Hangar 9 J-3 Piper Cub User manual

Specifications
Wingspan: 80-1/8"
Wing Area: 850 sq. in.
Weight (Approx.): 6.5-7.0 lbs.
Recommended Engines:
.40-.46 2-Cycle
.45-.60 4-Cycle
WE GET PEOPLE FLYING
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TM
Raising the Standard of Quality in
Almost Ready-To-Fly Aircraft
• Ultra Covering
• Pre-finished Fiberglass Cowl
• Highest Quality Craftsmanship
• 90% Pre-Built
• IMAA-Legal 80-1/8
" Wingspan
ALMOST READY-TO-FLY
PRE-BUILT
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ASSEMBLY MANUAL

2
Table of Contents
Introduction 3
Additional Equipment Required 4
Tools and Supplies Required 4
Section 1: Hinging The Aileron 5
Section 2: Joining the Wing Halves 6
Section 3: Installing the Aileron Servos 8
Section 4: Installing the Aileron Linkage 12
Section 5: Mounting The Wing 14
Section 6: Installing The Tail 17
Section 7: Hinging The Rudder 20
Section 8: Installing The Engine 22
Section 9: Landing Gear Assembly and Installation 25
Section 10: Assembling and Installing the Fuel Tank 26
Section 11: Installing The Radio 28
Section 12: Installing The Linkages 29
Section 13: Attaching The Cowl 34
Section 14: Installing The Windows 35
Section 15: Scale Detailing 35
Section 16: Balancing the J-3 Piper Cub 38
Section 17: Control Throw Recommendation 39
Section 18: Flying the J-3 Piper Cub 39
Pre-Flight Check 40
Pre-Flight at the Field 41
AMA Safety Code 42
Cowl Template (for Saito .50 or .56) 43

3
Throughout aviation history, select few aircraft have achieved
such a level of popularity that they transcend their eras. Such is
the case of the J-3 Piper Cub. This timeless classic is perhaps
even more famous today than when it was first introduced to the
army (then known as an L-4) in the late '30s. 4 out of 5 pilots in
the Second World War are claimed to have gotten their initial
flight training behind the stick of the Cub.
Hangar 9’s J-3 Piper Cub offers traditional scale appearance in
an IMAA-legal size that can be powered with any standard
.40-.46 size 2-cycle engine. Or, for enhanced scale realism,
a .45-.55 4-cycle engine can be used to power this Cub.
Hangar 9’s J-3 Piper Cub comes 90% pre-built to a high level of
craftsmanship and is pre-covered and trimmed in Ultra covering.
This means you can have a large (80-1/8" span), high quality
scale J-3 Piper Cub, showing it to your friends at the field in 20
hours or less. Best of all, they’ll never know it’s an ARF, and
chances are they’ll compliment you on your building and
finishing skill. Don’t worry . . . we won’t tell!
An R/C aircraft is not a toy! If misused, it can cause serious
bodily harm and damage to property. Fly only in open areas,
preferably AMA (Academy of Model Aeronautics) approved flying
sites, following all instructions included with your radio and
engine.
Introduction
Warning

Radio Equipment
4 Channels (minimum)
5 Standard Servos
Standard 450-650 mAh Receiver Battery Pack
Y-Harness
2 Servo Extensions
Engine Recommendations
.40-.46 2-Cycle Engines
.45-.55 4-Cycle Engines
Adhesives
Instant thin CA (cyanoacrylate) glue
Thick CA glue
CA remover/debonder
White canopy glue (e.g., R/C 56 or Formula 560)
6 minute epoxy
12 minute epoxy
30 minute epoxy
Blue Locktite 242
Tools
Drill
Drill bits: 1/4", 1/8", 1/16", 3/32"
Small and medium Phillips screwdrivers
Z-bend pliers
Needle nose pliers
Pliers
Small round file
Adjustable wrench
Razor saw
Heat gun
Moto-Tool with sanding drum
Hobby knife with #11 blade
Mixing stick
Epoxy brush
4
Additional Equipment Required
Tools and Supplies Required
Saito .50GK
Recommended JR Systems
JR F400 FM
JR XF642FM/PCM
JR XP783
JR XP8103 FM/PCM
Recommended 2-Cycle Engines
Thunder Tiger Pro .40
Thunder Tiger Pro .46
Webra Speed .40 Sport
Recommended 4-Cycle Engines
Saito .50GK
Saito .50
Saito .56GK
Saito .56
Thunder Tiger
Pro .40
1/16" x 36" music wire
Medium sandpaper
Masking tape
Straight edge
Measuring device
(e.g., ruler, tape measure)
Scissors
Paper towels
Wax paper
Rubbing alcohol
Pencil
Felt tipped pen
Fuel tubing (optional)
Hobby enamel paint: black, silver
Saito .56GK

