Great Planes GPMA0118 User Manual

Instruction Manual

™

™

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. Fur ther, 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 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 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 CONTAINS IMPOR TANT

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

PT24P03 V1.2 Printed in USA Entire Contents © Copyright 2004

Champaign, IL

[phone], Ext. 5

Fax:[phone]

[e-mail]

WARRANTY

MADE IN

USA

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

INTRODUCTION...............................................................3

Important Note About this Manual .................................3

DECISIONS YOU MUST MAKE........................................4

Engine Selection............................................................4

Wing Configuration ........................................................4

PREPARATIONS ..............................................................4

Accessories Required to Complete Your PT-20..............4

Accessories Required to Complete Your PT-40..............5

Suggested Supplies and Tools.......................................5

Optional Supplies and Tools...........................................5

Setting Up Shop.............................................................6

Building Notes................................................................7

Common Abbreviations..................................................7

Types of Wood................................................................7

The What and How of Adhesives...................................7

Metric Conversion..........................................................8

Get Ready to Build.........................................................9

DIE-CUT PATTERNS......................................................10

BUILD THE T AIL SURF ACES.........................................12

Build the Stabilizer and Fin..........................................12

Hinge the Elevator and Rudder....................................12

BUILD THE FUSELAGE.................................................14

Preparation ..................................................................14

Join the Fuselage Sides...............................................17

Install the Main Landing Gear......................................20

Install the Engine .........................................................21

Install the Nose Gear...................................................23

Attach the Stab and Fin to the Fuse ............................24

BUILD THE WING...........................................................26

Preparation ..................................................................26

Build the Wing Panels..................................................27

Join the Wing Panels....................................................28

Prepare the Wing for Sheeting.....................................31

Sheet the Wing.............................................................31

Fit the Aileron Servo Tray.............................................35

Wing Completion..........................................................36

Reinforce the Wing.......................................................39

FINISHING......................................................................40

Final Sanding...............................................................40

Fuelproofing.................................................................40

Balance the Airplane Laterally.....................................40

Cover the Structure......................................................41

Recommended Covering Sequence............................42

FINAL HOOKUPS AND CHECKS..................................43

Join the Control Surfaces.............................................43

Install the Landing Gear...............................................44

Preliminary Radio Installation ......................................44

Balance Y our Model .....................................................47

Final Radio Hook Up....................................................48

Aileron Lock for 3-Channel Operation..........................51

Checks and Final Setup...............................................51

Control Surface Throws................................................52

Ground Stance.............................................................53

PREFLIGHT....................................................................54

Charge the Batteries....................................................54

Balance the Propeller...................................................54

Find a Safe Place to Fly...............................................54

Ground Check the Model.............................................54

Range Check Your Radio.............................................54

Engine Safety Precautions...........................................54

AMA SAFETY CODE .....................................................55

FLYING............................................................................55

Taxiing..........................................................................56

Takeoff..........................................................................56

Flying ...........................................................................56

Landing........................................................................57

SOME MODELING TERMS & TRIVIA............................57

FLIGHT TRIMMING ........................................................61

FLIGHT TRIMMING CHART...........................................62

TWO-VIEW DRAWING...................................................64

Your PT is not a toy, but rather a sophisticated, working
model that functions very much like an actual airplane.

Because of its realistic performance, the PT, if not
assembled and operated correctly, could possibly cause
injury to yourself or spectators and damage property.

To make your R/C modeling experience totally
enjoyable, we recommend that you get help from an
experienced, knowledgeable modeler with assembly
and your first flights.

You'll learn faster and avoid risking
your model before you're truly ready to solo. Your local
hobby shop has information about flying clubs in your area
whose membership includes qualified instructors.

