Semi Scale Yak-54S, ARF 73”

ASSEMBLY MANUAL

Specifications

Wingspan: 73 in
Length Including Spinner: 69 in
Wing Area: 1,060 sq in
Weight (RTF): 11-12.5 lb
Radio: 4-6 Channel W/6 Servos
Recommended Engines:
2-Stroke 1.4-1.6
4-Stroke 1.4-1.80
Gas 26-30cc

1
Table of Contents
Quique’s Aircraft Company 3
Covering Colors 4
Going Over the Covering 5
Hardware Supplied 5
Additional Required Tools and Adhesives 6
Servo Selection 7
Using the Manual 7
Warning 7
Warranty Information 7
Section 1-Preparing Fuselage 8
Section 2-Horizontal Stab Installation 9
Section 3-Vertical Fin Installation 11
Section 4-Preparation and Installation of Hinges 13
Section 5-Elevator, Rudder and Aileron Control Horn Installation 15
Section 6-Rudder & Tail Wheel Installation 17
Section 7-Elevator Servo Installation 19
Section 8-Rudder Servo and Pull/Pull Installation 21
Section 9-Engine Mounting and Throttle Control Installation 24
Section 10-Landing Gear Installation 26
Section 11-Fuel Tank Installation and Engine Box Completion 28
Section 12-Engine Cowling 30
Section 13-Canopy Installation 34
Section 14-Wing Preparation and Aileron Servo Installation 37
Section 15-Battery Tray Installation 39
Section 16-Radio Equipment 40
Custom Muffler 41
Balancing the Model 42
Control Throws 43
Preflight at the Field 45

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 Quique’s Aircraft Company
3410 Saint Paris Pike
Springfield, OH 45504
Phone: (937) 629-0339
Fax: (937) 629-0335
Email: qqaircraft@gmail.com
Website: www.Somenzini.com
www.QQAircraft.com
Online-Support:http://www.rcuniverse.com/forum/forumid_437/tt.htm

Quique and I want to express our thanks to you for choosing our 73” Yak-54 S.
We think that you will enjoy one of the best flying model aerobatic airplanes
available. It is patterned after the 37% Yak-54 which took First Place honors at
the 2003 Free Style Championships in Lakeland Florida, First Place at the Don
Lowe Master competition 2003 & 2004, First Place Tucson Shoot Out 2004 Free
Style, First Place XFC 2004, precision and free-style and Third Place at the
Tournament of Championships in Las Vegas in 2002.

Quique and I have tried to prepare the best assembly manual possible along with
best support on our line of Aircrafts. We are happy to announce that we have a
support forum on www.Rcuniverse.com that is being led by
Mr. Reza Gholamipour. Imagine, you are building your plane during weekend
when we are close and you desperately need to get answer to your question so
you can continue building, well we are happy to tell you that your question is
most likely answered on Rcuniverse forum that we handle, if not, just post your
question and have the answer in matter of hours.

Good flying to you!

Quique & Wayne

3
Covering Colors
Ultra-cote covering used on this 73” Yak-54 S can be purchased from Horizon
Hobbies Website. The codes are as follows:

ƒ Sky Blue Hanu875

ƒ Smoke Purple Hanu868
ƒ White Hanu870
ƒ Bright Yellow Hanu872

Going Over the Covering

Before beginning the assembly of your Yak-54 S, remove each part from its bag
for inspection. If you find any wrinkles in the covering, use a heat gun or covering
iron to remove them. Use caution while working around areas where the colors
overlap to prevent separating the colors. Make sure you go over the edges with
your iron as well.

4
Hardware Supplied

Pull/Pull Rudder-4 hinges Aileron-12 hinges Elevator-6 hinges

Engine Mount Wheels Wing Anti-rotation pins

Engine Cowl & landing gear Tail Wheel Elevator & Wing connecting rods

Fuel Tank Engine Box cowl mount blocks

5
 Additional Required Tools and Adhesives

• Covering/Trim iron
• Xacto knife, #11 blade
• Pacer hinge glue (PT-55)
• 5, 15 and 30-minute epoxy
• Petroleum jelly/Lithium grease
• Acetone/Alcohol swabs
• Felt-tip marker
• Pencil and Marker
• Ruler
• Drill
• Drill bit #1, #3, #28, #51 and #52
• Wire cutter
• Course and fine sandpaper
• Thin, medium and think C/A
• Full threaded servo mounting screws
• Sullivan inner nyrod
• Pliers
• Masking tape
• 1/16” balsa strips
• Ultra fine point sharpie
• Electrical tape
• Double-sided tape
• Small sheet metal screws
• Rat-tail file
• Pin vise
• White glue such as Elmer’s Carpenter’s wood glue
• Round toothpick
• ¼”x3”x3-1/4” balsa wood
• Velcro
Extensions:
• (2) 9” servo extensions for Ailerons
• (2) 24” servo extension for Elevators
• (2) 3” servo extension from receiver to Ailerons

6
 Servo Selection

The servos used for the control surfaces of this Yak-54 S must have a minimum
of 130 ounce-inch of servo torque. In the prototype Yak-54 S, we used
JR8411SA on all control surfaces and on throttle we used one standard JR
servo. Best results can be obtained by using digital servos. Please do not risk
your plane by using low torque servos. This Yak-54 S has large control surfaces
and fully capable of any maneuvers that a pilot is able to perform, therefore using
weak servos will increase chance of flutter and can cause you crash.

Using the Manual

This manual is divided into sections to help make assembly easier to understand
and to provide breaks between each major section. Remember to take your time
and follow the directions.

