Skypilot_one:

I want to warn you of something before you start building.

I finally put on my cowl on yesterday evening. It doesn't fit. I have a OS 46FX and I bought a bisson muffler's inverted straight muffler. As you probably know, the Chipmunk has a very narrow fuselage. Well, up front where the engine sits, it's only 9cm wide! that means that you have no choice but mount the engine inverted. In the end I had to cut out a fairly large hole out of the side of the cowl to get it to fit.

In the beginning I was fairly sure the hole would be very small, that only a small amount of the muffler had to stick out. But as time went on, I realsed I had to cut more and more to get the cowl to fit. Had I known before-hand that the bisson muffler would not fit I would have kept the original OS stock muffler. I think the hole in the cowl to clear the muffler would have been more aesthetically pleasing!

Anyway, I'll post some pictures this evening so you can see what I mean. Also, I think with a 4-stroke engine it would fit perfectly.