Great Planes GPMA1190 User Manual

WARRANTY

Great Planes®Model Manufacturing Co.

guarantees this kit to be free from defects in both material and workmanship at the date of purchase. This
warranty does not cover any component parts damaged by use or modification.In no case shall Great Planes’liability exceed the original cost of
the purchased kit. Further, Great Planes reserves the right to change or modify this warranty without notice.

In that Great Planes has no control over the final assembly or material used for final assembly, no liability shall be assumed nor accepted for any
damage resulting from the use by the user of the final user-assembled product. By the act of using the user-assembled product, the user accepts all
resulting liability.

If the buyer is not prepared to accept the liability associated with the use of this product, the buyer is advised to return this kit immediately
in new and unused condition to the place of purchase.

To make a warranty claim send the defective part or item to Hobby Services at the address below:

Hobby Services

3002 N. Apollo Dr., Suite 1

Champaign, IL 61822

USA

Include a letter stating your name, return shipping address, as much contact information as possible (daytime telephone number, fax number, e-mail
address), a detailed description of the problem and a photocopy of the purchase receipt.Upon receipt of the package the problem will be evaluated as
quickly as possible.

READ THROUGH THIS MANUAL BEFORE STARTING
CONSTRUCTION.IT CONT AINS IMPOR T ANT INSTRUCTIONS
AND WARNINGS CONCERNING THE ASSEMBLY AND
USE OF THIS MODEL.

GPMZ0301 for GPMA1190 V1.0 Entire Contents © Copyright 2004

Champaign, IL

[phone], Ext. 5

[e-mail]

INSTRUCTION MANUAL

Wingspan: 33.5 in [850mm]
Wing Area: 297 sq in [19dm

2

]

Weight: 12–14 oz [330–380g]
Wing Loading: 6–7 oz/sq ft [17–20g/dm

2

]

Length: 33 in [840mm]
Radio: 4-channel w/ 3 micro servos and 20A ESC
Power System: Ball-bearing 280-sized motor, 5:1

reduction gearbox

INTRODUCTION................................................................2

AMA ...................................................................................2

SAFETY PRECAUTIONS..................................................2

LITHIUM BATTERY HANDLING & USAGE......................3

ADDITIONAL ITEMS REQUIRED.....................................3

Radio Equipment & Electronics...................................3

Adhesives & Building Supplies....................................3

Optional Supplies & Tools............................................3

IMPORTANT BUILDING NOTES.......................................4

COMMON ABBREVIATIONS............................................4

ORDERING REPLACEMENT PARTS...............................4

KIT CONTENTS .................................................................5

METRIC/INCH RULER ......................................................5

BUILDING INSTRUCTIONS..............................................6

Join the Wing Halves...................................................6

Prepare the Fuselage..................................................6

Assemble the Stabilator ...............................................6

Assemble the Fin & Rudder.........................................7

Join the Wing to the Fuselage.....................................8

Hinge the Ailerons .......................................................8

Install the Servos.........................................................8

Install the Control Horns & Pushrods ..........................9

Install the Motor & Speed Control .............................10

Final Setup.................................................................11

Apply the Decals ........................................................11

GET THE MODEL READY TO FLY..................................12

Check the Control Directions.....................................12

Set the Control Throws..............................................12

Balance the Model (C.G.)..........................................12

Balance the Model Laterally......................................13

PREFLIGHT.....................................................................13

Identify Your Model.....................................................13

Charge the Batteries ..................................................13

Balance the Propellers...............................................13

Range Check.............................................................13

MOTOR SAFETY PRECAUTIONS..................................14

AMA SAFETY CODE (excerpts)....................................14

CHECK LIST ....................................................................14

FLYING.............................................................................15

Launch.......................................................................15

Flight..........................................................................15

Landing......................................................................15

Troubleshooting..................................Back Cover Page

The YAK 55 EP 3D ARF is an excellent way to enjoy 3D
aerobatics without the cost and headaches of giant-scale
gasoline-powered models. A couple of hours on the
workbench, and your YAK 55 ARF will be ready to tackle
torque rolls, walls, harriers, high-alpha rolling circles, and
more! This airplane is a virtually unlimited 3D aerobat, but
flying it only involves plugging in the battery, throttling up,
and letting go!

Take care to build straight and true as you complete the
airplane. Misaligned parts will hur t the airplane’s ability to
perform the extreme aerobatics it is designed for.

For the latest technical updates or manual corrections to the
YAK 55 ARF visit the Great Planes web site at

www.g reatplanes.com

. Open the “Airplanes” link, then select
the Y AK 55 ARF.If there is new technical information or changes
to this model a “tech notice” box will appear in the upper left
corner of the page.

