NACA Ducts

Time: 2.5 hrs

Things done today:

  • Finished re plumbing the right static port
  • Tested static lines to 20inHg
  • Wrapped left front NACA duct in aluminum tape
  • Installed NACA ducts
  • Painted nose wheel gear grey

The rear NACA ducts were by far the most time consuming to install. Besides having to remove quite a bit of material from the top edge to get it to fit under the metal channel, they also needed some material removed around the rivet holes so the aluminum rivet backers would fit nice. I was also missing two holes that I needed to drill through the side skins and into the duct. The good news is that these rear NACA ducts don’t exist on the newer kits so if you get a kit now you won’t have to worry about them.

I was originally going to use countersunk rivets for the NACA ducts, but there are too many issues with doing this on the rear NACA ducts. Probably if I though about before putting on the side skin then it may have been doable. The fronts work be fairly easy to countersink, but I didn’t want to counter sink those and then use dome rivets on the rear. Oh well.

OK a note about the sikaseal. I bought some Sikaflex 295 UV Black sealant from Amazon. This is specified in the build manual for the canopy and other areas that need to be sealed. You use a caulking gun and it pretty much installs just like caulking. The main difference is that is makes a huge mess. Also if you don’t want your fingers to be black for days then wear gloves, though gloves make it difficult to smooth it out so maybe you just have to deal with black fingers 🙂

Used the dremel with a 200 grit drum sander bit and carefully sanded the areas around the rivet holes. The dremel takes off a lot of material quickly so you have to take it easy or you’ll sand right through the duct.

The rear NACA duct is fairly long and extends well passed the end of the opening in the skin. I decided that there should probably be a few rivets holding that end in, though probably not completely necessary. The two flecks on the fair left are the new rivet holes added.

Rear ducts installed with Sikaseal and rivets

Inside of the rear duct

Outside of one of the front ducts.

This is the inside of the left front NACA duct. I wrapped the top with some aluminum tape so that it contact through to the frame. This is because I will most likely install the GTP-59 Garmin temperature sensor here and the body of the sensor needs to go to frame ground. I tested with a meter and it seems to work fine. I don’t have the probe so I’m not sure what size hole or where it should go in the duct yet.



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