3D Hobby Shop YAK55 User manual

91” Yak55 Assembly Manual

Suitable for 55/60cc gas engines
or 12s Electric ower
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Thank you for purchasing this 3DHobbyShop ARF RC aircraft. If you have any issues, questions,
concerns or problems during assembly, please contact our tech department at:
[email protected]
SAFETY in Assembly
During assembly of this aircraft, you will be asked to use sharp knives, hot irons, and hobby adhesives.
Please follow all safety procedures recommended by the manufacturers of the products you use, and
always follow these important guidelines:
ALWA S protect your eyes when working with adhesives, knives, or tools, especially power tools. Safety
glasses are the best way to protect your eyes.
ALWA S protect your body, especially your hands and fingers when using adhesives, knives, or tools,
especially power tools. Do not cut toward exposed skin with hobby knives. Do not place hobby knives on
tables or benches where they can roll off or be knocked off.
ALWA S have a first-aid kit handy when working with adhesives, knives, or tools, especially power tools.
ALWA S keep hobby equipment and supplies out of the reach of children.
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SAFETY in Flying
ALWA S fly your aircraft in a safe area, away from spectators.
ALWA S fly your aircraft in a safe manner, within your control.
NEVER fly too close to yourself.
ALWA S wear eye protection while operating your model aircraft.
ALWA S keep your hands and body clear of propellers.
ALWA S observe lipoly battery safety procedures.
ALWA S handle gasoline in a safe manner.
ALWA S perform a ground test and range check of your radio system before flying.
REQUIRED ITEMS
Drill and drill bits
30 Minute Epoxy Glue (NOT 5-minute Epoxy)
Hobby Knife
Phillips Screwdriver
Set Metric Allen Wrenches
Small Pliers
Wire Cutters
Rubbing Alcohol
Paper Towels
Blue Loctite thread-locking adhesive
Dremel-type rotary tool
Small adjustable wrench or wrench set
IM ORTANT NOTE: 3DHS Recommends ONLY High-Torque, Digital, Metal-gear Servos for this
aircraft. Suitable part numbers include Futaba BLS157hv or BLS172hv, Hitec HS-7955TG, JR
8611A, and JR 8711A. DO NOT attempt to use nylon-geared servos on this airplane.
THIS AIRCRAFT IS NOT A TO ! IT IS A HIGH PERFORMANCE AEROBATIC AIRCRAFT AND
IMPROPER SETUP AND/OR USE COULD RESULT IN INJUR OR DEATH.
Assembly Instructions
Unpacking
Unpack your airplane and examine the components. Check for damage of any kind. If you find any
damage, contact 3DHobbyShop and report the damage. Shippers are not always kind to our planes but
we do our best to make the situation right if you receive a damaged item. Please contact 3dhs
immediately via email at: [email protected] or you can contact us via telephone at (717) 814-
5316. We do our best to answer or return phone calls but email may be a faster way to connect with us
depending on the time of year and our travel schedule.
Covering Seams
There are many seams in the covering on this aircraft where one color meets another. We recommend
using a covering iron or trim sealing tool to go over all of the covering seams on your ak. This will help
to prevent any peeling of the covering. Repeat this periodically. For long term durability, particularly on
gasoline powered aircraft, you can seal edges and points on the covering with clear fingernail polish.
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Wrinkles in the Covering
our ak was packed at the factory without any wrinkles in the covering. ou may notice some wrinkles
now; more likely, you will notice a few in a day or two or the first time you take the plane out to the flying
field. These wrinkles are the result of wood shrinkage and/or expansion. Balsa wood changes size and
shape slightly as it is exposed to varying humidity in the air. Wood also shrinks when exposed to sunlight
under dark colors of covering. This is a natural property of balsa wood. As your airplane adjusts to the
weather in your part of the world, wrinkles may appear and disappear.
Wrinkles may be removed with the gentle application of heat to the covering material on your airplane,
using an iron and/or heat gun. Apply the heat gently: the covering material will shrink as you apply the
heat, and this will remove the wrinkles. BE CAREFUL! Too much heat applied too quickly can damage
the covering, either by causing it to pull away from the wood at seams and corners or even by melting it.
