PHOTOGRAPHY: FRANK FANELLI
Foam needs good adhesives (above left). Pacer’s Formula 560 provided the necessary working time for easy spreading over large surfaces and Gorilla
While building the plane shouldn’t take too long, it will go faster if you have some tools and adhesives ready when you cut open the sleeve. First item to consider is the adhesives that can be used. The manual rec- ommends 15-minute epoxy thinned with al- cohol for the large sheet surfaces. That’s fine, but I found it easier to spread Pacer’s Formula 560 more uniformly since it allows a longer working time. Plus it’s an easy clean-up. 5-minute epoxy came in handy for quick jobs. And since Depron® doesn’t like regular CA, the foam safe type is needed, along with an accelerator. The CA, though, didn’t seem to really grab the foam, especial- ly the thin type.
One last adhesive to consider is the newer Gorilla glue that dries white and sets up more quickly than the original. I tried it in a few spots where some fill was needed and it worked well but the characteristic expan- sion of the glue had to be considered. Sand- ing it, though, isn’t near as difficult as epoxy.
Well, those are the adhesives. Use them judiciously and it will help speed the process, but also there are a few tools that will come in handy and also keep the work- flow going. First, have a sanding bar with 150-grit paper, and one with 220 grit. The first will provide the quick shaping needed. The second will provide a smoother, less granular surface.
Whatever cutting tool chosen, it should be fresh and very sharp. Even only slightly dull doesn’t cut when it comes to foam. I used a fresh #11 blade, but a fresh single edge razor
Glue’s new formulation was good in some filling needs. The Edge’s manual (above right) has to be downloaded from the 3DX site and is nicely illustrated.
worked even better. These instruments will really make beveling control surface leading edges much easier. Then the 220-grit sand- paper can smooth things.
Control surface bevels were just men- tioned and it’s a good time to decide which way to shape them. The manual suggests a tried and proven method of the over and un- der hinge. That means the leading edge needs to be beveled about 35–45 degrees ei- ther side of a center line. It’s the same method used years ago with cloth hinges and lately modified with plastic trim sheets. It works really well and is thoroughly reliable. A faster, easier way is using the alternate hinging method used on small foamies. The leading edge of the surface is beveled from the top to the bottom of the surface with a 45° bevel. One of the pictures will show the two ailerons masked top and bottom with “Frog” tape—it’s a variation on my favorite blue 3M painters tape—to show the 6mm offset between top and bottom of the surface. The single edge razor made the gross cuts to rough out the bevel and the sanding bar with 220-grit finished the surface. Blenderm tape, a 3M medical tape, was used as the hinging material. Du-Bro sells it as their Electric Flyer Hinge Tape (Cat. No. 916). Some pharmacies may also have it. It’s very flexible and has a pretty tenacious ad- hesive. With the respective control surface and the wing/stab/fin mated and held in place, a strip of the Blenderm is laid along the entire top of the hinge line. That takes care of the basic hinging, but some addition- al insurance is provided on the bottom side.
There’s no need to run a strip of the Blen- derm the entire length of the underside of the control surface. A few individual strips tucked into the bevel of the hinge line—not across—will provide extra hinging durabili- ty without stiffening the hinge movement. I may have gotten a little ahead of myself since the hinging of the control surfaces doesn’t happen until the basic wings are glued into the basic fuselage. This is where it’s appropriate to mention those carbon fiber spars for both wing and fuselage. Noth- ing much to mention except that they drop into the precut slots in the fuselage core and the wing core.
But there is something to say about the fuselage carbon fiber tube. It needs to be cut to length, and that’s where one other very handy tool comes into play and makes quick work of the cut. A Zona saw, with its 32- tooth razor blade will easily and smoothly cut the tube. Or, a fine tooth hack saw might also work. Of course a Dremel moto-tool with a silicon cutoff wheel will also work, but the cut will be on an angle.
One last thing to consider, and this is al- most an afterthought: the building board. Craft stores sell 36-inch squares of a thick, black foam board. It’s ¹⁄₂ inch thick foam sandwiched on either side with a heavy pa- per coating. Pins stick in it securely and it’s very flat. At that size it fit the Edge 540 quite nicely.
So assembling the Edge is easy because the laser cutting has done all the shaping al- ready. All the lightening holes in the foam cores are already cut. Some sanding is need-
Simple straight pins with a round head were used (above left) to align the bottom sheet and the center foam core while the Formula 560 cured. Here’s the
FLYING MODELS
36-inch square foam board (above right) mentioned in the text. Note the wax paper as a glue barrier, and the laser cutouts in the center foam core for lightness.
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