Anyone tried "FlyQuiet" mufflers?

[chlee]

Hello everyone,
Has anyone else tried these muffler/pipes for their Norvel .061s?

http://www.flyquiet.com/

I got one a few months ago, and I'm thinking of building a simple 60" span motor glider as a testbed.

- Chung

[PROACE]

It has always been my experience that muffling an engine to reduce noise has the side effect of reducing power due to exhaust restrictions needed to quiet down an engine.

[1705493]

I've been using Flyquiet tubing to good effect for exhaust extraction and also for boosting power a bit. The best of both worlds. On my Norvel .074s I replace the rear muffler cone with a specially made adapter that allows the tubing to slip directly on to the muffler. A 20" piece is used with a small outlet adapter on the end. The trick is to install a baffle inside the tubing. You slide this back and forth till you find a sweet spot. This boosts power about 500 rpm. Not quite a tuned pipe but you do get a bit of a tuning effect.

What you end up with is a long, skinny muffler with huge volume, (about 12") or so. The volume prevents any real restriction and back pressure. The baffle provides a bit of power and the small outlet at the end provides the final restriction for sound reduction.

I've installed aluminum wool between the baffle and the outlet for even more sound reduction with no loss of power or back pressure or engine overheating as you might find if you did this inside the muffler proper.

This can be seen in the May 2003 issue of Flying Models on page 33. You can see the zip tie securing the baffle at just the right spot along with the rear outlet. The tubing has since been moved under the wing for a cleaner appearance.