Right wing panel with aileron and hinges
Left wing panel with aileron and hinges
Note: The control surfaces, including the ailerons, elevators
and rudder, are pre-hinged with the hinges installed, but the
hinges are not glued in place. It is imperative that you
properly adhere the hinges and ailerons in place per the steps
below using high quality thin CA.
❑1. Carefully remove the aileron from one of the wing panels.
Note the position of the hinges. The J-3 Piper Cub comes
with high quality CA-type hinges, which are manufactured
in the USA.
❑2. Replace the aileron, making sure the hinges slide in place.
Deflect the aileron and apply a few drops of thin CA glue
directly to the center of each of the hinges. The aileron’s
front surface should lightly contact the wing during this
procedure. Ideally, when the hinge is glued in place, a
1/32" gap or less will be maintained throughout the length
of the aileron. The hinge is constructed of a special
material that allows the CA to wick or penetrate and
distribute throughout the hinge, securely bonding it to the
wood structure.
❑3. Turn the wing panel over and deflect the aileron in the
opposite direction and from the opposite side. Apply
several drops of thin CA glue to each aileron hinge,
making sure that the CA penetrates into both the aileron
and the wing.
❑ 4. Using CA remover/debonder and a paper towel, remove
any excess CA glue that may have accumulated on the
wing or in the aileron hinge area.
❑5. Repeat this process with the other wing panel, securely
hinging the aileron in place.
5
Section 1: Hinging The Ailerons
Instant thin CA glue
CA remover/debonder
Paper towels
Parts Needed Tools And Adhesives Needed

❑ 6. After both ailerons are securely hinged, firmly grasp the
wing and aileron to check that the hinges are immovable.
Do this by applying medium pressure, trying to separate
the aileron from the wing.
❑1. Locate the dihedral brace (also called the wing joiner).
Using a ruler, mark the exact center of the brace with a
pencil as shown in the photo below.
❑2. Trial fit the dihedral brace into one of the wing panels.
It should insert smoothly up to the center line marked in
Step 1. Now slide the other wing half onto the dihedral
brace until the wing panels meet. If the fit is overly tight,
it may be necessary to lightly sand the dihedral brace.
6
Section 1: Hinging The Ailerons
Right wing panel from Section One
Left wing panel from Section One
Dihedral brace
Trim Tape
30 minute epoxy
Masking tape
Paper towels
Rubbing alcohol
Wax Paper
Ruler
Pencil
Mediumsandpaper
Mixing stick
Parts Needed Tools And Adhesives Needed
Section 2: Joining the Wing Halves
CONTINUED

❑ 3. Next, check for the correct dihedral angle. Place the wing
on a large, flat surface with one wing panel resting on the
flat surface. The opposite wing tip should be exactly 2"
from the surface (see illustration below). If necessary,
sand the dihedral brace until this is achieved.
❑ 4. Mix up approximately three ounces of 30 minute epoxy.
Note: It is extremely important to use plenty of epoxy
when joining the wing halves.
❑ 5. Smear a generous amount of epoxy into the wing joiner
cavity of one wing half. A scrap piece of wood or mixing
stick is handy here.
❑ 6. Coat one half of the dihedral brace with epoxy up to the
pencil line drawn in Step 1. Note the orientation of the
V side of the dihedral brace; the V must face up. Install
the epoxy-coated side of the dihedral brace into the wing
joiner cavity of the wing half up to the center line, making
sure the V of the dihedral brace is positioned correctly.
❑7. Apply a generous amount of epoxy into the wing cavity of
the other wing half.
❑8. Now apply epoxy to all sides of the exposed area of the
dihedral brace and uniformly coat both wing roots with
epoxy.
7
Section 2: Joining the Wing Halves
CONTINUED
2 inches