Warning

I am sure that for the most of you this is not your first venture into the World of
flying radio controlled aircraft. For those of you that may be entering this exciting
sport early on in your modeling experience and for you with vast experience, I
think we all need to be reminded of the possible dangers that are associated with
a high performance aircraft of this type. This is not a toy. This aircraft flying at a
typical weight of ten pounds and up to one hundred miles per hour will inflect
unbelievable damage to property, life and limb. This aircraft must be flown in a
safe manner at all times. You should always do a preflight check including control
surfaces hook-ups, radio operation, (please refer to your radio equipment
instruction manual for range checks and other pertinent related information) and
all other checks relating to the safe operation of this aircraft.

Warranty Information

Quique’s Aircraft Company guarantees this kit to be free from defects in both
material and workmanship at the date of purchase. This warranty does not cover
any parts damaged by use or modification. In no case shall QQAC’s liability
exceed the original cost of the purchased kit.

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 Section 1-Preparing Fuselage

Required Tools and Adhesive Step 2

• Xacto knife, #11 Blade Cut the film on the horizontal stab
• Trim Iron openings, both elevator servo
• White Glue openings and the slots for the rudder
• 1/16” balsa strips cables. Please note that the elevator
servo opening on the right side of the
Step 1 fuse is forward of the elevator servo
opening on the left side of the
Use a Xacto knife with a # 11 blade fuselage. There is a hole on the right
and cut away the film covering on side of the fuse just opposite of
both sides of the fuselage for the opening on the left side however it is
wing openings, Figure 1. a lightning hole and a little smaller
Some modelers may want to overlap than a hole required for a servo.
the film covering down inside the
fuse in the opening for the wing. For Note: You may want to add four
example this type of an opening for pieces of 1/16 balsa strips
the wing may be done as follows. approximately ½ inch wide inside the
Simply cut the film about 1/8 of an fuselage on the foam in the locations
inch to the inside of the opening for shown in Figure 2. They are best
the wing. You may then bend this applied with white glue. We
extra 1/8 inch flap of film over ninety mentioned this small situation to our
degrees to the inside of the fuse OEM and these areas should be
opening and iron it to the edge of the covered with some small plywood
balsa sheeting over the foam. Use pieces on your Somenzini Yak-54S.
the trim iron for this application. Do
not touch the foam, bead board, with
your trim iron. Watch how much
heat you use here as too much will
melt the foam.

Figure 2

Figure 1

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 Section 2-Horizontal Stab Installation

Required Tools and Adhesive

• Ultra fine point Sharpie

• Acetone
• Xacto knife, #11 Blade
• Felt tip marker
• Thin and thick C/A

Step 1

Center the H. Stab so that the left tip

and right tip are equal distance from Figure 4
the fuselage sides. See Figure 3.
Step 3

Mark lines on both sides of the H.

Stab top and bottom with a fine felt
tip black marker, an Ultra Fine Point
Sharpie ® works well in this
application. Later when you are
ready to remove the black lines,
acetone works best.

Step 4
Figure 3
Remove the H. Stab from the fuse.
Mark a line, measured 1 mm on the
Step 2 inside of the two lines top and
bottom that you marked along the
Square up the H. Stab by measuring right and left sides of the fuse.
the diagonal distance from the turtle
deck to the back corners (left and
right) of the H. Stab. They must be
the same distance. See Figure 4.

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Step 5 To do this, you may sight down the
fuselage from the rear.
Use a new # 11 blade and gently cut See Figure 6. Make sure you are
through the ultra cote. See Figure 5. looking straight down the middle of
There are two layers, cut through the the fuse.
top layer first and remove it. You
have probably cut through the
second layer. If not you may cut
through the second layer. Be very
careful not to cut into the balsa
sheeting as this will weaken the
structure of the Horizontal Stab as
the skin sheeting is important to its
structural integrity.

Figure 6

Step 8

Sight both sides of the H. stab and

compare with both sides of the wing.
If one side is lower and the other
higher, you will need to shim so both
the H. stab and the wing halves are
Figure 5 parallel. Our prototype needed a little
adjustment. We used a round
Step 6 toothpick to wedge the one side
down a little. It was not enough so
Use your iron to seal down the Ultra- we used another round tooth pick on
cote where you removed the center the other side of the fuse on the
section before you make the final opposite side to bring the H. stab
attachment. parallel with the wing. See Figure 7.
It should not take much shimming to
Step 7 get it perfect. It is almost impossible
for our OEM to assemble this fuse so
Re-insert the H. Stab into the that the H. stab and wing are always
fuselage. IMPORTANT: Check the parallel. You can see that the little
measurements again, see Figure 3 & wedges with the round toothpicks
Figure 4 to make sure the H. Stab is can correct this small problem with
square. Before you make the final very little adjustment. Now you are
attachment of the H. stab to the fuse, ready to glue in place.
you must check to see that the H.
stab is parallel with the wing.

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 Section 3-Vertical Fin Installation

Required Tools and Adhesive

• Acetone
• Xacto knife, #11 Blade
• Felt tip marker
• 30-minute epoxy
• Alcohol Swab/Alcohol and
paper towel
• Round toothpick
• White glue
Figure 7
Step 1
Step 9
Insert the Vertical Fin in the fuse.
Place the fuse so the H. Stab is Mark a line along the V. Fin and
vertical so the thin C/A glue will flow fuse. See Figure 8.
into the fuse sides.
Apply the thin C/A glue along the H.
Stab on both sides that do not have
the tooth pick wedges. Let the thin
C/A set up and then apply some
more thin C/A on the sides with the
toothpick wedges. Be careful not to
glue the toothpicks in place, as you
will of course remove them as soon
as the thin C/A sets up.

Step 10
Figure 8

Remove the toothpick wedges. Step 2

Apply a fillet of medium C/A over all
of the areas between the fuse sides Mark another line about ¼ or an inch
and the H. stab. If there is a small below the first line that you drew.
gap, simply work more of the thick
C/A into the small gaps.