Protect Your Model,Yourself &

Others...Follow This Important

Safety Precaution

IF YOU DON'T READ ANYTHING ELSE...BEFORE YOU
BEGIN CONSTRUCTION, PLEASE READ THIS:

We realize there is a lot to read between the cover and
step one where you finally start gluing parts together (we
wrote it all). Please do not be tempted to just “skim over”
this preliminary reading material – it contains very
important information. Other manufacturers’ instructions
may be shorter, but in the end you'll be glad we gave you
the extra information. It is impor tant to get started on the
right foot if you are to build and fly y our PT successfully – the
rest of your modeling “career” depends on it! Our
suggestion is to forget about building until you have
carefully studied this preliminary information and
skimmed through the construction portion of the manual.
The PT is not at all a difficult model to build but a
methodical, patient outlook is the correct approach to
take – and following this advice is a good place to begin.

2

Table of Contents

You can also contact the national Academy of Model
Aeronautics (AMA), which has more than 2,300 chartered
clubs across the country. Through any one of them,
instructor training programs and insured newcomer training
are available.

Contact the AMA at the address or toll-free phone
number below.

Thank you for purchasing the Great Planes PT, the Perfect
Trainer, for possibly your first step into the exciting world of
R/C flying. If you aspire to progress in the hobby and are
using the PT as a “stepping stone” to more advanced
models, then you've made the right decision in not only
choosing an all wood kit, but choosing the PT – a kit that
will teach you many of the building skills required for your
next model. With its “Expert Tips” and thorough, detailed
instructions, this manual encourages you to “exercise and
develop” your building skills which will be of great value in
the future. Although your PT is intended as a trainer, you'll
probably find that long after you've completed it and “moved
on” to other models, you'll dust the PT off and take it out for
a few flights every now and then. A good high wing trainer
such as the PT is always a joy to fly no matter what your
skill level. After all, an air plane so easy to takeoff, fly and
land is a real confidence booster!

The PT family of trainers has been around for more than a
decade. As just about any old pro will tell you, no other
trainer model offers so many important features most
needed by a novice. While R/C flying can be learned by
practically anyone, it does require a fair amount of hand-eye
coordination – a skill that can only be learned by quality
“stick time.” This is where the PTs shine. They are all
designed to be rugged, stable and self-recovering and to
fly slowly enough to allow you time to think about your next
maneuver.

Once your PT has been trimmed for straight and level flight
(by an experienced pilot) you will be able to get out of most
situations by simply letting go of the sticks on your
transmitter. The PT will normally level its own wings and
resume stable flight within 50 - 100 feet.This feature alone
has helped many student pilots master the basics in the
shortest possible time.

The PT is designed for either 3 or 4-channel operation with
two different wing setups (see Wing Configuration on page
4 for further details).You can star t with just rudder, elevator
and throttle control, then add a fourth servo for the ailerons
when you want to refine your skills. The ailerons may be
locked in a neutral position after the wing is assembled, but
can be hooked up in just a few minutes with an additional
servo. We recommend the 3-channel setup for beginners.
Due to the dihedral (upward angle of the wing) built into the
wing and generous rudder size, the turn and bank
response is almost identical to using ailerons. When you
are ready to move up to advanced maneuvers such as
crosswind landings and basic aerobatics, all you have to do
is hook up the ailerons.

If you are already an experienced pilot who is just looking
for a sport model for those lazy summer afternoons, we
provide the necessary information to build the wing with
less dihedral and washout to allow more responsive flight
characteristics. Our goal is for you to experience the fun
and satisfaction that thousands of modelers the world over
enjoy, without the mistakes that have spoiled the hobby
for some.

Please inspect all parts carefully before starting to
build. If any parts are missing, broken or defective, or if
you have any questions about building or flying this
model, please call us at [phone] and we'll be
glad to help. If you are calling for replacement parts,
please look up the part numbers and the kit
identification number (stamped on the end of the
carton) and have them ready when calling.

Both the PT-20 and 40 are built from this manual.

Nearly all the parts in the PT ser ies are identical so most
of the differences are only in the sizes and thicknesses of
the pieces – you can't even tell from most of the photos.
When important differences do arise between the 20 and
40, they are clearly indicated so you'll have all the
information you need to build your model.

