Seagull Models BOOMERANG EP User manual

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ASSEMBLY MANUAL
MS: 211
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BOOMERANG EP
ARF TRAINER KIT
“ Graphics and specications may change without notice “ .
Specications:
Wingspan---------------56.0 in (142.2 cm).
Wing area----------------263.5sq.in (17.0 sq.dm).
Weight-------------------4.4 - 4.8 lbs (2.0 - 2.2 kg).
Length-------------------41.2 in (104.7cm).
Electric Power 32..............................................
Speed control 50A............................................
(APC) 11x6 EP..................................................
Radio--------------------4 channels with 4 servos.
Flying skill level intermediate/ advanced
ALMOST
READY TO FLY

BOOMERANG EP Instruction Manual.
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ank you for choosing the BOOMERANG EP ARTF by SEAGULL MODELS COMPANY
LTD,. e was designed with the intermediate/advanced sport yer in mind. It is a semi scale
airplane which is easy to y and quick to assemble. e airframe is onventionally built using bal-
sa, plywood to make it stronger than the average ARTF, yet the design allows the aeroplane to be
kept light. You will nd that most of the work has been done for you already. e motor mount
has been tted and the hinges are pre-installed. Flying the BOOMERANG EP is simply a joy.
is instruction manual is designed to help you build a great ying earoplane. Please read
this manual throughly before starting assembly of your BOOMERANG EP. User the parts
listing below to indentify all parts.
Please be awere that this aeroplane is not a toy and if assembley or used incorrectly it is
capable of causing injury to people or property. WHEN YOU FLY THIS AEROPLANE YOU
ASSUME ALL RISK & REPONSIBILITY.
If you are inexperianced with basic R/C ight we strongly recommend you contact your R/C
supplier and join your local R/C model Flying Club. R/C Model Flying Clubs oer a variety
of training procedures designed to help the new pilot on his way to successful R/C ight.
ey will also be able to advise on any insurance and safety regulations that may apply.
INTRODUCTION.
WARNING.
ADDITIONAL ITEMS REQUIRED.
TOOLS AND SUPPLIES.
• .40-.46 2-stroke engine.
• 4 channels radio with four servos.
• Glow plug to suit engine.
• Propeller to suit engine.
• Protective foam rubber for radio system.
• Silicone fuel line.
• Stick-on weights for balance
• ick 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.
• read-lock.
• Paper towels.
KIT CONTAIN.
FUSELAGE ASSEMBLY
- (1) Fuselage.
- (1) Pre-installed throttle pushrod & tube.
- (1) Pre-installed servo tray.
- (1) Pre-installed motor mount.
- (1) Pre-installed rudder pushrod.
- (1) Pre-installed elevator pushrod.
WING ASSEMBLY
- (1) Right wing half with preinstalled aileron.
- (1) Le wing half with pre-installed aileron.
- (1) Aluminium wing tube.
- (1) Covering strip for centresection joint.
TAIL SECTION ASSEMBLY
- (1) Vertical stabilizer with preinstalled rudder.
- (1) Horizontal stabilizer with preinstalled el-
evator halves

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HINGING THE AILERON.
e control surfaces, including the ai-
lerons, elevators, and rudder, are pre-
hinged with hinges in stalled, but the
hinges are not glued in place. It is im-
perative that you properly adhere the
hinges in place per the steps that fol-
low using a high-quality thin C/A glue.
Note :
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 aileron
until the T-pin is snug against the aileron.
is will help ensure an equal amount of
hinge is on either side of the hinge line when
the aileron is mounted to the wing panel.
3) Slide the aileron on the wing panel until
there is only a slight gap. e hinge is nowcen-
tered on the wing panel and aileron. Remove
theT-pinsandsnugtheaileronagainstthewing
panel. A gap of 1/64” or less should be main-
tained between the wing panel and aileron.
4) Deect the aileron and completely saturate
each hinge with thin C/A glue. e ailerons
front surface should lightly contact the wing
during this procedure. Ideally, when the hing-
es are glued in place, a 1/64” gap or less will
be maintained throughout the lengh of the ai-
leron to the wing panel hinge line.
e 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.
Note :
.
Hinge
C/A glue
C/A glue

