Seagull Models SEA53A_1 YAK 54 User manual

Kit features.
• Ready-made—minimalassembly&finishingrequired.
• Ready-coveredcovering.
• Photo-illustratedstep-by-stepAssemblyManual.
MadeinVietnam.
Specifications
Wingspan--------------------------------63.4in---------------------161cm.
Wingarea--------------------------------846sq.in-----------54.6sq.dm.
Weight-------------------------------------8.4-9.9lbs-------------3.8-4.5kg.
Length-------------------------------------61.4in--------------------156cm.
Recommendedenginesize--------.91-1.25cu.in--------2-4stroke.
RadioSystemrequired6channel with6digital servos.
Flyingskilllevel __ Intermediate/advanced.
ASSEMBLY MANUAL

YAK 54. Instruction Manual.
2
INTRODUCTION.
ThankyouforchoosingtheYAK54ARTFbySEAGULLMODELS.TheYAK54wasdesignedwith
the intermediate/advanced sport flyer in mind. It is a semi scale airplane which is easy to fly and
quicktoassemble.Theairframeisconventionallybuiltusingbalsa,plywood tomakeitstrongerthan
theaverageARTF,yetthedesignallowstheaeroplanetobekeptlight.Youwillfindthatmostofthe
work has been done for you already.Flying the YAK 54 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 54. 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
proceduresdesignedtohelpthenewpilotonhiswaytosuccessfulR/Cflight.Theywillalsobeable
to advise on any insurance and safety regulations that may apply.
ADDITIONAL ITEMS REQUIRED.
!.91-1.25 2-4 stroke engine.
!Computer radio with six digital
servos.
!Glow plug to suit engine.
!Propeller to suit engine.
!Protective foam rubber for radio
system.
!Siliconefuel 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.
PARTS LISTING.
FUSELAGE ASSEMBLY
!(1) Fuselage.
!(1) Canopy hatch.
WING ASSEMBLY
!(1) Right wing half/ aileron.
!(1) Left wing half/ aileron.
!(1) Aluminium dihedral brace.
Tail section assembly
!(1) Horizontal stabilizer/ elevator
halves.
!(1) Rudder halves.
Some more parts.
HARDWAREPACK
COWLING
Landinggear.....

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NOTE: To avoid scratching your new aero-
planewesuggestthatyoucoveryour
workbench with an old towel. Keep a
couple of jars or bowls handy to hold
the small parts after you open the
bags.
Pleasetrialfitallparts.Makesureyou
have the correct parts and that they
fit and are aligned properly before
gluing! This will ensure proper as-
sembly as the YAK 54 is made from
natural materials and minor adjust-
ments may have to be made.
The paint and plastic parts used in
this kit are fuel proof. However, they
arenottolerantofmanyharshchemi-
cals including the following: paint
thinner, cyano-acrylate glue accel-
erator,cyanoacrylategluede-bonder
andacetone.Do not letthesechemi-
calscome incontact withthe colours
onthecovering and theplasticparts.

YAK 54. Instruction Manual.
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The control surfaces, including the
ailerons, elevators, and rudder, are
prehinged with hinges installed, but the
hinges are not glued in place. It is
imperativethat youproperly adhere the
hingesin placeper the steps that follow
using a high-quality thin C/A glue.
!1) Carefully remove the aileron from one
of the wing panels. Note the position of the
hinges.
!2)Removeeach hinge fromthewingpanel
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
ofhingeison either sideofthehinge line when
the aileron is mounted to the aileron.
HINGING THE AILERONS.
Note:
!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
shouldbe maintained betweenthe wingpanel
andaileron.
!4)Deflect the aileron and completely
saturate each hinge with thin C/A glue. The
aileronsfrontsurfaceshould lightly contactthe
wing during this procedure. Ideally, when the
!5)Turnthe wingpanel over and deflect the
aileron in the opposite direction from the
opposite side. Apply thin C/A glue to each
hinge,makingsurethat the C/A penetrates into
both the aileron and wing panel.
The hinge is constructed of a special
material that allows the C/A to wick or
penetrateanddistribute throughout the
hinge, securely bonding it to the wood
structureof the wingpanel and aileron.
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:
Hinge.
T-pin.
Hinge.
T-pin.
T-pin.
T-pin.
C/Aglue.