11
Step 3 blade is helpful. Remove the black
ink line with acetone.
Remove the film covering as shown.
As with the Horizontal Stab there is Step 5
more than one layer of film. By
removing the film covering you will Glue in place with 15 to 30 minute
have a stronger bond between the epoxy glue. Remove any excess
Vertical Fin and the Fuse as shown. epoxy with alcohol and a paper
See Figure 9. towel.

Step 6

After epoxy hardens, check to make

sure the hinge slots between the
rudderpost and fuselage did not fill
up with epoxy. Before the epoxy
hardens, you might be able to clean
out most of the epoxy with a round
toothpick or thin piece of 1/64
plywood. The bottom hinge slots are
where the problem might occur. If
Figure 9
the epoxy hardens before you clean
out the hinge slots you will have a
Step 4 problem. White glue could also be
used to attach the vertical fin and
Be careful to make a very shallow clean up with water and a piece of
cut through the film on the V. Fin so paper towel would be much easier.
you do not cut too deeply into the V.
Fin sheeting. A very sharp # 11

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 Section 4-Preparation and Installation of Hinges

Required Tools and Adhesive

• Xacto knife, #11 Blade

• Lithium grease/Petroleum
Jelly
• Toothpicks
• Pacer hinge glue (PT-55) or
30-minute epoxy

The hinge slots are already installed

in the balsa hinge locations on both Figure 10
the fixed surfaces and the moveable
surfaces. However they are covered
up with the covering film so they may
be a little difficult to see and locate.
Look closely and you will find the
hinge holes. I find them more easily
by running my finger along the edge
where the hinges are located. You
should feel a little depression in the
film at the opened slots under the
film.

Step 1
Figure 11
Use a # 11 blade to open the flat
hinge slot. Step 3
The hinge slots will have to have a
larger opening cut out just on either Make a V- cut in the fixed and
side, top and bottom, of the pivot control surface area along the slot
point on both surfaces. So you will location of the flat hinge. This
need to open the area in the fixed additional V- slot will insure that the
and moveable surfaces of the hinge will insert far enough into the
ailerons, elevators and rudder. hinge slot so it is in the proper
location and provide enough depth
Step 2 for the each hinge. The gap between
the flying surface and the control
Use a #11 blade and make a wedge surface needs to be at a minimum.
tapered opening to accept the However we have to have enough of
pinned hinge area of the hinge. See a gap so full deflection is possible.
Figure 10 & 11.

13
Step 4

Check the gap on each control

surface. The gap should be
somewhere between 2 and 3 mm.
This procedure will take some time
to do all of the hinges but take your
time and do a nice job. As you do
each hinge and check out the proper
depth and shape of the V-slot
necessary for each hinge, the time
Figure 12
involved to do each subsequent
hinge will lessen.

Before you glue the hinges in Step 5

place:
Take some lithium grease or Sealing the Control Surfaces
Vaseline and apply a very small
amount on both sides of the hinge After you are done hinging the
point on the flat hinges. Quique used ailerons and elevators, make sure
a round toothpick. See Figure 12. you seal the hinge line by using clear
This will help prevent any glue in the ultracote. Unsealed control surfaces
pivot point. may cause flutter like aileron flutter,
Be very careful not to get any grease which may cause your plane to
etc. on the flat part of the hinges. crash, where sealed control surfaces
Also remember that you always glue will give you better and crisper
the hinges in to the fixed surfaces response in flight.
first, let the glue harden before you
then glue in the control surfaces. For each aileron, cut ¾”x32” of clear
Remember to check for the correct untracote and seal the hinge line
hinge gaps for rudder, elevators and from bottom using a straight edge
ailerons. You must have the correct and trim iron.
gap to insure the maximum control
deflection necessary for the best 3-D For each half elevator, cut ½”x10” of
aerobatics. For hinge attachment we clear unltracote and seal the hinge
like to use Hinge Glue by Pacer. line from bottom same way as you
You may use epoxy if you wish. If did your ailerons.
you use epoxy, use an epoxy with a
curing time that will give you enough
time to work the hinges in place
before the epoxy hardens.

14
Section 5-Elevator, Rudder and Aileron Control Horn Installation

Required Tools and Adhesive Step 3

• Course sandpaper Then clean with alcohol or acetone

• Xacto knife, #11 Blade and glue in place with epoxy. Be
• 30-minute epoxy sure that the attachment point on the
• Alcohol Swab/Alcohol and control horn is perpendicular to the
paper towel hinge line. See Figure 14.
Elevator Horn Installation

Step 1

Cut the slots in the bottom of the two

elevators to accept the two PC
Board elevator control horns. See
Figure 13. Notice that the slot is
located on the blue line. Again, rub
your finger over the approximately
location for the cut out to find it more
easily. Figure 14

Rudder Control Horn Installation

Step 1

Find the location in the rudder where

the P/C Board rudder control horn is
to be inserted. Remove the film
covering as shown in Figure 15.

Figure 13

Step 2

Rough up the surface of the P/C

board control horn with coarse
sandpaper only where it will be glued
into the elevator.

Figure 15

15
 Find the location on the ailerons for
Step 2 the P/C Board control horn and
remove the film for both locations.
Again rough up the surface on the See Figure 17.
P/C board control horn that will be
glued into the rudder. Clean with
alcohol or acetone and epoxy. Be
sure that the rudder horn is square to
the rudder. You should be able to
eyeball this. See Figure 16.

Figure 17

Note that the connecting hole on the

P/C board aileron control horn for the
connecting rod attachment should be
about 1/8 inch of an inch to the rear
Figure 16 of a line that is perpendicular to a
line drawn through the centerline
Aileron Horn Installation chord of the wing. See Figure 18,
which shows a straight edge with a
Step 1 projected perpendicular line.

