electrifly L-39 Instruction Manual

™

INSTRUCTION MANUAL

Wingspan: 25 in [635mm]
Wing Area: 141 sq in [9.1 dm2]
Weight: 17.5–18.5 oz [500–520g]
Wing Loading: 17.9–18.9 oz/sq ft [55–58 g/dm2]
Length: 31 in [780mm]
Radio: 3-Channel Minimum and Micro Receiver

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 modifi cation. 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 fi nal assembly or
material used for fi nal assembly, no liability shall be assumed nor
accepted for any damage resulting from the use by the user of
the fi nal user-assembled product. By the act of using the user­assembled 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

READ THROUGH THIS MANUAL BEFORE STARTING CONSTRUCTION. IT CONTAINS IMPORTANT

INSTRUCTIONS AND WARNINGS CONCERNING THE ASSEMBLY AND USE OF THIS MODEL.

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.

Entire Contents © Copyright 2008

Champaign, Illinois

[phone], Ext 5

[e-mail]

GPMA6002MNL V1.0

TABLE OF CONTENTS

AMA

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

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

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

LITHIUM BATTERY HANDLING AND USAGE ................ 3

RADIO EQUIPMENT .........................................................3

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

Adhesives and Building Supplies ............................... 3

Optional Supplies and Tools .......................................3

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

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

KIT INSPECTION .............................................................. 5

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

ASSEMBLE THE AIRPLANE ........................................... 6

GET THE MODEL READY TO FLY ................................... 8

Check the Control Directions ..................................... 8

Set the Control Throws .............................................. 9

Balance the Model (C.G.)...........................................9

PREFLIGHT .................................................................... 10

Identify Your Model ................................................... 10

Charge the Batteries ................................................ 10

Range Check ........................................................... 10

AMA SAFETY CODE (excerpts) .................................... 10

CHECK LIST ................................................................... 11

FLYING ............................................................................ 11

Takeoff ..................................................................... 11

Flight ........................................................................ 11

Landing .................................................................... 11

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 fl y at AMA clubs.
Though joining the AMA provides many benefi ts, one of the
primary reasons to join is liability protection. Coverage is not
limited to fl ying at contests or on the club fi eld. It even applies
to fl ying 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 country. Contact the
AMA at the address or toll-free phone number below.

Academy of Model Aeronautics

5151 East Memorial Drive

Muncie, IN 47302

Tele: [phone]

Fax [phone]

Or via the Internet at:

http://www.modelaircraft.org

IMPORTANT!!! Two of the most important things you can do

to preserve the radio controlled aircraft hobby are to avoid
fl ying near full-scale aircraft and avoid fl ying near or over
groups of people.

INTRODUCTION

Welcome to the exciting world of EDF (Electric Ducted Fan)
airplanes! The L-39 is sure to please with its scale appearance
paired with the convenience of being constructed from light
weight foam. In addition, the L-39 also includes a painted
stand and removable missiles and drop tanks (for display
only) that will allow the plane to double as a display model.
Using the included brushless motor, the L-39 achieves
incredible speeds, being clocked at 78 mph coming out of a
dive! The L-39 is a great, stable fl yer too and can comfortably
fl y at slower speeds.

For the latest technical updates or manual corrections
to the L-39 RXR visit the Great Planes web site at www.
greatplanes.com. Open the “Airplanes” link, then select the
L-39 RXR. 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.

PROTECT YOUR MODEL, YOURSELF

& OTHERS...FOLLOW THESE

IMPORTANT SAFETY PRECAUTIONS

1. Your L-39 RXR 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 L-39, 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 unfl yable model. In a few cases 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 correctly install all R/C and other components
so that the model operates correctly on the ground and in
the air.

2

5. You must check the operation of the model before every
fl ight to insure that all equipment is operating and that the
model has remained structurally sound. Be sure to check
pushrod connectors or servo arms often and replace them if
they show any signs of wear or fatigue.

6. If you are not an experienced pilot or have not fl own
this type of model before, we recommend that you get the
assistance of an experienced pilot in your R/C club for
your fi rst fl ights. 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.

