Seagull Models YAK 55 User manual

“Graphics and specifications may change without notice”.
ASSEMBLY MANUAL
MS: 131
Specifications:
Wingspan---------------------------68.9in(175cm).
Wingarea---------------1026.1sq.in(66.2sqdm).
Weight--------------------11.5-14.3lbs(5.2-6.5kg).
Length------------------------------64.8in(164.7cm).
Engine -----------------1.2-1.6cu.in-----2-stroke.
30-35 --- gasoline engine.
Radio-----------6channelswith6digitalservos.

YAK 55. Instruction Manual
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INTRODUCTION.
Thankyouforchoosingthe YAK 55 ARTFbySEAGULLMODELS.The YAK 55 wasdesigned
with the intermediate/advanced sport scale in mind. It is a semi scale airplane which is easy to fly
andquick toassemble.Theairframeisconventionallybuiltusingbalsa,plywood tomakeitstronger
thantheaverageARTF, yet the design allows the aeroplane to bekeptlight.Youwill find that most
oftheworkhasbeendoneforyoualready. Themotormounthasbeenfittedandthehingesarepre-
installed . Flying the YAK 55 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 YAK 55. 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
supplierandjoinyourlocalR/CModelFlyingClub.R/CModelFlyingClubsofferavarietyoftraining
proceduresdesigned tohelpthenew pilotonhiswaytosuccessfulR/C flight.Theywillalso beable
to advise on any insurance and safety regulations that may apply.
KIT CONTENTS
1
2
3
4
5
5
8
6
7
9
5

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ADDITIONAL ITEMS REQUIRED.
1.2-1.6 cu.in 2-stroke
30-35 gasoline engine.
Radio System required 6 channels
with 6 digital 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
Modellingknife
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
KIT CONTENTS
1 Fuselage
2 Left wing panel
3 Right wing panel
4 Canopy
5 Tail set
6 Aluminum wing tube
7 Scale pilot
8 Main landing gear
9 Fiberglass cowl
1) Sand each end of hinge point hinge
using coarsesandpaper.This will improve the
bond of the epoxy to the hinge. Apply a thin
coat of Petroleum jelly to the hinge point to
prevent the epoxy from gluing the hinge
surface.
3)Allow the glue to fully cure for at least 6
hours.When cured, work each hinge
throughout its full motion several times.This
willbreakfree any epoxy that may havefound
its way into the hinge joint. Move the hinge
throughout its full travel until no resistance is
felt. This may take as many as 40 - 45 times.
2) Mix minute epoxy. Using a glue syringe
or toothpick, place 30-minute epoxy into one
ofthe hingepocketsintheaileronleadingedge
oftheaileron. Some epoxy should ooze outof
the pocket as the hinge is installed. If not,
removethehinge and apply moreepoxy.Wipe
away any excess epoxy with rubbing alcohol.
Continue installing hinges in the leading edge
of the aileron. The control surfaces (aileron)
will be installed after the epoxy is fully cured.
HINGING THE AILERONS.
Properlyhingingthecontrol surfaces on
this models is very important.Poorly
installed hinges affect the model’s
precisionandcontrolresponseandcan
also be dangerous.
Note:
C/Aglue.
Epoxy.

YAK 55. Instruction Manual
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HINGING THE ELEVATOR.
HINGING THE RUDDER.
Glue the elevator hinges in place using the
same techniques used to hinge the ailerons.
Glue the rudder hinges in place using the
same techniques used to hinge the ailerons.
Work the aileron up and down several
times to “work in” the hinges and check
for proper movement.
Note:
 4) Mix 30 minute epoxy or use Pace PT-
55hinge glue.Placea sufficientamountof glue
ineachof the hinge pocketsinonewingpanel.
5)Pressthe aileronandwingtogether such
that less than a 1/64” hinge line gap exists
between the aileron and wing. The bevels
should virtually touch. Use a paper towel and
rubbingalcoholto wipeawayanyvisible epoxy
around the hinges.
6)Allow the glue to fully cure for at least 6
hours.
7) When fully cured, move each control
surface throughout is travel range serveral
times to break away any epoxy in the hinge.
Be sure to deflect the surface fully.
Epoxy.

