Extreme Flight YAK-54 ARF User manual

110 inch YAK-54 ARF
Instruction Manual
©Copyright 2008 Extreme Flight RC, Ltd.

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Please take a few moments to read this instruction manual before beginning
assembly. We have outlined a fast, clear and easy method to assemble this
aircraft and familiarizing yourself with this process will aid in a quick, easy
build.
Please read the following paragraph before beginning
assembly of your aircraft!
THIS IS NOT A TOY! Serious injury, destruction of property, or even death
may result from the misuse of this product. Extreme Flight RC is providing you,
the buyer with a very high quality model aircraft component kit, from which
you, the buyer, will assemble a flying model. However it is beyond our control to
monitor the finished aircraft you produce. Extreme Flight RC will in no way
accept or assume responsibility or liability for damages resulting from the use of
this user assembled product. This aircraft should be flown in accordance to the
AMA safety code. It is highly recommended that you join the Academy of Model
Aeronautics in order to be properly insured, and to operate your model at AMA
sanctioned flying fields only. If you are not willing to accept ALL liability for the
use of this product, please return it to the place of purchase immediately.
Extreme Flight RC, Ltd. guarantees this kit to be free of defects in materials and
workmanship for a period of 90 days from the date of purchase. All warranty
claims must be accompanied by the original dated receipt. This warranty is
extended to the original purchaser of the aircraft kit only. Please inspect the
model immediately upon receipt.
Extreme Flight RC in no way warranties its aircraft against flutter. We have put
these aircraft through the most grueling flight tests imaginable and have not
experienced any control surface flutter. Proper servo selection and linkage set-
up is absolutely essential. Inadequate servos or improper linkage set up may
result in flutter and possibly the complete destruction of your aircraft. If you are
not experienced in this type of linkage set-up or have questions regarding servo
choices, please contact us. It is your responsibility to ensure the airworthiness of
your model.

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Congratulations on your purchase of the Extreme Flight RC 110 inch YAK-54
ARF! This new Extreme Flight Yak-54 includes all first rate hardware and
components and thorough instructions to ensure a trouble free assembly and set-
up. Weight saving components are used throughout, such as carbon fiber wing
and stab mounting tubes, carbon fiber main landing gear, titanium pushrods and
a carbon fiber tail wheel assembly, all ensuring the lightest, most high
performance aircraft possible. You will notice there is a box built into the
bottom of the Yak’s fuselage. This is a pipe tunnel and will accommodate the full
range of canister mufflers and tuned pipes sold for the current makes of 100cc
class engines. Also included is a set of protective wing and stab bags and a
canopy/hatch cover to keep your investment looking great season after season.
The performance ability of the Extreme Flight RC Yak-54 is phenomenal! With
its low weight and enormous control surfaces, the Yak-54 is a 3D monster,
capable of all current 3D maneuvers as well as possessing the ability to forge new
ground in this exciting new style of flying. The Yak is also a topnotch precision
aerobatic machine. It is capable of performing the entire FAI catalog of
maneuvers and it has the kind of “40% plane” presence in the air that will
impress the judges. This makes the 110 inch Yak a great candidate for all classes
of IMAC competition.
We have spent a great deal of time and effort to provide you, the discriminating
aerobatic enthusiast, with the highest quality, most complete package possible.
We are very proud of the end result of our labor and wish you great success with
the assembly and flying of your Extreme Flight RC 100cc Yak-54!