Important Note About this Manual

INTRODUCTION

Academy of Model Aeronautics

5151 East Memorial Drive

Muncie, IN 47302

Office: [phone]

Toll Free: [phone]

Fax:[phone]

3

❏4-Channel radio with 3 or 4 servos;

see Wing

Configuration Section

.

❏ Engine;

see Engine Selection

❏ Spare Glow Plugs (O.S. #8 for 2-stroke engines,

OSMG2691), (O.S.#F for 4-stroke engines,
OSMG2692)

❏ Propeller (Top Flite

®

Power Point®); Refer to your

engine's instructions for proper size

❏ Top Flite Super MonoKote

®

Covering (Approximately

2 rolls);

see Covering

❏ Medium Fuel Tubing (GPMQ4131, 3')
❏ 1/4" Latex Foam Rubber Padding (HCAQ1000)
❏ 1/16" Foam Wing Seating Tape (GPMQ4422)
❏ 4 or 6 oz. Fuel Tank (4 oz. GPMQ4101),

(6 oz. GPMQ4102)

❏ (1) 2" Nose Wheel (GPMQ4221)
❏ (2) 2-1/4" Main Wheels (GPMQ4222)
❏ (6) 5/32" Wheel Collars (GPMQ4306, pkg.of 4)
❏ Fuelproof Paint;

see Finishing

❏ 2" Spinner (GPMQ4510 - white)
❏ #64 Rubber Bands - optional (HCAQ2020);

see Wing Configuration

Accessories Required to Complete

Your PT-20

PREPARATIONS

You also have the option of securing the wing to the
fuselage either with nylon bolts or rubber bands. The
hardware is furnished in the kit for both options. If this is
your first kit we recommend that you go with the rubber
band method. Rubber bands offer two advantages
over bolts: First, the model is easier to build. Second
(this is the important one), rubber bands allow the wing to
shift if your wing tip contacts the ground (or an obstacle)
upon takeoff or landing. Bolts are less forgiving in this
respect, and even a minor whack can cause enough
damage to send your PT back to the shop for repairs.

Wing Configuration

You have a choice in the type of wing to build – the
trainer (“A-wing”) or the spor t (“B-wing”). The A-wing
has more dihedral than the B-wing and will allow your PT
to fly just great as a 3-channel model without functioning
ailerons.We show you how to build the ailerons but “lock”
them down.You can always hook them up later. Building
the A-wing without functioning ailerons saves you a little
money (most four channel systems are sold with three
servos) and building time. If the PT is your first R/C
model we strongly (that's strongly) recommend that you
build the A-wing with more dihedral. If you build the sport
wing you will lose the full benefit of the self-recovery
features of the PT – features that will help you solo faster
and safer.

With the lower dihedral angle of the B-wing you may still
fly your PT without functioning ailerons, but it performs
best with ailerons – this configuration will suit
intermediate and sport flyers.

Engine Selection

There are many engines that will work well in your PT.
For the PT-20 we recommend a 2-stroke sport engine
such as the O.S.®.20 or .25 FP, or the .25 FX (high
performance). Generally, most beginners start out with a
2-stroke engine but for some of those who are a little
more ambitious and “must have” the sound of a
4-stroke, the O.S..26 FS is a good choice.

For the PT-40

we recommend a 2-stroke sport engine
such as the O.S..35 or .40 FP, or the .40 or .46 FX (high
performance). If you choose the 4-stroke option, the O.S.
.40 or .48 FS is a good choice. Super Tigre

™

also offers

the G-40 and G-45 sport engines.
Your dealer will be able to help decide which engine is

the best choice but basically, the O.S. FP series has
proven to be the highest quality yet most economical
choice. The O.S. FX series and the Super Tigre G series
are higher performance engines and might be a little
overkill for a trainer but would be good powerplants for
sport models you may build in the future.

4-Stroke engines are neat because they provide a
realistic sound (realism is generally not a requirement for
a trainer, mind you), are generally quieter than a
2-stroke and appeal to those who are a little more
technically or mechanically minded. 4-Stroke engines do
cost more and require a little more care than a 2-stroke.If
you use a 4-stroke in your PT you will have to relocate
the throttle pushrod exit location on your firewall so

plan ahead.