Find the location for the aileron

servos in the bottom of each wing.
Note that the openings are in the
middle purple stripe. The location for
the aileron servo is also located in
the middle purple stripe. Note that
there are two rectangle openings
there. Use the smaller opening
available that is closest to the
fuselage. The other hole is one of
many lightening holes to keep your
Figure 18
Somenzini designed Yak-54 extra
light. Every little bit helps.
Step 3
Step 2
Glue the control horns in place with 5
Cut out the film over the servo or 30-minute epoxy. If you work at a
location hole. slow pace, perhaps you should
choose the 30-minute.

16
 Section 6-Rudder & Tail Wheel Installation

Required Tools and Adhesive Step 3

• Xacto knife, #11 Blade Cut the wire that will go into the
• 30-minute epoxy rudder to about one inch in length.
• Alcohol Swab/Alcohol and
paper towel Step 4
• Wire cutter
Cut a V-slot in the bottom of the
You should have already prepared rudder to allow the space needed for
all flat hinge slots for all control the tail wheel wire.
surfaces. For flat hinge attachment
method, please refer again to Step 5
Section 4-Preparation and
Installation of Hinges. Drill a hole in the rudder for the tail
wheel wire one inch from the bottom
Step 1 of the rudder. Again please check
the v-slot in the bottom of the rudder
First place the plastic tail wheel to make sure it will allow the hinge to
bracket on the tail wheel wire. insert deep enough into the rudder.
See Figure 20.
Step 2

Bend a 90-degree angle in the

correct direction on the tail wheel
wire that will be inserted in to a hole,
which you will soon drill into the
rudder. See Figure 19 that shows a
one inch distance from the 90-
degree bend to the bottom of the
plastic tail wheel-mounting bracket.

Figure 20

Notice the hole that will accept the

tail wheel wire is just above the
hinge and the point of the Xacto
blade in this same picture.

Figure 19

17
Figure 21 shows the tail wheel Step 8
assembly ready for placement into
the rudder. Check the hinges for the proper
depth and allow the epoxy glue to
harden.

Step 9

Glue the rudder in place. Use

30- minute epoxy for the tail wheel
wire attachment wire that is inserted
into the rudder and also for the
hinges that will be inserted into the
rudder.
Figure 21
Step 10
Step 6 After you have the epoxy applied,
slip the rudder onto the hinges.
Use the four screws provided and Clean up any excess epoxy from all
attach the tail wheel bracket areas with alcohol to keep hinges
assembly to the fuselage. See from freezing up.
Figure 22.

Figure 22

Step 7

After you have checked to make

sure all hinge slots are deep enough
and also that the V-slots are properly
cut and you have made a dry run
attachment, you may glue the hinges
into the vertical fin and fuse.

18
 Section 7-Elevator Servo Installation

Required Tools and Adhesive

• 24” servo extension

• Sullivan inner nyrod
• Pin vise
• 2 full threaded servo mounting
screws

Step 1

Attach 24-inch servo extension wires Figure 23

to the elevator servos. You may want
to wrap the servo plug connections Step 4
with a small piece of tape.
Mount both elevator servos. Drill the
Step 2 proper diameter holes with a pin vise
into the hardwood servo mounting
To run the servo extension wires rails for the servo mounting screws.
forward, use a piece of Sullivan inner Mount the servos so the output shaft
Nyrod and place it through the oval end of the servo is toward the front
holes in the bottom of the fuse of the fuselage.
formers starting from the canopy
hatch area and exiting through the Step 5
elevator servo mounting opening.
Attach the two extended elevator
Step 3 control arms, provided, to the round
servo control arms with some small
Use a piece of tape and attach the screws. These screws are not
Nyrod to the end of the elevator provided. See Figure 24.
extension servo wire and gently pull
the extension through the oval holes
exiting into the canopy hatch area.
See Figure 23.

Figure 24

19
Step 6

To attach the elevator servo control

arms to the elevator control horns,
use the titanium elevator connecting
rods, provided. The longer titanium
control rod is for the right side of the
fuse. Note that the ball links provided
should be mounted as shown in
Figure 25.

Figure 25

The ball links are mounted on the

outside of the servo arms and on the
inside of the elevator control horns.
The titanium control rods have
reverse threads for easy adjustment.
The plastic ball link connectors do
not have any threads so when you
turn the titanium connecting rods in
place you are in essence making the
threads as you make your
connections.

20
 Section 8-Rudder Servo and Pull/Pull Installation

Required Tools and Adhesive avoid any metal-to-metal contact,

which might cause R/F interference.
• Pliers
• Masking tape
• 2 full threaded servo mounting
screws

Step 1

Install rudder servo as shown in

Figure 26. Notice the servo wire is
threaded through the oval holes in
the bottom of the fuse formers and
threaded forward to the radio
receiver-mounting tray.
Figure 27

Step 3

On one end of each cable only,

attach the pull/pull cable to the
brass-threaded connection pieces
using the brass tubes pieces, both
provided, as shown in Figure 28.

Figure 26

Step 2

Attach the black double rudder servo

arm as shown in Figure 27 with two
small screws (servo mounting type),
not provided. You may also attach
the ball links, provided, as shown in
Figure 28
the previous picture. Note that the
taper of the black rudder extended Step 4
servo arm is mounted so that the
tapered part of the arm is facing to Crimp the brass tubes pieces with
the front of the fuse. Also note that pliers. Make a good firm crimp and
the pull / pull control cables will be then it’s important to follow up with
crossed. They are plastic coated to some thin C/A applied on both ends

21
of the crimped brass tube pieces and neutral position also so you will be
the cable. able to determine the final length of
each pull/pull cable.
Step 5 Step 9

Screw the threaded brass Slip the brass sleeve over the end of
connectors half way into the plastic the cable and then through the hole
ball link connection on the extended in the end of the threaded brass
rudder servo arm as shown as connector.
shown in Figure 29.
Step 10

Put the loose end of the cable

through the brass tube.
Make your final length adjustment on
the pull/pull cables. See Figure 30.

