BUILDING THE PIPER J-3 CUB
INTRODUCTION Top Flite is proud to present it's large, scale version of the legendary J-3 PIPER CUB. Few aircraft in the history of aviation have had the overall appeal of this rugged, good-looking little airplane. "Cubs" have been used in a wide variety of roles including; trainer, bush plane, ranch work, crop duster, float plane, military and just for all-around fun. The gentle "lightly-loaded" flying characteristics of the original J-3 Cub have been faithfully reproduced for you with this kit.
6. With a razor blade, carefully cut away the T.E. sheeting and aileron cap strip to accept the 1/16" ply aileron horn plate — W-19 (PLY). Glue W-19 (PLY) in place. 7. Locate and remove all W-12 aileron riblets from their die cut sheets. Glue all W-12 riblets in place directly to the aileron L.E., the aileron L.E. cap strip and the bottom T.E. sheeting, using the plan for location and spacing. Be sure these are installed 90° upright and square with plan. 8. Develop Wing Construction Spacing: a.
11. Glue the bottom end of each full rib (W-2/W-3 (PLY), and all W-4's to the 1/16" x 1" x 36" bottom T.E. sheeting. The outboard W-4 rib is also glued to the inboard end of the aileron spar, BUT NOT the aileron L.E. Notice the 1/32" resulting gap between the inboard W-12 aileron riblet and the outboard end of the W-4 rib. This is the correct spacing for the wing/aileron relationship.
23. Locate and remove the 1/16" thick W-19A (PLY) horn plate doublers from their die-cut sheet. Glue in place on top of horn plate W-19 (PLY), as shown on the plans. Locate and remove 4 of the G-2, 3/32" balsa gussets and glue these in place into each corner of each aileron as shown on the plans. 24. Using a small sanding block and medium-to-coarse sandpaper, lightly sand the protruding tops of the aileron spar and aileron L.E. stock down to the airfoil level of the wing.
28. Using a sanding block, bevel the wingtip from the 1/8" x 1/4" sheeting spar, forward thru the 5/16" sq. L.E. to provide seating for the 1/16" balsa L.E. bottom sheeting. Glue and pin the L.E. sheet in place. Note that it is advisable to lightly score the sheeting just outboard of the W-9 rib to facilitate the slight compound curve required. Let this assembly dry. 29. Locate and glue 1/16" thick parts W-15 (PLY), W-14 (PLY) and both W-13 (PLY)'s in place per the plan.
RUDDER 1. Glue and pin in place die-cut parts R-2, R-3 and the 1/4" x 1/2" outline stock. As with the fin, note the piece of 1/4" sq. stock used to complete the outline, just above the top of the fin. Glue the 3/32" x 1/4" "ribs" in place. 2. When the fin and rudder assemblies are dry, remove them from the work surface. Inspect and clean-up the joints. Like the stabilizer and elevator assemblies, install the gussets, centered between the outside surfaces.
Cut two fuselage sides. Note that at the furthest aft point the fuselage side ends at F-4 on the top and angles forward to the bottom as shown on the plans. At the nose, the sides extend past the first upright to the ends of the top and bottom longeron. The firewall fits inside of the fuselage sides. With the fuselage side frames laying face down on the work surface, remember that the right side contains the door, glue the 1/8" sheet fuselage sides to the right and left fuselage frames. Pin in place.
10. NOTE: This step assumes that you will be mounting your engine to the right side as shown on the plans. Carefully cut-out the firewall template provided on plan sheet No. 2 and lightly glue it to the 1/4" plywood firewall. Drill four 3/16" diameter holes in the firewall using the template as a guide. Using the No. 4-40 x 5/8" bolts and the No. 4-40 blind mounting nuts provided, install the motor mount to the firewall. Tighten the bolts enough to force the blind nuts into the back of the firewall.
Epoxy F-14 (PLY) and F-15 (PLY) in place, on top of the fuselage longerons, against formers F-10 (PLY), F-11 (PLY) and F-4 (PLY) and keyed into the tabs on F-10 (PLY) and F-11 (PLY). Tape this assembly securely in place and allow glue to dry completely. Laminate and glue F-17 (PLY) to F-16 (1/4" balsa). Make a similar second part but make it just the opposite so that you have a right and left F-16/F-17 (PLY) assembly.
Remove the 1/4" die-cut F-21 fin supports from their sheet. Note that these fit in place in the notches provided on each side of F-9, back to the trailing edges of the fin. Bevel the inside edge of each F-21 to fit flush with the fin and glue in place. Allow to dry. 15. Note that notches have been provided in all formers from F-4 (PLY) thru F-9. These are to support the three 3/16" dia. stringer dowels. The two side dowels are to blend smoothly with F-21 at the tail.
4. Clean-up each of the solder joints with a wire brush and make sure that the joints are strong. With the 1/4" sheet provided, make two inserts to fill the triangle created by the front and rear main wires. Epoxy these in place, centering them on the front and rear wires. When dry, sand them to shape using the front and rear wires as the "leading and trailing" edges. Slip your wheels in place and secure with wheel collars (not furnished).
vent "snaking". The location of the rudder and elevator horns should be established, the holes drilled but not installed until after covering. The aileron servo should be first mounted to the manufacturer's aileron servo tray. The tray is then mounted to a 1/16" plywood plate that has been cut to size. The plate is then epoxied in the correct position to the inside roof of the cabin.
If, for any reason, you choose not to use Fabrikote for covering your Cub, we recommend that you use some kind of fabric covering, such as silk and dope. CLOTH COVERING IS RECOMMENDED ON THIS MODEL. ENGINE AND COWL MOUNTING 1. Use a few drops of cyanoacrylate glue to mount your engine temporarily to the motor mount, in the approximate position shown on the plans. Turn the fuselage so that the firewall is pointing straight up.
Repeat this step on the opposite wing panel. Once you are satisfied that the wing panel are aligned properly with both the fin and stab and each other, "lock" all four strut clevises in place by tightening the No. 2-56 nut firmly against the back of the clevises as shown on the plans. DO NOT forget to use small lengths of fuel tubing over each of the clevises when they are in place on your airplane.