BOOMERANG EP Instruction Manual.
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5) Turn the wing panel over and deect the
aileron in the opposite direction from the
opposite side. Apply thin C/A glue to each
hinge, making sure that the C/A pene-
trates into both the aileron and wing panel.
6) Using C/A remover/debonder and a pa-
per towel, remove any excess C/A glue that
may have accumulated on the wing or in the
aileron hinge area.
7) Repeat this process with the other wing
panel, securely hinging the aileron in place.
8) Aer both ailerons are securely hinged,
rmly grasp the wing panel and aileron to
make sure the hinges are securely glued and
cannot be pulled out. Do this by carefully ap-
plying medium pressure, trying to separate
the aileron from the wing panel. Use caution
not to crush the wing structure.
Work the aileron up and down sev-
eral times to “work in” the hinges
and check for proper movement.
Note :
HINGING THE RUDDER.
Glue the rudder hinges in place using the
same techniques used to hinge the ailerons.
WING ASSEMBLY.
See below pictures.
Aluminium wing tube
HINGING THE ELEVATOR.
Glue the elevator hinges in place using the
same techniques used to hinge the ailerons.
Epoxy.

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INSTALLING THE AILERON SERVO.
.
1) Install the rubber grommets and brass
collets onto the aileron servo. Test t the
servo into the aileron servo mount.
Because the size of servos dier, you may
need to adjust the size of the precut openingin
the mount. e notch in the sides of the mount
allow the servo lead to pass through.
2) Using a small weight (Weighted fuel pick-
up works well) and thread, feed the string
through the wing as indicated.
.
.
4) Tape the servo lead to the wing to prevent
it from falling back into the wing.
5) Reinstall the servo into the servo mount
and secure the servo inplace using the wood
screws provided with you radio system.
Electric wire.
Thread.
Plastic tape.
3) Attach servo lead to the aileron servo. At-
tach the string to the servo lead and care-
fully thread it though the wing. Once you
have thread the lead throught the wing, re-
move the string so it can use for the other
servo lead.
Repeat the procedure for the other wing
half.

BOOMERANG EP Instruction Manual.
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INSTALLING THE LANDING GEAR.
1) e 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.
3) Position the aileron horn on the bottom
side of aileron. e clevis attachment holes
should be positioned over the hinge line.
ControlHorn.
Mounting Screws. Mounting Plate.
4) Using a 1mm drill bit and the control
horns as a guide, drill the mounting holes
through the aileron halves.
5) Mount the control horns by inserting the
screws through the control horn bases and
aileron halves, then into the mounting back-
plates. Do not overtighten the screws or the
backplates may crush the wood.
6) read one nylon adjustable control horn
onto each aileron control rod. read the
horns on until they are ush with the ends of
the control rods.
8) Make a 90-degree bend at the mark and
cut o the excess wire leaving 10mm past the
bend.
9) Connect the linkage as shown and secure
the control wire with a wire keeper.
AILERON LINKAGE.
1) Using a ruler & pen to draw a straight line
as below picture.
2) Locate the two nylon control horns, two
nylon control horn backplates and four ma-
chine screws.
7) With the aileron servo centered and the
aileron even with the trailing edge of the
wing attach the clevis to the control horn.
Mark the control wire where it crosses the
servo arm hole.
3) Place the fuselage inverted on the work-
bench in a suitable stand. Set the landing
gear in place and use a screwdrive to secure
the landing gear to the fuselage using bolts
M4x20mm and washers. Make sure to use
the threadlock on the bolts so they don’t vi-
brate loose.
2x15mm

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.
M4x20mm
NOSE GEAR INSTALLATION.
See below pictures.
Collar.
Thread locker glue.
INSTALLING THE FUSELAGE SERVOS.
Because the size of servos dier, you may
need to adjust the size of the precut opening
in the mount. e notch in the sides of the
mount allow the servo lead to pass through.
Pushrod wire.
Steering arm.

BOOMERANG EP Instruction Manual.
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2) Secure the servos with the screws provid-
ed with your radio system.
Rudder servo.
Elevator servo.
Elevator servo arm.
Rudder servo arm.
ELECTRIC POWER CONVERSION.
1) Locate the items neccessary to install the
electric power conversion included with
your model.
M4x30mm
Tie wrap
Speed control
Battery
1) Install the rubber grommets and brass
collets onto the throttle servo. Test t the
servo into the aileron servo mount.