Figure 29

Step 6

Install both pull/pull cables on the

extended rudder servo control arm
as shown in the same picture. To Figure 30
complete the pull/pull attachment to
the rudder control horn, you will need Step 11
to turn on your radio to hold the
rudder servo arm firmly in neutral. Hold the threaded brass connection
Adjust the rudder servo arm with piece along the side of the plastic
your trim functions on the transmitter ball connector; you may tape it if you
so you have a good neutral. wish, where about half of the threads
would be inserted into the plastic ball
Step 7 connecting piece.

Cross the cables and exit them

through the slots at the rear of the
fuse.

Step 8

Tape the rudder to the front of the

vertical fin so it will be held in a

22
Step 12

Bend the cable over and slip the

loose end into the brass sleeve.
Important: Do not use the spacer
when assembling the ball link to the
rudder control horn. See Figure 31.
This spacer is not needed in this
application and think of all of the
weight you will save.

Figure 31

23
 Section 9-Engine Mounting and Throttle Control Installation

Required Tools and Adhesive

• Drill
• #3 (0.213”) drill bit
• #1 (0.228) drill bit

Step 1

Mount your engine on the two engine

mounts provided. Note that the prop
hub of the engine must be exactly
Figure 33
5.5 inches in front of the back of the
two engine mounts. This is shown in Step 3
Figure 32.
Look at Figure 34, which shows the
measurements from the outside of
the engine box to accommodate the
right thrust. This picture shows that
the centerline of the engine crank
shaft at the fire wall to be 78 mm
from the right side of the engine box.
This vertical line is not in the center
of the engine box because the
engine must be off set to
accommodate the right thrust of the
Figure 32 engine. We want the centerline of
the crankshaft to exit the middle of
Step 2 the front of the engine cowling or as
close as we can. The exact mounting
Look at Figure 33, which is the front holes for the mounting brackets will
of the engine firewall. There is one vary in width depending on which
horizontal and one vertical line engine you choose.
drawn. They are centered on the
centerline of the 22 mm diameter
hole cut in the firewall, which
represents the x and y for the
location of the centerline of the
crankshaft if it were to pass through
the middle of this hole. Notice that
the vertical line is 57 mm from the
top of the engine firewall.

Figure 34

24
Step 4 mounting should look something like
this. Figure 36 and 37.
Determine the location of the holes
on the firewall for installing the
engine mount, mark them and drill
the holes through the firewall using a
#3 drill bit .213 of an inch in diameter
to accept the blind nuts provided. A
good tool for the centering of the
holes for mounting the engine is
available from Central Hobbies. See
Figure 35. It has a small drill bit
which you turn by hand to locate a
Figure 36
starter hole and mark before drilling
the final holes for mounting the
engine.

Figure 37
Figure 35
The lengths of the blind nuts for Step 5
mounting the engine are a little too
long for the firewall. They will After the engine is mounted, install
protrude through the front of the the throttle control that is provided to
firewall. So you will need to counter the throttle servo. Depending on your
sink a clearance hole in the back of choice of an engine, the throttle
the plastic engine mounts. Use a no. control rod may enter either the left
1 drill bit, .228 inches in diameter side or right side of the fuselage
and drill a clearance hole that is passing by the fuel tank. In either
about 1/8 inch deep into the back of case it is not a problem as the
the plastic engine mounts which will engine control servo is mounted to
accept the blind nut protrusion accommodate the control rod
through the front of the firewall. Use connection on either side. The
a slow speed on your electric drill engine box will be finished later. The
and also do not push too hard. Do top needs to stay open at this point
this procedure very slowly, as would so you can install the fuel lines more
a brain surgeon. Don’t need any slip- easily. The fuel lines from the engine
ups here. Your engine after to the fuel tank should enter through
the round hole in the firewall.

25
 Section 10-Landing Gear Installation

Required Tools and Adhesive Mounting Landing Gear to

Fuselage:
• Drill and #3 (0.213”) drill bit
Step 3
Step 1
Place the landing gear on the fuse in
Drill two holes in the landing gear to the correct position and mark the two
attach the gear to the fuselage. See mounting hole locations with felt
Figure 38. tipped pen or similar marker through
the two landing gear holes.

Step 4

Remove the gear and drill the holes

in the fuselage landing gear plate
with a # 3 drill bit.

Step 5

Insert the two blind nuts as provided

on the inside of the fuselage on the
Figure 38 landing gear mounting plate. See
Figure 40. The blind nuts will
Step 2 protrude through the plywood
landing gear mounting plate as they
Drill the holes in the landing gear did on the engine firewall so you will
legs for the axle and the wheel pant have to drill a clearance hole in the
attachment screw. See Figure 39. gear to accept this protrusion. It will
only be a very shallow clearance
hole, maybe 1/16 inch so be very
careful when drilling this clearance
hole so that the drill bit does not grab
the landing gear.

Figure 39

Figure 40

26
Step 6

Attach the wheel and wheel pant to

the gear. Do not drill the hole in the
wheel pant to accept the wheel pant
screw just yet. Assemble as shown.
Use 4mm x 50mm axle screw. Use 3
washers and two lock nuts that are
provided as shown for each wheel.
Figure 42
Step 7

Put a washer on the gear axle and

place the axle though from inside of
the landing gear leg.

Step 8

Add a washer and one of the locking

nuts with the plastic locking ring
against the inside of the wheel.
Quique used a battery-powered drill
and held the lock nut in place with
pliers to attach the lock nut. Do not Figure 43
tighten completely as the wheel is
not ready to be installed. Step 10

Step 9 Measure the angle for the wheel

pant. With the wheel pants attached
Add the other lock nut with the nylon- to the landing gear but not yet fully
locking ring to the outside of the tightened, place the fuselage on a
wheel. See Figure 41, 42 and 43. table. Have a friend hold the tail of
the airplane up to a flight line
position. See Figure 44.

