
Made in Vietnam.
“Graphics and specfications may change without notice”.
Kit features.
• Ready-made—minimal assembly & finishing required.
• Ready-covered covering.
• Photo-illustrated step-by-step Assembly Manual.
Specifications
Wingspan---------------------------------------- 78.7 in---------------------------- 200cm.
Wing area-------------------------------------- 1032.8 sq.in---------------- 66.6 sq.dm.
Approximate flying weight-------------------10.6 lbs-----------------------------4.8kg.
Length-------------------------------------------- 52.9in--------------------------- 134.4cm.
Recommended engine size---------------- .1.20 cu.in--------------------- 4-stroke.
Radio System required 4 channels with 6 servos
Flying skill level Intermediate/advanced.
ASSEMBLY MANUAL
MS: 83

DECATHLON _ CODE SEA 83. Instruction Manual
2
INTRODUCTION.
Thank you for choosing the DECATHLON ARTF by SEAGULL MODELS. The DECATHLON
was designed with the intermediate/advanced sport scale in mind. It is a semi scale airplane which
is easy to fly and quick to assemble. The airframe is conventionally built using balsa, plywood to make
it stronger than the average ARTF , yet the design allows the aeroplane to be kept light. You will find
that most of the work has been done for you already. The motor mount has been fitted and the hinges
are pre-installed . Flying the DECATHLON is simply a joy.
This instruction manual is designed to help you build a great flying aeroplane. Please read this
manual thoroughly before starting assembly of your DECATHLON. Use the parts listing below to
identify all parts.
WARNING.
Please be aware that this aeroplane is not a toy and if assembled or used incorrectly it
is capable of causing injury to people or property. WHEN YOU FLY THIS AEROPLANE YOU
ASSUME ALL RISK & RESPONSIBILITY.
If you are inexperienced with basic R/C flight we strongly recommend you contact your R/C
supplier and join your local R/C Model Flying Club. R/C Model Flying Clubs offer a variety of training
procedures designed to help the new pilot on his way to successful R/C flight. They will also be able
to advise on any insurance and safety regulations that may apply.
ADDITIONAL ITEMS REQUIRED.
.1.20cu.in 4-stroke engine
4 chanels with 6 servos
Glow plug to suit engine
Propeller to suit engine
Protective foam rubber for radio
system
Silicone fuel line
TOOLS & SUPPLIES NEEDED.
Thick cyanoacrylate glue
30 minute epoxy
5 minute epoxy
Hand or electric drill
Assorted drill bits
Modelling knife
Straight edge ruler
2mm ball driver
Phillips head screwdriver
220 grit sandpaper
90° square or builder’s triangle
Wire cutters
Masking tape & T-pins
Thread-lock
Paper towels
PARTS LISTING.
FUSELAGE ASSEMBLY
(1) Fuselage
WING ASSEMBLY
(1) Right wing
(1) Left wing
(1) Aluminium dihedral brace
Tail section assembly
(1) Horizontal stabilizer/ elevator
halves.
(1) Rudder halves.
Some more parts.
HARDWARE PACK
COWLING
Landing gear.....

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1) Carefully remove the aileron from one
of the wing panels. Note the position of the
hinges.
2) Remove each hinge from the wing panel
and aileron and place a T-pin in the center of
each hinge. Slide each hinge into the wing
panel until the T-pin is snug against the wing
panel. This will help ensure an equal amount
of hinge is on either side of the hinge line when
the aileron is mounted to the aileron.
3) Slide the wing panel on the aileron until
there is only a slight gap. The hinge is now
centered on the wing panel and aileron.
Remove the T-pins and snug the aileron
against the wing panel. A gap of 1/64” or less
should be maintained between the wing panel
and aileron.
The control surfaces, including the
ailerons, elevators, and rudder, are
prehinged with hinges installed, but the
hinges are not glued in place. It is
imperative that you properly adhere the
hinges in place per the steps that follow
using a high-quality thin C/A glue.
Note:
4)Deflect the aileron and completely
saturate each hinge with thin C/A glue. The
ailerons front surface should lightly contact the
wing during this procedure. Ideally , when the
hinges are glued in place, a 1/64” gap or less
will be maintained throughout the lengh of the
aileron to the wing panel hinge line.
Note:
The hinge is constructed of a special
material that allows the C/A to wick or
penetrate and distribute throughout the
hinge, securely bonding it to the wood
structure of the wing panel and aileron.
To avoid scratching your new aeroplane we suggest that you cover your workbench with an old towel. Keep a couple of jars
or bowls handy to hold the small parts after you
open the bags.
Please trial fit all parts. Make sure you have the
correct parts and that they fit and are aligned
properly before gluing! This will ensure proper
assembly as the DECATHLON is made from
natural materials and minor adjustments may
have to be made. The paint and plastic parts
used in this kit are fuel proof. However, they are
not tolerant of many harsh chemicals including the following: paint thinner, cyano-acrylate
glue accelerator, cyanoacrylate glue de-bonder
and acetone. Do not let these chemicals come
in contact with the colours on the covering and
the plastic parts.
NOTE:
HINGING THE AILERONS.
Hinge.
T- pin.
Hinge.
T- pin.
C/A glue.