❑ 9. Carefully slide the two wing halves together. Firmly press
the halves together, allowing the excess epoxy to run out.
Using rubbing alcohol and a paper towel, clean off the
excess epoxy. There should not be any gap between the
wing halves.
❑10.Apply masking tape at the wing joint to hold the wing
halves together securely. Place the wing on a large, flat
surface. With one wing panel lying flat on the surface, the
opposite wing tip should be propped up exactly 2" from
the surface. Apply more masking tape to the center wing
joint and recheck the 2" measurement. Allow the wing
joint to dry overnight.
Note: It is a good idea to place a sheet of wax paper under the
wing’s center joint so any excess epoxy doesn’t adhere to the
surface of the work area.
❑11.When the wing center joint is completely dry, remove the
masking tape and apply the included trim tape to cover the
center joint.
❑1. Hold the assembled wing up to a strong light. Note the
aileron servo cut-outs on the bottom side of each wing.
Using a very sharp hobby knife, carefully trim away the
covering material where the aileron servos will be
mounted.
8
Section 2: Joining the Wing Halves
Section 3: Installing the Aileron Servos
CONTINUED
Assembled wing
Two standard size servos
w/mounting hardware
Y-harness
Servo extensions (2)
Wood servo blocks
w/screws
Aileron covers
Hobby knife
Small Phillips
screwdriver
Drill
1/16" drill bit
1/16"x36" music
wire
Masking tape
Scissors
Pencil
Felt tipped pen
30 minute epoxy
Parts Needed Tools And Adhesives Needed
2 inches
bottom of the wing

❑2. Install the grommets and eyelets on both aileron servos.
Now place the servo blocks on the servo as shown and
mark with a pencil where the servo screws attach the
servo to the blocks.
❑3. Using a 1/16" drill bit, drill the marked location on the
blocks.
❑4. Mount the blocks to the aileron servo as shown using the
screws included with your servos.
❑5. Using scissors, cut out the aileron cover. Also, using a
hobby knife cut out the opening where the linkage exits
the aileron cover.
❑6. Temporarily install a servo arm with a hole located
between 10-12mm out from the center on the servo as
shown. Now trial fit the servo on the aileron servo cover
as shown with the servo arm aligned in the middle of the
linkage opening in the aileron cover.
❑7. Using a felt tipped pen, trace around the wood servo
blocks where it contacts the aileron cover.
9
Section 3: Installing the Aileron Servos
CONTINUED

Section 3: Installing the Aileron Servos
CONTINUED
❑8. Now mark two equidistant holes as shown on the servo
cover where the servo blocks are to be mounted. Two
sheet metal screws, included with the J-3 Cub, will be
used to mount each block to the servo cover.
❑9. Using a 1/16" drill bit, drill the servo cover at the four
marked locations.
❑10.Holding the servo in place, drill four 1/16" pilot holes into
the wood servo blocks.
❑11.Using 30 minute epoxy, glue the servo blocks in place,
then screw them into position with 4 sheet metal screws.
❑12.Center the aileron cover over the aileron cut-out in the
wing and drill four 1/16" holes at each corner of the
aileron cover through the wing’s bottom surface.
❑13.Screw the aileron cover in place with four sheet metal
screws as shown.
❑14.Now repeat these steps to install the servo on the other
wing half.
❑15.Remove the aileron covers from the wing halves.
10

