Extreme Flight 91" Yak-54 ARF User manual

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91" Yak-54 ARF
Assembly Manual
Copyright 2013 Extreme Flight RC
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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 consumer, with a
very high quality model aircraft component kit, from which you, the consumer, 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 with the AMA safety code. It is highly recommended that you join the
Academy of Model Aeronautics in order to be properly insured and 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 30 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. 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 at [e-mail] or 770-887-1794. It is your responsibility to ensure
the airworthiness of your model.

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Congratulations on your purchase of the Extreme Flight RC 91 inch Yak-54 EXP ARF!
This all new design is the result of applying what we have learned from 10 years of flying
the Yak-54 design. Highly refined and thoroughly tested, this new Extreme Flight Yak-54
EXP features weight saving, performance enhancing components. These include carbon
fiber wing and stab mounting tubes, carbon fiber fuselage longerons and wing spars,
carbon fiber 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 50-60cc 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 EXP 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-54 is also a topnotch precision aerobatic machine. It is
capable of performing the entire FAI catalog of maneuvers and it has the kind of “big
plane” presence in the air that will impress the judges. This makes the 88 inch Yak-54 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 Yak-54 EXP!

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Items needed for completion:
Masking tape.
Hobby knife with #11 blades.
Thin and medium CA. We highly recommend Mercury M5T thin and M100XF
medium formulas as well as the Mercury glue tips.
30 minute epoxy. Mercury Adhesives Epoxies have worked very well for us.
Blue and Red Loctite.
Electric drill with an assortment of small drill bits.
Small flat head and Phillips head screw drivers.
Standard and needle nose pliers.
Side cutter.
Metric ball driver or allen key set.
Sanding block and sandpaper.
5 x Ultra high torque metal gear servos (HS-7950TH or comparable).
1 x standard size servo for the throttle.
2 x 1.5” single aluminum Servo Arms for the ailerons
2 x 2” single aluminum arms for the elevators
1 x 4” double aluminum offset arm for the rudder.
2 x 6” Servos Extensions.
2 x 12” Servo Extensions.
2 x 36” Servo Extensions.
4” Spinner.
50cc-70cc gas engine.
Engine Manufacturer recommended prop.

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Tips for Success:
1. Before starting assembly, take a few minutes to read the entire instruction manual
to familiarize yourself with the assembly process.
2. Go over all the seams on the aircraft with a covering iron on a medium heat setting.
Also, due to climate changes, wrinkles may develop in the covering however; these
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.
3. Apply CA to high stress areas such as servo mounting trays, landing gear mounts,
anti-rotation pins, wing and stab root ribs, and motor box joints etc.
4. By the time your aircraft 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. An effective method to restore these imperfections to original condition is
to use a very fine tipped hypodermic needle and 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.
5. Use a high quality epoxy for installing the composite control horns and hinges. We
highly recommend Pacer Z-Poxy 30 minute Epoxy. We very pleased with the results
and ease of application and cleanup of this product.
6. When applying decals, first clean the area where the decal will be applied with
alcohol. Mist the area lightly with Windex or Rapid Tack before applying the decal
which will allow you to properly position it, and then use a rubber squeegee to push
all of the liquid from under the decal. This will result in very few air pockets
trapped under the decal.
7. Take the time to properly balance and trim your aircraft and set up rates and
exponential values. Your flying experience will be greatly enhanced once your plane
is properly dialed in.