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A few tips to ensure success and airframe longevity
1. We are very pleased with the level of craftsmanship displayed by the builders in our
factory. Through many grueling test flights containing maneuvers that no aircraft
should be subjected to, our Yak prototypes have remained rigid and completely
airworthy. However, it is impossible for us to inspect every glue joint in the aircraft.
Take a few minutes and apply some medium CA to high stress areas such as servo
mounting trays, landing gear blocks, the intersection of the wing root rib and wing
sheeting, anti rotation pins, etc. A few minutes spent here inspecting the joints and
applying glue where needed is time well spent
2. Having survived the journey half way around the world while experiencing several
climate changes, it is not uncommon for a few wrinkles to develop in the covering. Fear
not! These are not manufacturing defects, and are easily removed with a little bit of
heat. Use a 100% cotton tee-shirt and your heat gun and heat the covering while gently
rubbing the covering onto the wood with the t-shirt. Be careful not to use too much
heat as the covering may shrink too much and begin to lift at the edges. Take your
time, and a beautiful, paint like finish is attainable. The black covering may require a
little bit more attention than other colors due to its tendency to absorb heat.
3. By the time the Yak arrives at your door step it will have been handled by a lot of
people. Occasionally there are small dings or imperfections on some of the surfaces. A
neat trick to restore these imperfections to original condition is to use a very fine tipped
hypodermic needle to inject a drop of water under the covering material and into the
ding in the wood. Apply heat to the area with a sealing iron and the imperfection will
disappear. Deeper marks may require that this process be repeated a couple of times to
achieve the desired result, but you will be surprised at how well this technique works.
4. DO NOT SKIMP ON SERVOS! The Yak-54 is equipped with very large control
surfaces that deflect over 45 degrees. A lot of servo power is required to prevent flutter
and to maintain the required deflection for maneuvers. We absolutely recommend the
use of high torque METAL GEAR servos. We have had great success with the Hitec
HS-5955 servos in our prototypes. We also recommend the JR 8611A or new 8711 or
other 180oz torque or higher for all flight surfaces. Note: unless using the JR8711 or
higher torque servo, you may need two ganged servos for the rudder to attain 400oz.
5. Use a high quality epoxy for installing the composite control horns and hinges. We
highly recommend the use of Pacer Z-Poxy 30 minute formula. We have used this glue
for many years with zero failures.

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Hardware
Your new Extreme Flight 110 inch Yak includes all necessary hardware with the exception
of main wheels, axles and collars. These items were omitted as I have been unable to
source satisfactory versions of these items in China. I recommend Dubro 3/16” axles and
collars and 4.5 inch main wheels. If you intend to use the wheel spats I highly recommend
that you use a stiff set of wheels versus soft foam wheels. This will help to prevent the spats
from touching the ground and possibly damaging them.
On the following page is a photo of the various connectors used for the Yak. You will
notice 3 sets of 3mm bolts. The 4 shortest of these (1/2” long) 3mm bolts are the stab
retention bolts which mate up with the pre-installed blind nuts in the rear of the fuselage.
The 2 medium length (5/8”long) 3mm bolts are for securing the carbon fiber tailwheel
assembly (the appropriate blind nuts are already installed in the bottom rear of the
fuselage to accept these bolts). The 4 longest 3mm bolts are for securing the canopy.
You will find a complete pull-pull system, as well as high quality Dubro heavy duty ball
links, titanium turnbuckle pushrods and composite control horns, and a carbon fiber
tailwheel assembly. You will find a white ball link for use on your throttle linkage.
The bonded sealing washers are used when mounting the cowl and canopy/hatch. When
the bolts used to retain the canopy/hatch and cowl are tightened against the bonded sealing
washer, the rubber on the washer compresses, preventing the bolt from backing out. The
rubber on the washer also protects the surface of the cowl. Tighten the bolts until the
rubber compresses, but do not allow the metal part of the washer to make contact with the
cowl.
There are 6 titanium pushrods included in the hardware package. The titanium
turnbuckle style pushrods are used for elevator and aileron actuation.

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Let’s Begin!
Elevator Assembly
1. Locate the horizontal stabilizer/elevator assemblies as well as the composite
control horns and base pieces from the elevator hardware package.
2. Use a sharp #11 blade to open the 2 slots near the bottom leading edge of the
elevator.

