Black Horse Model Cobra Owner's manual

SPECIFICATION
MadeinVietnam.
Wingspan : 1,360 mm 53.5 in
WingArea: 36.4 dm2 564 sq.in
Length : 1,310 mm 51.6in
Weight : 2,700 gr 5.94 lbs
Engine : 46 cu.in 2 stroke
72 cu.in 4 stroke
Radio : 4 channels
Servo : 5 servos
Instruction Manual book

COBRA. Instruction Manual
2
This instruction manual is designed to help you build a great flying aeroplane. Please read this
manualthoroughlybeforestartingassemblyofyour COBRA. Use thepartslistingbelowtoidentify
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.
IfyouareinexperiencedwithbasicR/CflightwestronglyrecommendyoucontactyourR/Csupplier
and join your local R/C Model Flying Club. R/C Model Flying Clubs offer a variety of training
proceduresdesignedtohelp thenewpilotonhisway tosuccessfulR/Cflight.Theywill alsobeable
to advise on any insurance and safety regulations that may apply.
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.
Some more parts.
HARDWAREPACK
COWLING.
Landinggear.....
Toavoidscratching your new airplane, do not
unwrap the pieces until they are needed for
assembly. Cover your workbench with an old
towel or brown paper, both to protect the
aircraftandtoprotectthe table. Keep a couple
of jars or bowls handy to hold the small parts
after you open the bag.
Pleasetrialfitall theparts.Makesureyouhave
the correct parts and that they fit and are
alignedproperlybeforegluing!Thiswillassure
proper assembly. COBRA ARF is hand made
from natural materials, every plane is unique
andminoradjustments may have tobe made.
However, you should find the fit superior and
assembly simple.
The painted and plastic parts used in this kit
are fuel proof. However, they are not tolerant
of many harsh chemicals including the
following: paint thinner, C/A glue accelerator,
C/A glue debonder and acetone. Do not let
these chemicals come in contact with the
colors on the covering and the plastic parts.
PARTS LISTING
FUSELAGE ASSEMBLY
(1) Fuselage.
WING ASSEMBLY
(1) Right wing half with pre-installed
aileron.
(1) Left wing half with pre-installed
aileron.
Tail section assembly
(1) Vertical stabilizer with pre-
installedrudder.
(1) Horizontal stabilizer with pre-
installedelevatorhalves.
SUGGESTION
NOTE

COBRA. INSTRUCTION MANUAL
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+ This is not a toy
+ Be sure that no other flyers are using your
radio frequency.
+ Do not smoke near fuel
+ Store fuel in a cool, dry place, away from
children and pets.
+ Wear safety glasses.
+Theglowplug clipmustbesecurelyattached
to the glow plug.
+ Do not flip the propeller with your fingers.
+ Keep loose clothing and wires away from
thepropeller.
+ Do not start the engine if people are near.
Do not stand in line with the side of the
propeller.
+ Make engine adjustments from behind the
propeller only. Do not reach around the
spinningpropeller.
SAFETY PRECAUTION
INSTALLING THE AILERON SERVOS
1) Install the rubber grommets and brass
eyelets onto the aileron servo.
Bottomside
Aileron
C/Aglue
C/Aglue
C/Aglue
C/Aglue
Top side.
Bottom side
C/Aglue

COBRA. Instruction Manual
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4) Using the thread as a guide and using
masking tape, tape the servo lead to the end
of the thread: carefully pull the thread out.
When you have pulled the servo lead out,
remove the masking tape and the servo lead
from the thread.
Repeat the procedure for the other wing
half.
5) Instal servo tray with aileron servo into
the wing as same as picture below.
Servowire.
Wing.
Servotray.
Top side
2)Drill1,5mm pilot holes through the block
of wood for each of the four mounting screws
providedwiththeservo.Installservointoaileron
servo tray as same as picture below:
Aileronservotray.
3) Using a modeling knife, remove the
covering at possition show below.
Bottomofwing.
Remove the covering.
1) Using a ruler & pen to draw a straight
line as below picture.
INSTALLINGTHEAILERON CONTROL HORN

COBRA. INSTRUCTION MANUAL
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5) Mountthecontrol horns by insertingthe
screws through the control horn bases and
aileron halves, then into the mounting
backplates.
Do not overtighten the screws or the
backplates may crush the wood.
6)Threadonecleviscontrol horn ontoeach
aileron torque rod. Thread the clevis on until
theyareflushwith the ends of the torque rods.
Aileron torque rod.
Clevis.
2) Locate nylon control horns, nylon con-
trol horn backplates and 2 machine screws.
Straitghline.
Servoarm.
2MM x 20MM
4) Using a 1mm drill bit and the control
horns as a guide, drill the mounting holes
through the aileron halves.
ControlHorn.
MountingScrews. Mounting Plate.
3) Position the aileron horn on the bottom
side of aileron. The clevis attachment holes
should be positioned over the hinge line as
shown below. Cut.