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INSTALL AILERON CONTROL HORN.
Aileroncontrol horn.
INSTALL ELEVATOR CONTROL HORN.
Epoxy.
Elevator control horn.
Epoxy.
Epoxy.
INSTALL RUDDER CONTROL HORN.
Epoxy.
Fiberglass control horn.
Fiberglass control horn.
Fiberglass control horn.

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Ruddercontrolhorn.
1) Locate the items necessary to install the
engine mount included with your model. .
ENGINE MOUNT INSTALLATION.
4x30mm.
2) Usefour4x30mmhead bolts and four 4mm
washers to attach the engine mount rails to
thefirewall.Tightenthescrews . Make sureto
use threadlock on the screws to help prevent
them from vibrating loose.
Thread locker glue.
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.
INSTALLING THE STOPPER ASSEMBLY.
2) Usingamodeling knife, cut one length
ofsiliconfuelline. Connectoneendoftheline
totheweighted fuel pick up and the other end
to the nylon pick up tube.(The silicon tube is
not included).
Epoxy.
Epoxy.
AB

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5) With the stopper assembly in place,
the weighted pick-up should rest away from
therear 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.
6) When satisfied with the alignment of
the stopper assembly tighten the 3 x 20mm
machine screw until the rubber stopper ex-
pands and seals the tank opening. Do not
overtighten the assembly as this could cause
the tank to split.
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.
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.
Venttube. Fuel pick up tube.
Fuel fill tube.
FUEL TANK INSTALLATION.
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.
Fueltank.
C/Aglue.
Balsa wood included.
 8) Use balsa stick to help prevent moveable
from transferring to the fuel tank.
 7) Slide the fuel tank into the fuselage.
Guide the lines from the tank through the hole
in the firewall.
C/Aglue.
A
Fueltank.
B

YAK 55. Instruction Manual
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Fuel pick-up tube. Fuelfill tube.
Venttube.
Blow through one of the lines to ensure
thefuel lines have not become kinked in-
side the fuel tank compartment. Air should
flowthrough easily.
 9) Connect the lines from the tank to the
engine and muffler. The vent line will connect
to the muffler and the line from the clunk to the
carburetor.
Pushrodwire.
1) Locate the items neccessary to install
the wheel and wheel pants as shown.
WHEEL AND WHEEL PANTS
INSTALLATION.
Repeat steps as above to attach remain-
ing wheel pants to the landing gear.
2) You have to trim each axle using a tool
cutting and cut-off wheel.
Caution when cutting the axles and
wear protective goggles.
Aluminumlandinggear.

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INSTALLING THE MAIN ALUMINUM
LANDING GEAR TO FUSELAGE.
Lockerglue.
.
M4x 20mm.
 3) The blind nuts for securing the landing
geararealreadymountedinsidethefuselage.
 4) Using the hardware provided, mount
the main landing gear to the fuselage.
 5) Placethefuselageinvertedon the work-
benchinasuitablestand.Setthe landing gear
in place and use a screwdrive to secure the
landing gear to the fuselage using bolts
M4x20mmandwashers.Make sure to use the
threadlock on the bolts so they don’t vibrate
loose.
FUSELAGE SERVO INSTALLATION.
We recommended to use long servos arm
(70mm diameter)for all servos without throttle
servo.
Because the size of servos differ, you
mayneed toadjustthe sizeoftheprecutopen-
ing in the mount. The notch in the sides of
themountallowtheservoleadtopassthrough.
Install the rubber grommets and brass
collets onto the servo. Test fit the servo into
the servo mount.
1) Usingasmallweight (Weighted fuelpick-up
workswell) and string, feed the string through
the wing as indicated.
String.
Small weight.
2) Place the servo between the mounting
blocksand spaceitfromthehatch.Useapencil
to mark the mounting hole locations on the
blocks.
3) Use drill bit in a pin vise to drill the mouting
holes in the blocks.
5) Use dental floss to secure the connection
so they cannot become unplugged.
4) Apply 2-3 drops of thin C/A to each of the
mounting holes. Allow the C/A to cure without
using accelerator.
C\Aglue.

