� �� Piper J-3 Cub 40 ASSEMBLY MANUAL Specifications Wingspan: ....................................... 80" (2032mm) Fuselage length: ........................... 49.9" (1268mm) Wing area: ........................ 919 sq. in. (59.3 sq dm) Weight: ............................ 6.75–7.5 lbs (3–3.4 kg) Engine: ............ .36–.46 2-stroke, .56–.82 4-stroke Radio: .................................
Table of Contents Contents of Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Additional Required Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Covering Colors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Additional Required Tools and Adhesives. . . . .
Contents of Kit A C E G D F B Large Parts: A. Fuselage B. Wing C. Cowling D. Tail Set E. Landing Gear F. Wing Strut Set G.
Additional Required Tools and Adhesives Tools • Adjustable wrench • Crimping tool • Drill • Drill bit: 1/16”, 5/64”, 3/32” • Felt-tipped pen • Heat gun • Hobby knife • Hobby scissors • Petroleum jelly • Phillips screwdriver (small) • Phillips screwdriver (large) • Pliers • Rotary tool w/sanding drum • Ruler • Sandpaper • String • Threadlock • T-pins Adhesives • 6-minute epoxy • Thin CA • Medium CA Other Required Items • Epoxy brushes • Felt-tipped pen or pencil • Measuring device (e.g.
Using the Manual This manual is divided into sections to help make assembly easier to understand, and to provide breaks between each major section. Remember to take your time and follow the directions. Before Starting Assembly Before beginning the assembly of your J-3 Cub, remove each part from its bag for inspection. Closely inspect the fuselage, wing panels, rudder, and stabilizer and for damage. If you find any damaged or missing parts, contact the place of purchase.
Section 1: Hinge Installation Required Parts • Stabilizer • Fuselage • Wing • Tail gear wire Step 3 • Elevator • Rudder • Aileron (R&L) • Hinge (17) Place the hinges in the stabilizer. Required Tools and Adhesives • Thin CA • T-pins • 6-minute epoxy • Petroleum jelly • Drill • Drill bit: 1/16", 3/32" • Hobby knife Step 1 Step 4 Locate three hinges. Place a T-pin in the center of each hinge. Slide the elevator and stabilizer together. Remove the T-pins.
Section 1: Hinge Installation Step 6 Step 9 After the CA has cured, flex the surfaces several times to break in the hinges. Coat the tail gear wire near the bushing with petroleum jelly. Work the lubricant into the bearing to prevent epoxy from entering the bearing, gluing the bearing to the wire. Step 7 Pull on both surfaces to make sure the hinges are secure. Step 10 Drill a 3/32" hole in the rudder 1 1/4" from the bottom. Step 8 Repeat Steps 1 through 7 for the aileron hinges.
Section 1: Hinge Installation Step 11 Step 13 Cut a groove from the hole to the bottom of the rudder to allow clearance for the tail gear bearing. Cut a slot in the end of the fuselage to accept the tail gear bearing. Step 12 Step 14 Apply a thin layer of lubricant where the bearing will ride in the rudder. Use 6-minute epoxy to glue the wire into the rudder. Install three hinges into the rudder. Test fit the rudder to the fuselage, sliding the hinges and tail wheel bracket into position.
Section 2: Engine Installation Required Parts • Fuselage assembly • Engine mount • 8-32 x 3/4" bolt (4) • 8-32 lock nut (4) • 14 1/4" pushrod wire • Clevis retainer • Engine mount plate (2) Step 2 • Fuel tank assembly • 8-32 X 1" bolt (4) • #8 washer (4) • Clevis Position the engine so the drive washer is 4 1/2" forward of the firewall. Use the engine mount plates, 8-32 x 1" bolts, 8-32 lock nuts and #8 washers to attach the engine to the mount.
Section 2: Engine Installation Step 4 Step 7 Attach the muffler to the engine using the hardware provided with your particular engine. Attach the vent line to the muffler and the line from the clunk to the carburetor. Note: It may be necessary to rotate the end of the muffler to point the stinger straight down, away from the fuselage. Step 5 Check the tank and note which fuel line is vent and which is attached to the clunk. Make a note of the line colors and which they correspond to.
Section 3: Servo Installation (Aileron) Required Parts • Wing (L&R) • #2 x 3/8" screw (8) • 2mm x 20mm screw (6) • Clevis retainer (2) • 4 3/4" pushrod wire (2) • Pushrod wire keeper (2) Step 2 • Servo hatch (L&R) • Control horn (2) • Clevis (2) Install the recommended servo hardware (grommets and eyelets) supplied with the servo. Temporarily install a long half servo arm (JRPA212) onto the servo and position the servo onto the hatch so the servo arm is centered in the notch.
Section 3: Servo Installation (Aileron) Step 4 Step 6 Place the aileron servo between the mounting blocks and use a felt-tipped pen to mark the location of the four servo mounting screws. Note that the servo must not touch the hatch in order to isolate engine vibration. Connect a 12" Servo Lead Extension (JRPA098) to the servo lead.