Figure 41
Figure 44

27
 Section 11-Fuel Tank Installation and Engine Box Completion

Required Tools and Adhesive

• Medium C/A
• 15-30 minute epoxy
• Velcro
• ¼”x3”x3-1/4” balsa wood
• Masking tape
• Sandpaper
• Double sided tape

Step 1

Assemble the fuel tank hardware as Figure 46

shown. See Figure45. Be sure the
vent tube with the short piece of fuel Step 3
tubing is cut at an angle that is
located at the top of the inside of the Place a piece of double sided servo
fuel tank when the tank is mounted mounting tape 3 inches long by 1- ½
in vertical position. The tank should inch wide on top of the fuel tank
be mounted in the fuselage so it is floor.
tall and less wide. Now install the fuel tank with Velcro
and double sided tape between the
tank and tank plate. See Figure 47.

Figure 45

Step 2 Figure 47

Before you mount the fuel tank you Important: Make sure the tank is
need to make a floor for the fuel firmly secured. Keep in mind that
tank. with a full fuel tank, say 12 ounces,
Glue a piece of balsa 1/4” x 3” x 3- with an airplane pulling 10 G’s
1/4” with the grain of the balsa creates a force of 120 ounces or 7.5
running the 3-1/4” direction. See pounds. With this much force the full
Figure 46. fuel tank might just like to take on a

28
mind of its own. Ten G’s would not
be uncommon in some violent 3-D
maneuvers, which this Yak-54 is
capable of doing certainly with the
control surface throws that you have
available.

Step 4

Install the fuel lines per the

manufacturer’s instructions for the
Figure 49
engine of your choice shown in
Figure 48 are the lines that Quique
installed for his YS-140 Sport Step 6
engine.
Lightly sand the burnt laser cut
edges on top side of the fuse sides
and firewall where the top lid of the
engine box is to be secured.

Step 7

Attach the plywood piece to the top

of the engine box with 15 minute or
so epoxy. Important: do not apply
any epoxy on the top piece or the
vertical plywood former just in front
Figure 48 of the canopy hatch where the slot is
located to hold the canopy in place.
Step 5 Also do not apply epoxy on the
engine box lid where the slot is
After the fuel lines are installed, you located in the vertical half former just
may glue the lite-ply top piece onto in front of the canopy hatch. Use
the top of the engine box. But before masking tape as a clamp to hold the
you do that you should glue the three lid down while the epoxy is
triangle stock reinforcing strips hardening. See Figure 50.
around the inside at the top of the
box with medium C/A glue. See
Figure 49.

29
Figure 50 Figure 51

If you inadvertently get any epoxy in Figure 52 shows the location of the
that slot area, make sure you clean it bottom blocks.
out. If any excess epoxy gets in that
slot and hardens it won’t be much
fun to clean out and the canopy
hatch will not slip into position.

Step 7

Install the muffler and get ready for

next section to cut the cowl.

Section 12-Engine Cowling

Figure 52
Required Tools and Adhesive
Very Important: Before you mark
• Course sandpaper
and make the final locations for the
• 15-30 minute epoxy
four cowl mounting screws, always
• Pencil/Marker have the canopy hatch in place.
• Drill & #51 drill bit Other wise you will not be able to slip
• Masking tape the canopy hatch under the engine
cowling.
Step 1
Follow below steps to mark the four
Rough up the areas of contact with cowling screw attachment location.
some coarse sandpaper before you
attach the four hardwood blocks to Step 2
the round fuse former at the rear of
the engine cowling and the engine Put some masking tape on the fuse
box with epoxy. Make sure that the behind the four hardwood blocks that
beveled part of the blocks is flush you installed.
with the round fuse side, see Figure
51. This picture shows the two top
block locations.

30
Step 3 the top of the cowling is parallel to
the canopy hatch behind it.
Draw a line that matches up with the
middle of the hardwood blocks and Step 6
back onto the masking tape pieces
you just placed on the fuse. Cut the holes needed in the engine
cowling for the clearance of the
Step 4 engine head, muffler and any other
protrusions that will ultimately be
Measure back one half inch from the outside of the engine cowling.
front of the fuse former and make a Please read the second paragraph
vertical line. That is the distance of from here for cutting out the holes in
the overhang of the engine cowling the engine cowling for some helpful
over the fuselage. See Figure 53. hints. If you do this now before
making the final attachment of the
engine cowl, it will be easier to make
sure that the crank case will be
centered in the front of the engine
cowling. See Figure 54 as an
example of the holes to be cut in the
engine cowling.

Figure 53

Step 5

Slip the engine cowling, on the

fuselage, remember with the canopy
hatch always in place, over the four
pieces of masking tape you have
affixed with the one half inch vertical Figure 54
lines with the back of the engine
cowling on those vertical marks. Step 7
Double check to make sure the
engine prop hub is somewhere close Slip the engine cowling on the
to the center of the hole in the fuselage and put some masking tape
engine cowling. If not you may want just in front of horizontal lines that
to make some slight adjustments by you put on the masking tape on the
shifting the engine cowling. However fuse. Extend the horizontal lines that
it is probably more important to you see in picture 53 on forward onto
check to see if the cowling overall the engine cowling.
looks straight on the fuselage. Like if

31
Step 8 muffler that will protrude outside of
the engine cowling.
Mark a vertical line one inch in front
of the back of the engine cowling. Step 12
These are the locations for the four
holes to fasten the cowling to the Cut a hole in the front of the engine
fuselage. See Figure 55. cowling for the air to enter and cool
the engine. You will also need to
make sure you have enough area
cut out in the engine cowling behind
the incoming air hole to allow the
incoming air to exit properly. A
general rule of thumb is to have the
exit area at least two to three times
the area of the incoming air. Be
careful and do not make the income
air hole too large. It can be smaller
than you may think. Specifically, it
should not be any wider that the
Figure 55
outside of the cooling fins on the
engine. Figure 56 shows the cut outs
Step 9 used for the YS-140 Sport Engine
used in Quique’s proto-type test Yak-
Drill the four holes with a # 51 drill bit 54.
through the cowling and on into the
wood blocks. Go ahead and insert
each screw as you drill each hole.
This will help to hold the cowling in
place as you drill the other holes.
Check to make sure the cowl hasn’t
shifted position after you attach each
new screw.