COBRA. Instruction Manual
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3) Usingthetwo landing gear strapsas a
guide, mark the locations of the four 3mm x
12mm mounting screws onto the wing sur-
face.
Repeat the procedure for the other wing
half. INSTALLINGTHE LANDING GREAR
1) Insert the 90º bend of one main gear
wire into the predrilled hole in one mounting
slot.
2) The landing gear wire is held in place
using two nylon landing gear straps and four
3mm x 12mm wood screws.
The straps should be located equal distance
from the inside and outside ends of the wire.
5) Reinstall the gear wire and install the
straps using the four 3mm x 12mm wood
screws. Tighten the screws completely to
secure the gear wire in place.
4) Remove the two straps and the gear
wire. Drillfour 1.5mm pilot holesinto the wing
for the wood screws. Be careful not to drill
through the top of the wing!

COBRA. INSTRUCTION MANUAL
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7) Slide one 60mm diameter wheel onto
eachaxleandpushthemupagainstthewheel
collars. Slidetheremainingwheel collars with
3mm x 6mm set screws onto the axles. Push
them up against the wheels and tighten the
set screws. The wheels should spin free and
notbindinanyway. If they do bind, loosen the
setscrewsintheouterwheel collars and move
the collars out a small amount. Retighten the
set screws.
6) Slide one wheel collar with 3mm x
6mm set screw onto each axle. Push the
wheel collars on as far as they will go and
tighten the set screws.
Be careful not to overtighten the set
screws. Overtightening may cause the
threads to strip.
Dowel.
Alumiumbrace.
Dowelbrace.
JOINING THE WING HALVES
1) Locate the aluminium wing dihedral
brace.
2) Test fit the dihedral brace into each
wing half. The brace should slide in easily . If
not, use 220 grit sandpaper with a sanding
block and sand down the edges and ends of
the brace until it fits properly.
NOSE GEAR INSTALLATION

COBRA. Instruction Manual
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Installing steering arm as below.
Adjustthenosegearsteering arm until thearm
is parallel with the fire wall.
Steering arm.
Steering arm.
Install the pushrod wire as shown.
Pushrod
throttle.
Slide one 60mm diameter wheel collar onto
the axle and tighten. Slide the nose wheel on
and push it up against the wheel collar. Slide
the remaining wheel collar on and push it up
against the wheel and tighten the set screw.
The wheels should spin free and not bind in
any way.
Pushrod wire
INSTALLING THE NOSE GEAR WHEEL
INTALLING THE ENGINE MOUTH
M4.
INSTALLING THE STOPPER ASSEMBLY
1.The stopper has been pre-assembled at
the factory.
2.Usingamodelingknife, cut one length of
siliconfuel line (the lengthof silicon fuel lineis
calculated by how the weighted clunk should
restabout8mm away from the rear ofthetank
andmovefreelyinside the tank). Connect one
end of the line to the weighted clunk and the
other end to the nylon pick up tube in the
stopper.
FUEL TANK

