martinarcher

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Hey guys. I just finished a set of fiberglass cowl baffles for my 37% BME Ultimate. I took a ton of pics and they turned out pretty good so I figured I'd do a how-to.

Here goes....

I started with a profile of the cowl inlets.

martinarcher

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I then glued two sheets of pink insulation foam together and traced the profile onto the foam.

martinarcher

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Take measurements of the area to be cooled (the head). Then fit the cowl onto the plane and measure the longest distance between the cowl and engine head. Then cut the foam block depth to this measurement.

martinarcher

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Mark the cooling area onto the back of the foam block. Now shape the block to the desired shape of the baffle. I use a sanding sponge - one of the best tools on my bench.

martinarcher

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Test fit the mold...

martinarcher

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Next, if you have a contour gauge take the shape of the engine head. I didn't have one on hand so I improvised and cut peices of cardboard and taped them together adding one piece at a time. After the "gauage" is complete cut it to fit the front edge of the cowl.

martinarcher

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Next transfer the contour onto the foam and cut it out. When cutting, smooth out the jagged edges.

martinarcher

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Now the mold plug will need a larger diameter front piece in order to fit over the back of the cowl inlet so it ca be glued on. I just traced the profile onto a 1/4" piece of foam with an extra 1/8" to the outside of the profile. Cut out the "disk" and epoxy it to the mold as centered as possible.

martinarcher

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I covered the plug so the fiberglass would not stick to the foam, but instead release easily from the covering. It sure is a test of covering skills on a curved surface! The smoother the covering, the smoother the inside of the baffling will turn out. Make sure to cut the covering along the edges of the mold so you can use it as a cutting guide for the fiberglass.

Another tip is to use a dark color of covering so you can see it easily through the fiberglass and cut along the edge after the fiberglass has been applied.

martinarcher

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Prepare a strip of fiberglass that is twice as wide as the mold is deep and long enough to wrap around it twice. I used 30 minute epoxy as a resin and it turned out great. I would imagine regular glass resin would work fine. I used strips of balsa to spread the epoxy onto the fiberglass. I also used pam cooking spray as a mold release agent and sprayed a thin layer on the mold before glassing it.

Be sure to use protective gloves when glassing as you don't want epoxy and fiberglass all over you.

martinarcher

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As you fiberglass make sure to get all the bubbles out and make sure the fiberglass is tight to the mold. I wrapped a rubber band around the mold where the "lip" piece meets the body of the mold so it creates a good contour on the finished mold. I stuck the finished product onto a hobby knife propped vertically and let dry for 24 hours.

martinarcher

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After the fiberglass is dry and hardened, I used a dremel cutting wheel to rough cut the fiberglass, and then a sanding wheel to smooth out the edges. Then break the foam out of the mold and pull the covering off the fiberglass.

martinarcher

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Here's the final product...

martinarcher

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Test fit it onto the motor and make sure it turned out good. I am showing the opposite side baffle in these pics - I guess I never took finished pics of the other side against the block.

martinarcher

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Glue the baffle onto the back of the cowl. I used Shoe Goo and it works fantastic.

martinarcher

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Here it is all mounted up on the plane after the Shoe Goo dried.

I think it turned out pretty good. Hope you guys get some good ideas from it!

as722

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Very nice ! Little touches like that make all the difference.


Albert

fancman

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I'm woking on refurbishing a BME 33% Ultimate. Your baffles look great. How much would you sell a set for? Might as well get some reward for your great work.

martinarcher

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Is it a 33% or 37%? Also, what engine would you be using?

fancman

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I have the 37% using a 3W 100 engine.

martinarcher

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I doubt my baffles would fit a different engine. They are kind of a custom fit to the DA. The killer would be the spacing between the cowl and the engine heads.

RTK

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Good way of making that inlet martinarcher

mrbigg

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Very nice. Great job.

martinarcher

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Thanks guys. Like as722 said, I like to mess with the little touches - they do make a difference. In this case hopefully my DA will stay a little cooler. [8D]

airlyons

Nice work!

I have a few questions... hope you don't mind answering!

What is the black stuff you applied to the pink foam? (black paint?)

What kind of glue do you use to glue the pink foam halves together?

When doing the fibreglassing... do you just use epoxy then? (do you thin it out a little? I've done that with rubbing alcohol and used a brush... it seemed to work)

(and also to the above question - so I just need to buy the cloth or should I buy a "kit" that has everything in it for a car?)

Do you just use one layer of fiberglass cloth or several?

Is the rubber band stuck onto it?

Thanks in advance... I obviously don't know a thing about fiberglassing!!!!!!

Chris

ps I changed muffers on my SD 30% yak from a pits to a DA stock muffler and would like to fill in one part that juts down from the bottom of the cowl that I had to cut out when I put the pits in but now can fill it in. (it exits out the back of the cowl so it would create a natural vacuum) Would doing this foam trick work well for that?