Section 3: Servo Installation (Aileron) Step 7 Step 8 Tie a wheel collar onto a piece of string. Drop the wheel collar into the wing from the root and retrieve it from the servo opening. Tie the string onto the servo extension. Gently pull the extension through the wing using the string. Untie the string when the servo lead has been pulled through. Use tape to secure the servo lead to the wing to prevent it from falling back into the wing panel. Step 9 Secure the hatch using four #2 x 3/8" screws.
Section 3: Servo Installation (Aileron) Step 10 Step 12 Place a clevis retainer onto a clevis. Thread the clevis onto a 4 3/4" pushrod wire. Remove the backplate from a control horn, and then attach the clevis to the control horn. Drill the locations marked in the previous step using a 3/32" drill bit. Step 13 Step 11 Position the control horn on the aileron. Use the pushrod wire as a guide to align the horn to the servo arm. Position the horn so the holes align with the hinge line.
Section 3: Servo Installation (Aileron) Step 14 Step 15 Plug in the aileron servo to the radio system. Center the trims on the transmitter to center the aileron servo. Hold the aileron in neutral. Use a felt-tipped pen to mark the pushrod wire where it crosses the servo arm. Bend the pushrod wire at the mark. Use a pushrod wire keeper to secure the pushrod wire to the servo arm. Step 16 Repeat Steps 1 though 15 for the remaining wing panel.
Section 4: Servo Installation (Fuselage) Step 2 Step 5 Slide the wing strut mount into the opening. Secure the mount using two #4 x 3/8" screws. Place a clevis retainer onto a clevis. Thread the clevis onto a 32" pushrod wire. Remove the backplate from a control horn, and then attach the clevis to the control horn. Slide the pushrod into the rudder pushrod tube in the fuselage. Position the horn so the holes align with the hinge line.
Section 4: Servo Installation (Fuselage) Step 7 Step 9 Plug in the rudder servo to the radio system. Center the trims on the transmitter to center the rudder servo. Hold the rudder in neutral. Use a felt-tipped pen to mark the pushrod wire where it crosses the servo arm. Center the throttle stick and trim with both the receiver and transmitter on. Install the throttle servo arm in the neutral position. Step 8 Remove the pushrod wire from the fuselage and remove the clevis.
Section 4: Servo Installation (Fuselage) Step 11 Step 14 Remove the pushrod wire from the fuselage and remove the clevis. Bend the pushrod wire at the mark. Slide the pushrod back into the fuselage from the radio compartment, and then put the clevis back onto the wire. Use a pushrod wire keeper to secure the pushrod wire to the servo arm. Cut a groove into the pushrod from the hole to the end of the pushrod. Repeat for the opposite side so you end up with two grooves.
Section 4: Servo Installation (Fuselage) Step 17 2 1/ Slide the 8" piece of heat shrink over the wires and dowel. Use a heat gun or lighter to shrink the tubing. Once the tubing has been shrunk, apply thin CA to each end of the shrink to complete this part of the pushrod assembly. Step 18 Repeat Steps 13 through 17 for the opposite end of the dowel, but only drill one hole and prepare one 6" pushrod wire. Step 19 Slide the elevator pushrod wire in position into the fuselage.
Section 5: Window Installation Required Parts • Side window (L&R) • Support (2) Step 3 • Front windscreen • Fuselage hatch Cut and fit the two supports to the fuselage. Use medium CA to glue them into position. Required Tools and Adhesives • Hobby scissors • Canopy glue • Hobby knife Step 1 Use hobby scissors and a hobby knife to trim the side windows from their sheets. Leave a 1/8" lip to glue the windows to the fuselage. Step 4 Test fit the front windscreen into position. Trim as necessary.
Section 6: Landing Gear Installation Required Parts • Landing gear • 3.35" (85mm) wheel (2) • Wheel cap (2) • Inner wheel hub (2) • Outer wheel hub (2) • 1" (25mm) wheel • Landing gear strap (4) • 2mm x 14mm screw (8) • Large wheel collar w/setscrew (4) • 3mm x 10mm screw (8) • Small wheel collar w/setscrew Step 2 Position the 3.35" (85mm) wheel onto the inner hub. Attach the outer wheel hub to the inner wheel hub using four 2mm x 14mm screws.
Section 6: Landing Gear Installation Step 5 Position the landing gear to the bottom of the fuselage. Secure the position of the gear using four landing gear straps and eight 3mm x 10mm screws. Step 6 Secure the tail wheel using the small wheel collar and setscrew.
Section 7: Installing the Stabilizer Required Parts • Stabilizer assembly • Fuselage • #4 washer (4) • #2 washer (3) • 2-56 x 1/2" screw (3) • 2-56 nut (3) • Clevis (4) • Clevis retainer (4) • Cable ends (4) • Brass crimps (8) • Cable • Pushrod wire keeper • Control horn (2) • 2mm x 12mm screw (6) • Brass fitting (small) (6) • Brass fitting (large) (2) • #2 x 1/2" sheet metal screw • 4-40 x 1/2" socket head screw (4) Required Tools and Adhesives • Threadlock • Pliers • Drill • Drill bit: 3/32" • Adjustable
Section 7: Installing the Stabilizer Step 4 Step 8 Repeat Steps 2 and 3 for the remaining elevator control horn. Attach the small brass fitting to the fin and stabilizer using 2-56 x 1/2" screws, #2 washers and 2-56 nuts. Fittings are placed on both sides of the rudder and the top and bottom of the stabilizer. Step 5 Attach the elevator pushrod to the servo arm of the elevator servo using a pushrod wire keeper. Step 6 Bend each of the fittings (small and large) to about a 45-degree angle.
