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My friend has a 750 with a fuel injected Rotax. There are 2 potted electronics boxes on the side of the Motor's computer. They get hot, and we are going to put in cooling ducts and tubes to direct the air in the top cowling.
Is there a need to put something in the duct to prevent water from rain etc. getting to the electronics? What are the tricks for doing this?
Thanks,
Greg
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If you use ram air in the rain, you're almost guaranteed to get water. There are several ways to do this, though I haven't personally done them. The simplest is to not have a ram air inlet duct facing directly into the airflow where it will ingest water, such as facing down as opposed to forward. That also allows gravity to assist. Properly designed outlet ducts will actually suck air through the system, but I am no expert in designing those. I do know you don't need high airflow for electronics. If you want to get fancy, there are devices designed for this, such as a cyclonic separator. It spins the airflow to remove anything that isn't air. I have no idea where to get them or how much they cost, but you can actually make your own if you're so inclined. You can search for that stuff. Here's one link:
https://powderprocess.net/Equipments%20html/Cyclone_Design.html
You can actually use ram air to drive the separator if you want, called secondary airflow.
I wish I could provide more info, but I have no direct experience in this. I was hoping someone who did would chime in. I do know there are other forums centered on aircraft design that discuss airflow and ducting. One such forum is homebuiltairplanes.com. Maybe someone there could provide better info. Or maybe a Rotax forum?
From an electronics standpoint, I would probably also try a heatsink. Just make sure to properly secure it.
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