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3. Insert the 2 control horns into the base plate as shown in the following
picture. Carefully insert the control horns into the slots and push down until the
base plate is flush with the control surface. You may need to trim the edge of
the base plate to prevent it fro overhanging the bevel. Use a fine tipped felt
marker to trace the outline of the base plate and remove the control horn
assembly. Use a sharp #11 hobby blade to remove the covering 1/16” inside the
lines you drew. Do not cut into an open bay area or into the sheeting, cut
the covering only. Make your cut only where there is sheeting below the
covering.

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4. Use some denatured alcohol to remove any residue or oils from the composite
control horns and base plate. If you wish to paint the control horns for a more finished
appearance now is the time to do so. Use some fine sandpaper to roughen the portion
of the control horns that will be inserted for gluing. Mix up some 30 minute epoxy
(add a little milled fiberglass if you have it) and using a toothpick or an old #11 blade
to force glue into the slots and make sure they are thoroughly coated with epoxy. Use
an epoxy brush to thoroughly coat both sides of each control horn as well as the
bottom of the base plate. Use an abundance of glue here, as any excess will be forced
out of the slot when you insert the horns.
5. Insert the horns and push them into the slots until they are seated flush with the
base plate and the base plate is flush with the control surface. Insert one of the 3mm
bolts through the 2 control horns as shown to insure proper alignment. Use some
denatured alcohol and paper towels to remove the excess glue and inspect the
assembly. When satisfied set this assembly aside to dry. Repeat this process for the
other elevator half.
6. Locate 4 hinges per elevator half. There are two hinges that have one end
shorter, these go into the inner two holes of the horizontal such that they will
not interfere with the socket. Be sure the hinges clear the socket before gluing.

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7. In this step I will outline the procedure we use to install the hinges. There
are several ways to do this and several adhesives you can use. We will describe
the way we do it, as this method has proven itself over many years of model
building. If you are new to this type of hinging process then I recommend that
you install a single hinge first just to acquaint yourself with this method.
Before starting the process get a few items together that will aid you as you
proceed. You will need the following items: 30 minute epoxy (again, we
recommend Pacer Z-Poxy), a scrap piece of pushrod, toothpick or 1/8” dowel,
paper towels and denatured alcohol. Mix a generous batch of 30 minute epoxy.
Use the pushrod or dowel to thoroughly coat the hinge hole with epoxy, then
coat the hinge with epoxy. Push the hinge into its hole until the joint is about a
¼” from its final position and use a paper towel to remove the excess epoxy that
has been forced from the hole. Push the hinge the rest of the way in and make
sure the hinge pin is centered in the hinge line. Use some denatured alcohol
and a paper towel to remove all excess epoxy, especially on the hinge pin.
When you are satisfied with the result set the surface aside to dry. Position the
drying piece so that any excess epoxy will pool around the rear of the hinge.
TIP: you may coat the pin section only with petroleum jelly (or something
similar) to keep epoxy from drying in the pin section. Be sure not to coat
anything but the pin (center) section as that would hinder the epoxy from curing
at full strength. Be sure the hinge is not sideways in the hole.
8. When you are comfortable with this process you should be able to do one
side of a surface per batch of epoxy. Glue all hinges into the stabilizer first.
After the glue has set trial fit the elevator to the stab and adjust if necessary.
There should be as little gap as possible between the stab and elevator. When
satisfied with the fit remove the elevator and repeat the gluing process outlined
above. Be sure to wipe away all excess epoxy! Set aside to dry. Repeat this
process for the other stab/elevator half.
9. After the hinges have dried thoroughly, pull on them to make sure they are
properly installed. The hinges will probably feel a little stiff as it is almost
impossible to get all of the glue out of the joint. Use a fine tipped hypodermic
needle and place one (only one!) drop of acetone on each side of the hinge pin.
Move the elevator back and forth a few times and you will feel it loosen up. Be
careful to only use one drop as you don’t want to weaken the glue joint!
Add a drop of penetrating oil to each hinge pin and you will ensure a smooth
operating surface with no binding. Seal the bottom of the hinge gap with a strip
of Ultracote or Blenderm tape. Be sure to fully deflect the control surface when
applying the tape or Ultracote to allow full deflection once the gap is sealed.

