fiberglass cloth is applied in four or five pieces that overlap and coated with 30- minute epoxy. You can also use regular weight (1.5-ounce) cloth, which is easier to work with, but you will need to apply sev- eral layers. I use epoxy on the cloth in- stead of fiberglass resin because the resin
tends to dissolve the Styrofoam. After the epoxy has cured for at least 12 hours the Styrofoam is carved away using a Dremel tool and drum sander. A layer of regular weight cloth is added to the inside of the cowl.
You can also make the cowl out of balsa, but
a fiberglass cowl is thinner, giving more cool- ing space inside the cowl. Wing: The wing is built in three pieces. The two outer panels are built first, then joined to the small center-section. Wing spars are in- side the wing, giving a smoother covering job, but you can put the spars on the bottom of the wing if desired. All wing spars should be from medium hard balsa and free of warps. Since this is a scale model, I built in the ailerons. They are non-functional, but they can be made to operate if desired. You can also build the wing without ailerons which will save some building time and weight. Starting on the outer panels, the 1⁄16-inch bottom sheeting is cut to size and pinned in place, along with the 1⁄16-inch trailing edge bottom. Ribs W2 are glued to the bottom sheeting. The first W2 rib is canted for the dihedral angle. A simple template can be made to get the correct angle. After these ribs have been pinned and glued in place, slide the ¼ × 1⁄2-inch main spar in place and glue it to the W2 ribs. Add the leading edge then slide the rest of the ribs in place and glue. You may need to trim the ribs so they will fit properly on the spar. Slide the 1⁄8 × 1⁄4-inch spar in place and glue. A 3⁄16 × 1⁄2-inch strip is glued on top of the 1⁄16 × 1-inch trailing edge. The wing tip is made from 3⁄32-inch balsa.
If adding the ailerons, use 3⁄16 × 3⁄8-inch balsa for the trailing edge section. The lead- ing edge is cut from 3⁄16-inch sheet. The small center section is built next. There is not much to it, just cut the bottom sheeting to size and pin in place. Glue in the ribs and spars. The small top window can be omitted if you are not that much into scale. Glue the dihedral braces to the center sec- tion. Before joining the wing panels togeth- er trial fit them in place to make sure every- thing fits correctly. Dihedral should be 1¼ inches, measured under the last rib. After the wing panels are joined, add bal- sa blocks at the rear where the holddown bolts go. Locate, and drill holes for the 3⁄16- inch front hold-down dowels. Fit the wing in place and make sure it aligns correctly be- fore gluing the dowels into the wing. Final- ly add the top sheeting.
The wing struts are made from hard balsa or basswood. To attach them to the wing, slots are cut into the struts and .020 alu- minum tabs are glued in. The struts are held in place with 2-56 screws and blind nuts. The struts plug into the fuselage using .032 mu- sic wire pins. These pins go into 1⁄16-inch brass tubes and are glued into the fuselage side.
Putting it all together With all the surfaces complete, fit the wing
and tail assemblies in place and carefully check alignment. The stabilizer is glued in place, then the rear top block. Drill holes for the 1⁄8-inch dowels and glue the fin in place. The pushrods are installed at this time. I made mine up from 3⁄16-inch hardwood dow- els and used .032 music wire on the ends, with Z-bends for the rudder and elevator and E-Z connectors at the servo ends. The servos that were used are micro ser- vos. Any servo with at least 20 ounce-inch of torque would be suitable. Servo rails were
cut from 1⁄8-inch, 5-ply plywood and glued to 3⁄16 × 1⁄4-inch balsa that is glued between F3 Order Plan CD442 for $11.00 and F4.
FLYING MODELS 21
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