We urge you to join the AMA (Academy of Model Aeronautics)
and a local R/C club.The AMA is the governing body of model
aviation and membership is required to fly at AMA clubs.
Though joining the AMA provides many benefits, one of the
primary reasons to join is liability protection. Coverage is not
limited to flying at contests or on the club field. It even applies
to flying at public demonstrations and air shows. Failure to
comply with the Safety Code (excerpts printed in the back of
the manual) may endanger insurance coverage. Additionally,
training programs and instructors are available at AMA club
sites to help you get started the right way. There are over
2,500 AMA chartered clubs across the countr y. Contact the
AMA at the address or toll-free phone number below:

IMPORTANT!!! Two of the most important things you can
do to preserve the radio controlled aircraft hobby are to
avoid flying near full-scale aircraft and avoid flying near or
over groups of people.

1. Your YAK 55 ARF should not be considered a toy, but
rather a sophisticated, working model that functions very
much like a full-size airplane. Because of its performance
capabilities, the YAK 55 ARF, if not assembled and operated
correctly, could possibly cause injury to yourself or
spectators and damage to property.

2. You must assemble the model according to the
instructions. Do not alter or modify the model, as doing so
may result in an unsafe or unflyable model. In a few cases

PRO TECT YOUR MODEL,YOURSELF

& OTHERS...FOLLOW THESE

IMPORTANT SAFETY PRECAUTIONS

Academy of Model Aeronautics

5151 East Memorial Drive

Muncie, IN 47302

Tele: [phone]

Fax [phone]

Or via the Internet at:

http://www.modelaircraft.org

AMA

INTRODUCTION

TABLE OF CONTENTS

2

the instructions may differ slightly from the photos.In those
instances the written instructions should be considered
as correct.

3.You must take time to build straight, true and strong.

4. You must use an R/C radio system that is in first-class
condition, and a correctly sized motor and components
throughout the building process.

5.You must correctly install all R/C and other components
so that the model operates correctly on the ground and in
the air.

6.You must check the operation of the model before every
flight to insure that all equipment is operating and that the
model has remained structurally sound. Be sure to check
clevises or other connectors often and replace them if they
show any signs of wear or fatigue.

7. If you are not an experienced pilot or have not flown this
type of model before, we recommend that you get the
assistance of an experienced pilot in your R/C club for your
first flights. If you’re not a member of a club, your local
hobby shop has information about clubs in your area whose
membership includes experienced pilots.

8.While this kit has been flight tested to exceed normal use, if
the plane will be used for extremely high-stress flying, such as
racing, or if a motor larger than one in the recommended
range is used, the modeler is responsible for taking steps to
reinforce the high-stress points and/or substituting hardware
more suitable for the increased stress.

Remember: Take your time and follow the instructions to
end up with a well-built model that is straight and true.

WARNING!! Read the entire instruction sheet included with

this battery. Failure to follow all instructions could cause
permanent damage to the battery and its surroundings, and
cause bodily harm!

• ONLY use a Li-Po approved charger. NEVER use a
NiCd/NiMH peak charger!

• NEVER charge in excess of 4.20V per cell.

• ONLY charge through the “charge” lead. NEVER charge
through the “discharge” lead.

• NEVER charge at currents greater than 1C.

• ALWAYS set charger’s output volts to match battery volts.

• ALWAYS charge in a fireproof location.

• NEVER trickle charge.

• NEVER allow the battery temperature to exceed
150°F (65°C).

• NEVER disassemble or modify pack wiring in any way or
puncture cells.

• NEVER discharge below 2.5V per cell.

• NEVER place on combustible materials or leave
unattended during charge or discharge.

• ALWAYS KEEP OUT OF REACH OF CHILDREN.

(Note: Recommended part numbers are include
in parentheses)

❏ 4-Channel radio

❏ 3 Sub-micro servos (0.3 oz [9g] or less each) (FUTM0042)
❏ Micro receiver (FUTL0442-3)
❏ 6” Servo extension (HCAM2000)
❏ 12” Servo extension (HCAM2100)
❏ 20-amp Brushed ESC (GPMP2020)
❏ 1200–1500mAh 3-series Lithium Polymer battery pack

(GPMP0821, GPMP0831)

❏ Deans Ultra Male plug (WSDM1302)
❏ Lithium-Polymer Charger (GPMP3150, GPMP3010)

In addition to common household tools and hobby tools, this
is the “short list” of the most important items required to
build the YAK 55 ARF.