COBRA. INSTRUCTION MANUAL
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5. Test fit the stopper assembly into the
tank. It may be necessary to remove some of
the flashing around the tank opening using
amodelingknife. Ifflashing is present, make
sure none of it falls into the tank.
6. When satisfied with the alignment of the
stopper assembly tighten the 3mm x 20mm
machine screw until the rubber stopper
expands and seals the tank opening. Do not
over tighten the assembly as this could cause
the tank to split.
7. Using a modeling knife, cut 3 lengths of
fuel line 150mm long. Connect 2 lines to the 2
vent tubes and 1 line to the fuel pickup tube in
the stopper.
Blow through one of the lines to ensure
the fuel lines have not become kinked inside
the fuel tank compartment. Air should flow
througheasily.
9. To secure the fuel tank in place, apply a
bead of silicon sealer to the forward area of
thetank,whereitexitsthefuselagebehindthe
enginemountingbox andtotherearofthe tank
at the forward bulkhead.
Do not secure the tank into place
permanentlyuntilafter balancing the airplane.
You may need to remove the tank to mount
the battery in the fuel tank compartment
8. Feed three lines through the fuel tank
compartment and through the pre-drilled hole
in the firewall. Pull the lines out from behind
the engine, while guiding the fuel tank into
place. Push the fuel tank as far forward as
possible,thefrontofthetankshouldjustabout
touch the back of the firewall.
When the stopper assembly is installed in the
tank, the top of the vent tube should rest just
belowthetop surface of thetank.It should not
touch the top of the tank.
3.Carefullybendthesecond nylon tube up
ata45degreeangle(usingacigarette lighter).
This tube will be the vent tube to the muffler.
4.Carefullybendthethird nylon tube down
ata45degreeangle(usingacigarette lighter).
This tubewillbeventtubetothefuelingvalve.
Fueltank.

COBRA. Instruction Manual
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2) While keeping the back edge of the
cowl flush with the marks, align the front of
thecowlwiththecrankshaft of theengine. The
front of the cowl should be positioned so the
crankshaft is in nearly the middle of the cowl
opening. Hold the cowl firmly in place using
pieces of masking tape.
Trimandcut.
Pushrodwire.
INTALLING THE ENGINE-THROTTLE
COWLING
1) Slide the fiberglass cowl over the en-
gine and line up the back edge of the cowl
with the marks you made on the fuselage.

COBRA. INSTRUCTION MANUAL
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4) Installthemufflerand mufflerextension
onto the engine and make the cutout in the
cowl for muffler clearance. Connect the fuel
and pressure lines to the carburetor, muffler
andfuel filler valve.
3) Slide the cowl back over the engine
and secure it in place using four wood
screws.See picture below.
Machinescrew.
Install the spinner backplate, propeller
andspinnercone. The spinner cone isheldin
place using two 3mm x 12mm wood screws.
INSTALLING THE SPINNER
See picture below
C/Aglue
C/Aglue
SERVO INSTALLATION
Rudder servo.
Elevator servo.
Throttle servo.
HORIZONTAL STABILIZER INSTALLA-
TION
C/Aglue
Bottom side

COBRA. Instruction Manual
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3) 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.
2) Slidethestabilizerintoplacein thepre-
cut slot in the rear of the fuselage. The stabi-
lizer should be pushed firmly against the front
of the slot.
Pen.
C/Aglue
C/Aglue
1) Using a ruler and a pen, locate the
centerlineofthehorizontalstabilizer,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 down the backof the trailing edgeof
the stabilizer.
C/Aglue
C/Aglue
Top side
C/Aglue
Top side
Centerline.
Top side

COBRA. INSTRUCTION MANUAL
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4) Remove the stabilizer. Using the lines
youjust drew as a guide,carefully remove the
coveringfrombetweenthemusingamodeling
knife.
When cutting through the covering to remove
it, cut with only enough pressure to only cut
through the covering it’s self. Cutting into the
balsastructuremayweakenit.Thiscouldlead
to possible failure during flight
5) 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.
6) When you are sure that everything is
aligned correctly, mix up a generous amount
ofFlash30MinuteEpoxy. Applyathinlayerto
the top and bottom of the stabilizer mounting
area and to the stabilizer mounting platform
sides in the fuselage. Slide 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 ep-
oxy using a paper towel and rubbing alcohol.
7) After the epoxy has fully cured, re-
move
the masking tape or T-pins used to hold the
stabilizer in place and carefully inspect the
glue joints. Use more epoxy to fill in any
gaps that were not filled previously and
clean up the excess using a paper towel and
rubbingalcohol.
Removecovering.
VERTICAL STABILIZER
INSTALLATION
See picture below
C/Aglue
C/Aglue
C/Aglue