DECISIONS YOU MUST MAKE

4

❏ 4-Channel Radio with 3 or 4 Servos;

see the Wing

Configuration section

❏ Engine;

see Engine Selection

❏ Spare Glow Plugs (O.S. #8 for most 2-stroke engines,

OSMG2691), (O.S.#F for 4-stroke engines,
OSMG2692)

❏ Propeller (Top Flite Power Point); Refer to your

engine's instructions for proper size

❏ Top Flite Super MonoKote covering (Approximately

2 rolls);

see Covering

❏ Medium Fuel Tubing (GPMQ4131, 3')
❏ 1/4" Latex Foam Rubber Padding (HCAQ1000)
❏ 1/16" Foam Wing Seating Tape (GPMQ4422)
❏ 6 or 8 oz. Fuel Tank (6 oz. GPMQ4102),

(8 oz. GPMQ4103)

❏ (1) 2-1/4" Nose Wheel (GPMQ4222)
❏ (2) 2-1/2" Main Wheels (GPMQ4223)
❏ (4) 3/16" Wheel Collars (GPMQ4308)
❏ (2) 5/32" Wheel Collars (GPMQ4306)
❏ 2-1/4" Spinner (GPMQ4515 - white)
❏ #64 Rubber bands - optional (HCAQ2020);

see Wing Configuration

These are the building tools, glues, etc.that you will need to
complete your PT-20 or PT-40.

We recommend Great Planes Pro™CA and Epoxy

❏2 oz.Thin CA (GPMR6003)
❏ 2 oz. Medium CA+ (GPMR6009)
❏ CA Applicator Tips (HCAR3780)
❏ Accelerator (GPMR6035)
❏ 30-Minute Epoxy (GPMR6047)
❏ #1 Hobby Knife Handle (XACR4305)
❏ #11 Blades (HCAR0311, 100 qty.)
❏ Razor Saw
❏ X-Acto

®

(or similar) Building Square (XACR7726)

or Building Triangle (XACR7725)

❏ Medium T-Pins (HCAR5150)
❏ Waxed Paper
❏ Masking Tape
❏ Electric Power Drill
❏ Drill Bits: 1/16", 5/64" (or #47), 3/32", 1/8",

5/32", 3/16", #10 (or 13/64"), 15/64" (or 7/32"),
1/4", 17/64"

❏ Pliers
❏ Scissors
❏ Straightedge
❏ String
❏ Masking tape
❏ Screwdrivers (Phillips and Flat Blade)

❏ Bar Sander or Sanding Block and Sandpaper

(coarse, medium, fine grit);

*see the following

Expert Tip

❏ HobbyLite

™

Balsa Filler (HCAR3401)

❏ Sealing Iron (TOPR2100)

We've listed the following items separately as they are not
absolutely required for you to complete your PT, but these
items will facilitate some of the building procedures or
provide better results. These are items that you will surely
acquire as you progress in the hobby anyway. Don't worry,
even veteran modelers take time to accumulate all the tools

Optional (but highly recommended)

supplies and tools

EX

P

E

RT TIP

Suggested Supplies and Tools

Accessories Required to Complete

Your PT-40

5

In our busy workshop we use the Great Planes
Easy-Touch™Bar Sanders equipped with Great Planes
#80, #150 and #220-grit Easy-Touch Adhesive-Backed
Sandpaper. Great Planes Easy-Touch Bar Sanders are
made from lightweight, rigid, extruded aluminum and can
be found at most hobby shops. They are available in
three sizes – 5-1/2" (GPMR6169), 11" (GPMR6170) for
most general purpose sanding and 22" (GPMR6172) for
long surfaces such as wing leading edges.The Easy-Touch
Adhesive-Backed Sandpaper comes in 2" x 12' rolls of
80-grit (GPMR6180), 150-grit (GPMR6183) and 220-grit
(GPMR6185) and an assortment of 5-1/2" long strips
(GPMR6189) for the short bar sander.The adhesive-backe d
sandpaper is easy to apply and remove from your
sanding bar when it's time for replacement.