Great Planes Pro™CA and Epoxy

glue are recommended.

❏ 6-minute Epoxy and/or foam safe CA
❏ 60/40 Tin/lead solder
❏ Soldering iron
❏ Covering iron (or household iron)
❏ Hobby knife with #11 blade

Here is a list of optional tools mentioned in the manual that
will help you build the YAK 55 ARF.

❏ Great Planes C.G. Machine

™

Optional Supplies & Tools

Adhesives & Building Supplies

Radio Equipment & Electronics

ADDITIONAL ITEMS REQUIRED

LITHIUM BATTER Y HANDLING

& USA GE

We, as the kit manufacturer, provide you with a top
quality, thoroughly tested kit and instructions, but
ultimately the quality and flyability of your finished model
depends on how you build it;therefore, we cannot in any
way guarantee the performance of your completed
model, and no representations are expressed or implied
as to the performance or safety of your completed model.

3

• When you see the term

test fit

in the instructions, it
means that you should first position the part on the
assembly without using any glue, then slightly modify or

custom fit

the part as necessar y for the best fit.

• Whenever the term

glue

is written you should rely upon
your experience to decide what type of glue to use.When a
specific type of adhesive works best for that step, the
instructions will make a recommendation. Since this model
is constructed from foam, we recommend the use of foam­safe CA glues and epoxy

only.Do not use standard CA

glue on this model as it will dissolve the structure.

• Whenever just

epoxy

is specified you may use either
30-minute (or 45-minute) epoxy or 6-minute epoxy. When
30-minute epoxy is specified it is highly recommended that
you use only 30-minute (or 45-minute) epoxy, because you
will need the working time and/or the additional strength.

•

Photos

and

sketches

are placed before the step they
refer to. Frequently you can study photos in following steps
to get another view of the same parts.

Fuse = Fuselage

Stab = Horizontal Stabilizer

Fin = Ver tical Fin

LE = Leading Edge

TE = Trailing Edge
LG = Landing Gear
Ply = Plywood

" = Inches

mm = Millimeters

SHCS = Socket Head Cap Screw

COMMON ABBREVIATIONS

IMPORTANT BUILDING NOTES

4

Replacement parts for the Great Planes YAK 55 ARF are available using the order numbers in the Replacement Parts List that

follows.The fastest, most economical service can be provided by your hobby dealer or mail-order company.

To locate a hobby dealer, visit the Hobbico web site at

www.hobbico.com

.Choose “Where to Buy” at the bottom of the menu on the left side

of the page. Follow the instructions provided on the page to locate a U.S., Canadian or International dealer. If a hobby shop is not available,
replacement parts may also be ordered from Tower Hobbies at

www

.towerhob

bies.com

, or by calling toll free [phone].

Parts may also be ordered directly from Hobby Services by calling [phone], or via f acsimile at [phone], but full retail
prices and shipping and handling charges will apply. Illinois and Nevada residents will also be charged sales tax. If ordering via fax,
include a Visa

®

or MasterCard®number and expiration date for payment.

Mail parts orders and payments by personal check to:

Hobby Services

3002 N. Apollo Drive, Suite 1

Champaign, IL 61822

Be certain to specify the order number exactly as listed in the Replacement Parts List. Payment by credit card or personal check
only; no C.O.D.

If additional assistance is required for any reason contact Product Support by e-mail at

[e-mail]

, or by

telephone at [phone].

Replacement Parts List

Because the Yak 55 ARF is built as a one-piece airframe, there are no replacement airframe parts available. Replacements for small
parts are available, however:

Or

der Number Description How to purchase

Missing pieces..........................Contact Product Suppor t

Instruction manual ....................Contact Product Support

Full-size plans..........................Not available

GPMG0215 Gear Drive
GPMG0860 Replacement Shaft with Spur Gear
GPMG0239 Pinion Gear
GPMG0311 Replacement Motor
GPMQ1682 10x4.75 Propeller
GPMQ4620 Prop Saver
GPMA2792 Hardware Bag
GPMA2793 Decal Set
GPMG0216 Motor/Gear Drive Assembly
GPMQ4619 Prop Saver Rubber Bands

ORDERING REPLACEMENT PARTS

................