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10. Use a sharp #11 blade to remove the covering from the slot for the elevator
servo control horn. You may have to slightly enlarge this hole to allow for
maximum travel.
11. Before installing the elevator servos, I highly recommend that you
temporarily install the servo arms and electronically center the servos. It will
be much easier to match up the servos at this point than when they are installed.
I also recommend that you thin a small amount of epoxy with a few drops of
alcohol and apply a light coat to the inside of the stab and to the servo mounting
rib as well as to the root rib and mounting tabs. Over time exhaust residue
begins to collect here and by sealing it with epoxy you will prevent degradation
of the wood.
12. Use the manufacturer supplied mounting hardware and install the elevator
servo with the output shaft toward the front of the stab.
This area may
have to be
len
g
thened.

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13. Thread 2 of the heavy duty ball links onto one of the titanium pushrods.
Remember that the ends of the pushrods are reverse threaded so that they can be
adjusted like a turnbuckle without removing the linkage. Insert a 3mm socket
head cap screw into the ball link and into the servo arm. If using the SWB
arms you will need to drill out the hole to accept the 3mm bolt. Secure with a
3mm nylon insert locknut.
14. Place the servo arm onto the servo (which you should have electronically
centered in a previous step) and make sure the elevator is in the neutral position.
Adjust the ball links until the linkage fits between the composite control horns
and lines up with the desired pre-drilled hole. Insert a 3mm socket cap screw,
through one side of the composite control horn, through the ball link, and
finally through the other composite control horn. Secure with a 3mm nylon
insert lock nut. Use blue Loctite on all bolts! Below is the finished set-up.

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15. As mentioned previously, you may need to adjust the size of the servo arm
exit slot to achieve maximum travel. A ¼” Drum sander in a moto-tool makes
quick work of this. Repeat these steps for the other stab/elevator half. Before
you set aside the stabs take a moment with your covering iron and go over all of
the seams with a medium heat setting, paying special attention to the ends of
thin trim stripes. At this point clean the 2 elevator/stab assemblies with Windex
and a soft cloth and put them away in their protective bag.
NOTE: the methods used to install the control horns, servos, hinges and
linkages is virtually the same for the ailerons and to some degree the rudder.
Wing Assembly
16. The assembly process for the wing is almost identical to that of the
stab/elevator. For this reason we will not go into quite as much detail as in the
previous procedure. Remove the aileron from the wing panel. Locate the 4
slots for the control horns and remove the covering from the slots. Follow the
same procedure as outlined previously to install the control horns into the
control surface and hinging the wing. You may need to trim 1/16” from the
front of the composite base plate to prevent overhanging the bevel. Repeat this
procedure for the other wing.

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17. Locate the aileron servo holes and remove the covering from these areas.
Use a sealing iron to seal the edges of the covering to the insides of the servo
opening. Take a few minutes to apply some CA to the joints of the servo rails
and the ribs.
18. The 110” Yak requires 2 servos per aileron. Use the manufacturer supplied
mounting hardware and install the servos with the output shaft toward the
leading edge of the wing and the servo arm pointing to the wing root rib.
We used Hitec 5955TG digital servos and used the Hitec digital servo
programmer to ensure that the 2 servos were properly matched and working
together. Then the 2 servos were attached to a Y-Harness and plugged into a
single port in the receiver. The 2 servos in the other wing were set up the same
way and plugged into an auxiliary port in the receiver and the 2 ailerons were
connected electronically within the transmitter’s programming menu.

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19. We will fabricate the linkage much in the same way as the elevator linkage.
Aileron control horn length should be 1.50”. As always, use blue Loctite on
ALL bolts!

