Matt's RV-8 Project



Matt Dralle's RV-8 Project
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Date:  2-22-2010
Number of Hours:  2.00
Manual Reference:  
Brief Description:  Cowling Inlet Duct Baffles - Part 1

The top of the engine cowling has two fiberglass inserts that need to be fitted and installed. These ducts are suppose to smooth the airflow and force the air to more smoothly flow over the engine cylinders. Once again, I've been kind of dreading this job as there didn't seem to be a good way to *accurately* install them. They are just two oddly shaped pieces of fiberglass that have to somehow be installed to the top of the cowling right behind the left and right air intakes. Well, it turned out that they weren't all that hard to align. If you draw a line 1/4" back from the front edge of the baffle, and then draw another line 1/4" from rear of the cowling lip, you can use the two holes drilled in the cowling to perfectly align the baffle. Magically, the shape of the fiberglass baffles matches the contour of the cowling in the back very nicely. In fact, on the left side, the fit was perfect. On the right side, it was very close, but took a little pushing.

Once I cleco'd everything in, I trial fit the cowling over the engine. To my dismay, the prop governor landed right in the middle of the left baffle! I used a Sharpie pen and made some outline doodles on the baffle, then squared them up and cut them out with a cutoff wheel on the Dremel tool. There was also some interference with the rubber baffle gasket material on sides both on the right and left side. But, again, with some judicious trimming on the fiberglass intake baffles, things were good to go.

I bonded the ducts to the cowling with some standard mix epoxy resin and added a couple of pop rivets in the front to hold it nicely. In the back I used clecos which I will fill later. I added a layer of 9oz glass cloth on the rear as well. The plans don't call for it, but it just seem to be calling out for some extra support there.

Over all, the baffles came out really nice. I don't know what I was fretting about! ;-)
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Ducts Marked 1/4

Ducts Marked 1/4" Back

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Ducts Marked 1/4

Ducts Marked 1/4" Back

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Aligned And Drilled

Aligned And Drilled

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