Step 10

After all of the holes are drilled,

remove the cowl and enlarge the Figure 56
holes in the cowl to accept the
diameter of the cowl mounting
screws. Now it is time for the fun
part.

Step 11

Cut out the engine cowling and

remove enough material to make
room the part of the engine and

32
Notice the hole cut out in the front of
the engine cowling in the area that is
painted black. This of course is for
the incoming air that will pass
through and around the cylinder to
cool the engine. When you are ready
to attach the engine cowling, we
have found that it is very helpful to
use a small O-Ring, 3/32” I.D.,
provided, between the two metal
washers used to attach the cowl.
Figure 58
See Figure 57.

Figure 57

When using a rubber O-Ring and the

two metal washers, we have not had
any problem with the cowl screws
coming loose. Figure 58 shows the
cowling with the YS-140 Sport
engine installed and the entire
engine cowling cutouts for incoming
air and exiting air.

33
 Section 13-Canopy Installation
nuts that you will install in the inside
Required Tools and Adhesive of the tabs.

• Xacto knife, #11 blade Step 4

• Drill and drill bit #28
• Thin/Medium C/A Insert the blind nuts on the inside of
• Rat-tail file the canopy hold down tabs and
tighten the 3mm screws with the
There are two holes in the fuse, one Allen wrench provided to seat the
on each side, to accept the screws to blind nuts firmly into the plywood tab.
hold the canopy in place. See Figure 60.

Step 1

Find the locations for the two screw

holes. They are 1-1/2 inches forward
from the back of the canopy hatch
and 5/16 inch below the canopy
hatch line.

Step 2

Use your Xacto # 11 blade and Figure 60

remove the Ultra-Cote.
See Figure 59. You should run a little thin or
medium C/A around the blind nuts
on the inside of the tabs to help them
stay in place.

Step 5

If you have measured correctly, you

should now be able to insert the two
canopy hold down screws that are
3mm x 20mm into the blind nuts.
Make sure the length of these
Figure 59 screws is at least 20mm. If the
screws do not line up with the blind
Step 3 nut hole in the canopy hold down
tab, open up the hole in the fuse side
Now slip the canopy in place onto a little with a small rat-tail file until
the fuselage and drill the holes in the the screws go in properly.
canopy plywood tabs for the blind

34
Step 6

At this point you should drop a little

thin C/A glue around this hole in the
fuselage side to make the lite-ply
fuse side harder. The C/A will soak
in and make the light ply more like
regular aircraft plywood.

Step 7

Tighten the canopy screw down

firmly it won’t crush the harden lite-
plywood. We want to do all we can to
prevent the canopy from removing
itself during flight. It is very important
to use a 3/32” diameter O-Ring on
the canopy hatch like on the engine
cowling screws. Use flat steel-
washers, O-Ring and another flat
steel washer. If tightened properly,
you should never loose a canopy in
flight.

35
 Section 14-Wing Preparation and Aileron Servo Installation

Required Tools and Adhesive Important: the measurement from

the root chord rib to the center of the
• Xacto knife, #11 blade locking pinhole is 9mm. See Figure
• Fine sandpaper 61.
• Thin C/A
• 5-15 minute epoxy
• Alcohol swab/Acetone
• 9” servo extensions (2)
• Small sheet metal screws
• Ruler

Step 1

Cut out the film covering over the

access holes for the aileron servo Figure 61
mounts. Please note that the aileron
servo is located on the bottom of the Also, equally important, the locking
wing, approximately in the middle of pinhole must be vertical. See Figure
the middle purple stripe. There are 62.
two rectangle openings in the middle
purple stripe. The aileron servo cut
out is the rectangle opening closest
to the fuselage. Remove the film
covering here. The other hole is a
lightning hole.

Step 2

Next, install the anti-rotation pins as

follows: Lightly sand the aluminum Figure 62
anti-rotation (AR) pins on the end
that inserts into the wing sockets You will find that the two holes in
with 400 or very fine sand paper. Of each of the wing roots that accept
course the hole in the pin goes into the anti-rotation pins are a little
the fuselage. oversized. This should not be a
major problem. However you may
Step 3 have to adjust the size of the hole in
the fuse sides into which the pins
Clean sanded pin with alcohol or slip. You may do this with a small
acetone. Slip pins in the sockets. rat-tail file. Be very careful that you
don’t make the hole size too big.

36
Step 4

After you have checked all of these

four holes for proper depth, use thin
C/A glue and apply around the pins
to affix them to the root rib of each
wing.

Step 5

Use some epoxy and make a fillet of

Figure 64
epoxy inside the wing around the
anti-rotation pin and the second wing
rib. See Figure 63. Step 9

Slip the wings onto the airplane and

attach the donut and locking key it
should look like Figure 65.

Figure 63

Step 6
Figure 65
Install two (AR) pins per each wing
half.
You should be able to install and
Step 7 remove the rear locking pins with
only your hand. As the front locking
Make up the four-donut cushion wing pins are close to the fuel tank, you
keepers that you will use when may want to use a pair of needle
attaching the wing halves to the fuse. nose pliers to insert and remove.

Step 8 Step 10

Glue the black O-ring to the metal Now install the aileron servos.
washer with thin C/A. Four required.
See Figure 64.