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20. Before beginning the next assembly process, take a few minutes with your
sealing iron on a medium heat setting and go over all seams, paying special
attention to thin trim stripes and the seam at the leading edge of the wing. If
there are wrinkles in the covering on the leading edge sheeting use a heat gun
with a 100% cotton t-shirt to remove them and prevent digging into the wood
with an iron. Use caution and avoid excessive heat as you may cause the
Ultracote to shrink too much and lift at the seams. Also take the time to seal the
hinge gaps with Ultracote or Blenderm tape. Clean the wings with Windex and
put them away in their protective bag.
Rudder Assembly
21. Locate the rudder, the rudder control horns and the 2 slotted base plates.
Use a sharp #11 blade to remove the covering from the 2 pre-cut slots in the
rudder.
22. Trial fit the 2 servo horns through the base plate and into their proper position
flush against the rudder surface. You may need to trim the front of the base plate
so that it does not overhang the hinge line as shown in the photo.
23. Mix up some 30 minute epoxy and milled fiberglass and use a small blade to
fill the 2 slots with epoxy. Use plenty of epoxy and be sure to completely fill the
two slots. Use an epoxy brush to completely cover the areas on the rudder horns
and base plate that will glue into the rudder. Slide the rudder horns back into their

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proper position and immediately wipe the excess epoxy from the horns. Carefully
check and re-check alignment to insure proper positioning. Use some denatured
alcohol and a paper towel to remove any excess epoxy. Re-check the alignment
one more time and set the assembly aside to dry. Repeat for the other side of the
rudder.
Tail Wheel assembly
24. Locate the bag with all the tail wheel parts. Take the main carbon fiber
gear leg and mount the support bushing with the nylon insert nut on top and
tighten. The metal portion that the wheel fits onto, locate that, the top tiller and
1 wheel collar. You will need to grind some flat spots onto the metal wire
portion of the tail wheel assembly, to allow all set screws to mate against a flat
spot to prevent slippage.
25. Slide a wheel collar onto the top of the metal gear. Now slide the gear up
thru the metal support bushing and past the nylon nut. Now position the main
tiller onto the top until it bottoms out and tighten the bolt. Position the main
tiller against the nylon nut and then slide the bottom wheel collar up against the

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metal support bushing and tighten. Now position the rudder tiller in the very
center of the rudder’s bottom and about ¼” from the leading edge of the rudder.
Mark the hole locations and drill for the supplied wood mounting screws and
mount the rudder tiller. See pictures for detail.

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26. Feel along the bottom of the aft bottom fuselage area and you will notice
two holes under the covering. Open these holes and position the carbon gear leg
over them and mount with the supplied machine bolts. Now locate the springs
and mount them within each outer hole of the tillers.

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Fuselage Assembly
27. We’ll begin by installing the landing gear. Locate the carbon fiber main
landing gear. Insert the gear into the slot on the bottom of the fuselage and
center it in the slot. Use the pre-drilled holes as guides and drill through the
plywood landing gear plate and aluminum mounting bracket.
28. The pipe tunnel has a piece of plywood still attached at the front just below
the motor box. It has been laser cut but has some points not cut to hold it in
place. Cut these areas and remove the plywood such that you can see down the
pipe tunnel. Place a washer on one of the longer 4mm mounting bolts and
insert them through the holes you just drilled from the landing gear side. The
preceding pictures show how the bolts will be placed.
29. Secure the landing gear with 4 washers and nylon insert lock nuts from
inside the tunnel.
30. Attach the landing gear fairings with silicon glue. You may want to scuff
the inside of the fairings with sandpaper for better adhesion.
TIP: you may fit these flush with the fuselage, but I left a small 1/16” gap to
allow the landing gear to flex without damaging the fuselage.

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31. Locate the 2 wheel spats and 2 plywood mounting plates. Use sandpaper
to scuff the inside of the spat for better glue adhesion. Drill a hole as shown in
each ply plate about ¼” below center. This will allow the spat to be positioned
slightly higher than center to prevent it from making contact with the ground.
Be sure to position the hole fore and aft properly for tire clearance.
TIP: since the spat is so big and rough fields can wreak havoc on spats, here is a
suggestion. Glue two small carbon strips inside the spat as shown above before
proceeding with step 32.