DECATHLON _ CODE SEA 83. Instruction Manual
4
HINGING THE ELEVATOR.
8) Af ter both ailerons are securely hinged,
firmly grasp the wing panel and aileron to
make sure the hinges are securely glued and
cannot be pulled out. Do this by carefully
applying medium pressure, trying to separate
the aileron from the wing panel. Use caution
not to crush the wing structure.
7) Repeat this process with the other wing
panel, securely hinging the aileron in place.
HINGING THE RUDDER.
Glue the elevator hinges in place using the
same tectniques used to hinge the ailerons.
Glue the rudder hinges in place using the
same tectniques used to hinge the ailerons.
TURNBUCKLE INSTALLATION.
Installing the turnbuckle for the wing as
same as pictures below.
Work the aileron up and down several
times to “work in” the hinges and check
for proper movement.
Note:
5) Turn the wing p anel over and deflect the
aileron in the opposite direction from the
opposite side. Apply thin C/A glue to each
hinge, making sure that the C/A penetrates into
both the aileron and wing panel.
6) Using C/A remover/debonder and a
paper towel, remove any excess C/A glue that
may have accumulated on the wing or in the
aileron hinge area.
The hole location of turnbuckles shown in picture below .
Washer.
washer.
Turnbuckle.
Turnbuckle.

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Aileron control horn: See pictures below.
AILERON CONTROL HORN
ELEVATOR CONTROL HORN.
M3 LOCK
NUT.
ALUMINUM WASHER.
ALUMINUM WASHER.
CONTRONL HORN
M3 SCREW.
16mm.
Epoxy.
Wing
Epoxy.
Wing
Hinge.
Install the elevator control horn using the
same method as with the aileron control
horns.
2 sets.
3x35mm.
2 sets.
3x40mm.
Aluminum Washer.
16mm.
CONTRONL HORN M3
M3 LOCK NUT.
Epoxy.
Epoxy.
Aluminum Washer.
Wing.
Aileron.
Horizontal
Stabilizer.
Horizontal
Stabilizer .

DECATHLON _ CODE SEA 83. Instruction Manual
6
16mm.
See pictures below.Make yourself the
template of your engine on paper.
ENGINE MOUNT INST ALLATION.
Mark and drill 4 holes for engine mount.
Insert 4 blind nuts to firewall.
4x30mm.
Thread locker glue.
Rudder control horn:
Using the same tectniques used aileron control
horn. See picture below.
2 sets.
3x35mm.
EPOXY .
Rudder control horn.
Rudder.
FUSELAGE.
RUDDER CONTROL HORN.
Elevator control horn.
CONTRONL HORN
M3 SCREW
.
M3 LOCK NUT.
ALUMINUM WASHER.
EPOXY .
FUSELAGE.
ALUMINUM WASHER.
Rudder.

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2) Using a modeling knife, cut one length
of silicon fuel line. Connect one end of the line
to the weighted fuel pick up and the other end
to the nylon pick up tube.(The silicon tube is
not included).
3) Carefully bend the second nylon tube
up at a 45º angle. This tube is the vent tube.
1) Using a modeling knife, carefully cut
off the rear portion of one of the 3 nylon tubes
leaving 1/2” protruding from the rear of the
stopper. This will be the fuel pick up tube.
INST ALLING THE STOPPER ASSEMBL Y.
Vent tube.
Fuel pick up tube.
Fuel fill tube.
4) Test fit the stopper assembly into the
tank. It may be necessary to remove some of
the flashing around the tank opening using a
modeling knife. If flashing is present, make
sure none falls into the tank.
5) With the stopper assembly in place,
the weighted pick-up should rest away from
the rear of the tank and move freely inside the
tank. The top of the vent tube should rest just
below the top of the tank. It should not touch
the top of the tank.
Important: When the stopper assembly is in-
stalled in the tank, the top of the vent tube
should rest just below the top surface of the
tank. It should not touch the top of the tank.
Carefully use a lighter or heat gun to
permenently set the angle of the vent tube.
FUEL TANK INSTALLATION.
6) When satisfied with the alignment of
the stopper assembly tighten the 3 x 20mm
machine screw until the rubber stopper expands and seals the tank opening. Do not
overtighten the assembly as this could cause
the tank to split.
You should mark which tube is the vent
and which is the fuel pickup when you
attach fuel tubing to the tubes in the stopper.
Once the tank is installed inside the fuselage,
it may be difficult to determine which is which.
C/A glue attched.
Fuel tank.
Balsa block.

