Piper J3 Cub 40 Almost-Ready-to-Fly
INSTRUCTION MANUAL
Specifications Wingspan: 70.6 in (1795mm)
Length: 45in (1145mm) Wing Area: 682sq in (44 sq dm)
Flying Weight: 5.3 ‐ 6.0lb (2400 ‐ 2700g)
Features Excellent scale details and classic trim scheme
Easy fuselage access with top fuselage hatch
Light‐weight balsa and plywood contruction
Complete hardware included
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Dear Customer, Congratulations on your purchase of piper J3 Cub 40 ARF from Value Hobby. We thank you for your generous support, and hope you enjoy your new airplane.
At Value Hobby, we hope to offer competitive prices, good performance, and products that you can setup and use with ease. That’s why we extensively researched and tested this airplane, and suggested all the products necessary for you to setup properly. We understand that you have many choices when purchasing, and we are grateful you choose to buy from us.
As vendors, one of the most gratifying things for us is to hear from our customers. We would welcome any suggestion to help us improve. Please make us aware of any errors and imperfections in the airplane or the instructions, or about the setup that we suggested. We hope you’ll find our setup suggestions to be helpful, and enjoy flying your new airplane. Please feel free to contact us at (630) 948‐0947 or email us at [email protected]
Disclaimer By purchasing and/or building this model, user assumes ALL liability and risk involved with this product. This model should be built and flown by an experienced pilot and only flown at AMA sanctioned sites.
Value Hobby guarantees this model to be free of defects in materials and workmanship at the date of purchase. This warranty does not cover any parts damaged by use or modifications. In no way shall Value Hobby’s liability exceed the original cost of the purchased model. Further, Value Hobby reserves the right to modify this warranty without notice. Value Hobby has no control over the final stages of assembly or the material used for the final assembly. No liability shall be assumed nor materials used for the final user‐assembled product. By the act of using the final product the user accepts all resulting liability. Value Hobby, as a R/C product vendor, provides a top quality airplane and instructions to complete the model. The quality and flight characteristics of the finished model depend greatly on how it is built; we cannot guarantee the performance for the completed model and representations are expressed or implied as to the performance of the completed model. If the buyer is not prepared to accept the liability associated with the use of this product, the buyer is advised to return this kit immediately, in new and unused condition.
Safety in Assembly During assembly of this aircraft, you will be asked to use sharp knives and hobby adhesives. Please follow all safety procedures recommended by the manufacturers of the products you use, and always follow these important guidelines: ALWAYS protect your eyes when working with adhesives, knives, or tools, especially power tools. Safety glasses are the best way to protect your eyes. ALWAYS protect your body, especially your hands and fingers when using adhesives, knives, or tools, especially power tools. Do not cut toward exposed skin with hobby knives. Do not place hobby knives on tables or benches where they can roll off or be knocked off.
ALWAYS have a first‐aid kit handy when working with adhesives, knives, or tools, especially power tools. ALWAYS keep hobby equipment and supplies out of the reach of children.
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Safety in Flying This is NOT a toy! It is a very high‐performance RC airplane capable of high speeds and extreme maneuvers. It should only be operated by a competent pilot in a safe area with proper supervision. ONLY fly your aircraft in a safe, open area, away from spectators and vehicles–and where it is legal to fly. NEVER fly over an unsafe area, such as a road or street. Never fly too close to yourself or spectators. Never run your motor inside a house or building with the propeller attached – Remove the prop for safety.
Required Items CA Glue – Thin and Thick Epoxy glue Hobby Knife Small Phillips Screwdriver Set Metric Allen Wrenches Scissors Small Pliers Wire Cutters Masking tape Optional – Heat gun
Before Starting Assembly Examination Unpack your airplane and examine the components. Check for damage of any kind. If you see any damage, please contact Value Hobby immediately. Covering Your airplane was packed in plastic at the factory without any wrinkles in the covering. You may notice some wrinkles now; more likely, you will notice a few in a day or two or the first time you take the plane out to the flying field. These wrinkles are the result of wood shrinkage and/or expansion. Balsa wood changes size and shape slightly as it is exposed to varying humidity in the air. This is a natural property of balsa wood. As your airplane adjusts to the weather in your part of the world, wrinkles may appear and disappear. Wrinkles may be removed with the gentle application of heat to the covering material on your airplane. The best tool to use is a hobby heat gun. Apply the heat gently: the covering material will shrink as you apply the heat, and this will remove the wrinkles. BE CAREFUL! Too much heat applied too quickly can damage the covering, either by causing it to pull away from the wood at seams and corners or even by melting it. The covering will shrink at low temperature with patient application of heat.