Let's begin!
Elevator Assembly
1. Locate the horizontal stabilizer/elevator assemblies as well as the composite control
horns and base plates from the elevator hardware package. Use a sharp #11 blade
or soldering iron to remove the covering over the 2 slots for the elevator control
horns on the bottom of the elevator surface.
2. Insert the 2 control horns into the base plate and trial fit thehorns into the slot,
making sure they seat properly against thebase and elevator surface.
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3. Trace around the base plate with a felt tipped marker.
4. Remove the horn assembly and use a #11 blade to remove the covering from inside
the ink line you traced around the control horn base.
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5. Wipe away the ink line with a cotton cloth or paper towel soaked in denatured
alcohol.
6. Use sandpaper to scuff the portion of the horns and base plate that will be inserted
into the elevator.
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7. Apply 30 minute epoxy to the elevator slots using a zip tie to ensure the slots are
filled will epoxy.
8. Also, apply a generous amount of epoxy to the bottom of the G-10 control horns and
base plate.
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9. Reinsert the assembly into the elevator and wipe away any excess epoxy with a cloth
and denatured alcohol. Place a 3mm bolt through the horns to help insure proper
alignment and set aside to dry. Repeat for the other elevator half.
10. Next, remove the pin hinges from the horizontal stabs. Take note there are two pins
that are shorter than the others - this is to allow for clearance of the stab tube.
Note: There are several methods and adhesives that can be used for installing the
hinges. We will describe the way we do it as this method has proven itself over many
years of model building.
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11. Use a cotton swab to apply petroleum jelly ONLY to the knuckle of the hinge. This
will keep the epoxy from getting into the hinge which can cause it to bind.
12. Mix a generous batch of 30 minute epoxy. Use a zip tie or an old pushrod to
thoroughly coat and fill the hinge holes on the stab with epoxy.
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13. Next, coat one side of all 4 hinges with epoxy and push the hinges into the holes of
the horizontal stab. Remember the short hinges go in the two holes closest to the
fuse.
14. Make sure the hinge pins are centered in the hinge gap and that they pivot 90
degrees to the stab.
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15. Now coat the other side of the hinges as well as the hinge holes in the elevator with
epoxy and install the elevator into the stab. Don’t forget to apply epoxy in the hinge
holes on the stab before installing the stab to the elevator.
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16. Use denatured alcohol and a cloth to remove all excess epoxy, especially on the hinge
pin. Make sure you have full deflection in both directions – once satisfied with the
results, set the surface aside to dry. After the hinges have dried thoroughly, pull on
them to make sure they are properly installed.
Note: Before installing the servos, it’s a good time to seal the hinge gap with a strip
of Ultracote or Blenderm tape. Also, I 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 to protect
against exhaust residue that can collect in these areas.
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17. Before installing the elevator servos, temporarily install the servo arms and
electronically center the servos.
18. Using the manufacturer supplied mounting hardware, install the elevator servo with
the output shaft toward the front of the stab and re-attach the servo arm.
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19. Thread 2 of the heavy duty ball links onto one of the 2 longer 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.
20. As shown in the picture below, secure one end of the ball link to the servo arm using
a 3mm socket head cap screw, washer and nylon insert locknut. If using the SWB
arms, you will need to drill out the hole to accept the 3mm bolt. Secure the other end
of the ball link to the control arm with a 3mm bolt, 2 washers, and nylon insert
locknut being careful not to over-tighten and damage the control arms.
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21. With the servo arm centered (as described in Step 17), adjust the turn buckle on the
control rod until the elevator is in the neutral position.
22. Set the servo endpoints to achieve maximum travel. You may need to enlarge the
size of the servo arm exit slot. Repeat these steps for the other stab assembly.
Note: Now is a good time to take a 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.
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Wing Assembly
23. Locate the wing/aileron assemblies as well as the composite control horns and base
plates from the elevator hardware package. Following the same procedure as
outlined with the elevator / stabs, install the control horns and hinges for both
wings. Each wing has 6 hinges so it’s best to install the hinges in the aileron first
then mix a second batch of epoxy to install the aileron hinges to the wing.
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Note: Before moving to the next step – it would be a good time to seal the hinge gap
with a strip of Ultracote or Blenderm tape. Be sure to fully deflect the control
surface when sealing the gap to allow for full deflection once the gap is sealed.
Also, take a few minutes to go over the wings with a trim iron on a medium heat to
seal all the trim seams and remove any wrinkles in the covering. Use caution and
avoid excessive heat as this may cause the Ultracote to shrink too much and lift at
the seams.
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24. Locate the aileron servo mount and remove the covering from this area. Use a
sealing iron to seal the edges of the covering to the sides of the servo opening. Take a
few minutes to apply some CA to the joints of the servo rails and the ribs.
25. Attach a 6” servo extension to your servo and secure with thread or heat shrink
tubing. Use the manufacturer supplied mounting hardware to install the servo with
the output shaft toward the leading edge of the wing. Electronically center the servo.
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