Section 3: Installing the Aileron Servos
CONTINUED
❑16.Near the center section on the bottom of the wing, locate
the two servo lead openings and carefully cut away the
covering with a sharp hobby knife.
❑17.Carefully feed a 1/16" x 36" piece of music wire (or
equivalent wire) in through the servo lead opening inside
the wing toward the servo aileron opening. It may be
helpful to slightly bend the music wire. Using masking
tape, tape the aileron’s servo connector to the end of the
music wire closest to the aileron opening. Pull the music
wire (or equivalent) and the servo connector through the
wing until it comes out the servo lead opening.
Note: With most servos, it will be necessary to use an
extension.
❑18.Repeat this procedure for the opposite aileron servo.
❑19.Plug both aileron servo connectors into a Y-harness and
feed the excess servo lead wire back into the wing.
11

❑1. Center the aileron servos by plugging the Y-harness into
the aileron channel in the receiver. Turn on both the
transmitter and receiver and center the aileron trim lever
on the transmitter. Select a servo arm that has a hole
located between 10-12 mm out from the center.
❑2. Install the arm onto the aileron servo so the arm is
positioned 30° toward the leading edge of the wing.
See photo below.
Note: The 30° control horn offset provides the necessary
aileron differential (more up aileron than down) to correct
adverse yaw tendencies of the J-3 Piper Cub. If your radio’s
system is equipped with aileron to rudder mixing, you may also
want to mix approximately 25% aileron to rudder mixing to
further improve the turn coordination. Interestingly, both full and
scale models of the J-3 Piper Cub exhibit these flight tendencies.
❑3. Place a piece of masking tape on the top of the aileron
cover so the edge of the tape lines up with the output hole
on the servo arm. See the photo below.
❑4. Reinstall the aileron cover on the wing. Place an aileron
linkage perpendicular to the aileron hinge so it passes
directly in line with the servo arm under the aileron cover.
With a felt tipped pen, mark the center location of the
aileron control horn.
❑5. Center a control horn over the mark you just made.
Carefully align the clevis’ attachment holes (4) so they
are directly in line with the aileron hinge.
❑6. Using a pencil, mark the screw hole locations (2) for the
control horn.
12
Section 4: Installing the Aileron Linkage
Wing assembly from Section Three
Aileron linkages (2)
Control horns with linkages (2)
Clevis (2)
Drill
1/16" drill bit
Z-bend pliers
Small Phillips screwdriver
Felt tipped pen
Pencil
Masking tape
Fuel tubing (optional)
Parts Needed Tools Needed

❑7. Use a 1/16" drill bit to carefully drill through the aileron at
the marked locations, making sure the drill is exactly
perpendicular to the aileron’s surface.
❑8. Attach the control horn to the aileron surface using the
provided long 2mm Phillips head screws and the control
horn back plate. The control horn back plate attaches to
the opposite side of the aileron’s surface, and the long
2mm screws thread into it, securing the control horn in
place.
❑9. Thread a clevis onto one of the aileron linkages — 16
turns.
❑10.Install the clevis in the outermost hole. With the aileron in
the neutral position and the servo arm 30° offset from
Step 2, mark the position where the linkage will attach to
the servo arm — a small piece of masking tape works
well for this.
❑11.Using Z-bend pliers, make a Z-bend at the marked
location. Cut off any excess linkage rod that extends past
the Z-bend.
❑12.Install the Z-bend into the servo arm (10-12 mm from
center).
Note: It may be necessary to slightly enlarge the hole in the
servo arm.
13
Section 4: Installing the Aileron Linkage

❑1. Trial fit the wing onto the fuselage. Be sure the wing
properly rests on the wing seat. Place a narrow strip of
masking tape at exactly the center of the top of the
fuselage just ahead of where the vertical fin will be
installed later. This tape will be used as a reference line in
aligning the wing.
❑2. With the wing trial fitted in place, measure the distance
from the back of the wing tip where it meets the aileron to
the tape mark. Compare the right and left distances and
adjust the wing until both are the same.
14
Section 4: Installing the Aileron Linkage
Section 5: Mounting The Wing
Completed wing assembly
Wing dowel rods (2)
Fuselage
Wing hold down plate
Wing hold down screws
Blind nuts (2)
Drill
1/4" drill bit
Medium Phillips screwdriver
Small round file
12 minute epoxy
Measuring device
(e.g., 36" ruler or tape
measure)
Masking tape
Pliers
Parts Needed Tools And Adhesives Needed
Adjust the length of the linkage until the aileron is exactly neutral
with the trailing edge.
❑13.It is a good idea to place a piece of fuel tubing over the
clevis (as shown below) as extra insurance to prevent the
clevis from accidentally coming open.
❑14.Repeat this procedure for the remaining aileron linkage.
CONTINUED