Contact Your Hobby
Supplier to Purchase
These Items

5

Kit Contents

1. Fuselage

2. Propeller

3. Motor & Gear Drive

4. Hardware Bag

5. Horizontal Stab (L&R)

6. Rudder

7. Fin

8. Left Wing Half

9. Left Aileron

10. Right Wing Half

11. Right Aileron

Kit Contents (not photographed)

(3) Control Horns
(3) Control Horn Retainers
(2) Stabilator Spacer/Control Horns
(2) Nylon Pin Hinges
(4) Micro FasLinks
(5) Propeller Rubber Bands
(1) Double-sided Control Horn Extension
(2) Single-sided Control Horn Extension
(1) Hook and Loop Fastener

(1) Elevator Pushrod
(1) Rudder Pushrod
(2) Aileron Pushrods
(1) Prop Saver
(1) Tape

Before starting to build, take an inventory of this kit to make sure it is complete, and inspect the parts to make sure they are of
acceptable quality. If any parts are missing or are not of acceptable quality, or if you need assistance with assembly, contact Product

Support.When reporting defective or missing parts, use the part names exactly as they are written in the Kit Contents list.

Great Planes Product Support:

3002 N Apollo Drive, Suite 1

Champaign, IL 61822

Telephone: [phone], ext. 5

Fax: [phone]

E-mail:

[e-mail]

KIT CONTENTS

1

2

5

7

8

6

10

9

11

To convert inches to millimeters, multiply inches by 25.4

3

4

❏ 1. Glue the two wing halves together, making sure to

align the root sections.

❏ 2. Glue the carbon wing joiner tube into the slot on the

bottom of the wing. Make sure it is fully seated in the slot.

❏ 3. Glue the foam inserts into the wing slot over the carbon

joiner.Make sure they are fully seated against the joiner. The
foam inserts will not be flush with the bottom of the wing.

❏ 1. Cut away the covering from the fuse in the openings

shaded above.

❏1.Slide a control horn/spacer onto the stab joiner.Do not

glue it in place yet.

❏2. Use 6-minute epoxy to glue the joiner into the bottom of

one stabilator half. Slide the flat side of a control horn/spacer
against the stabilator.Glue it to the stabilator half.

Assemble the Stabilator

Prepare the Fuselage

Join the Wing Halves

BUILDING INSTRUCTIONS

6

❏ 3. Slide the joiner tube through the fuselage bushings.

❏ 4. Slide the other control horn/spacer onto the joiner

tube. Do not glue it in place yet.

❏ 5. Test fit the other stabilator half onto the joiner rod.

Lengthen the slot in the stabilator half if necessary to allow
it to fit snugly against the spacer.

❏ 6.

Tip: Use 6-minute epoxy for this step to allow yourself

enough working time.

Glue the stabilator half and spacer to
the joiner tube. Use two square sticks (any scrap you have
will do) and

lightly

clamp the stabilator halves between them

to align everything while the glue hardens.

❏1.Glue two nylon pin hinges into the precut slots in the fin.Be

careful not to get glue into the pivoting section of the hinge.

❏ 2. Glue the hinges into the precut slots in the rudder.

❏3. Glue the fin to the fuselage. Make sure that it is straight

and centered both vertically and longitudinally.

Assemble the Fin & Rudder

7

❏ 1. Cut the covering away from the wing in the shaded

area shown. Do this on both the top and the bottom.

❏ 2. Glue the wing into the fuselage, making sure that it is

centered and square.

❏1.Use the included clear tape to hinge the ailerons to the

wing.Tape the top of the hinge first, then fold the aileron up
as far as possible and tape the bottom side.

❏ 1. Remove the screws and servo arms from your servos.

Push each screw through the center hole of a servo arm
extender (1 double-sided and 2 single-sided).

Install the Servos

Hinge the AileronsJoin the Wing to the Fuselage

8

❏ 2. Place the original ser vo arm over the screw, and glue

the top of the arm to the extender with thin CA.

Some servo
arms have small flanges projecting from the top. If your
servo arms have these flanges, sand them off before gluing.

❏ 3. Glue a servo into the top of the rear servo cutout from

the left side of the plane.The output shaft should be toward
the rear. Center the servo with your radio and screw the
extended arm onto the output shaft with the arm oriented
straight down.

❏4.Glue the other tail servo into the cutout from the right side

of the plane side with the output shaft toward the rear. Center
the servo with your radio and screw the e xtended arm onto the
output shaft with the arm oriented straight down.

❏ 5. Center your aileron servo with your radio and screw

the extended double-sided arm onto the servo. Glue the
aileron servo into the cut out in the fuselage.

❏ 1. Install the Z-bend end of the elevator pushrod into the

elevator servo arm.

❏2.Connect the other end of the elevator pushrod to the outer

hole on the elevator control horn using a micro FasLink.

❏ 3. Cut a slot in the rudder in the location shown. This slot

cuts through part of the rudder hinge for strength.