RADIO EQUIPMENT

The L-39 EDF RXR requires a 3+ channel transmitter and a
micro receiver. If you already have a transmitter you are going
to use to fl y the L-39, you can get the receiver separately:

❏ Futaba R617FS FASST

-or-

❏ Futaba

(Low Band: FUTL0442; High Band: FUTL0443)

®

R114F 4-Channel FM Micro Receiver w/o Crystal

❏ Futaba FM Single conversion receiver crystal for R114F

(Low Band: FUTL62**; High Band: FUTL63**)

™

Receiver (FUTL7627)

We, as the kit manufacturer, provide you with a top quality,
thoroughly tested kit and instructions, but ultimately the
quality and fl yability of your fi nished 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.

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

LITHIUM BATTERY

HANDLING & USAGE

WARNING!! Read the entire instruction sheet included with
the battery. Failure to follow all instructions could cause
permanent damage to the battery and its surroundings, and
cause bodily harm!

• ONLY use a LiPo 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 fi reproof location.

• NEVER trickle charge.

• NEVER allow 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.

A lithium-polymer battery pack and suitable charger are
also required. Although there are different battery packs
and chargers available that will work with the L-39 RXR, the
economical choices recommended by Great Planes are:

❏ Great Planes LiPo 11.1V 910mAh 20C Discharge

w/Balance (GPMP0605)

❏ Great Planes LiPo 11.1V 1250mAh 20C Discharge

w/Balance (GPMP0609)

❏ Great Planes ElectriFly DC peak charger (GPMM3010)
❏ Great Planes Equinox

Note: Battery choice will affect the balance of the plane. The
1250mAh pack will result in a forward C.G. position, and the
910mAh pack will provide a more aft C.G. position.

™

Cell Balancer (GPMM3160)

ADDITIONAL ITEMS REQUIRED

Adhesives and Building Supplies

Foam safe CA glue and 30-minute epoxy are used in the
assembly of the L-39 RXR. Order numbers are provided
below.

❏ Great Planes Pro

(GPMR6043)

™

Epoxy 30-Minute Formula 4 oz.

❏ Great Planes Pro Foam Safe CA- Thick Glue 1 oz.

(GPMR6072)

❏ Denatured alcohol (for epoxy clean up)

Optional Supplies and Tools

Here is a list of items that will help you build the L-39 RXR.

❏ CA debonder (GPMR6039)
❏ Epoxy brushes (6, GPMR8060)
❏ Mixing sticks (50, GPMR8055)
❏ Mixing cups (GPMR8056)
❏ CG Machine
❏ Hobbico

™

(GPMR2400)

®

Flexible 18" Ruler Stainless Steel (HCAR0460)

3

IMPORTANT BUILDING NOTES

• When you see the term test fi t in the instructions, it means
that you should fi rst position the part on the assembly
without using any glue, then slightly modify or custom fi t
the part as necessary for the best fi t.

• Whenever the term glue is written you should rely upon
your experience to decide what type of glue to use. When
a specifi c type of adhesive works best for that step, the
instructions will make a recommendation.

• Whenever just epoxy is specifi ed you may use either
30-minute (or 45-minute) epoxy or 6-minute epoxy. When
30-minute epoxy is specifi ed 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.

ORDERING REPLACEMENT PARTS

Replacement parts for the L-39 RXR 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.

If additional assistance is required for any reason, contact
Product Support by telephone at [phone], or by
e-mail at [e-mail].

Replacement Parts List

Order Number Description How to Purchase

Missing pieces ............... Contact Product Support

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

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

Contact your hobby supplier for the following parts:

GPMA2772 ........... Wing Set with Tip Tanks

GPMA2773 ........... Fuse Kit with Hatch

GPMA2774 ........... Tail Set

GPMA2775 ........... Canopy Hatch

GPMA2776 ........... Armament Set

GPMA2777 ........... Display Stand

GPMA2778 ........... Tip Tanks (2)

GPMA2779 ........... Decal Sheet

GPMA2795 ........... Canopy with Pilot Figures

GPMA3124 ........... Motor Lead Extension

GPMG3900 ........... HyperFlow Ducted Fan Unit

GPMG3940 ........... Ducted Fan Rotor Blade

GPMG3941 ........... Ducted Fan Miscellaneous Parts

GPMG3942 ........... Ducted Fan Outer Duct

GPMG3943 ........... Ducted Fan Adapter

GPMM1210 ..........ES50 Nano Servo

GPMM1820 ..........SS25 Brushless 25A ESC

To locate a hobby dealer, visit the Great Planes web site
at www.greatplanes.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.

Parts may also be ordered directly from Hobby Services by
calling [phone], or via facsimile 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.

