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Author Topic: Engine shroud  (Read 157 times)
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SolarCyclone
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« on: April 15, 2018, 03:04:53 PM »

Hello, does anyone have a used/new engine cowl similar to this style? Or know of any US suppliers? Thanks
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Engine shroud
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Konrad
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Measure twice cut once



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« Reply #1 on: April 15, 2018, 04:16:46 PM »

Look up presure cowl. These are usually made by the builder.  What class (size) are you looking for.

I would tape up the motor to get about 1mm to 2mm clearance around the cooling fins. Then add some clay to make sure all surfaces showed positive rake allowing the mold or cover to lift off vertically. Wax the fuselage to protect it from the epoxy. Apply mold release agent to everything. Start your layup with small pieces of glass cloth and laminating epoxy.  

If making more than one or two models with the same engine and fuselage (pan) I would make a heavy layup and use this as a female mold for a low production run of parts. If only need one I would make a light layup and use it as my finished part, after some clean up.
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Cut it twice and it's still too short!
Konrad
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« Reply #2 on: April 16, 2018, 09:19:54 AM »

Sorry, in mold making I think the term is draft not rake. What you want is for there to be no "overhang" that would lock the rigid epoxy and class cloth to the mold. This requierment is why we often need to make multi piece molds for more complicated parts.

The cowl you show was made with a two piece mold (centerline partline) as there is a little feature (triangle webge) going part way around behind the cylinder. This feature (baffle) is used to deflect more air behind the cylinder and can be added after you make the initial part. You may or may not want this depending on your cylinder's and head's cooling fin configuration.
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Cut it twice and it's still too short!
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