Install the Control Horns & Pushrods

9

❏ 4. Glue a control horn into this slot from the right side of

the airplane.

❏ 5. Push a control horn retainer onto the back side of the

rudder control horn. Secure it with a drop of glue.

❏ 6. Install the rudder pushrod in the same manner as the

elevator pushrod.

❏ 7. Cut slots in the ailerons in the positions shown.

❏ 8. Glue control horns into these slots from the top.

❏ 9. Push control horn retainers onto the backs of the

aileron control horns. Secure the retainers with a drop of
glue each.

❏ 10. Install the aileron pushrods with the Z-bend through

the servo arm. Secure the pushrods to the control horn with
a micro FasLink.

❏ 1. Solder the output wires of your ESC to the motor.The

positive side of the motor is marked with a red dot. The
output wires should be soldered to the same connection
post as the presoldered capacitors and brush wires.

Install the Motor & Speed Control

10

❏ 2. Slide the gearbox onto the 10mm square stick in the

nose. Secure it with a screw.

❏ 3. Install the prop saver onto the gearbox output shaft.

The screws should seat down into the flat spots on the shaft.

❏ 4. Install the ESC as shown. If your ESC has a BEC

switch, install it in the provided cutout.

❏ 5. Attach the propeller to the prop saver with two

rubber bands.

❏ 1. Connect the servos and ESC to their channels on the

receiver. You may need to use extensions to allow the
aileron servo and ESC lead to reach the receiver. Power up
your radio system and center the servos. If necessary,
adjust the center point of the control surfaces by tightening
or enlarging the “V” bend in each pushrod.

❏2.Tape the receiver into its cavity on the fuselage, and cov er

the servo wires in the groove with the red trim tape provided.

❏ 3. Apply the other piece of tr im tape to the other side of

the fuselage to match.

❏ 4. Apply the red triangle trim to the bottom of the wing

1.Use scissors or a sharp hobby knife to cut the decals from
the sheet.

2. Be certain the model is clean and free from oily fingerpr ints
and dust. Prepare a dishpan or small bucket with a mixture of
liquid dish soap and warm water–about one teaspoon of soap

Apply the Decals

Final Setup

11

per gallon of water.Submerse the decal in the soap and water
and peel off the paper backing. Note: Even though the decals
have a “sticky-back” and are not the water transfer type,
submersing them in soap & water allows accurate positioning
and reduces air bubbles underneath.

3. Position the decals on the model where desired. Holding the
decal down, use a paper towel to wipe most of the water away.

4. Use a piece of soft balsa or something similar to
squeegee remaining water from under the decal. Apply the
rest of the decals the same way.

❏ 1. Turn on the transmitter and receiver and center the

trims. If necessary, remove the servo arms from the servos
and reposition them so they are centered. Reinstall the
screws that hold on the servo arms.

❏ 2. With the transmitter and receiver still on, check all the

control surfaces to see if they are centered.If necessary, adjust
the clevises on the pushrods to center the control surfaces.

❏ 3. Make cer tain that the control surfaces respond in the

correct direction as shown in the diagram.If any of the controls
respond in the wrong direction, use the servo reversing in the
transmitter to reverse the servos connected to those controls.
Be certain the control surfaces have remained centered.
Adjust if necessary.

Use a ruler to accurately measure and set the control throw
of each control surface as indicated in the chart that follows.
If your radio does not have dual rates, we recommend
setting the throws at the high rate setting.

Note: The throws are measured at the widest par t of the
elevators, rudder and ailerons.

At this stage the model should be in ready-to-fly condition
with all of the systems in place including the motor,
propeller, battery, and the radio system.

❏1. Use a felt-tip pen or 1/8" [3mm]-wide tape to accurately

mark the C.G. on the top of the wing on both sides of the

More than any other factor, the C.G. (balance point) can
have the greatest effect on how a model flies, and may
determine whether or not your first flight will be
successful. If you value this model and wish to enjoy it for
many flights, DO NOT OVERLOOK THIS IMPORTANT
PROCEDURE. A model that is not properly balanced will
be unstable and possibly unflyable.

Balance the Model (C.G.)

IMPORTANT: The YAK 55 ARF has been extensively

flown and tested to arrive at the throws at which it flies
best. Flying your model at these throws will provide you
with the greatest chance for successful first flights.If, after
you have become accustomed to the way the YAK 55
ARF flies, you would like to change the thro ws to suit y our
taste, that is fine. However, too much control throw could
make the model difficult to control, so remember , “more is
not always better.”