Wrinkles in the covering DO NOT affect flight performance. Remove the canopy before attempting to use heat on your covering! The canopy is made of thermo‐activated plastic and WILL deform with the application of heat. Do not apply heat to the canopy. If you need to clean your airplane, we recommend using a damp towel. The paint used on the canopy and cowl is not safe for all cleaners. In particular, DO NOT use alcohol on these parts, it will remove the paint.
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Recommended Setup
Main Parts of the Airplane
Accessories and small parts not pictured
Configuration Model Qty
Radio 4 channel 1
Motor Size GForce G32 Brushless Outrunner Motor(4250‐800KV) 1
Speed Control 80A Brushless ESC 1
Recommended
Battery(LiPO) GForce 30C 4000mAh 4S14.8V LiPO 1
Prop Size 14 X 7 or 15 X 6 1
Servos Standard servos 5 (nitro)
4 (electric)
Y‐Harness Universal Servo Y‐Harness (300mm)11.8‐Inch (Futaba "J" and
JR Compatible) 1
Extension Universal Servo Extension (600mm)23.6‐Inch (Futaba "J" and
JR Compatible) 2
Charger GT POWER X‐CHARGER C6 6S LiPO Charger 1
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Section 1: Aileron Installation Step1. Locate the aileron hinges from the hardware
pack, and insert the hinges in the slots in the trailing
edge of the wing.
Step2. Saturate each of the hinges with thin CA. Make
sure to glue both the top and bottom.
Step3. Use the hinge to put the aileron in position.
Use a hobby knife to set the gap between the control
surface and the wing. Also check that the aileron can
move freely without rubbing at the wing tip.
Step4. Flex the aileron up and down several times to
break in the aileron hinges.
Step5. Repeat steps 1 through 4 to install the
remaining aileron.
Section 2: Aileron Servo & Control Horn Installation Step1. Locate the items shown in the picture below.
(Servos and Y‐Harness sold separately).
Step2. Remove the covering for the inboard servo in
the bottom of the wing as shown.
Step3. Glue the servo mounting blocks to the servo
hatch. (The location has been marked).
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Step4. Place aileron servo between the mounting
blocks and mount the servo to the blocks. (Please
center the servo arm electronically before mounting).
Step5. Use two self‐tapping screws to secure the
blocks wont loose.
Step6. 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.
Step7. 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.
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Step8. Secure the hatch to the wing.
Step9. Connect the clevis to the control horn. Center
the control surface and use a pen to mark the
pushrod where it crosses the hole of the servo horn as
shown.
Step10. Bend the pushrod 90‐degree at the mark, trim
the excess wire depending on the length of the wire
needed, and use a pushrod connector to secure the
pushrod wire to the servo horn.
Step11. Repeat steps 1 through 10 to install the
remaining servo.
Section 3: Elevator Installation Step1. Slide the horizontal stabilizer into the slot in
the fuselage, and center the stabilizer in the fuselage.
Step2. Trace the outline of the fuselage on the
horizontal stabilizer using a felt‐tipped pen.
Step3. Remove the covering from the horizontal
stabilizer inside the line drawn in the previous step.
Step4. Position the stabilizer and elevator on a flat
surface as shown, and make sure they are in
alignment with each other. Then center the joiner
wire on the elevator and mark the elevator.
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Step5. Carve slots and drill holes for the joiner wire on
the locations marked on the leading edge of the
elevators.
Step6. Slide the joiner wire into the slot in the
fuselage as shown.
Step7. Insert four hinges into the slots in the elevators
and saturate each of the hinges with thin CA. Make
sure to glue both the top and bottom.
Step8. Use the hinges and joiner wire to place the
elevators in position, and flex the elevators
45‐degrees a few times up and down, make sure the
elevator can move freely. Then apply thin CA on the
hinges.
Step9. Carefully check the alignment of the stabilizer
to the wing to make sure A=B as shown.
