that used in gas home appliances and or water distribution but its small , workable and not bad in weight , even the connections are light .
The issues is will the silver solder hold to high heat and if not its not worth the effort because I have read countles post on radio interfernace and its all from medal to medal vibration .

nashtm

Silver solder will most definitely hold up to exhaust heat.

Just don't use a special low temp silver solder Sta Brite makes one.

LDM

My Feedback: (15)

Tim I tried to get silver solder at home depo , they dont carry any time at all , do the Hobby shops sell it ?? or can you suggest a source ?

flipstart

I have built two copper exhaust systems, one for an Albatros and for a Bird Dog-it was a learning process. The K & B brass tubing will not hold up to vibration, but the copper tubing and L fittings work fine. Try a welding supply store for the 15% silver brazing rod, it comes in sticks, requires mapp gas and using one of those turbo type burners increases the heat enough for solder to melt without over stressing the copper. They also have the flux to use, I think both products are made by JK Harris. Works great and sounds much better than factory muffler. Both of mine have held up for a bunch of flights using 4 strokes. Sure cracked some brass tubing and burned up some silicon couplers to start with. Good Luck with your project.

LDM

My Feedback: (15)

Thanks , great advice

Kmot

My Feedback: (24)

7797A11 Aluminum Brazing Kit

http://www.mcmaster.com/

LDM

My Feedback: (15)

kMOT , THANKS GREAT WEBSITE !!!