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Baffles for N2188 printer friendly version
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dannparks
Sergeant Major

Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 376

Click here to see the profile for dannparks Visit https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1 Send email to dannparks Send private message to dannparks Find more posts by dannparks Edit or delete this message Reply w/Quote
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]

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Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1

Jorgen
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Gender: Male
Location: Lund, Sweden
Registered: Apr 2007
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Posts: 777

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Posted Saturday, August 18, 2012 @ 06:55 PM  

Dann,
I'm doing the wave in a standing ovation as I'm writing this, that's an outstanding and beautiful engine and baffle installation! I'm also blushing with shame when I realise in what a poor cooling environment I let my tried old 1400 Rectimo work. For instance, there is no hole in the baffle plates one inch behind the oilcooler- how efficient is that?

If you plan on doing a lot of aeros you might want to consider adding oilvents for the head cowls(connected to the crankcase breather)- Bob G has them on "G-AWGN" and if I understood him correctly he's very pleased with them.

Excellent idea with the cold air blast tubes for the magneto- I might copy that. Are you still contemplating a rear upper cowl exit for the oilcooler exhaust? I would be most interested to see your solution for that. Maybe it's enough to allow a slot between the upper cowl and the firewall?

May the 4's be with you/ Jörgen

[Edit by Jorgen on Saturday, August 18, 2012 @ 07:01 PM]

dannparks
Sergeant Major

Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 376

Click here to see the profile for dannparks Visit https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1 Send email to dannparks Send private message to dannparks Find more posts by dannparks Edit or delete this message Reply w/Quote
Posted Sunday, August 19, 2012 @ 01:31 PM  

Thanks for the kind comments.

I don't imagine there is much air flow through your oil cooler as is. If you're having oil temp issues, I'd look at creating a tunnel between your oil cooler and the back baffle and opening up the baffle. Although I was intrigued by having the oil cooler air go in and out through the top of the cowl, the consensus from forum members was that the hot air from the oil cooler moving through the back of the engine does not seem to cause issues. So I stayed with the proven system -- with the blast tube on the mag.

The blast tubes are leftovers from the RV construction. It's a plastic corrugated tube. Drill a 3/4" hole in the baffle and pop it in. Simple. Much easier than Scat tube and all the fittings. The stuff is available from Vans Aircraft (or maybe even a local crafts store or industrial supply). I've got about 10' of it if any of the local Pacific Northwest Fornaviators want some.

I noticed photos of breather tubes on valve covers, but I never really knew their purpose (pressure relief, drainage?). I don't really plan on doing acro, but if I do, I'll look into that mod.

--------------------
Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1

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