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Work the aileron up and down several
times to “work in” the hinges and check
for proper movement.
HINGING THE ELEVATORS.
Note:
!8)Afterbothailerons are securelyhinged,
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.
!6)UsingC/Aremover/debonderandapaper
towel, remove any excess C/A glue that may
haveaccumulatedonthe wing orintheaileron
hingearea.
C/Aglue.
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.
Because the size of servos differ, you
mayneedtoadjustthesize of the precut open-
ing in the mount. The notch in the sides of
themountallowtheservoleadtopassthrough.
Thread. Small weight.
INSTALLING THE AILERON SERVOS.
We recommended to use long servos arm
(70mmdiameter) forallservos without throttle
servo.
Install the rubber grommets and brass
collets onto the aileron servo. Test fit the
servo into the aileron servo mount.
Using a small weight (Weighted fuel pick-up
workswell) and thread, feedthestring through
the wing as indicated.
Servo.
Small weight.
Thread.

YAK 54. Instruction Manual.
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Attach the string to the servo lead and
carefully thread it though the wing. Once you
havethreadthe leadthroughtthewing,remove
the string so it can use for the other servo
lead.Tape the servo lead to the wing to prevent
it from falling back into the wing.
Wing bottom.
Thread.
Small weight.
Electric wire.
Thread.
Repeat the procedure for orther wing
haft.
Secure the servos with the screws pro-
vided with your radio system.
Wing panel
bottom.
Thread.
Electric wire.
Pull.
Plastic tape.
Aileronelectric.
Wing bottom.
ENGINE MOUNT.
See pictures below:
Mark and drill 4 holes for engine mount.
4x30mm.

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!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.
!2) Usinga modeling knife, cut onelength
ofsilicon fuel line. Connectoneend oftheline
tothe weightedfuel pick up andthe otherend
to the nylon pick up tube.
!3) Carefully bend the second nylon tube
up at a 45º angle. This tube is the vent tube.
INSTALLING THE STOPPERASSEMBLY.
FUEL TANK.
Balsa wood.
Vent tube.
FuelPick-upTube.
FuelFill Tube.
Carefully use a lighter or heat gun to
permenently set the angle of the vent tube.
Important: When the stopper assembly is
installed 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.
!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
therear of the tank and move freely insidethe
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
thestopperassemblytightenthe3mmx20mm
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.
Attach the silicone fuel and pressure pipes
tothetank. The lowerpipeis the‘feed’and the
uppertwo the ‘pressureand fill’.The fill pipeis
the next pipe.

YAK 54. Instruction Manual.
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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
thetank isinstalled inside the fuselage, itmay
be difficult to determine which is which.
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.
Engine 1.25 - 4 stroke.
Servo tray.
!1) Locate and cut out the covering film
fromthe servo holesin bothsides of fuselage.
!2) Installthe rubbergrommets and brass
collets onto the elevator servo. Test fit the
servo into the elevator servo mount.
Because the size of servos differ, you
mayneedtoadjustthesize of the precutopen-
ing in the mount. The notch in the sides of the
mount allow the servo lead to pass through.
C/Aglue.
Rudder
servo.
Throttle servo.
Left side.
Remove
covering.
Rubber band.
Balsa wood.
Fueltank.
INSTALLING THE FUSELAGE SERVO.
Throttle servo.
Rudder servo.
Engine .91 - 2 stroke.
Fuel pick-up
tube. Fuelfill tube.
Venttube.
ELEVATOR SERVO INSTALLATION.