These are the recommended control surface throws:

High Rate Low Rate

ELEVATOR: 2-1/2" [63.5mm] up 3/4" [19mm] up

2-1/2" [63.5mm] down 3/4" [19mm] down

RUDDER: 2-1/2" [63.5mm] right 1" [25.4mm] right

2-1/2" [63.5mm] left 1" [25.4mm] left

AILERONS: 2" [50.8mm] up 1" [25.4mm] up

1-1/2" [38mm] down 7/8" [22mm] down

Set the Control Throws

Check the Control Directions

GET THE MODEL READY TO FLY

12

fuselage. The C.G. is located 3" [76.2mm] back from the
leading edge of the wing.

❏ 2. With all parts of the model installed, including the

battery (ready to fly) lift it upside-down on your fingertips at
the balance point you marked.

❏ 3. If the tail drops, the model is “tail heavy” and the

battery pack and/or receiver must be shifted forward or
weight must be added to the nose to balance. If the nose
drops, the model is “nose heavy” and the battery pack
and/or receiver must be shifted aft or weight must be added
to the tail to balance. If possible, relocate the battery pack
and receiver to minimize or eliminate any additional ballast
required. If additional weight is required, begin by placing
incrementally increasing amounts of weight on the bottom of
the fuse until the model balances. Once you have
determined the amount of weight required, it can be
permanently attached.

❏ 4. IMPORTANT: If you found it necessary to add any

weight, recheck the C.G. after the weight has been
permanently installed.

❏ 1. With the wing level, have an assistant help you lift the

model by the motor propeller shaft and the bottom of the
fuse under the TE of the fin.Do this several times.

❏2.If one wing always drops when you lift the model, it means

that side is heavy. Balance the airplane by adding weight to the
other wing tip.An airplane that has been laterally balanced will
track better in loops and other maneuvers.

No matter if you fly at an AMA sanctioned R/C club site or if
you fly somewhere on your own, you should always have
your name, address, telephone number and AMA number
on or inside your model. It is required at all AMA R/C club

flying sites and AMA sanctioned flying events. Fill out the
identification tag on the decal sheet and place it on or inside
your model.

Follow the battery charging instructions that came with your
radio control system to charge the batteries. You should
always charge your transmitter batteries the night before
you go flying, and at other times as recommended by the
radio manufacturer.

Charge the flight battery using a charger designed for
Lithium-Polymer batteries. Charging with any other type of
charger is very dangerous, and may cause the batteries to
combust violently.

Carefully balance your propeller and spare propellers before
you fly. An unbalanced prop can be the single most
significant cause of vibration that can damage your model
and may also damage your radio receiver and battery.

We use a Top Flite Precision Magnetic Prop Balancer

™

(TOPQ5700) in the workshop and keep a Great Planes
Fingertip Prop Balancer™(GPMQ5000) in our flight box.

Ground check the operational range of your r adio bef ore the
first flight of the day. With the transmitter antenna collapsed
and the receiver and transmitter on, you should be able to

Range Check

Balance the Propellers

CAUTION: Unless the instructions that came with your

radio system state differently, the initial charge on new
transmitter batteries should be done for 15 hours using
the slow-charger that came with the radio system. This
will “condition” the batteries so that the next charge may
be done using the fast-charger of your choice.If the initial
charge is done with a fast-charger the batteries may not
reach their full capacity and you may be flying with
batteries that are only partially charged.

Charge the Batteries

Identify Y our model

PREFLIGHT

Balance the Model Laterally

This is where your model should balance for the first
flights. Later, you may wish to experiment by shifting the
C.G. up to 1/2"

[13mm] forward or 1/2" [13mm] back to
change the flying characteristics.Moving the C.G.forward
may improve the smoothness and stability, but the model
may then require more speed for takeoff and make it
more difficult to slow for landing. Moving the C.G. aft
makes the model more maneuverable, but could also
cause it to become too difficult to control. In any case,
start at the recommended balance point and do not at
any time balance the model outside the specified range.

13

walk at least 100 feet away from the model and still have
control. Have an assistant stand by your model and, while
you work the controls, tell you what the control surfaces are
doing. Repeat this test with the motor running at various
speeds with an assistant holding the model, using hand
signals to show you what is happening. If the control
surfaces do not respond correctly, do not fly! Find and
correct the problem first. Look for loose servo connections
or broken wires, corroded wires on old servo connectors,
poor solder joints in your battery pack or a defective cell, or
a damaged receiver crystal from a previous crash.

Keep your f ace and body as well as all spectators a wa y from
the plane of rotation of the propeller whenever the battery
is connected.

