On 21 Jul 2021, at 2:33 am, David Leonard wdleonard@gmail.com <flyrotary@lancaironline.net> wrote:

Hi Steve,

For sure, Mild steel will not hold up in the early parts of the rotary's exhaust system.  304 usually does pretty well, but I used 316 whenever I could find the size and shape I needed in 316.  In particular, the welds on the 304 have needed touching up after 1200 hrs, but the 316 is fine except for the welds to the turbo flange, which I have also had to touch up.  They eventually developed cracks and leaks.  

I have also tried a muffler similar to the one you show.  It held up fine to 20 or so flight hours, but there was a very noticeable power loss so I removed it.

Best,

Dave Leonard

On Mon, Jul 19, 2021 at 6:10 PM Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:

Hi people

After only ~40 hours of flight + ground testing the mild steel 2.5” resonator in our system was looking a lilt worse for wear.

The leading edge of the internal auger/spiral was disintegrating.

We have purchased a 304 stainless version that’s an inch longer and having it ceramic coated inside and out before reinstalling.

When I had the Glasair on the apron at full tilt the other day for some tuning of the newly installed EC3, a guy 

commented on its noise being similar to other quiet Lycomings. As in loudness, not pitch. 

I don’t know how much back pressure this type generates. Here they are called a “Gonzo”. They claim to be used in drag rotary application.

Would be interesting to instrument it, but I don’t think I can be bothered, as it seems to be developing good horsepower.

I expect this new stainless version will last much longer and be at least as effective.

But the proof will be when I run it up and next annual.

Here are some photos

Cheers

Steve Izett

Glasair Super IIRG

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