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Updraft Engine Baffling


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So after some back and forth, and some discussion with a knowledgeable Cozy III owner, we decided to pull out our Cozy MK IV plans-built baffling and replace it with a new set based on an existing O-320 design. My approach was to install the O-320 paper templates on the O-360, then add and subtract as required to get a proper fit. About 5 or 6 sets of templates later we had a winner!!!


I ended up making a very rudimentary 3D CAD model (SolidWorks) of the O-360 cylinders and some other areas, trying to capture only the details that were relevant to the baffling. From there I was able to digitally wrap the engine in 0.040" thick aluminum sheet metal, which then provided me with the flat-pattern cutouts. I made a final set of paper templates from the flat-pattern to make a final fit check before construction. Fingers crossed.


As it turns out, one of the machine shops I do a bunch of work with has a waterjet cutting machine. All they need is a 2D CAD file of the flat-pattern and away they go. I dropped off two 4X8 sheets of 0.040 aluminum (they only needed one it turns out) and 16 minutes and ~750 inches of cutting later, I had an entire set of baffles cut out and ready for bending!!!!!!!! Price ... about $45.


Last night we went over to my company's machine shop and formed all the pieces into shape, using the flat-pattern bend lines and 3D model as a guide. It only took about 1 1/2 hours to get the job about 80% complete, with the remaining pieces to be formed at the hangar this weekend with the engine within arms reach for fit checks. I'll probably go ahead and anodize all the pieces afterward ... probably blue or red.


Below are a couple of pictures from the process along with a YouTube video link showing the waterjet cutter. I'd recommend this approach to anyone as it will probably get us some fine looking baffles. Hopefully they'll cool the engine properly too!!







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Self confessed Wingnut.

Now think about it...wouldn't you rather LIVE your life, rather than watch someone else's, on Reality T.V.?

Get up off that couch!!! =)


Progress; Fuselage on all three, with outside and inside nearly complete. 8 inch extended nose. FHC done. Canard finished. ERacer wings done with blended winglets. IO540 starting rebuild. Mounting Spar. Starting strake ribs.

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Excellent work. Would you be willing to share the SolidWorks files? We're going down a similar, though not exactly the same, path for out Mk-IV. Having the model as a starting point would be really helpful.


Where did you get a jet cutter that'll do parts for $45??!! Around here the set-up fee is usually at least that, so I'd guess 2-3 times that for finished baffles.


Also, any interest in having sets cut and selling them?




Kevin R. Walsh & Michael Antares

Cozy Mk-IV #413


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Also, any interest in having sets cut and selling them?

I was thinking the same thing as I was reading the original post! You have done what looks like some really nice work. After you get 100 hours or so on your design and if the cooling is working well, it should be a good seller for somebody. A "turn key" engine baffle system, if it works, might get some attention. There are lots of posts on engine baffling and cooling issues through the years.

Andrew Anunson

I work underground and I play in the sky... no problem

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So I installed the V1 set of baffles this past weekend. Most of the pieces fit fine ... amazingly fine actually. It looks really really great. However, there are a couple of pieces that were absolute crap!! All the misfit pieces could be hacked a little and made to fit, but I'm going to edit the 3D model and have another set cut ... V2!! Hopefully this week.


Attached is the VERY low-level 3D CAD model of my O-360-A1A. It's basically a rudimentary stab at the cylinders, with a tight-fitting profile sketch on which I based the baffles. The rocker box profile and 1/4-20 holes are accurate, which should be a great starting point. Hope it's helpful to someone out there.


As for selling the baffles, that will be handled by Dale Martin of Owl Eagle Aerial Composites (niceez@gmail.com). I've basically taken his O-320 baffle plans and modified them to fit the O-360 with guidance from him. Making them digital (and waterjet / laser cut-able) was my idea, but only because I'm less digitally lazy than physically lazy :). In the end he'll likely sell either a copy of the plans with installation instructions or pre-assembled baffles ready to bolt in. In any case, go ahead and contact him if you're interested.


I'll post some pictures of the V2 install when it's final.


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  • 6 months later...

Does anyone have some ready-made paper templates for a cozy diffuser? Not looking for the as designed NACA---but the diffuser on the other side of the firewall. Plan was to hotwire the mold out of foam, glass it, then bolt it on. Looking to save a step if someone already has good luck with it.

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