❑3. Using a 1/4" drill bit, drill through the front face of the
wing using the holes in the front fuselage former as a
guide. Be sure the wing is securely held in the correct
position when drilling (see below photo) — a second set
of hands to hold the wing in place makes this task easier.
❑4. Remove the wing and glue both wing dowels in place
using 12 minute epoxy. The dowel rods should extend
3/8" out of the wing.
❑5. Press the blind nuts into position below the rear wing
hold down plate in the fuselage. Use pliers to squeeze the
blind nuts so the “teeth” penetrate the wood and stay in
place. Note: It may be helpful to place a piece of wood
on the top side of the hold down plate before squeezing
the pliers. This will keep the pliers from “crushing” the
rear wing hold down plate. Additionally, a small amount of
epoxy or thick CA will permanently attach the blind nut to
the rear wing hold down plate.
❑6. Thread the wing hold down screws into the bottom side of
the blind nuts so that the ends of the screws extend 1/8"
of an inch above the wing seat.
15
Section 5: Mounting the Wing
CONTINUED

Section 5: Mounting The Wing
CONTINUED
❑7. Fit the wing back into position on the fuselage, carefully
sliding the leading edge dowel rods into the front
bulkhead. Align the wing by measuring the distance from
the wing tip to the center mark as in Step 2 of this section.
When the wing is properly aligned, press downward firmly
on the rear center section of the wing. The wing bolts will
make an indentation in the covering of the wing at the
proper location to drill.
❑8. Using a 1/4" drill bit, drill the exact center of the marked
locations on the bottom of the wing. Be careful that the
drill bit doesn’t tear the covering when it exits through the
top surface of the wing.
❑9. Trial fit the wing into position on the fuselage. Thread the
wing hold down bolts into the wing and loosely tighten.
Check the alignment of the wing by measuring from a
fixed point on each wing tip to the narrow strip of tape on
the fuselage as you did in Step 2. It may be necessary to
slightly enlarge the holes with a small round file to obtain
proper alignment.
❑10.Remove the wing. Using 12 minute epoxy, glue the wing
hold down plate in place. Reattach the wing to the
fuselage. The wing hold down bolts will assist in holding
the wing hold down plate in position until dry. Also, use
masking tape around the edges of the wing hold down
plate to help hold it in place until the epoxy dries.
16

❑1. Hinge the horizontal stabilizer and elevators using the
same techniques as in Section 1, Hinging The Ailerons.
Be sure to apply thin CA to both sides of the hinge. After
the hinges are dry, check that they are securely in place by
trying to pull the elevator from the horizontal stabilizer.
Note: Do not glue the hinges into the vertical
stabilizer/rudder at this time.
❑2. On the rear of the fuselage, slots are pre-cut in the wood
structure for the horizontal and vertical stabilizers. The
covering, however, must be carefully cut away. Using a
hobby knife with a sharp #11 blade, carefully cut away the
covering at the openings for the horizontal stabilizer.
❑3. Using a razor saw, carefully cut out the area rearward of
the horizontal stabilizer slots in the fuselage and extend
the slots to the rear of the fuselage.
❑4. Hold up the horizontal stabilizer to a strong light and note
the cut-out notch on the leading edge of the stabilizer.
The vertical fin keys into this notch when the tail is
assembled. Using a hobby knife, carefully trim the
covering from this notch.
❑5. Using a hobby knife, trim the covering on the top rear of
the fuselage where the vertical fin inserts into the fuselage.
17
Section 6: Installing The Tail
Fuselage and wing from Section 5
Horizontal stabilizer with elevators
Vertical stabilizer with rudder
Instant thin CA glue
CA remover/debonder
30 minute epoxy
Hobbyknifewith#11 blade
Razor saw
Straight edge
Pencil
Masking Tape
Parts Needed Tools And Adhesives Needed