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8) A string has been provided in the wing to
pull the aileron lead through to the wing root.
Remove the string from the wing at the servo
location and use the tape to attach it to the
servoextensionlead.Pulltheleadthroughthe
wing and remove the string.
6) Secure the servo to the aileron hatch using
Phillips screwdriver and the screws provided
with the servo.
7) Apply 1-2 drops of thin C/A to each of the
mounting tabs. Allow the C/A to cure without
using accelerator.
1)Elevatorservos:Installtheservosin the
both side of fuselage.
Drill a 1mm pilot hole before installing the
screw. Using the screws included with the
servos, fasten the servos in place.
Left side.
Elevator servo.
Right side.
Elevator servo.

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Installtheswitchintotheprecutholeinthe
side of fuselage.
INSTALLING THE SWITCH.
Switch.
MOUNTING THE ENGINE.
150mm.
 1) Positiontheenginewiththedrivewasher
(150mm) forward of the firewall as shown.
5.2mm diameter.
4) On the fire wall has the location for the
throttle pusshrod tube (pre-drill).
5) Slide the pushrod tube in the firewall and
guide it through the fuel tank mount. Use
medium C/A to glue the tube to the firewall and
the fuel tank mount.
6) Connect the Z-bend in the 600mm throttle
pushrod to the outer hole of the carburetor arm.
2) Use a pin drill and 4mm drill bit to drill a
small indentation in the mount for the engine
mounting screw.
3) Use a drill to drill the four holes in the engine
mount rails.

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MachineM5x30mm Screw
Pushrodwire.
7) Slide the throttle pushrod wire into the tube.
Position the engine between the mounts. Use
four M5x30mm machine screws to secure the
engine to the mount as shown.
8) Reinstall the servo horn by sliding the
connector over the pushrod wire. Center the
throttle stick and trim and install the servo horn
perpendicular to the servo center line.
9) Move the throttle stick to the closed position
and move the carburetor to closed. Use a 2.5mm
hex wrench to tighten the screw that secures
the throttle pushrod wire. Make sure to use
threadlock on the screw so it does not vibrate
loose.
COWLING INSTALLATION.
1) Slide the fiberglass cowl over the
engine and line up the back edge of the cowl
withthemarksyoumadeonthefuselagethen
trim and cut as shown.
Epoxy.
Cut.

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Becauseofthesizeofthecowl,itmaybenec-
essarytouse a needle valve extension forthe
highspeedneedlevalve. Makethisoutofsuf-
ficient length 1.5mm wire and install it into the
end of the needle valve. Secure the wire in
placebytighteningthe set screw in the side of
the needle valve.
Trim and cut.
Trim and cut.
 3) Install the muffler and muffler extension
onto the engine and make the cutout in the
cowl for muffler clearance. Connect the fuel
and pressure lines to the carburetor, muffler
and fuel filler valve. Secure the cowl to fuse-
lage using the 3x10mm screws to tighten the
screws.
2) While keeping the back edge of the
cowl flush with the marks, align the front of
thecowlwith thecrankshaftofthe engine. The
front of the cowl should be positioned so the
crankshaft is in nearly the middle of the cowl
opening.Use thespinnerbackplateasaguide.
Hold the cowl firmly in place using pieces of
masking tape.

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SPINNER INSTALLATION.
Install the spinner backplate, propeller and
spinner cone.
The propeller should not touch any part
of the spinner cone. If it does, use a
sharp modeling knife and carefully trim away
the spinner cone where the propeller comes
in contact with it.
String.
Small weight.
1) Usingasmallweight (Weighted fuelpick-up
workswell) and string, feed the string through
the wing as indicated.
Servos. Smallweight.
Thread.
INSTALLING THEAILERON.
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.
Wing bottom.
String.
Small weight.
Attach the string to the servo lead and
carefully thread it though the wing. Once you
havestringthelead throught the wing, remove
the string so it can use for the other servo
lead.Tapetheservo leadtothe wingtoprevent
it from falling back into the wing.
Electric wire.
String.

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Repeat the procedure for orther wing.
Secure the servos with the screws
provided with your radio system.
Plastic tape.
Aileronelectric.
Wing bottom.
Servo 1.
AILERONPUSHRODHORNINSTALLATION
M3x30mm.
Repeat the procedure for the other
aileron pushrod.
Wing.
M3lock nut.
Aileron.
INSTALLING HORIZONTAL FIN.
1) Remove the covering at the rear tail
root of horizontal fin as picture shown below.