Step10. Apply the thin CA on both the top and bottom
of the stabilizer to secure the stabilizer onto the
fuselage.
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Section 5: Rudder and tail wheel Installation Step1. Slide the fin back into the fuselage. Check the
alignment of the fin to the stabilizer using a square.
The fin must be 90 degrees to the stabilizer when
properly aligned.
If not, carefully sand the bottom of the fin to provide
the clearance to align the fin.
Step2. Insert the fin into the slot in the fuselage and
apply some glue. Make sure the fin is fully secured.
You might also use 30‐minute epoxy to secure the fin.
Apply the epoxy to both the exposed wood on the fin
and the slot in the fuselage. Use care not to get epoxy
on the elevator joiner wire. Insert the fin and use tape
to hold the fin in position until the epoxy fully cures.
Step3. Locate the tail wheel assembly. Roughen the
tail gear wire using medium grit sandpaper where it
will enter the rudder. Get them assembled.
Step4. Drill a hole in the rudder for the tail wheel wire.
Insert the hinges into the slots in the rudder and test
fit the wheel wire into the groove. (Bend the wire
90‐degrees so it can insert the pre‐drilled hole).
Step5. Secure the tail wheel bracket to the fuselage
using two#2x3/8in sheet metal screws.
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Step6. Slide the wheel collar against the tail wheel
bracket and tighten the setscrew.
Section 6: Linkage Installation (Rudder and Elevator Servo)
Step1. Locate the items necessary for this section.
Step2. Thread a clevis onto a 6in wire a minimum of
10 turns.
Step3. Remove the back plate from a control horn
using side cutters or a sharp hobby knife. Position the
control horn on the elevator so the horn aligns with
the hinge line of the elevator. Mark the position for
the mounting holes using a felt‐tipped pen.
Step4. Drill three 3/32in holes through the elevator at
the locations marked in the previous step.
Step5. Place 2‐3 drops of thin CA into the hole to
harden the wood. Repeat this for each of the three
holes.
Step6. Attach the control horn using three 2‐56x1/2
screws and the control back plate.
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Step7. Attach the pushrod connector to the hole of
the servo arm as shown.
Step8. Slide the wire through the outer hole in the
elevator servo arm. Secure the wire using a nylon wire
keeper. It may be necessary to drill out the hole in the
servo arm using a 5/64" drill bit.
Note: Use a 1/4" piece of heat shrink tubing on the
clevis to keep it from opening during flight.
Step9. Repeat Steps 2 through 8 for the rudder
linkage.
Section 7: Nitro Motor Installation
Step1. Locate the items shown in the picture.
Step2. Using four PM4X .7874in SHCS, four M4 fiat
washers, four M4 lock washers, and thread locking
compound, attach the engine mount rails to the
firewall. Leave the screws slightly loose. Test fit your
engine between the mount halves. Slide the mount
halves against the sides of the engine and finish
tightening the mount screws.
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Step3. Position the front of the engine drive washer
4.1338in(105mm) from the front of the engine
mounting box. Mark the location of the engine mount
holes onto the mount rails using a Dead Center Hole
Locator Remove the engine from the mount and use a
Ф4 tap and drill set to create threads in the four
mounting holes. Attach the engine to the mount using
four PM420mm SHCS, four Ф4 fiat washers, and four
Ф4 lock washers.
Step4. Prepare an assembled servo horn arm as
shown.
Step5. Attach a quick connector to the servo arm
using quick connector washers and retainers. Center
the throttle stick and trim with both the receiver and
transmitter on. Install the throttle servo arm in the
neutral position.
Step6. Move the servo to the throttle open position
using the radio system. Manually move the throttle
arm on the carburetor to the open position. Use a
3mm setscrew to secure the throttle pushrod wire.
Step7. Check the movement of the throttle to verify
there is no binding at either low or high throttle. If
there is, make the necessary adjustment to eliminate
any binding. Install the throttle servo arm screw when
complete.