DECATHLON _ CODE SEA 83. Instruction Manual
8
Fuel pick-up tube.
Fuel fill tube.
Vent tube.
Landing Gear.
wheel Pant.
Locker glue.
2) Follow diagram below for wheel pant
installation:
wheel collar .
wheel.
Lite-Plywood
block.
Axle.
Washer .
M3.
wheel Pant.
wheel.
M3.
M3.
wheel collar.
Lite-Plywood
block.
nut.
Axle.
Washer .
1) Assemble and mounting the wheel pants
as shown in the following pictures.
WHEEL AND WHEEL PANTS
INSTALLATION.
Blow through one of the lines to ensure
the fuel lines have not become kinked inside the fuel tank compartment. Air should
flow through easily .
14mm.
7mm.

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1) The blind nuts for securing the landing
gear are already mounted inside the fuselage.
2) Using the hardware provided, mount
the main landing gear to the fuselage.
INSTALLING THE MAIN LANDING GEAR.
3) A drop of C/A glue on the wheel collar
screws will help keep them from coming lose
during operation.
Repeat the process for the other wheel.
C/A glue.
Alumium Sp ar.
M4 x 10mm.
Alumium Sp ar.
Alumium Sp ar.
M6 x 20mm.
M4 x 10mm.
Plastic part.
Fuselage.

DECATHLON _ CODE SEA 83. Instruction Manual
10
COWLING INST ALLA TION.
Trim and cut.
Trim and cut.
Pushrod wire.
4) Bolt the engine to the engine mount using
the four machine screws. Double check that
all the screws are tight before proceeding.
155mm
.
4.2 mm diameter.
Machine Screw 4x30mm.
Pushrod wire.
MOUNTING THE ENGINE.
3) Remove the engine. Using an drill bit,
drill the mounting holes through the engine
mount at the four locations marked.
1) Place your engine onto the engine
mount. Adjust the engine is centered of the
edges of the engine case.
2) When you are satisfied with the alignment, mark the locations of the engine
mounting.

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Trim and cut.
Machine Screw 3x10mm.
1.5mm were
(needle valve).
Trim and cut.
INSTALLING THE SWITCH.
Install the switch into the precut hole in the
side of fuselage.
Switch.

DECATHLON _ CODE SEA 83. Instruction Manual
12
Remove covering.
When cutting through the covering to re-
move it, cut with only enough pressure
to only cut through the covering itself. Cutting
into the balsa structure may weaken it.
Draw center line.
Throttle servo arm.
Elevator servo.
Elevator servo.
Rudder servo.
Epoxy.
INSTALLING THE HORIZONTAL
STABILIZER.
Adjustable Servo
connector.
Servo arm.
Loctite secure.
1 pcs.
Remove covering.
2) Secure the servos with the screws provided with your radio system.
INSTALLING THE FUSELAGE SERVO.
1) Install the rubber grommets and brass
collets onto the throttle servo. T est fit the servo
into the aileron servo mount.
Because the size of servos differ, you
may need to adjust the size of the precut opening in the mount. The notch in the sides of the
mount allow the servo lead to pass through
.
THROTTLE SERVO ARM INSTALLATION.
Install adjustable servo connector in the servo
arm .
Elevator servo.
Rudder servo.
Elevator servo.
Throttle servo.
Epoxy.

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Epoxy.
Hinge slot.
Put the vertical stabilizer into the in the top
of the horizontal fin. The bottom edge of the
stabilizer should also be firmly pushed against
the top of the horizontal stabilizer .
When cutting through the covering to re-
move it, cut with only enough pressure
to only cut through the covering itself. Cutting
into the balsa structure may weaken it.
INSTALLING THE VERTICAL
STABILIZER.
Hinge slot.
Remove covering.
Epoxy.
90º
Vertical
Stabilizer.
Horizontal
Stabilizer.
Epoxy .
C/A glue.
Hinge.

DECATHLON _ CODE SEA 83. Instruction Manual
14
Attach the string to the servo lead and carefully thread it though the wing.
INSTALLATION THE PUSHROD.
Wing.
Aileron.
String.
Small Weight.
Wing.
Wing rib.
String.
Small Weight.
M2 lock nut.
M2 clevis.
75mm.
110mm.
INSTALLING THE AILERON SERVOS.
String.
Small weight.
Servos.
Small weight.
Thread.
Electric wire.
Aileron
servo.

