Muffler under fuselage?

There's a company called Gromolzig (German) that makes a muffler designed to connect to a 4-into-1 exhaust header, and to hang under the fuselage. They use a ball joint to connect, and, presumably, flexible hangers. They told me today that the cost is about $4000! (3200 Euros, plus shipping.)

Apparently they have some European customers, noise standards being far more strict there than here. Does anyone have any experience with the Gromolzig muffler, or any other under-fuselage mount muffler?

I'm thinking about this for an RV-7, wondering if the noise reduction would be worth the power and drag penalties.

Try Larry Vetterman

Larry Vetterman sells full-up exhaust systems with mufflers inside the cowl for way less than that. I'm planning to go with his crossover design with mufflers for my RV-7A with IO-360 and vertical induction.

http://www.vettermanexhaust.com/

:-0

$4000? Sounds certified. I'll bet you can make your own for a LOT less -- look at Tony's books for his design. Might try to get away from the packing as a noise reduction plan, as that will surely blow out due to heat. You might need to build from iconel in the high heat areas, but you can surely get to a similar product for a lot less...

There are 'sound reduction' units available for race cars here in the US - maybe you can adapt one of those?

Carry on!
Mark

Muffler under fuselage

The RV14 has one. Appears to be a Supertrapp muffler. You can see it on the walk around video on Vans website.

There is also another man in germany who makes neat mufflers, small with very good noise results.
http://www.hliese.de/International/international.html
If you look under the experimental section:
http://www.hliese.de/Experimental/experimental.html

Both are fine for the very restrictive SWISS regulations!

Hello

In switzerland and germany, both are used to bring the RV into Noise-Class D which reduce the landig fees and alow to fly longer in the evening.

Liese looks like this:
and is used after a Exaust system from Vetterman

1x RV-7 / O-320 / two muffler on two pipes /all is fine since 1000h
1x RV-7A / IO-320 / two muffler on two pipes
1x RV-7A / IO-360 / two muffler on to pipes
1x RV-7A / IO-360 / one muffler at the end of a 4into1 (Berni's RV)

Gomolzig
1x RV-6A / O-320 / one muffler at the end of a crossover, into one
1x RV-6 / O-320 / one muffler at the end of a crossover, into one

The Liese System was in the past certified, then the european regulations changed (EASA) so that it was not worth to re-certify for them.
The muffler is just attached to the Vetterman pipes, thats it. They come with the clamps. Lise is around 1200$ (bought them 2 years ago)

Pictures will placed soon here.

Hope it helps,

Regards, Dominik

I just made some pics a few days ago with the Liese mufflers on a RV-7A.
Two mufflers, one on each pipe, price as mentioned about 1000 Euros or around 1200 USD.

muffler more cheap

There is also a German company called Liese ( They have the slogan: Leise durch Liese, this means calm with Liese) and their muffers are more cheaper. About 1200 USD. Without any power reduction. Many RV in Europe have one. I will buy one in the next week. Just google for Liese muffler. Mr. Liese is a very nice man.

I agree, make your own. Find an automotive muffler and hang it for under $100. You're allowed to do that in our experimental category.

Best,

"Swiss Muffler"?

I remember reading about something called the "Swiss Muffler" that was developed for use in European countries. I googled it and found plenty of pictures, cheap too!