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Section 8: Fuel Tank Installation
Step1. The fuel tank can be assembled as a two line
system consisting of a vent (pressure) line to the
muffler and a carburetor line. Filling and emptying of
the tank would need to be done through the
carburetor line, or an optional fuel fill valve. The tank
can also be assembled as a three line system having a
vent line, carburetor line, and fill line. If install a fill
line, puncture the top of the stopper above the sealed
off fuel tube hole. The fill and carburetor lines should
extend out 13mm beyond the stopper and the vent
line should be bent upwards and left uncut. With the
tubes installed in the stopper, the stopper plates
loosely in place with the PM3x25mm screw to hold
the assembly together.
12mm
Step2. Fit the stopper assembly into the tank with the
vent line pointing toward the top of the tank, but not
touching. The fuel tubing and clunks (fuel pickup) on
the carburetor and fill lines should almost reach the
back of the tank but not touch. The clunks must be
able to move freely inside the tank when assembled.
Adjust the length of the fuel tubing accordingly. When
satisfied, tighten the PM3x25mm screw in the stopper
to secure it in place (do not over‐tighten). Mark the
side of the tank that must face up when installed in
the plane. We also suggest marking the tubes in the
stopper.
Step3. Insert the tank into the fuselage with the
correct side facing up. The fuel tubing should be
routed through the hole in the center of the firewall.
Section 9: Landing Gear & Wheels Installation Step1. Locate the parts of the main landing gear from
the hardware pack.
Step2. Install the main wheels on the wheel pants as
shown below.
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Step3. Repeat steps 2 for the other side of the landing
gear.
Step4. Install the landing gear legs into the fuselage
with the provided 3mm screws as shown below.
Section 10 – Electric Motor and ESC Installation Step1. Locate the items for this section.
Step2. Install your brushless motor onto the motor
mount using the 4 black 3mm allen‐head screws
included in your kit. Make sure the motor spins freely.
Depending on the size of the shaft collar on your
motor, you may need to remove a small amount of
wood from the firewall for free rotation.
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Step3. Install the ESC inside the motor box or inside
the fuselage, depending on the requirement of
balancing the CG.
Section 11: Cowling and Spinner Installation Step1. Install the cowl and align carefully so that the
spinner matches the cowl as desired. Be sure canopy
hatch is in place for this step.
Step2. Use a hobby knife to make small holes through
the paper strips into the cowling. This locates the cowl
screws accurately so that they will screw into the
plywood. Use the 4 small remaining wood screws to
mount the cowl.
Step3. Fix carefully the prop and spinner as shown
below.
Section 12: Windows Installation
Step1. Locate the front windscreen and side windows.
Use the hobby scissors to trim the side windows from
their sheets.
Step2. Remove the coverings for side windows.
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Step3. Use 4 screws to secure the front windscreen to
the fuselage.
Step4. Use thin CA to secure the side windows to the
fuselage.
Step5. The hatch is removable.
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Section 13: Wing Installation
Parts Required.
Step1. Slide the wing tube into the wing panel. Slide
the tube and panel into position on the fuselage.
Step2. Secure the wing panel using a M6*25MM
nylon bolt.
Section 14: Setting CG and Control Throws
Recommended CG
For the first flights, the recommended Center of
Gravity location is 84mm behind the leading edge of
the wing against the fuselage. Use the battery pack,
moving it forward or backward, to achieve the correct
balance.
Low / Precision Rates (in degrees) and
Corresponding Exponential
Elevator
Low Rate
11/16" (11.5º) Up 9/16" (10º) Down
High Rate
1/4" (19.5º) Up 1" (18º) Down
Linear measurement (Inches) measured at widest
part of elevator (roughly in the center).
Aileron
Low Rate
3/8" (8º) Up 1/2" (9º) Down
High Rate
7/8" (21º) Up 11/16" (22º) Down
Linear measurement(inches) measured at root.
Rudder
11/2" (28º) Left 11/2" (28º) Right
Linear measurement(inches) measured at front of
counterbalance. Note: Use the Low Rate for most flying. The High
Rate is used specifically for performing spin
maneuvers Note: that Futaba and Hitec radios require
NEGATIVE exponential, while JR and Spektrum use
POSITIVE exponential.
Range test your radio
step1. Before fly, be sure to range check your radio as
manufacturer’s instruction manual of your
radio‐system recommends.
step2. Double‐check all controls (aileron, elevator,
rudder and throttle) move in the correct direction.
step3. Be sure that your LiPO battery is fully charged.
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Finally... Enjoy Your Piper Cub J3 40
Have a nice flight!