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Switch.
!3)Secure theservos withthe screws pro-
vided with your radio system.
INSTALLING THE SWITCH.
Installthe switch intothe precut holein the
side of the fuselage.
Rightside.
Elevator servo.
Left side.
Elevator servo.
HORIZONTALSTABILIZER.
!2)Usinga modeling knife, carefully remove
thecoveringat mountingslotof horizontal sta-
bilizer ( both side of fuselage).
!1) Using a ruler and a pen, locate the
centerlineof thehorizontalstabilizer, atthetrail-
ing edge, and place a mark. Use a triangle
and extend this mark, from back to front,
across the top of the stabilizer. Also extend
thismark downthe back of the trailing edge of
the stabilizer.
Center line.
Switch.
! 3) Slide the stabilizer into place in the pre-
cut slot in the rear of the fuselage. The stabi-
lizer should be pushed firmly against the front
of the slot.
! 4) With the stabilizer held firmly in place,
use a pen and draw lines onto the stabilizer
where it and the fuselage sides meet. Do this
on both the right and left sides and top and
bottom of the stabilizer.
Remove covering.

YAK 54. Instruction Manual.
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Remove covering.
! 8) After the epoxy has fully cured, re-
move the masking tape orT-pins used to hold
the stabilizer in place. Carefully inspect the
glue joints. Use more epoxy to fill in any gaps
that may exist that were not filled previously
and clean up the excess using a paper towel
and rubbing alcohol.
VERTICAL STABILIZER INSTALLATION.
in the fuselage. Slide the stabilizer in place
and realign. Double check all of your mea-
surementsoncemore beforetheepoxy cures.
HoldthestabilizerinplacewithT-pinsor mask-
ing tape and remove any excess epoxy using
a paper towel and rubbing alcohol.
Covered wood
filler piece.
Hingeslot.
Hinge.
! 7) When you are sure that everything is
aligned correctly, mix up a generous amount
of 30 Minute Epoxy. Apply a thin layer to the
topand bottom ofthe stabilizermounting area
and to the stabilizer mounting platform sides
! 5) Remove thestabilizer. Using the lines
youjust drewas a guide, carefully removethe
covering from between them using a model-
ingknife.
When cutting through the covering to
remove it, cut with only enough pressure to
only cut through the covering itself. Cutting
into the balsa structure may weaken it.
! 6) Using a modeling knife, carefully re-
move the covering that overlaps the stabilizer
mounting platform sides in the fuselage. Re-
move the covering from both the top and the
bottom of the platform sides.
Pen.
Removecovering.
!1) Using a modeling knife, remove the
covering from over the precut hinge slot cut
intothelowerrearportionofthe fuselage. This
slot accepts the lower rudder hinge.

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!2) Slidethe verticalstabilizer into theslot
in the top of the fuselage. The rear edge of
thestabilizer shouldbe flushwiththerearedge
of the fuselage and the lower rudder hinge
should engage the precut hinge slot in the
lowerfuselage. The bottomedge of the stabi-
lizer should also be firmly pushed against the
top of the horizontal stabilizer.
!3) While holding the vertical stabilizer
firmly in place, use a pen and draw a line on
each side of the vertical stabilizer where it
meets the top of the fuselage.
Pen.
!6) When you are sure that everything is
alignedcorrectly,mixupagenerousamountof
30MinuteEpoxy. Applyathinlayertothemount-
ingslotinthetopofthefuselageandtothesides
and bottom of the vertical stabilizer mounting
area. Applyepoxy tothebottomand top edges
!4) Remove the stabilizer. Using a mod-
eling knife, remove the covering from below
the lines you drew.
When cutting through the covering to re-
moveit, cut with only enoughpressure to only
cut through the covering itself. Cutting into
the balsa structure may weaken it.
!5) Slide the vertical stabilizer back in
place. Using a triangle, check to ensure that
thevertical stabilizeris aligned 90ºto thehori-
zontal stabilizer.
90º
Vertical
Stabilizer.
Horizontal
Stabilizer.
Remove
covering.
of the filler block and to the lower hinge also.
Set the stabilizer in place and realign. Double
checkallofyourmeasurements once more be-
foretheepoxycures.Holdthestabilizerinplace
with T-pins or masking tape and remove any
excess epoxyusing a paper toweland rubbing
alcohol. Allow the epoxy to fully cure before
proceeding.
C/Aglue.