4

KIT INSPECTION

Before starting to build, 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

6

2

1

10

9

8

7

1. Fuselage

2. Ducted Fan Access Hatch

3. Wing w/Ailerons

4. Horizontal Stabilizer w/Elevators

5. Vertical Fin

6. Clear Canopy Hatch

11

3

7. Drop Tanks (2)

8. Missiles (2)

9. Wing Tip Tanks (2)

10. Canopy Hatch

11. Servo Horn Cover (2)

5

4

5

ASSEMBLE THE AIRPLANE

❏ 1. Position the motor lead extensions into the slot in the

fuselage, down the channel in the wing saddle, and through
the hole to the radio compartment.

❏ 3. Coat the wing saddle on the fuselage with 30-minute

epoxy. Insert the aileron servo wires through the hole in the
fuse and into the radio compartment. Place the wing onto the
saddle by fi tting the alignment keys on the top of the wing
into the mating cutouts in the wing saddle. Tape the wing to
the fuse while the epoxy cures or place a weight on the top
of the fuse to press it against the wing. If using tape, avoid
damaging the paint by fi rst lining the outside of the model with
sheets of paper or something similar. Wrap the tape tightly
around the paper instead of directly onto the model.

❏ 2. Attach the included Y-harness to the aileron servo leads.

❏ 4. The vertical fi n and horizontal stabilizer are keyed to fi t

together and therefore must be glued in place at the same
time. Coat with epoxy the key on the bottom of the fi n, the
slot in the horizontal stabilizer, and the stab saddle on the
fuselage. Do not put epoxy on the foam piece glued to

the front of the fi n that fi ts into the ducted fan access
hatch! Position the parts onto the fuselage, making sure

that the vertical fi n is being glued square to the horizontal
stabilizer. The parts can be taped or held in place while the
epoxy cures.

666

❏ 5. Attach the elevator pushrod to the outer hole in the elevator

control horn and secure it using the 90° pushrod connector.

❏ 6. Connect the ESC to the motor lead extensions and

connect the servos and ESC to your receiver. This is a good
time to confi rm the correct rotation of your ducted fan unit. If the
unit rotates the wrong direction when powered up, disconnect
two of the three motor leads and swap their positions.

❏ 8. Apply the hook side of the included hook and loop

material to the bottom of the radio compartment. Brushing
on a thin coat of epoxy and letting it cure before attaching the
hook material will help it adhere to the foam. Apply the loop
side to your battery pack.

❏ 7. Feed the receiver antenna through the antenna tube

and out the back of the fuselage. Use the included double­sided tape to secure the ESC and receiver to the side of the
radio compartment. Be sure they are positioned at the back
of the compartment and that the wires are tucked neatly out
of the way.

❏ 9. Assemble and glue the display stand together as shown

using foam-safe glue. The long slots in the two large pieces
interlock and the four cross braces are glued into the small slots.

7

loosen the knurled thumb screws in the screw-lock pushrod
connectors and adjust the pushrods until the control surfaces
are centered. When satisfi ed, re-tighten the thumb screws
using a fl at head screwdriver.

3-CHANNEL RADIO SETUP

(STANDARD MODE 2)

❏ 10. Finish the model by test fi tting the removable drop tanks

and missiles to the underside of the wing. These parts are
attached magnetically and are for display purposes only. Be
sure to remove them prior to fl ight! The included clear canopy
hatch is also recommended for display purposes only.

GET THE MODEL READY TO FLY

Check the Control Directions

ELEVATORS MOVE UP

RIGHT AILERON MOVES UP

LEFT AILERON MOVES DOWN

FULL THROTTLE

❏ 3. Make certain that the control surfaces and the throttle

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.

❏ 4. If the ESC makes continued low-pitched beeps when

the transmitter is turned on and the throttle stick is in the
idle position, then the throttle channel is reversed in the
transmitter.

❏ 5. The SS-25 brushless ESC is equipped with a safety

feature that prevents the motor from rotating before the ESC
has been armed. To arm the ESC, turn the transmitter on
and move the throttle stick to idle. Plug the battery into the
ESC. Move the throttle stick to full throttle until you hear a
beep. Move the throttle stick back to the idle position and you
will hear two beeps. The ESC is now armed.