Wrinkles do not affect flight performance.
Covering Materials
our ak is covered with genuine OraCover material. If you need to repair larger sections, matching
covering is sold at most hobby stores under the “UltraCote” brand.
Assembly Order
Like many ARF’s, the assembly order for a plane like this one is flexible. Many people choose to put the
landing gear on the fuselage first and get the plane on its wheels on a build table. Others assemble the
plane on a stand and put the gear on last. ou can choose to mount the engine first, or last. The same
holds true for the radio gear. The photos in this manual are only suggestions and you may alter some
steps to suit your style. Take your time and enjoy the build, no matter what order you choose.
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Opening up holes in the covering
Using a hot fine tipped soldering iron or sharp hobby knife, trim the necessary openings in the covering
for installing the landing gear, servos, servo horns, wing screws, belly vents, wing locating pins, servo
arms, etc. Work slowly and carefully to make sure you cut the openings OU need for your build.
If you use a soldering iron, it tends to melt the edge of the covering, sealing it to the wood. If you use a
knife, we recommend following up with a covering iron to seal the edges around the openings you’ve just
made.
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Hinging the control surfaces
The aileron and elevator hinging is done for you already.
The rudder is a removable type, retained with a steel-wire hinge axle, inserted from the top of the rudder.
This wire is taped inside your kit box. To attach the rudder, slide the wire down through the hinges as
shown. This feature can make transporting your ak much easier if you have a small vehicle. Trim this
wire flush with the bottom of the rudder.
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Control Horn Installation
Cut the covering for control horns as shown and install with 30 minute epoxy. Do NOT use CA for gluing
control horns on this airframe! Take your time and clean up any extra epoxy with alcohol as needed.
Once you open the slots up, use the square plates and a sharpie marker or pencil to trace the area where
you need to cut the square. Dry fit the control horns fully into the surface to make sure the slots are clear
before mixing epoxy.
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Repeat the procedure for the rudder, trimming the covering from both sides for the fiberglass plates. Dry
fit the control horns through the rudder before mixing epoxy. While glue is curing put the 4/40 ball link and
screw in its place to align the control horns properly. NOTE: The rudder in these photos has a different
type of hinge than your ak.
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Elevator Servo Installation
Elevator servos on your ak mount inside the horizontal stabilizers. The openings are sized for 'standard'
servo cases such as used on the Hitec HS-7955TG servo. If it is necessary to slightly enlarge the
opening for your larger servos, we find that the best technique is to use a coarse file. Only remove a
small amount of wood as required to fit servos of your choice while keeping the “filing” to a minimum.
This airframe has been tested with servos up to the size of a Futaba BLS157 with excellent performance.
The elevator servos must be installed using a long screwdriver or ball driver to access the mounting
screws. The servo arm must be inserted and tightened properly before flight. The use of thread locking
compound or lock washers is always recommended on all surface control hardware to prevent loosening
in flight. The Photos below illustrate elevator servo mounting and hardware installation. Do not forget to
use some type of lock on all your servo wire to extension plugs.
Center the servos, and slide your servo arms onto the servo output splines. Rotate the servos and arms
as necessary to access all fasteners to lock the arms in-place. Use thread locking compound if indicated
by the servo-arm manufacturer. We also use a dab of silicone adhesive on the servo arm screw to lock it
in place against vibration.
Assemble the elevator pushrod as shown. The elevator pushrods are the shorter of the included
pushrods. The longer ones are for the ailerons. Note that the pushrods have one left-hand thread and
one right-hand thread, so that you can adjust their length after they are installed.
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Assemble control linkages using the 4/40 screws, ball links, and locking nuts as shown. Linkages should
be adjusted to suit your servo installation.
For this aircraft, we recommend 1.5" arms for the ailerons, 1.75-2.0" for the elevators. For the rudder
installation, a 3" double-sided arm is recommended.
Note: Servo arms come in a variety of shapes and sizes. We provide a basic set of 4-40 sized screws
and nuts appropriate to most servo arms. If your arms are different, for instance very thick aluminum,
obtain the correct length screws.