YAK 54. Instruction Manual.
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Repeat the procedure for the other
wing.
! 2) Thread the screw (insert the aluminium
washer) into the hole from the top of surface.
Wipeaway any excessepoxy on thewing and
screwwith rubbingalcohol anda papertowel.
Screw the M3 nut (insert the aluminium
washer) in place as shown. Alllow the epoxy
to fully cure.
Aluminiumwasher.
M3 nut.
M3 lock nut.
Wing bottom.
M3control horn.
Wing bottom.
Aileroncontrol horn.
Right side.
Elevator control horn.
ELEVATORCONTROLHORNINSTALLATION.
! 1) Elevator control horn:
Mix a small amount of 30 minute epoxy and
lightlycoattheinside of theholeinthe elevator
and the 3x40mm control horn screw.
!
2) Thread the screw(insert the aluminium
washer) into the hole from the top of surface.
Wipe away any excess epoxy on the fin and
screwwith rubbingalcohol anda papertowel.
Screw the M3 nut (insert the aluminium
washer) in place as shown. Alllow the epoxy
to fully cure.
Repeat the procedure for orther
elevator.
Horizontalfin.
Elevator.
75mm.
ELEVATOR PUSHROD INSTALLATION.
C/Aglue.
Elevator pushrods assembly follow pictures
below.
AILERONCONTROLHORNINSTALLATION
2 sets.
3x45mm.
!
1) Aileron control horn:
Mix a small amount of 30 minute epoxy and
lightly coat the inside of the hole in the aileron
and the control horn screw.
Wing.
Aileron.

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RUDDER CONTROL HORN
INSTALLATION.
!1) Position the rudder control horn on the
left - right side of the rudder.
! 2) Locate the two nylon control horns, two
nylon control horn backplates and three
machine screws.
Elevator pushrod.
Repeat the procedure for orther
aileron.
Repeat the procedure for wing panel as
same as elevator pushrod.
AILERON PUSHROD INSTALLATION.
Center the servo using the radio system.
Attach the servo arm to the servo using the
screw provided with the servo.
Repeat the procedure for orther
elevator.
Pushrod.
80mm.
Rudder
control horn.
3x30mm.
2x20mm.
! 3) Position the rudder horn on the both
side of rudder. The clevis attach- ment holes
should be positioned over the hinge line.
!5) Mount the control horns by inserting the
bolts through the control horn bases and
elevator halves, then into the mounting
backplates. Do not overtighten the nuts or the
backplates may crush the wood.
Elevator control horn.
Rudder control horn.
! 4) Using a 1.5mm drill bit and the control
horns as a guide, drill the mounting holes
through the rudder halves

YAK 54. Instruction Manual.
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Cable.
Left side.
!2) Follow diagram below for wheel pant
installation:
!1) Assembleand mountingthewheelpants
as shown in the following pictures.
Cable.
Metalclevis.
Control horn. Pushrod.
! 2) With the radio on, check the operation
of the rudder. Adjust the cables so when the
rudder servo is centered, the rudder is
centered as well. There will be tension on the
cables.Adjustmentscanbemadeattherudder
control horn and at the servo arm. Once
adjustments are made, secure the servo arm
to the rudder arm servo using the screw that
came with the servo
RUDDER PULL - PULL CABLE SYSTEM.
See pictures below:
M3lock nut.
! 1) Insert servo arm into servo.
WHEEL AND WHEEL PANTS.

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14mm.
7mm.
!3) You have to trim each axles and using a
tool cutting and cut-off wheel.
Caution when cutting the axles wear
protective goggles.
52mm.
WheelCollar.
Axle.
Wheel. Nut.
Wheel Pant.
LandingGear.
Nut.
Plywood Washer.
Plywood Washer.
lite-plywoodblock.
! 4) A drop of C/A glue on the wheel collar
screws will help keep them from coming lose
duringoperation.
Repeat the process for the other wheel.

