Hi Everyone,
There was some discussion regarding NACA inlets during the "Vent"
discussion. I needed some NACA's but I could not find them in the size I
needed so I made mine.
It's a bit time consuming but once you have made the templates you can make
as many as you need. Unfortunately we generally only need a couple.
I don't recall the source of the attached spreadsheet but it does a nice
job of calculating the profile. From the profile I created two templates
for the depth and two for the sides out of aluminum. I then used the
templates to hot wire a foam core.
Once I had cut the core I covered it with heat shrink plastic and used it
as a plug for my layups. If you're lucky and the plug releases you end up
with a perfectly smooth surface and you can re-use it to make the second
one.
I'm sorry that I don't have any pictures of the process. They seemed to
have disappeared in the black hole called "hard drive"
A few other comments. The inlet ramp needs to be blemish free and a smooth
transition with no bumps. As others have mentioned they need to be
correctly aligned with the airflow and a smooth transition on the outlet
side to your hose.
I have oil streaked mine and the airflow is correct.
Paul
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