37
Step 11

Attach a nine-inch servo extension

cable to the servo. You do this by
using the same system you used to
install the elevator servo extension
cables. To insert the aileron servo
extension wires, use a music wire
with a loop end and pull the
extension through the servo lead
hole in the wing root rib.
Figure 67
Step 12

Install the aileron servo.

Step 13

Attach the extended aileron servo

arm, provided, to the round servo
arm that came with your servo. Use
small sheet metal screws, not
provided. See Figure 66.

Figure 66

Use the two short titanium rods and

ball links provided to make the
connection between the extended
aileron servo arm and the P/C board
aileron control horn. Your final
assembly should look like Figure 67.

38
 Section 15-Battery Tray Installation

Required Tools and Adhesive

• Pencil/Marker
• Drill & drill bit #52
• 30-minute epoxy
• Double-sided tape
• Electrical tape
• Velcro
• Sandpaper (fine)

Align the battery tray to the engine Figure 68

mount. Take a pencil and mark.
Then sand the area where the tray
will be glued and then clean with Note: This installation is required if
alcohol. Drill 4 holes for the wooden you are using a glow engine
screw provided with a distribution as weighing 32-34 oz, to help balance
it is shown in the picture. The most your model. For example a YS 1.40
important are the two front screws. weighs 33 oz or an OS 1.60 weighs
These two screws will be screw to 34 oz. Weights are without muffler.
the center of the firewall.
Once you drill the holes you are If you are using a gas engine, your
ready to apply 30 minutes epoxy. receiver battery can be installed next
Apply the epoxy and precede to tight to receiver as is depicted in
the screws while the epoxy is fresh Figure 69 because your ignition
so screws will hold the piece in module and ignition up in front will
place. Let it dry well. Then take the help balancing your model.
battery pack and wrapped with foam.
I use electrical tape over the foam.
Then use double side tape to put in
between the battery pack and the
tray this is to avoid the battery will be
shifting under vibration (this is very
important) then use Velcro to tight
the battery down. Run the battery
lead as it is shown in the picture.

39
 Section 16-Radio Equipment

You are now in the final stages in Here are some better views (See
completing the assembly of your Figure 70 & 71) of the switch mount
Yak-54. Quique’s method of inside and the push/pull rod outside
mounting the radio receivers in his the fuse. You may need to make
proto-type airplanes: Starting with your own music wire rod to connect
the plywood mounting plate for the the receiver switch to the outside of
receiver, motor control servo and the the fuse. You may also need to drill a
radio switch: hole in the switch button to accept
the music wire. Perhaps your switch
1. Apply some beads of medium already has the parts necessary to
C/A. make the connection outside the
2. Attach a piece of foam the size of fuse.
the bottom of the receiver to the
base.
3. Cover the bottom of the receiver
completely with wide masking
tape.
4. Apply more beads of medium C/A
glue to the masking tape and
place the receiver on the top of
the foam.
This system has worked very well for
him for many years. The receiver
floats gently but is not fixed too
Figure 70
firmly. If a receiver is fastened too
tight in the airplane there could be
problems with engine vibration
transmitted to the receiver. See
Figure 69 for an overall view of the
fuel tank; throttle servo, receiver and
switch.

Figure 71

Figure 69

40
 Custom Muffler

Central Hobbies has a custom muffler available for this Somenzini Yak-54 for the
YS-140 Sport engine that Quique’s uses in this airplane. You may contact them
at their website, www.centralhobbies.com.

See Figure 72 & 73 for Quique’s custom muffler installation. Between the muffler
can and the plywood piece on the bottom of the engine box, you can see that he
uses a piece of silicone tubing to separate the two and then he uses electrical tie
wraps for attachment.

Figure 72

Figure 73

41
 Balancing the Model

Perhaps one of the most important things that you need to check before you fly
your plane is your model C.G. Correctly balancing an aerobatic model is critical
to its performance and flight characteristics. An unbalanced model can be very
hard to control. Please make sure that you carefully check the C.G of your plane
before you attempt to fly it.

C.G Location

Measuring 174 mm from trailing edge forward to wingtip would give you best 3D
and precision flying. However, the furthest you can go from trailing edge to wing
tip is 184mm that means you would have a slightly nose heavy model and the aft
limit from trailing edge to wing tip is 168mm. See Figure 74 & 75 for these three
locations.

Quique’s Recommended C.G.

Figure 74 Figure 75

42
 Control Throws

Aileron (As shown in Figure 76 & 77)

Low Rate High Rate

39 mm Up 59 mm Up
39 mm Down 59 mm Down

Figure 76 Figure 77

Elevator (As shown in Figure 78 & 79)

Low Rate High Rate

8 mm Up 61 mm Up
8 mm Down 61 mm Down

Figure 78 Figure 79

43
Rudder (As shown in Figure 80 & 81)

Low Rate High Rate

34 mm Right 70 mm Right
34 mm Left 70 mm Left

Figure 80 Figure 81

44
Preflight at the Field

Range Test Your Radio

Make sure you range check your radio before you attempt to fly your plane. Turn
on your transmitter with antenna fully collapsed and walk away 100 ft. Move all
your control surfaces and make sure everything is fine. If you are running a gas
engine not only you need to range test your plane when it’s not running but also
when the engine is running. Make sure your model is secured and anchored. If
you noticed any problems such as shorter range, servos jittering or PCM receiver
locking out, you have problem. Do not fly your plane!
Ignition module on gas engines can cause RF interference with your receiver.
Make sure your ignition module is at least 12” away from your receiver.

Check Your Batteries

Make sure your receiver, ignition and transmitter batteries are fully charged.
Always double check before you fly.

Fasteners

Make sure all the bolts such as prop bolt, hatch and cowl are tight. After each
flight check for possible loose bolts.

45