COBRA. Instruction Manual
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6) When you are sure that everything is
alignedcorrectly, mix upagenerousamountof
Flash30MinuteEpoxy. Applyathinlayertothe
mounting slot in the top of the fuselage and to
the sides and bottom of the vertical stabilizer
90º Vertical
Stabilizer.
Horizontal
Stabilizer.
Tailstrut.
4) Remove the stabilizer. Using a mod-
eling knife, remove the covering from below
the lines you drew. Also remove the covering
from the bottom edge of the stabilizer and the
bottomandtopedgesofthefillerblock. Leave
the covering in place on the sides of the filler
block.
Pen.
Removecovering.
Hinge.
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.
C/Aglue
2) Slidethe vertical stabilizer into theslot
in the top of the fuselage. The rear edge of
thestabilizer shouldbeflushwiththerearedge
of the fuselage and the lower rudder hinge
should engage the precut hinge slot in the
lowerfuselage. The bottom edge of thestabi-
lizer should also be firmly pushed against the
top of the horizontal stabilizer.
1) Using a modeling knife, remove the
covering from over the precut hinge slot cut
intothelowerrearportion of the fuselage. This
slot accepts the lower rudder hinge.
5) Slide the vertical stabilizer back in
place. Using a triangle, check to ensure that
thevertical stabilizer is aligned 90ºto the hori-
zontal stabilizer.
When cutting through the covering to re-
move it, cut with only enough pressure
toonly cut throughthe covering itself. Cutting
into the balsa structure may weaken it.
Hinge.
Hingeslot.

COBRA. INSTRUCTION MANUAL
15
CONTROL HORN INSTALLTION
1) Locate the two nylon control horns, two
nylon control horn backplates and four M2 x
16mm machine screws.
 2) Position the elevator horn on the bot-
tom side of elevator. The clevis attachment
holesshouldbepositionedoverthehingeline.
ControlHorn.
MountingScrews. Mounting Plate.
mountingarea. Applyepoxytothe bottom and
top edges of the filler block and to the lower
hinge also. Set the stabilizer in place and re-
align. 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 alcohol. Allow the epoxy to
fully cure before proceeding.
Thread two nylonclevisesontothethreaded
wires at least 10 turns.Attach the clevises to
the elevator and rudder control horns. You
may find it necessary to make slight bends in
the wires so they will align with the control
horns without binding.
PUSHROD INSTALLATION
Rudder
control horn.
Elevator
control horn.

COBRA. Instruction Manual
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Install one adjustable metal connector
through the third hole out from the center of
one servo arm, enlarge the hole in the servo
arm using a 2mm drill bit to accommodate the
servoconnector.Removetheexcessmaterial
from the arm.
After installing the adjustable metal
connector apply a small drop of thin C/A to
thebottomnut.Thiswillprevent the connector
from loosening during flight.
Servo arm.
Coloa.
INSTALLING THE THROTTLE PUSHROD


1) Cut out the switchholeusinga modeling
knife. Use a 2mm drill bit and drill out the two
mounting holes through the fuselage side.


2) Secure the switch in place using the
two machine screws provided with the radio
system.
INSTALLING THE SWITCH
Switch.
Snapkeeper.
Nose gear pushrod.
Elevator pushrod.
Throttleservo.
Rudderservo.
Nosegearpushrod.

COBRA. INSTRUCTION MANUAL
17


2) Turn the airplane upside down. Place
yourfingersonthemaskingtapeand carefully
lift the plane .
Ailerons : 15mm up 15mm down
Elevator : 15mm up 15mm down
Rudder : 20mm right 20mm left


1) We highly recommend setting up a
plane using the control throws listed.


2) The control throws should be
measured at the widest point of each control
surface.


3) Check to be sure the control surfaces
move in the correct directions.
CONTROL THROWS
CG
135MM


1) Completely charge your transmitter and
receiver batteries before your first day of
flying.


2) Check every bolt and every glue joint in
your plane to ensure that everything is tight
and well bonded.


3) Double check the balance of the
airplane.


4) Check the control surface.


5) Check the receiver antenna . It should
be fully extended and not coiled up inside the
fuselage.


6) Properly balance the propeller.
We wishyou enjoy.
AileronsControl
Seepicture wingattach tofuselage.
Installing the canopy hatch as same as picture
below.


1)Itiscritical that yourairplanebebalanced
correctly. Improper balance will cause your
plane to lose control and crash.
THE CENTER OF GRAVITY IS LOCATED
135 mm BACK FROM THE LEADING EDGE
OF THE WING.
BALANCING
WING ATTACHMENT
PRE-FLIGHT CHECK
Wingbolt.