Extreme Flight RC YAK-54 AFR User manual

110 inch YAK-54 ARF
Instruction Manual

©Copyright 2008 Extreme Flight RC, Ltd.
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 setup 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.
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 setup. 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!
A few tips to ensure success and airframe longevity
1. 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. 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. 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. 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 and now the 7955 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. 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.
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 or 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.
Let’s Begin!
Elevator Assembly
1. 1. Locate the horizontal stabilizer/elevator assemblies as well as the
composite control horns and base pieces from the elevator hardware
package.
2. 2. Use a sharp #11 blade to open the 2 slots near the bottom leading
edge of the elevator.
3. 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.

1. 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.
1. 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.
2. 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.
1. 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.
2. 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.
3. 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.
4. 12. Use the manufacturer supplied mounting hardware and install the
elevator servo with the output shaft toward the front of the stab.
5. 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.
6. 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.
7. 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
1. 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.
2. 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.
3. 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!
4. 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.

1. 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.
2. 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
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
1. 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.
2. 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
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.

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.

18
Fuselage Assembly
1. 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.
2. 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.
3. 29. Secure the landing gear with 4 washers and nylon insert lock nuts
from inside the tunnel.
4. 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.

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.