I have seen this term show up in several posts lately on RC Universe. I know they are mufflers made from aluminum cans, but what exactly do they do for an airplane other than look funny, or give you a use for the aluminum budlight bottle from the sporting events.


http://www.rcuniverse.com/forum/m_8430199/tm.htm

Expansion chamber just like an old school 2 stroke dirt bike.

I don't know what that means either. Does it add power? or noise? or both? or neither?

http://en.wikipedia.org/wiki/Expansion_chamber

Buzz words. Don't-cha just love em? [sm=48_48.gif]

Just a basic muffler made from a commonly available mousse can. I've made a few similar to the above post with good success for my combat models.

You make it out of a mousse can, as in hair product. The new aluminum beer bottles are being used now too.

they were originaly a real mouse can, adapted to half of a stock muffler. alot of guys now use a small aluminum lotion type bottle with a mac's header. It gives my combat planes OS 25fx with a 9-4 prop about 19000 rpms, about 1000 more than the stock muffler. it works on the high end of the rpm range. its perfect for combat

There are even manufactured mufflers now called mousse can mufflers.

yes, there are a couple of places who manufacture and sell them

Ahh man that takes the fun out of it!!! Got go out and make your own. I've even made after mufflers using the sample shaving cream cans without a loss of power or increased heat on the engine. Made the engine pretty quiet.

This is part of the hobby... Got out and experiment a little and learn from your adventures.

Back to the original question... your answer is, the idea of the mousse can muffler or beerbottle muffler is to reduce noise output.

Thanks for the info. It's pretty interesting. Does it work on all 2 cycle motors like 60 or 90 size, or is it more effective on the smaller engines like 25's. I have only heard it mentioned on smaller motors like in combat planes.

It works on bigger engines too, youi just need a bigger can.

Jack

The ones that are built right are not mufflers, they are "folded" tuned pipes [with an inner chamber] that give a true supercharging effect.
The SPAD website........Spads to the Bone.......IIRC is where I found a great step by step MCP construction article. I built a couple of them for OS LA .40s and got a 1500 rpm increase over the stock muffler. The pipe allows the LA .40 to be 3D capable with a 4 pound plane.
Pure magic.

the noise is about the same until you hit that high rmp and the prop unloads, then they sound cool passing by.

Most such home made mufflers are to reduce noise with a minimum loss of power, an ideal way to learn a little bit about engines is to make your own muffler. It helps satisfy your curiosity also and give some a sense of satisfaction in being able to produce something useful on their own. It also allows you to adapt to special physical constraints if you are designing your own model. True, you may have little or no success but then again, many are quite good. All who tried learned something, often something useful.

If you build a MCP per the instructions at STTB, there will be no minimal loss of power.
The Neilson Polls in your neck of the woods might show that most home made mufflers are only to reduce noise, but around here we only go to this much trouble to increase power over the stock muffler.