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

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

control surfaces to see if they are centered. If necessary,

❏ 6. The SS-25 brushless ESC is equipped with a “brake”

feature. To toggle the brake on and off, turn the transmitter on
and move the throttle stick to full throttle. Plug the battery into
the ESC. You will hear two quick beeps after a few seconds.
Move the throttle stick to the idle position. Continue with the
arming procedure as described in step 5.

❏ 7. To download the complete SS-25 brushless ESC

manual, visit www.greatplanes.com.

8

Set the Control Throws

Balance the Model (C.G.)

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

At this stage the model should be in ready-to-fl y condition
with all of the systems in place including the receiver, ESC,
and battery pack.

❏ 1. The C.G. is located 1-15/16" [49mm] back from

the leading edge of the wing at the fuselage (the seam

where the wing panels have been joined to the fuselage).
If you mark the C.G. position onto the top of the wing, be
very careful if using tape as it could damage the paint when
removed. Also, do not attempt to remove felt-tip pen marks
with alcohol. We suggest making small marks on the wing
beneath the ducted fan inlets.

Use a Great Planes AccuThrow™ (or 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
low rate setting.

These are the recommended control surface throws:

ELEVATOR (High Rate): 5/16" [8mm], 10° up

5/16" [8mm], 10° down

AILERONS (High Rate): 3/16" [4.8mm], 8° up
3/16" [4.8mm], 8° down

ELEVATOR (Low Rate): 1/8" [3.2mm], 4° up
1/8" [3.2mm], 4° down

AILERONS (Low Rate): 3/32" [2.4mm], 4° up
3/32" [2.4mm], 4° down

NOTE: The throws are measured at the widest part of
the control surfaces.

IMPORTANT: The L-39 RXR has been extensively fl own
and tested to arrive at the throws at which it fl ies best. Flying
your model at these throws will provide you with the greatest
chance for successful fi rst fl ights. If, after you have become
accustomed to the way the L-39 RXR fl ies, you would like
to change the throws to suit your taste, that is fi ne. However,
too much control throw could make the model diffi cult to
control, so remember, “more is not always better.”

This is where your model should balance for the fi rst
fl ights. Later, you may wish to experiment by shifting the
C.G. up to 3/16" [4.8mm] forward or 1/8" [3.2mm] back to
change the fl ying characteristics. Moving the C.G. forward
may improve the smoothness and stability, but the model
may be more diffi cult to slow for landing. Moving the C.G.
aft makes the model more maneuverable, but could also
cause it to become too diffi cult to control. In any case,
start at the recommended balance point and do not at
any time balance the model outside the specifi ed range.

❏ 2. With all parts of the model installed (ready to fl y), place

the model upside-down on a Great Planes CG Machine, or
lift it upside down 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 to balance. If
the nose drops, the model is “nose heavy” and the battery
pack and/or receiver must be shifted to balance. This model
is very weight sensitive. We do not recommend adding any

9

additional weight to achieve the suggested balance point
unless absolutely necessary. Instead, shift the battery pack
and receiver forward or aft to alter the C.G.

PREFLIGHT

Identify Your Model

No matter if you fl y at an AMA sanctioned R/C club site or
if you fl y 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
fl ying sites and AMA sanctioned fl ying events. Fill out the
identifi cation tag on the back cover of this manual and place it
on or inside your model.

Charge the Batteries

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

AMA SAFETY CODE (excerpts)

Read and abide by the following excerpts 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 fl y my model aircraft in sanctioned events, air
shows, or model fl ying demonstrations until it has been
proven to be airworthy by having been previously,
successfully fl ight tested.

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

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

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 fl ying
with batteries that are only partially charged.

Range Check

Ground check the operational range of your radio before the
fi rst fl ight of the day. With the transmitter antenna collapsed
and the receiver and transmitter on, you should be able to
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 fl y! Find and correct the
problem fi rst. 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.

5) I will not fl y my model unless it is identifi ed with my name
and address or AMA number, on or in the model. Note:
This does not apply to models while being fl own 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 fi rst fl ight of a new or repaired model.

2) I will not fl y my model aircraft in the presence of spectators
until I become a qualifi ed fl ier, unless assisted by an
experienced helper.

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

4) I will operate my model using only radio control frequencies

currently allowed by the Federal Communications Commission.

5) I will not knowingly operate my model within three miles

of any pre-existing fl ying 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 fl ight; nor should any part of the

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

10

CHECK LIST

During the last few moments of preparation your mind may
be elsewhere anticipating the excitement of the fi rst fl ight.
Because of this, you may be more likely to overlook certain
checks and procedures that should be performed before
the model is fl own. 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.