Keep these items away from the prop: loose clothing, shirt
sleeves, ties, scarfs, long hair or loose objects such as
pencils or screwdrivers that may fall out of shirt or jacket
pockets into the prop.

Read and abide by the following e xcerpts from the Academy
of Model Aeronautics Safety Code.For the complete Safety
Code refer to

Model Aviation

magazine, the AMA web site

or the Code that came with your AMA license.

GENERAL

1. I will not fly my model aircraft in sanctioned events, air
shows, or model flying demonstrations until it has been
proven to be airworthy by having been previously,
successfully flight tested.

2. I will not fly my model aircraft higher than approximately
400 feet within 3 miles of an airport without notifying the
airpor t operator. I will give right-of-way and avoid flying in
the proximity of full-scale aircraft. Where necessary, an
observer shall be utilized to supervise flying to avoid having
models fly in the proximity of full-scale aircraft.

3.Where established, I will abide by the safety rules for the
flying site I use, and I will not willfully and deliberately fly my
models in a careless, reckless and/or dangerous manner.

5. I will not fly my model unless it is identified with my name
and address or AMA number, on or in the model.Note: This
does not apply to models while being flown indoors.

7. I will not operate models with pyrotechnics (any device
that explodes, burns, or propels a projectile of any kind).

RADIO CONTROL

1. I will have completed a successful radio equipment ground
check before the first flight of a new or repaired model.

2. I will not fly my model aircraft in the presence of
spectators until I become a qualified flier, unless assisted b y
an experienced helper.

3. At all flying sites a straight or curved line(s) must be
established in front of which all flying takes place with the
other side for spectators.Only personnel involved with flying
the aircraft are allowed at or in the front of the flight line.
Intentional flying behind the flight line is prohibited.

4. I will operate my model using only radio control frequencies
currently allowed by the F ederal Comm unications Commission.

5. I will not knowingly operate my model within three

miles of any pre-existing flying site except in
accordance with the frequency sharing agreement
listed [in the complete AMA Safety Code].

9.Under no circumstances may a pilot or other person touch
a powered model in flight; nor should any part of the

model other than the landing gear, intentionally touch
the ground, except while landing.

❏ 1. Check the C.G. according to the measurements

provided in the manual.

❏ 2. Be certain the battery and receiver are securely

mounted in the fuse.Simply stuffing them into place
with foam rubber is not sufficient.

❏ 3. Extend your receiver antenna and make sure it has

a strain relief inside the fuselage to keep tension off
the solder joint inside the receiver.

❏ 4. Balance your model

laterally

as explained in

the instructions.

❏ 5. Make sure all hinges are securely glued in place.
❏ 6. Confirm that all controls operate in the correct direction

and the throws are set up according to the manual.

❏ 7. Secure connections between servo wires and

Y-connectors or servo extensions, and the

During the last few moments of preparation your mind
may be elsewhere anticipating the excitement of the first
flight. Because of this, you may be more likely to overlook
certain checks and procedures that should be performed
before the model is flown.To help avoid this, a check list
is provided to make sure these important areas are not
overlooked. Many are covered in the instruction manual,
so where appropriate, refer to the manual for complete
instructions. Be sure to check the items off as they are
completed (that's why it’s called a

check list!

).

CHECK LIST

AMA SAFETY CODE (excerpts)

Failure to follow these safety precautions may result
in severe injury to yourself and others.

MOTOR SAFETY PRECAUTIONS

14

connection between your battery pack and the
on/off switch with vinyl tape, heat shrink tubing or
special clips suitable for that purpose.

❏ 8. Make sure any servo extension cords you ma y hav e

used do not interfere with other systems (servo
arms, pushrods, etc.).

❏ 9. Balance your propeller (and spare propellers).
❏ 10. Place your name, address, AMA number and

telephone number on or inside your model.

❏ 11. If you wish to photograph your model, do so before

your first flight.

❏ 12. Range check y our radio when you get to the flying field.

The YAK 55 ARF is a great-flying model that flies smoothly
and predictably. The YAK 55 ARF does not, however,
possess the self-recovery characteristics of a primary R/C
trainer and should be flown only by experienced R/C pilots.

For the first flight, it is a good idea to have a friend launch the
airplane for you. This allows you to keep your hands on the
radio sticks and correct any trim problems that are present.

Have your friend hold the YAK 55 ARF by the canopy.
Throttle up to full power , and ha ve your friend give the plane
a gentle underhanded toss at about a 30° angle upward.
Since the YAK 55 ARF has a very high thrust to weight ratio,
the plane will accelerate to flying speed almost instantly.
Climb to a comfortable altitude and throttle back to a lower
power setting. This plane flies great at about half-throttle
when in standard forward flight.

