My new OS 120 four stroke Surpass came with a 45 degree muffler pipe that wouldn't mount underneath the plane as the angel is too large. So, I purchased a flexible pipe to use instead, picture below.

Has anyone else done something similar? I'm wondering if this pipe, which is fairly rigid, but still flexible, will hold the muffler in place in flight without it vibrating loose before I fly it.

Thanks in advance.

Where did you get the flexible pipe? How is the muffler attached to it?

Kitbuilder, OS and Saito sell those flex pipes. Check Tower and Horizon.

Cappaj1, that will work just fine, but wrap a piece of copper wire (or other soft wire) around the muffler and attach it to the engine mount just in case.

If you want something pre-made, you can get [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXB858]one of these[/link] which will fit your 1.25" muffler.

At the very least get the clamp Joe posted. Even with it the odds are pretty goot it's going to break right about at the head of the engine.

Thanks, Guys, I ordered one of the suggested clamps.

What I'm looking into as a final solution is cutting a section out of the stock pipe that came with the muffler and re-welding it back together to end up with a 25 or 30 degree bend in it instead of a 35.

I've bent those elbows with a God awful amount of heat and even more muscle. Got 5 or more degrees out of a Magnum .91 bending it.

How did you grip the ends without damaging the threads? Thanks.

I kept the nuts on it, clamped one end in a vise, and a steel rod (that matched inner diameter) inserted in the other end. Heated it to cherry red, and it still took all I had to get it to budge.

Where did you get a rod that large in diameter, and did you use a regular propane torch or something hotter?

I think the rod I used was actually a rat tail file. And all I used for heat was a regular propane torch. The nuts kept the pipe from deforming.

Thanks, I'm going to try it!

I was just going to say to bend your own but dead beat me to it. Last time I did it I still had my gas torches, it took about 30 seconds. I have some very long, round punches that I use to get inside the header and do the bending.

One thing I read recently...but I have not tried it........was ....."to bend a tube without kinking it..one should fill it with sand first." Sounds good...but??? Rich

I had a similar issue where I could not pass the club noise test with the standard muffler and needed a larger aftermarket muffler.

I tried a variety of flexible connections and alternative mufflers and that big rattly old thing just broke them or shook them loose. At best I would get about 10 flights and then I .would land with the bits dangling on safety lines. I spent hours fiddling with that setup/

If you can stay with the stock muffler and a short stiff header.

The sand trick works great but I have never tried it on the header. I have only had to bend the one. I have ended up using the headers as they are and just extended them with neopreen and run that out the bottom of the cowl. These were four strokes in big bipes, sounded cool but didn't have a muffler.

Well, I had a friend with an acetylene torch bend the pipe. He inserted two 12" steel rods, large enough to fit inside each end of the new pipe, and heated the center section up until it was red hot, then unbent the pipe to a so it was about 35 degrees, and it fits perfectly, pictures attached. There's about 1/4" between the fuse and muffler and the closest spots, even though the pictures don't show it that well. Thanks for the tips!!

Looks good!!

Thanks, can't wait to get the new cowl cut and mounted now.

Looks great. Isn't it nice to have the correct tools? I had to leave my tourches behind when I moved, no room here to store them. Didn't use them often but when needed they were always there. The flex pipe has it's uses and if mounted correctly it works OK but it does have some problems, your header looks better and is a lot stronger. Your complete plane looks great!!