This setup is all that is required for almost any sanding
task. Custom sanding blocks can be made from balsa or
hardwood blocks and sticks for sanding difficult to reach
spots.We also keep some #320-grit wet-or-dry sandpaper
for finish sanding just before covering.

EX

EX

RT TIP

E

P

RT TIP

E

P

they'll need to do the best job possible.In some instances it
may not be clear exactly what the optional item is used for
so, where appropriate, we’ve listed the page number and/or
the step where that item is used. While you’re shopping,
you can reference the manual and decide ahead of time
whether not to make the additional purchase.

❏ 6-Minute Epoxy (GPMR6045) see page 7
❏ 1 oz.Thick CA- (GPMR6014) see page 7
❏ Epoxy Brushes (GPMR8060)
❏ Epoxy Mixing Sticks (GPMR8055, qty. 50)
❏ CA Debonder (GPMR6039)
❏ T-Pins (HCAR5100 - small, HCAR5200 - large)
❏ Hot Sock

™

(TOPR2175)

see page 41,

Cover the Structure

❏ Trim Seal Tool (TOPR2200)

see page 41, step B,

Expert Tip – Covering Technique

❏ Heat Gun (TOPR2000)
❏ Single Edge Razor Blades (HCAR0312, 100 qty.)
❏ Razor Plane (MASR1510)

see page 14,

step B, Expert Tip

❏ Z-Bend Pliers (HCAR2000)

see page 23, step 3

❏ Straightedge (Fourmost Non Slip FORR2149)
❏ 3/16" dia. Antenna Tube (GPMQ3710 - or similar)

see page 18, step 9

❏ 1/8" Brass Tube,

see page 38, step 17

❏ Denatured or Isopropyl Alcohol (for epoxy clean-up)
❏ Dremel

®

MultiPro™Tool or similar w/Sanding Drum,

Cutting Burr and Cut-off Wheel

If this is your first model there are a few necessary supplies
and tools that you should gather before going any further.
The single most important item that is required for any
modeling project is a flat work surface.The kitchen table is
generally not a good idea. A space where you can work,
leave stuff out, make a mess, spill glue and paint without
worry, and has adequate ventilation is ideal. Hey, the
garage sounds like a good place!

A workbench can be as simple as a solid flat table or made
from some two-by-fours and a solid core door. Hollow core
interior doors work fine, but the cheaper ones are prone
to warping.

Here is a suggested approach for building an inexpensive
workbench. You will need (7) 6' - two-by-fours of good
quality pine or fir, a 30" x 82" door, some 16d (penny)
common nails, a handsaw and a hammer.

Assemble the workbench as follows:

1) Cut one two-by-four into three sections, two 24" long
and one 21" long.

2) Nail the 24" pieces to the two ends of two straight 6'
pieces to make the frame for the top. Nail the 21" piece
in between the two 6' pieces across the center of the frame.

3) Cut two two-by-fours in half to make four 36" legs. Nail
(or bolt) the four legs to the frame with the 2" side facing
the long sides of the frame.

4) Cut two 21" side rails from one of the remaining boards.
Nail the two boards to the sides of each pair of legs.

5) Nail the last 6' board to the front side of the back legs,
level with the two side pieces. One-by-three cross
braces may be nailed to the back legs for more rigidity.

6) Center the door on the frame and either glue or use
double sided foam back sticky tape to hold it in position.

You will need to cover your work surface with something
you can push pins into.The back side of a 2' x 4' sheet of
ceiling tile makes a great building surface, or if you want to
cover a larger area you can buy a 4' x 8' sheet of Celotex
insulation board from your local building supply store.

Most of the tools listed previously can probably be found
around the house.A few items like a razor saw, hobby knife,
sealing iron, heat gun and glues can be purchased at your
hobby dealer. As you get more involved with the hobby you
will probably want to add a few power tools such as a
Dremel tool, belt sander and a scroll saw, but in the case of
the PTs, everything you need has already been covered.