Section 7: Installing the Stabilizer Step 10 Step 11 Cut the cable into four equal pieces. Prepare one cable by sliding the cable through a crimp, through the cable end, then back through the crimp twice. Pull the excess cable tight and use a crimping tool to complete the job. Repeat for all four of the ends. Attach the four connectors to the brass fittings of the stabilizer. Step 12 Repeat Step 10, only passing the cable through the brass fittings instead of the cable ends.
Section 8: Cowling Installation Required Parts • Fuselage • Propeller • #2 x 3/8" sheet metal screw (4) Required Tools and Adhesives • Phillips screwdriver (small) • Ruler • Drill • Drill bit: 1/16", 5/64" • Hobby scissors • Felt-tipped pen • Rotary tool w/sanding drum Step 3 Remove the engine and slide the cowling onto the fuselage. Position it so the opening for the crankshaft is 4 1/8" forward of the firewall. Transfer the locations from the card stock onto the cowling using a felt-tipped pen.
Section 8: Cowling Installation Step 5 Step 6 Drill 1/16" holes through the cowl and into the fuselage sides at the locations marked in the last step. Enlarge the holes in the cowl using a 5/64" drill bit. Secure the cowl to the fuselage using four #2 x 3/8" screws. Attach the propeller following the instructions provided with your particular engine.
Section 9: Wing Installation Required Parts • Wing • Fuselage • 4-40 lock nut (16) • 4-40 nut (4) • Strut support anchor (4) • Strut bracket (4) • Strut end (4) • Strut (narrow) (L&R) • Strut (wide) (L&R) • Strut brace (long) 2 • Strut brace (short) (2) • Strut cross brace (2) • #2 x 3/8" screw (4) • Fuselage hatch • 1/4-20 x 2" nylon bolt (2) • 4-40 x 1/2" socket head screw (24) Step 2 Thread the strut support anchors into the holes in the wing. The anchors have external threads.
Section 9: Wing Installation Step 4 Thread a 4-40 nut onto the threaded end of the strut. Thread a strut end onto the strut. The nut will be used once the strut has been adjusted. Step 5 Photo Step 6 Slide the wing tube into the wing panel. Slide the tube and panel into position on the fuselage. Step 5 Install the short strut brace to the rear strut support anchor and the long strut brace to the front strut support anchor using 4-40 x 1/2" socket head screws and 4-40 nuts.
Section 9: Wing Installation Step 8 Step 9 Support the fuselage so the wing is not resting on the work surface. Adjust the strut end so it aligns with the wing strut mount. Attach the wing struts using two 4-40 x 1/2" socket head bolts and two 4-40 locking nuts. Once attached, tighten the 4-40 nuts on the strut to prevent the end from rotating when the wing is removed for storage. Repeat Steps 1 through 8 to install the remaining wing panel and strut.
Adjusting the Engine Step 1 Step 3 Completely read the instructions included with your engine and follow the recommended break-in procedure. Before you fly, be sure that your engine idles reliably, transitions and runs at all throttle settings. Only when this is achieved should any plane be considered ready for flight. Step 2 At the field, adjust the engine to a slightly rich setting at full throttle and adjust the idle and low-speed needle so that a consistent idle is achieved.
Recommended CG An important part of preparing the aircraft for flight is properly balancing the model. This is especially important when various engines are mounted. Caution: Do not inadvertently skip this step! The recommended Center of Gravity (CG) range for the Piper J-3 Cub is 31/4" (82.5mm) behind the leading edge of the wing against the fuselage. It is suggested to start at the forward end of the range until comfortable with the flight characteristics of your aircraft.
Range Testing the Radio Before each flying session, range-check your radio. This is accomplished by turning on your transmitter with the antenna collapsed. Turn on the radio in your airplane. With your airplane on the ground, you should be able to walk 30 paces away from your airplane and still have complete control of all functions. If not, don’t attempt to fly! Have your radio equipment checked out by the manufacturer.
2005 Official AMA National Model Aircraft Safety Code GENERAL 1) I will not fly my model aircraft in sanctioned events, air shows or model flying demonstrations until it has been proven to be airworthy by having been previously, successfully flight tested. 2) I will not fly my model higher than approximately 400 feet within 3 miles of an airport without notifying the airport operator. I will give right-of-way and avoid flying in the proximity of full-scale aircraft.
2005 Official AMA National Model Aircraft Safety Code 5) Flying sites separated by three miles or more are considered safe from site-to site interference, even when both sites use the same frequencies. Any circumstances under three miles separation require a frequency management arrangement, which may be either an allocation of specific frequencies for each site or testing to determine that freedom from interference exists.
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