NG-30s

Step 2 FABRICATION OF NG-30s

I started fabrication of the NG-30s while I was still working on the tip fairings for the canard. With some scrap BID, I made a 20 ply layup big enough for all the pads made later in the step. I got this idea from Rick Maddy, thanks Rick! Anyway, underneath the layup is a piece of paper with a drawing of the pads on it, 6 of them, so I would make the layup big enough. After completing the number of layers I needed (I needed 5 more to get a 1/4" thick pad) I laid plastic over the top. Then, using some 1/4" ply as spacers, I put a piece of marble I have over the whole layup. This squeezes out extra epoxy, and, makes the layup the right thickness.

Here's the foam rough cut to size. I made up some CAD drawings of the NG-30s (two the same, more on that later) and used those to make sure I made the right sized pieces.

I used the plastic method for the 2 ply BID layups that go over the MKNG-6 pivot area. Don't forget the peel ply piece that goes down first!

Lay down plastic, lay up 2 plys of BID, put another sheet over the top, then, squeegee the bubbles and extra epoxy out. Cut to size, with the plastic on, then remove the top later of plastic (next picture......)

Place on the part where needed, squeegee and stipple through the plastic as needed. Remove the top layer of plastic....

...and you have a perfectly sized, cleanly installed, bubble-free, resin low layup installed! Now, repeat for the second NG-30. If you look closely at this picture, you'll see there's no drawing/paper on the 2nd NG-30. This is because I printed to NG-30s that were the same, not mirror images. Later steps have you matching them, so I just removed the paper from the 2nd one and turned it over when I did the layups so I would have 2 mirror image pieces.

I did the 4 ply BID and 2 ply UNI layup (see newsletter #85 page 2 for the plans change here) at the same time for both NG-30s. I wasn't sure exactly where, in the layup schedule, to add the UNI so I added 2 UNI after 3 layers of BID and finished with the 4th layer of BID.

...and then into the vacuum bag it goes, after 2 layers of peel ply and a couple layers of paper towels. If I did this again, I would have put some peel ply underneath. The edges of the layup wicked some epoxy onto the back side of the part that I had to scrape off later. Peel ply on the back would have prevented that.

Removing the peel ply and paper towels, after cure, from a complex shaped part like this can be a bit of a pain. The peel ply tends to rip. I'm using thinner peel ply, it's sold in 63" widths as simple dacron for covering fabric wings. This thinner peel ply conforms better in the vaccum bag so I keep using it. Doing this part, in a vacuum bag setup, with strips of peel ply - no way!

I used the band saw to rough trim the parts to shape. I couldn't knife trim because I vacuum bagged. Once I had both parts trimmed roughly to size, I used the CAD drawing to get them exactly to shape and size.

Here's the two NG-30s (note they're mirror images) final trimmed and ready for the next steps.

Test fitting the ply and aluminum doublers, as well as the pads I made in earlier steps. I've since cut out the pads, from the big "blank" or 20 layer piece I made, using a hole saw. Worked great. 20 identical 1.2" diameter pads, the right thickness, ready to be installed with a little flox in preparation for the next layup. Further, I didn't have to make those during that layup, which wasn't too bad but had 4 BID and UNI in it's schedule already, in addition to the extra 2 BID for the 2nd piece of aluminum doubler.

I used the same hole saw (after adjusting the size, of course) to cut the foam out for the pads after locating them accurately. This isn't rocket science, but, I had to be careful here. The saw needed to cut the pads to 1.2" diameter, outside, but be reduced in size to cut these to 1/2" inside diameter. Further, I had to be really careful not to cut into the fiberglass layup on the back side at all. Worked out fine. The sound of the drill changed as it encountered the micro/foam layer, so, I just stopped there. I used a Dremel and chisel to remove the last bits of foam and micro down to the glass.

After adding the layups per plan on the outside of the NG-30s, I drilled the pads out using the "NG-51" piece that came with my Wilhelmson nose lift. I proceeded very carefully here to make sure all the holes line up accurately. I bolted the pieces together using the MKNG-6 pivot hole, then, drilled a small hole and installed a bolt into one of the holes. Then, I drilled through the "NG-51", full size, and both NG-30s. Install a bolt there, do the same on the next hole. Repeat until all holes are drilled to the full 1/4" size.

I used the Shurform plane to final trim the glass on the edges of the NG-30s. I had never used this tool for this before, even though I've done tons of foam shaping with it. It works great! Slices though cured e-glass like a cheese grater through cheese. Touch up with the sanding block when you get close and you have a perfect edge. Note that I have the NG-30s bolted together and clamped to the jig table vertically to make this easier.

I drilled the holes for the rudder pedals to 3/4" since I'm using a set of Dennis Oelmann's pedals. They're a tad under 3/4 in diameter, but, the 1/2" per plans won't work. 3/4" is a bit sloppy for them though. I hope I can find a teflon bushing or something like that to make this pivot point work crisply and smoothly without binding or play later on in the construction phase.

I used my Fein Sander to cut out the perimeter of the cutouts on the inside of the NG-30s. Marked the lines with a pencil, installed the high-speed steel blade then went to town. I then used a chisel and sand paper to get the rest of the foam and etc. off. Find the peel ply layer, pull it off and you're ready for the next layup.

I again used the plastic layup method for these 2 ply BID layups. The piece of black tape is a plug for a hole - made by my compass which I used to draw the nice circle for the top of the layup.

And, of course, I vacuum bagged these layups for good contact and smooth edges. This is a tricky bag setup to do, easy to get a "bridge" if you don't massage the bag down into the corners. Also easy to get a bunch of wrinkles as the bad squishes down into the depression. Your finger and a credit card helps here, also, I used strips of peel ply, about 3/8" wide, arranged in a radial pattern, and 3 or 4 paper towel layers to avoid the bridging.

That completes step 2 - click here for the next step, "worm drive"