❏ 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.

❏ 3. Confi rm that all controls operate in the correct direction

and the throws are set up according to the manual.

❏ 4. Check the operation of the ducted fan unit prior to

each fl ight.

❏ 5. Make sure that all servo arms are secured to the servos

wtih the screws included with your radio.

❏ 6. Place your name, address, AMA number and telephone

number on or inside your model.

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

fi rst fl ight.

❏ 8. Range check your radio when you get to the fl ying fi eld.

IMPORTANT: Confi rm that the transmitter operates the
controls properly by moving the sticks and watching the
surfaces respond.

When ready to launch, the assistant should hold the L-39
behind the canopy hatch, with the model in front of him and
pointed into the wind. With the pilot (that would be you!)
standing behind the plane, fully advance the throttle to start
the motor. When the motor is at full power, the hand launcher
should fi rmly give the model an underhand toss into the air
with a slightly nose-up attitude. Be certain the model is being
launched into the wind and be immediately ready to make
corrections to keep the airplane fl ying straight, level and into
the wind.

When the model has gained adequate fl ying speed under
its own power, gently pull the elevator stick back until the
airplane starts a gradual climb. Many beginners tend to pull
too hard causing the model to stall, so be gentle on the
elevator and don’t panic. If you do pull too hard and you
notice the model losing speed, release the elevator stick and
allow the model to regain airspeed.

Continue a gradual climb and establish a gentle turn (away
from yourself and others) until the airplane reaches an
altitude of 20 to 30 meters [75 to 100 feet].

FLYING

IMPORTANT: If you are an inexperienced modeler we strongly
urge you to seek the assistance of a competent, experienced
R/C pilot to check your model for airworthiness AND to teach
you how to fl y. No matter how stable or “forgiving” the L-39 is,
attempting to learn to fl y on your own is dangerous and may
result in destruction of your model or even injury to yourself
and others. Therefore, fi nd an instructor and fl y only under
his or her guidance and supervision until you have acquired
the skills necessary for safe and fully controlled operation of
your model.

Takeoff

Less-experienced fl yers should fl y the L-39 only in calm
(less than fi ve miles per hour) conditions. Frequently, winds
are calm in the early morning and early evening. Often these
are the most enjoyable times to fl y anyway!

Until you have the L-39 properly trimmed for level fl ight, we
recommend having an assistant hand-launch the model
instead of launching it yourself.

Turn on the transmitter and plug the battery into the speed
control. Secure the canopy hatch in place.

Flight

The main purpose of the fi rst few fl ights is to learn how the
model behaves and to adjust the trims for level fl ight. After the
model has climbed to a safe altitude, reduce the throttle slightly
to slow the model, yet maintain altitude. The L-39 should fl y
well and maintain adequate airspeed at about 1/2 throttle.

Adjust the elevator trim so the model fl ies level at the throttle
setting you are using. Adjust the aileron trim to level the wings.
It may take a few minutes to get the trims adjusted, but this
should be your fi rst priority once at a comfortable altitude.
Continue to fl y around, executing turns and making mental
notes (or having your assistant take notes for you) of what
additional adjustments or C.G. changes may be required to
fi ne tune the model so it fl ies the way you like.

Landing

Begin the landing approach by fl ying downwind at an altitude
of approximately 6 meters [20 feet]. When the airplane is
approximately 15 to 30 meters [50 to 100 feet] past you,
gradually reduce power and make the “fi nal” 180° turn into
the wind aligning the airplane with the runway or landing
area. Do not dive the airplane, as it will pick up too much
speed. Instead, allow the airplane to establish a gradual
descent. Concentrate on keeping it heading into the wind
toward the runway. When the plane reaches an altitude of
about 1 meter [3 feet], gently apply a little “up elevator” to
level the plane, but be careful as too much up elevator will

11

cause it to stall. While holding a slight amount of up elevator
the airplane will slow and descend as it loses fl ying speed,
thus touching-down on the runway. Be sure to throttle back to
idle to prevent the ducted fan from sucking in debris.

Until you are able to accurately judge how far the L-39 can
glide, it may be helpful to reserve some battery power to run
the motor so the plane can be fl own back to the runway.

Best of luck and happy fl ying!

Make a copy of this identifi cation tag and put it on or
inside your model.

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