❑6. Trial fit the horizontal stabilizer in place in the fuselage.
With the wing installed, check the alignment of the
horizontal stabilizer by measuring from a fixed point on
the wing to the hinge line at the tip of the horizontal
stabilizer. Both right and left dimensions should be the
same. Then sight the stabilizer alignment from the rear of
the airplane, making sure the stabilizer is exactly level
with the wing.
❑7. Trial fit the vertical fin in position, making sure the base of
the fin keys into the notch in the leading edge of the
horizontal fin. Then carefully check the fin to be sure it is
aligned 90° to the horizontal stabilizer.
Note: The back of the vertical fin and the back of the horizontal
stabilizer must be even with the back of the fuselage.
❑8. Double check the horizontal stabilizer and vertical fin
alignment. It may be necessary to slightly trim the balsa
wood on the fuselage with a sharp hobby knife to achieve
exact alignment.
❑9. When you are satisfied with the alignment, carefully mark
the position with a pencil at the junction where the
horizontal stabilizer meets the fuselage top and bottom
and where the vertical fin meets the fuselage. The pencil
should leave a light indentation in the covering.
18
Section 6: Installing The Tail
CONTINUED
90° 90°

Section 6: Installing The Tail
❑10.Remove the horizontal stabilizer and the vertical fin and
carefully cut away the covering with a sharp hobby knife
inside the lines you marked in Step 9. Be careful not to
cut into the wood — this will weaken the structure. A
straight edge is helpful here.
❑11.Mix up approximately 1/4 ounce of 30 minute epoxy and
apply it to the top and bottom of the horizontal stabilizer
where the fuselage comes in contact with the stabilizer.
❑12.Insert the horizontal stabilizer into the fuselage and
position it in the approximate location. Wipe away any
excess epoxy with a paper towel and rubbing alcohol.
❑13.Apply 30 minute epoxy to the vertical fin where the
fuselage contacts the fin. Also apply epoxy to the base of
the fin where it keys into the horizontal stabilizer. Insert
the fin into the fuselage in approximately the correct
position and wipe away any excess epoxy.
❑14.Precisely align the horizontal stabilizer and vertical fin as
before, using masking tape to hold the stabilizer and fin in
correct alignment. Double check the alignment and allow
to fully cure over night.
Note: Be sure the back of the vertical fin lines up with the back
surface of the fuselage.
19
CONTINUED

❑1. Trial fit the rudder in position with the four hinges in
place. Note that the three hinges attach to the fin, while
one hinge attaches the rudder to the fuselage.
❑2. Insert the tail wheel wire into the pivot bushing. With the
pivot bushing resting against the bend in the tail wheel
wire, use needle nose pliers to make a 90° bend in the
direction shown, 1/8" above the top of the pivot bushing.
❑3. Hold the tail wheel assembly up to the fuselage in the
correct position. Temporarily mark, with a felt tipped pen,
the position where the hole is to be drilled into the rudder.
Also mark the position of the slot where the pivot bushing
will fit into the back of the fuselage.
❑4. Remove the rudder. Using a 3/32" drill bit, drill into the
exact center of the rudder to accept the tail wheel wire as
shown.
❑5. Using a hobby knife, cut a slot in the back of the fuselage
as marked to accept the tail wheel pivot bushing.
❑6. Trial fit the tail wheel assembly and rudder in place.
Deflect the rudder, making sure the tail wheel wire turns
freely with the rudder.
20
Section 7: Hinging The Rudder
Fuselage from Section 6
Rudder
Rudder hinges (4)
Tail wheel assembly
Instantthin CAglue
CAremover/debonder
Blue Locktite 242
30 minute epoxy
Drill
3/32" drill bit
Needlenose pliers
Hobby knife
Felt tipped pen
CA remover
Paper towels
Rubbing alcohol
Items Needed Tools And Adhesives Needed