For reassurance and to keep an e y e on other traffic , it is a good
idea to have an assistant on the flight line with you.Tell him to
remind you to throttle back once the plane gets to a comf ortable
altitude. While full throttle is usually desirable for takeoff, most
models fly more smoothly at reduced speeds.

Take it easy with the YAK 55 ARF for the first few flights,
gradually getting acquainted with it as you gain confidence.
Adjust the trims to maintain straight and level flight. After
flying around for a while, and while still at a saf e altitude with
plenty of fuel, practice slow flight and execute practice
landing approaches by reducing the throttle to see how the
model handles at slower speeds.Add power to see how she
climbs as well. Continue to fly around, executing various
maneuvers and making mental notes (or having your
assistant write them down) of what trim or C.G. changes
may be required to fine tune the model so it flies the wa y you
like. Mind your fuel level, but use this first flight to become
familiar with your model before landing.

To initiate a landing approach, lower the throttle while on the
downwind leg. Allow the nose of the model to pitch
downward to gradually bleed off altitude. Continue to lose
altitude, but maintain airspeed by k eeping the nose do wn as
you turn onto the crosswind leg.Make your final turn toward
the landing area (into the wind) keeping the nose down to
maintain airspeed and control. Level the attitude when the
model reaches an altitude of about 10 feet, modulating the

Landing

Flight

Launch

CAUTION (THIS APPLIES TO ALL R/C AIRPLANES): If,

while flying, you notice an alarming or unusual sound
such as a low-pitched "buzz," this may indicate control
surface

flutter

. Flutter occurs when a control surface
(such as an aileron or elevator) or a flying surface (such
as a wing or stab) rapidly vibrates up and down (thus
causing the noise). In extreme cases, if not detected
immediately, flutter can actually cause the control surface
to detach or the flying surface to fail, thus causing loss of
control followed by an impending crash.The best thing to
do when flutter is detected is to slow the model
immediately by reducing power, then land as soon as
safely possible. Identify which surface fluttered (so the
problem may be resolved) by checking all the servo
grommets for deterioration or signs of vibration. Make
certain all pushrod linkages are secure and free of play.If
it fluttered once, under similar circumstances it will
probably flutter again unless the problem is fixed. Some
things which can cause flutter are; Excessive hinge gap;
Not mounting control horns solidly; Poor fit of clevis pin in
horn; Side-play of wire pushrods caused by large bends;
Excessive free play in servo gears; Insecure servo
mounting;and one of the most prevalent causes of flutter;
Flying an over-powered model at excessive speeds.

FLYING

15

throttle as necessary to maintain your glide path and
airspeed. If you are going to overshoot, smoothly advance
the throttle (always ready on the right rudder to counteract
torque) and climb out to make another attempt.When you're
ready to make your landing flare and the model is a foot or
so off the deck, cut your throttle and smoothly increase up
elevator until it gently touches down on its belly.

Make sure
that you cut your power completely before touchdown, or
gearbox damage may result.

One final note about flying your model.Have a goal or flight
plan in mind for every flight. This can be learning a new
maneuver(s), improving a maneuver(s) y ou already know, or
learning how the model behaves in certain conditions (such
as on high or low rates).This is not necessarily to improve
your skills

(though it is never a bad idea!)

, but more
importantly so you do not surprise yourself by impulsively
attempting a maneuver and suddenly finding that you'v e run
out of time, altitude or airspeed. Every maneuver should be
deliberate, not impulsive.For example, if you're going to do
a loop, check your altitude, mind the wind direction
(anticipating rudder corrections that will be required to
maintain heading), remember to throttle back at the top, and
make certain you are on the desired rates (high/low rates).
A flight plan greatly reduces the chances of crashing your
model just because of poor planning and impulsive moves.

Remember to think.

The Yak 55 ARF is primarily designed for low-speed 3D
aerobatics, and has an all-flying stabilator to give it very
strong pitch authority. In some cases, the elevator pushrod
can become flexible over time, allowing the stabilator to
oscillate when the plane is flown at high speed. If this
problem appears when flying the plane at high speed,
simply stiffen the pushrod by securing a second length of
1/16" [1.5mm] wire to the original pushrod with thread and
thin CA.This will stiffen the pushrod sufficiently to eliminate
the problem.

Have a ball! But always stay in control and fly in a
safe manner.

GOOD LUCK AND GREAT FLYING!

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