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Repeat the procedure for the other wing.
Elevator and rudder pushrods assembly follow pictures below.
Wing.
Aileron.
Aileron.
Aileron.
ELEVATOR - RUDDER PUSHROD
INSTALLATION.
Elevator control horn.
Rudder control horn.
M2 lock nut.
M2 Lock nut.M2 clevis.
Attach to servo arm in fuselage.
Attach to elevator - rudder control horn.

DECATHLON _ CODE SEA 83. Instruction Manual
16
INSTALLING TAIL STRUT SUPPORT
The tail strut system assembly follow pic-
tures below.
Rudder pushrod.
Control horn.
Elevator Pushrod.
Metal clevis.
Elevator pushrod.
M2 lock nut.
Elevator.
Elevator.
Rudder.
Throttle.
Throttle.
Elevator.
Rudder.
2
1

DECATHLON _ CODE SEA 83. Instruction Manual
18
4
M3 x10 mm.
90mm.
3
3
4
3
4
4
3
4
3
3
4
4
1
1
2
2
4
4
M3 x 10mm.

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MOUNTING THE TAIL WHEEL.
See picture below.
3x25mm.
3 x10 mm.
3x10 mm.
3x25 mm.
Aluminum tail
Landing gear.
2) Wrap the receiver and battery pack in
the protective foam rubber to protect them
from vibration.
3) Route the antenna in the antenna tube
inside the fuselage and secure it to the bottom of fuselage using a plastic tape.
INSTALLING THE BATTERY-RECEIVER.
ATTACHMENT WING-FUSELAGE.
Attach the aluminium tube into fuselage.
Antenna.
Battery.
Receiver.
T ail landing gear .
Spring.
1) Plug the six servo leads and the switch
lead into the receiver. Plug the battery pack
lead into the switch also.

DECATHLON _ CODE SEA 83. Instruction Manual
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Parts requirement.See pictures below.
INSTALLING THE WING STRUT.
M4x15mm.
M4x60mm.
M4x60mm.
5mm diameter pilot horn.
Insert two wing panels as pictures below.
3x50mm.
Wing tube.
Wing bolt.
Aluminum tube.
Plastic Screw.
C/A glue.

DECATHLON _ CODE SEA 83. Instruction Manual
22
4) By moving the position of the adjustable control horn out from the control surface,
you will decrease the amount of throw of that
control surface. Moving the adjustable control horn toward the control surface will increase the amount of throw.
INITIAL FLYING
3) When the elevator, rudder and aileron
control surfaces are centered, use a ruler and
check the amount of the control throw in each
surface. The control throws should be
measured at the widest point of each surface!
2) Turn on the radio system, and with the
trim tabs on the transmitter in neutral, center
the control surfaces by making adjustments
to the clevises or adjustable servo connectors.
The servo arms should be centered also.
2) If the nose of the plane falls, the plane
is nose heavy. To correct this first move the
battery pack further back in the fuselage. If
this is not possible or does not correct it, stick
small amounts of lead weight on the fuselage
sides under the horizontal stabilizer . If the tail
of the plane falls, the plane is tail heavy .
T o correct this, move the battery and receiver
forward orif this is not possible, stick weight
onto the firewall.When balanced correctly , the
airplane should sit level or slightly nose down
when you lift it up with your fingers.
1) We highly recommend setting up the
DECA THLON using the control throws listed
at right. We have listed control throws for both
Low Rate (initial test flying/sport flying) and
High Rate (aerobatic flying).
10cm.
CONTROL THROWS.
1) It is critical that your airplane be balanced correctly . Improper balance will cause
your plane to lose control and crash. The cen-
ter of gravity is locate
10cm back from the
leading edge of the wing, measured at wing
tip.
3
BALANCING.

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AEROBA TIC FL YING
PREFLIGHT CHECK.
1) Completely charge your transmitter
and receiver batteries before your first day of
flying.
2) Check every bolt and every glue joint
in the DECATHLON to ensure that everything
is tight and well bonded.
3) Double check the balance of the airplane. Do this with the fuel tank empty .
4) Check the control surfaces. All should
move in the correct direction and not bind in
any way.
5) If your radio transmitter is equipped
with dual rate switches double check that they
are on the low rate setting for your first few
flights.
6) Check to ensure the control surfaces
are moving the proper amount for both low
and high rate settings.
8) Properly balance the propeller . An out
of balance propeller will cause excessive vibration which could lead to engine and/or airframe failure.
We wish you many safe and enjoyable
flights with your DECATHLON .
7) Check the receiver antenna. It should
be fully extended and not coiled up inside the
fuselage.