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COWLING
1) Slide the berglass cowl over the motor
and line up the back edge of the cowl with
the marks you made on the fuselage then
trim and cut as shown.
2) While keeping the back edge of the cowl
ush with the marks, align the front of the
cowl with the cranksha of the engine. e
front of the cowl should be positioned so the
cranksha is in nearly the middle of the cowl
opening. Use the spinner backplate as a
guide. Hold the cowl rmly in place using
pieces of masking tape.
3) Install the muer and muer extension
onto the engine and make the cutout in the
cowl for muer clearance. Connect the fuel
and pressure lines to the carburetor, muer
and fuel ller valve. Secure the cowl to fuse-
lage using the M3x10mm screws.
3x10mm

BOOMERANG EP Instruction Manual.
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INSTALLING THE SPINNER.
Install the spinner backplate, propeller and
spinner cone.
e 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.
HORIZONTAL STABILIZER.
1) Using a ruler and a pen, locate the center-
line of the horizontal stabilizer, at the trail-
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
this mark down the back of the trailing edge
of the stabilizer.
Draw center line
2) Using a modeling knife, carefully remove
the covering from over the vertical stabilizer
mounting slot in the top of the fuselage.
3) Slide the stabilizer into place in the precut
slot in the rear of the fuselage. e stabilizer
should be pushed rmly against the front of
the slot.
4) With the stabilizer held rmly 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 le sides and top and
bottom of the stabilizer.
5) Remove the stabilizer. Using the lines you
just drew as a guide, carefully remove the
covering from between them using a mod-
eling knife.
Remove the covering
Pen.

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When cutting through the covering
to remove it, cut with only enough pres-
sure to only cut through the covering it-
self. Cutting into the balsa structure may
weaken it.
6) Using a modeling knife, carefully remove
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.
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
bottom of the stabilizer mounting area and
to the stabilizer mounting platform sides in
the fuselage. Putting the stabilizer in place
and realign. Double check all of your meas-
urements once more before the epoxy cures.
Hold the stabilizer in place with T-pins or
masking tape and remove any excess epoxy
using a paper towel and rubbing alcohol.
Epoxy
Epoxy
VERTICAL STABILIZER
INSTALLATION.
10) Aer the epoxy has fully cured, remove
the masking tape or T-pins used to hold the
stabilizer in place. Carefully inspect the glue
joints. Use more epoxy to ll in any gaps that
may exist that were not lled previously and
clean up the excess using a paper towel and
rubbing alcohol.
1) Using a modeling knife, remove the cov-
ering from over the precut hinge slot cut into
the lower rear portion of the fuselage. is
slot accepts the lower rudder hinge.
2) Slide the vertical stabilizer into the slot in
the top of the fuselage. e rear edge of the
stabilizer should be ush with the rear edge
of the fuselage and the lower rudder hinge
should engage the precut hinge slot in the
lower fuselage. e bottom edge of the stabi-
lizer should also be rmly pushed against the
top of the horizontal stabilizer.
Epoxy

BOOMERANG EP Instruction Manual.
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3) While holding the vertical stabilizer rm-
ly 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.
4) Remove the stabilizer. Using a modeling
knife, remove the covering from below the
lines you drew.
Remove the covering
Knife.
90º
Vertical
Stabilizer.
Horizontal
Stabilizer.
6) When you are sure that everything is
aligned correctly, mix up a generous amount
of 30 Minute Epoxy. Apply a thin layer to
the mounting slot in the top of the fuselage
and to the sides and bottom of the vertical
stabilizer mounting area. Apply epoxy to the
bottom and top edges of the ller block and
to the lower hinge also. Set the stabilizer in
place and realign. Double check all of your
measurements once more before the epoxy
cures. Hold the stabilizer in place with T-
pins or masking tape and remove any excess
epoxy using a paper towel and rubbing al-
cohol. Allow the epoxy to fully cure before
proceeding.
Epoxy
CONTROL HORN INSTALLATION.
1) Locate the nylon control horns- nylon
control horn backplates and machine screws.
2)e position of elevator control horn on
the le side of elevator. e clevis attach-
ment holes should be positioned over the
hinge line.
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.
5) Slide the vertical stabilizer back in place.
Using a triangle, check to ensure that the ver-
tical stabilizer is aligned 90º to the horizontal
stabilizer.