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2)Sand the aluminium tube using
sandpaper. This will improve the bond of the
epoxy to the cardboard horizontal fin.
Coat both sides of one half of the aluminium
tube with 30 minute epoxy. Next, pour some
epoxy into the cardboard horizontal fin. Use
enough epoxy to fill any gaps.
3) Insertaluminiumtubeinto thecardboard
of fuselage.
4) Slide the two horizontal fin halves
together and carefully align them at the
possition on the fuselage. Wipe away any
excess epoxy using paper towels.
 5) Bolt the horizontal fin to the fuselage
using the 4 machine screws (3x15mm).
Double cheek that all the screws are tight
beforeproceeding.
INSTALLING THE RUDDER.
1) Remove the covering of vertical fin as
same as picture below.
2) Mix 30 minute epoxy or use Pace PT-
55hinge glue.Placea sufficientamountof glue
in each of the hinge pockets in vertical fin.
3) Pressthe rudderandverticalfin together
suchthat lessthana 1/64”hingeline gapexists
betweenthe rudderandverticalfin. Thebevels
should virtually touch. Use a paper towel and
rubbingalcoholto wipeawayanyvisible epoxy
around the hinges.
Remove covering.
Machinescrew
(3x15mm).
Machinescrew
(3x15mm).

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4)Allow the glue to fully cure for at least 6
hours.
5) When fully cured, move each control
surface throughout is travel range serveral
times to break away any epoxy in the hinge.
Be sure to deflect the surface fully.
ELEVATOR - RUDDER CONTROL HORN
INSTALLATION.
Elevator control horn.
 1) Install the elevator control horn using
the same method as with the aileron control
horns.
 2) Position the elevator control horn on
the both side of elevator.
Rudder control horn.
Elevator control horn.
Rudder control horn.
RUDDER PULL PULL CABLE
INSTALLATION.
M3lock nut.
See pictures below:
 1) Prepair the rudder servo arm by attach
four balllinkassameaspictureshownbelow.

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MOUNTING THE TAIL WHEEL.
See pictures below.
Cut.
Elevator pushrod.
Control horn.
Metalclevis.
Rudder pushrod.
M2lock nut.
Rudder pushrod.
 2) Insert servo arm into servo.
Rudderservoarm.
ELEVATOR PUSHROD INSTALLATION.

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INSTALLATION PILOT.
1) A scale pilot is included with this ARF. The
Seagull Pilot included fitting well to the cockpit.
(or you can order others scale pilot figures
made by Seagull factory. They are available at
Seagull distributors.)
If you are going to install a pilot figure, please
use a sanding bar to sand the base of the figure
so that it is flat.
2) Position the pilot figure on the canopy floor
as show. Locate the oval shaped on the canopy
floor and remove the covering. Use epoxy to
glue this into the base of the pilot figure, please
see pictures as shown.
Epoxy.
- Apply a bead of canopy glue around the inside
edge of the canopy. Position the canopy onto
the hatch. Use tape to hold the canopy secure
until the glue fully cures.
3) Position the canopy onto the fuselage. Trace
around the canopy and onto the fuselage using
a felt-tipped pen.
123
2

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Wing bolt.
Insert two wing panels as pictures below.
Wing tube.
Attach the aluminium tube into fuselage.
ATTACHMENT WING - FUSELAGE.
INSTALLING THE BATTERY-RECEIVER.
Receiver.
1)Plugthefive servo leads and the switch
lead into the receiver. Plug the battery pack
lead into the switch also.
2) Wrap the receiver and battery pack in
the protective foam rubber to protect them
from vibration.
 3) Route theantenna in the antennatube
inside the fuselage and secure it to the bot-
tom of fuselage using a plastic tape.
APPLY THE DECALS.
1) If all the decals are precut and ready to
stick.Pleasebecertainthemodelis clean and
free from oily fingerprints and dust. Position
decal on the model where desired, using the
photos on the box and aid in their location.
2) If all the decals are not precut, please use
scissors or a sharp hobby knife to cut the
decals from the sheet. Please be certain the
model is clean and free from oily fingerprints
and dust. Position decal on the model where
desired, using the photos on the box and aid
in their location.
M2 x 6mm.
C/Aglue.
4) Install the canopy and secure it with M2x6mm
screws.
1
3
Battery. 2mm.