Posted Friday, August 17, 2012 @ 06:06 PM
After weeks of cutting patterns and fitting, and cutting, and fitting, the baffles are finally done.
Since cooling is a big issue, I decided to build a completely new baffle system with a few modifications from the original. I knew there were going to be leaks around the exhaust that I couldn't really do much about, so I focused on reducing all other leakage to compensate. The two main changes to note are how the front baffle wall goes all the way down to the bottom of the cowl, forming a complete seal around the engine, and second, is how the side walls are angled back 45 degrees. This added more room for the spark-plug adapters and wires, and allowed the seal material to meet the upper cowl at a 90 degree angle for a more efficient and controllable seal. I also sealed the gap around the intake manifolds and the oil cooler tunnel. The air-blast tube off the back of the right side goes to the voltage regulator on the firewall, and the one on the left side puts cool air around the magneto. You can also see how scalloping the attach point of the seal material forces the flap part to lay over flat on the inside of the cowl with no leaks. There are also some VW-made baffles under each cylinder to keep air channeled around the fins as it exits.
The other project was to create fairings inside the cowl to help airflow into the top. There has been some discussion on this in other threads using expanding foam and concerns about flammability. So I did this with a couple layers of fiberglass over in-place molds made of insulation foam covered with duct tape to act as a mold release. When the resin has cured, the pieces are popped off, the foam mold removed, and the pieces are bonded to the cowl and finished. It looks a bit sloppy in production, but it works great.
I used the rear baffle panels (heavily modified) from the AeroConversions baffle kit for their 2180 VW. Everything else was custom. I have the paper patterns if anyone is looking to make some new baffles for the 1600cc engine and a Eugenio cowl and would like a starting point.
It's getting very close to finished and flying. Thanks again to everyone for posting their information, pictures, comments and suggestions.
[Edit by dannparks on Saturday, August 18, 2012 @ 01:35 AM]
Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1