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ControlHorn.
Mounting Screws. Mounting Plate.
3) Using a 2mm drill bit and the control
horns as a guide, drill the mounting holes
through the elevator halves.
4) Mount the control horns then into the
mounting backplates. Do not overtighten the
screws or the backplates may crush the wood.
5) Position the rudder control horn on the
le side of the airplane.
6) Install the rudder control horn using the
same method as with the elevator control
horns.
Elevator control horn.
Rudder control horn.
2x12mm.
ELEVATOR PUSHROD
INSTALLATION.
Elevator pushrod
Control horn
Rudder pushrod
Control horn
62mm.
58.2 mm.
RUDDER PUSHROD INSTALLATION.
2x12mm.

BOOMERANG EP Instruction Manual.
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INSTALLING THE RECEIVER.
1) Plug the ve 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 the antenna in the antenna tube in-
side the fuselage and secure it to the bottom
of fuselage using a plastic tape.
ATTACHMENT WING-FUSELAGE.
Receiver.
Tie wrap.
Wing bolt
BALANCING.
1) It is critical that your airplane be bal-
anced correctly. Improper balance will
cause your plane to lose control and
crash. THE CENTER OF GRAVITY IS
LOCATED 72MM BACK FROM THE
LEADING EDGE OF THE WING AT
THE WING ROOT.
2) Mount the wing to the fuselage. Using
a couple of pieces of masking tape, place
them on the top side of the wing 72mm
back from the leading edge of the wing at
the wing root.
3) Turn the airplane upside down. Place
your ngers on the masking tape and
carefully li the plane .
Accurately mark the balance point on the
top of the wing on both sides of the fuse-
lage. e balance point is located 72mm
back from the leading edge of the wing at
the wing root. is is the balance point
at which your model should balance for
your rst ights. Later, you may wish to
experiment by shiing the balance up
to 10mm forward or back to change the
ying characteristics. Moving the bal-
ance forward may improve the smooth-
ness and arrow- like tracking, but it may
then require more speed for take o and
make it more dicult to slow down for
landing. Moving the balance a makes
the model more agile with a lighter and
snappier ”feel”. In any case,please start at
the location we recommend .

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With the wing attached to the fuse-
lage, all parts of the model installed
( ready to y), and empty fuel tanks,
hold the model at the marked bal-
ance point with the stabilizer level.
Li the model. If the tail drops when you
li, the model is “tail heavy” and you
must add weight* to the nose. If the nose
drops, it is “nose heavy” and you must
add weight* to the tail to balance.
*If possible, rst attempt to balance the
model by changing the position of the re-
ceiver battery and receiver. If you are un-
able to obtain good balance by doing so,
then it will be necessary to add weight to
the nose or tail to achieve the
proper balance point.
72 MM
CONTROL THROWS.
Ailerons :
- Up : 10 mm
- Down : 10 mm
Elevator :
- Up : 10 mm
- Down : 10 mm
Rudder :
- Right : 15 mm
- Le : 15 mm

BOOMERANG EP Instruction Manual.
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FLIGHT PREPARATION. PREFLIGHT CHECK.
Check the operation and direction of the
elevator, rudder, ailerons and throttle.
A) Plug in your radio system per the
manufacturer’s instructions and turn
everything on.
B) Check the elevator rst. Pull back
on the elevator stick. e elevator halves
should move up. If it they do not, ip the
servo reversing switch on your transmit-
ter to change the direction.
C) Check the rudder. Looking from
behind the airplane, move the rudder
stick to the right. e rudder should
move to the right. If it does not, ip the
servo reversing switch on your transmit-
ter to change the direction.
D) Check the throttle. Moving the
throttle stick forward should open the
carburetor barrel. If it does not, ip the
servo reversing switch on your transmit-
E) From behind the airplane, look at
the aileron on the right wing half. Move
the aileron stick to the right. e right ai-
leron should move up and the other ai-
leron should move down. If it does not,
ip the servo reversing switch on your
transmitter to change the direction.
1) Completely charge your transmit-
ter and receiver batteries before your rst
day of ying.
2) Check every bolt and every glue joint
in the BOOMERANG EP to ensure that
everything is tight and well bonded.
3) Double check the balance of the air-
plane. 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
rst few ights.
6) Check to ensure the control surfaces
are moving the proper amount for both
low and high rate settings.
7) Check the receiver antenna. It should
be fully extended and not coiled up inside
the fuselage.
8) Properly balance the propeller. An
out of balance propeller will cause exces-
sive vibration which could lead to engine
and/or airframe failure.
We wish you many safe and enjoyable ights
with your BOOMERANG EP.