TIP: We have found that it is possible to assemble ball links and pushrods quickly using a cordless
variable speed drill to turn the metal threaded pushrod in the proper direction while holding the plastic ball
joint gently with pliers. Use a slow speed so you do not melt or damage the plastic ball ends
NOTE: We do not recommend using pure nylon/plastic servo arms on this aircraft. We recommend
either metal, or composite-reinforced arms. Check with your servo mfg. if needed to determine what
material you have.
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Stabilizer Installation
After installing the servos and setting up the elevator linkages, install the carbon stabilizer spar tube and
both stabilizers with elevators using the screws and washers provided. It is helpful to use one of the
common techniques to prevent these screws from loosening during flight. We prefer a slice of glow fuel
tubing behind the washer to prevent these screws from backing out during flight. Thread locking
compound is also suitable but it will be more difficult to remove than if using a rubber backed or fuel-tube
backed washer.
The ak includes a fiberglass tube installed into the fuselage to assist in cleanly routing your elevator
servo extensions into the rear of the fuselage. A pull-string is pre-installed to help pull your servo
extensions through the fiberglass tube.
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Landing gear
Attach the tail wheel to the bottom of the fuse as shown with wood screws and washers. Install one strap
just at the rear of the fuselage and the front strap just behind where the gear enters the fuselage. Take
the time to install all 4 screws, then remove them one by one and apply thin CA glue to the wood at each
screw. It is OK if the CA is still wet when you re-install the screw as this tends to prevent loosening in
flight. ou can also glue the end of the wire into the fuse for added security using epoxy or gorilla glue.
Use wood screws and the same CA technique to put the rudder spring “T” on the bottom of your rudder
as shown. Install the tail wheel springs slightly stretched (about 1/4" of stretch or 'preload') so they are in
tension with a straight rudder.
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The main Gear is mounted onto the fuselage with 4mm hex screws, washers, and locking nuts as shown.
The gear IS DIRECTIONAL and has been designed to sweep slightly forward. Pay attention to your gear
installation to make sure you have not installed it backwards.
Use a wrench or locking pliers to hold the nuts inside the fuselage as you tighten the screws from outside.
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Locate the balsa wood cover plate for the bottom of the landing gear. Adhere it over the gear mounting
area with rubber cement, silicone caulk, 'welder' adhesive, or another vibration-resistant glue.
Locate the landing gear-to-fuselage fairings (also called 'cuffs'). They are different, right to left. Try them
on each side to determine which is which. They are attached to the landing gear using 4-40 screws and
washers. NOTE: Thread the screws into the gear without the cuffs once to be certain you can easily do
this. Slide the cuffs on and probe with a sharp point to locate the holes, then tighten the screws. We
prefer to put some silicone caulk on and around these screws to prevent vibration from loosening the
cuffs.
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Install each main wheel onto each axle with a wheel collar as shown. It is recommended to grind or file a
small flat area on each axle for the collar set screw to 'grab'. The axles are plated with a very hard,
corrosion-resistant layer, and it is difficult for the set screws to clamp to this layer. A few seconds with a
Dremel tool or a file will break through this layer and allow the set screws to grab. Loctite is also
recommended for these screws.
Install the wheel and axle into the wheel pant. Bolt the axle/pant/wheel unit onto the main landing gear
with the locking nut as shown:
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Install the wheel pants screws as shown. Use loctite.
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ull- ull cables
The pull-pull cables for the rudder are assembled as shown in the following diagram:
Assemble the pull-pull cables at the rudder end first, as shown, and feed the cables through the slots in
the fuselage and pull them to the front of the fuselage. Use thin CA and Kicker on your crimped
connections for added security against cable slip. Cross the cables to form an “X” inside the fuselage.
For a proper pull-pull setup, the holes you use in your double sided servo arm on the servo should be of
approximately equal width from right to left as the mounting holes you use on the rudder control horn.
Center the rudder servo. Install the rudder servo as shown and finish cable installation inside the
fuselage as shown in the photos below. Make sure to have the brass connectors threaded adequately
into the plastic ball links but don’t forget to provide yourself adequate threaded length to properly tension
the cables following installation and the first few flights as the cables and your connections may stretch
slightly.
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