Chapter 7
Fuselage Exterior
In the first part of this chapter, I'll be fabricating the NACA scoop and rounding/contouring the corners/sides to an "aerodynamic and visually aesthetic shape".(In other words, make it look cool.), then install antennas and glass the outside
Below is a shot of the tools I used to sand the foam. Shureform plane, long and short Perma-Grits, a 2X4 with 36 grit belt sander glued on it, The curved thing you see on the left I made from 6 pieces of scrap ply-wood cut to shape of the fuselage bottom template in the plans. (It worked great, even if I do say so myself) I held it together with long drywall screws. I also wrapped masking tape around the ends to kind-of serve as a guide along the sides and bottom.
Above and below are views of the NACA scoop fabrication. This foam is extremely easy to sand. So, be careful what you set on it and how you remove tools from it or you'll find some shapes/gouges which are not pleasing.
Here is a view of the fuselage bottom, prior to the UND glassing. My decision to place the NAV antenna where you see it was based solely on the fact the RST manual stated the optimum angle for it was 10-30 degrees. If you place the antenna per plans, there is no way you can fit it with less than 45 degrees. THERE!!!
For the coax routing, I chose to merely Dremel a channel just wide enough for the coax, stuff it down. Then take some left over bulkhead foam, taper it a little on one edge. Put some micro in the channel. Jam the bulkhead foam into it. After it cures in place, sand it level. Worked pretty good, if I do say so myself. Others have "pour foamed" the coax in place, but I'm trying to stay as far away from that stuff after reading how it sometimes wants to expand/contract after cure.
Here's a shot of the bottom after glassing. This is where I learned 2 things. #1. When microing, I found it works best if you scrape as much of the micro off as possible before laying the dry cloth. THIS WILL MAKE IT MUCH EASIER TO MOVE THE CLOTH PRIOR TO WETTING OUT. I wish I had known this from the beginning. My part weights are @10% above archive averages. #2. In order to keep the necessary movement of cloth after initially laying it down, having help is a MUST. There's an art to it, but once you get the feel, you will be able to lay it with a minimum of "post-lay" movement with a helper.(Epoxy Woman came through again.). I found it extremely gratifying to see the fibers all going in a straight line with a minimum of nudging.Watchout you don't overlap the UNI selvage. It's better to have a small gap between fibers than a small bump like I'll have to deal with during finishing. Oh well. I used the "duct tape" method described in Norm Muzzy's website for determining the line to cut and keep errant globs of micro and resin from ruining the pristine blue foam on the sides. It worked great!
Here is how I dealt with the Infamous Joggle Problem: After sanding the foam and bulkheads to the perfect desired shape, take some blue foam and sand it to the rough curve of the joggle. Lay some Saran Wrap over the area. Mix up some Bondo an lay it over the joggle area. Then, press the blue foam into the goo. After a few minutes of cure, Presto! With a little sanding, you've got a custom jig which you can use to hold the glass down to form the perfect flange for the LG cover.
I've decided to put a few thoughts in this spot as I review the plans page by page.
When building the NACA scoop, make sure you cover your work with some nice, flat cardboard so when you lay your tools down while working on another area, you don't screw up the area you just finished!
Pay close attention to areas where Nat tells you to MAKE OPPOSITES.
Take your time. The foam you aggressively sand now may be the foam you sheepishly replace later.
Buy a GOOD quality tool to cut metal with. The archives are chuck full of suggestions. I went with the Bosch saber saw, and haven't regretted it yet. Also, my bench grinder came in handy as well.
Having both the Roto-Zip tool w/ sander attachment and a Dremel-type tool came in very handy. Sometimes the Roto-Zip was just too powerful for the more detailed work.
I think the time spent making the custom sander for the fuselage bottom corners was worth it.
When working with large pieces of cloth, get a friend. (Although, I was able to glass one side w/o help by using the frame used in shaping the fuse bottom as a kind of big, long cloth holder to minimize movement of the cloth after placement.
Pay close attention to ensure you don't overlap sides/ends of UNI layers. You'll end up with an unsightly bump which you'll have fun sanding off.
Sleeves are a wonderfull thing when sanding fiberglass.
So is a respirator.
So are goggles.
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