YAK 54. Instruction Manual.
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4.2mm.
!4) Remove the engine. Using an drill bit,
drill the mounting holes through the engine
mount at the four locations marked.
! 6) AttachtheZ-Bendin thepushrodwire to
thethrottlearmonthecarburetor.You will need
toremovethethrottlearmfromthecar-buretor
to be able to attach the Z-bend. When
complete,re-attach the throttlearm tothe car-
buretor.
! 5) Bolttheengineto theenginemountusing
the four machine screws. Double check that
all the screws are tight before proceeding.
140mm.
4x30mm.
Engine .91 - 2 stroke.
! 2) Place your engine onto the engine
mount. Adjust the engine is centered of the
edges of the engine case.
! 3) When you are satisfied with the align-
ment, mark the locations of the engine
mounting.
MOUNTING THE ENGINE.
!1) Install the pushrod housing through the
predrilledholein the firewallandinto the servo
compartment. The pushrod housing should
protrude 1/4" out past the front of the firewall.
Make aZ-Bend 1/4" fromoneend of theplain
wire pushrod.
!1) The blind nuts for securing the landing
gearare already mountedinside the fuselage.
!2) Usingthe hardwareprovided, mountthe
main landing gear to the fuselage.
INSTALLINGTHE MAIN LANDING GEAR.
6 X 20mm.

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Engine 1.25 - 4 stroke.
Markpoint.
Paper tape guide.
1mm drill bit.
Paper tape guide.
Trim and cut.
Markpoint.
COWLING.
!1) Slide the fiberglass cowl over the en-
gineandline up thebackedge of thecowlwith
themarks youmade on the fuselage thentrim
and cut.
Paper tape guide.
Pushrod wire.
4x30mm.
Pushrod wire.
Trim and cut.

YAK 54. Instruction Manual.
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Elevator bottom.
Turnbuckle.
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.
Install the spinner backplate, propeller and
spinner cone.
INSTALLING THE SPINNER.
!3) Installthemufflerandmufflerextension
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 3mmx10mm screws (4).
!2) While keeping the back edge of the
cowl flush with the marks, align the front of
thecowlwiththecrankshaftoftheengine. The
front of the cowl should be positioned so the
crankshaft is in nearly the middle of the cowl
opening.Usethespinnerbackplateasaguide.
Hold the cowl firmly in place using pieces of
masking tape.
Because of the size of the cowl, it may
be necessary to use a needle valve exten-
sion for the high speed needle valve. Make
thisout ofsufficient length 1.5mm wire andin-
stall it into the end of the needle valve. Se-
cure the wire in place by tightening the set
screw in the side of the needle valve.
3x10mm.
1.5mm wire
(needlevalve).
INSTALLING TAIL STRUT SYSTEM.
Tail strut system assembly follow pictures
below.
3x10mm.

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62cm.
Aluminium
strap.
3x10mm.
2.
Plastic clip.
1.
2.
1.
33mm.
MOUNTING THE TAIL WHEEL.
!1) You have to trim each axles and using a
tool cutting and cut-off wheel.
Caution when cutting the axles wear
protective goggles.

YAK 54. Instruction Manual.
20
AdjustableServo
connector.
Servoarm.
Because the size of servos differ, you
mayneedtoadjustthesize of the precutopen-
ing in the mount. The notch in the sides of the
mount allow the servo lead to pass through.
! 3) Secure the servos with the screws pro-
vided with your radio system.
! 4) Install the pushrod throttle.
! 3) Using a pen, mark the locations of the
four mounting screws. Remove the tail wheel
bracket and tiller and drill 1mm pilot holes at
the locations marked.
!2) Installthe rubbergrommets and brass
colletsonto the throttleservo. Test fit theservo
into the throttle servo mount.
! 4) Secure the tail wheel bracket in place
using two 3x25mm wood screws. Be careful
not to overtighten the screws.
THROTTLE SERVO ARM
INSTALLATION.
!1) Install adjustable servo connector in
the servo arm.
! 2) Set the tail wheel assembly in place.
The pivot point of the tail wheel wire should
be even with the rudder hinge line and the tail
wheel bracket should be on the plywood
plate.
3x25mm.