Setting Up Shop

6

• There are two types of screws used in this kit:
Sheet metal screws are designated by a number and

a length.

For example #4 x 5/8".

Machine screws are designated by a number (threads per
inch) and a length.

For example 4-40 x 3/4".

• When you see the term “test fit” in the instructions, it
means you should first position the part on the assembly
without using any glue, then slightly modify or “custom fit”
the part as necessary for the best fit.

• Whenever just “epoxy” is specified you may use

either

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

Fuse = Fuselage
Stab = Horizontal stabilizer
Fin = Vertical fin
LE = Leading edge (front)
TE = Trailing edge (rear)
LG = Landing gear
Ply = Plywood
" = Inches

Cyanoacrylate or CA glue has changed the way models
are built more than any other advance in modeling
technology. In the good ol' days, model cement like
Ambroid, Duco, Comet and Sigment were the glues of
choice. They all had a strong odor that could cause
dizziness, dried slowly (compared to CA) and became
brittle with age. CA, on the other hand, is stronger, works
almost instantly and is bottled in three different viscosities
(thicknesses).CA is used for most glue joints, except where
epoxy is specified.CA does emit rather strong fumes (some
say it's like tear gas) as it cures, so rule number one is to

work in a well ventilated area.

All CA glues work best if the joints are smooth and the
parts fit well.

Thin CA is also known as plain CA.

This is the instant variety, used for
most initial assembly and tack gluing.
Thin CA is usually “wicked” into a
tightly fitting joint by putting a few
drops on the seam, then holding the
parts together while the CA
penetrates and bonds the parts.
When gluing plywood or hardwood, a
mist of accelerator (see page 8) will
help the CA work a little better.

CA+ is also known as medium or
gap filling CA. CA+ is used for

surface gluing, filling small gaps
between poorly matched parts and
for general purpose applications. It
cures slower than thin CA, allowing
you to apply a bead to two or three
parts before assembly. Also, because
it cures slower than thin CA, it
penetrates the wood for a stronger
bond. Curing time without accelerator
is 20 - 30 seconds.

CA- or thick CA is used when extra
positioning time is needed. CA- is a
great gap filler and is also used to
make fillets when a little extra
strength is required. Curing time is
about 1 - 2 minutes.

The What and How of Adhesives

Types of Wood

Common Abbreviations Used in this

Manual and on the Plans

Building Notes

7

Balsa Basswood Plywood

#4 x 5/8" Sheet Metal Screw

4-40 x 3/4" Socket Head Cap Screw

Accelerator is a liquid chemical for
use in speeding up the cure time of
all CA types. It should be misted on,
not sprayed heavily on the joint. A
typical use of accelerator is to spray
a light mist on a fillet of thick or
medium CA to prevent it from running
or dripping. Another use of accelerator
is to “prime” one of the parts you are
joining before you apply the CA, then
add thick or medium CA to the part
that has not been primed.The CA will
cure immediately when the parts
contact each other, so be careful as

this leaves no time for positioning.

There are special instances where this method comes in
handy but we do not suggest you build your entire model in
this manner. Sometimes, when you glue a joint with thin
CA, the CA is so thin that it is drawn deep into the wood
and away from the glue joint.This can be prevented by first
priming the joint with accelerator, then adding thin CA.The
CA will cure “on the spot” before it has a chance to be
drawn away from the joint.

During the later stages of construction be aware of areas
that you may have sprayed with accelerator. Often times,
residual accelerator, even if sprayed on hours before, may
cause the CA on a nearby joint to cure prematurely and
unexpectedly – it's pretty potent stuff!

Overuse of accelerator may cause CA to bubble and
sometimes change color.A drawback to accelerator can be
that the CA cures before it has time to fully penetrate the
wood, so it should only be used sparingly – only when
necessary. For future reference, keep accelerator away
from clear canopies and other plastic parts such as cowls
and wheel pants. Accelerator will “fog” the butyrate plastic
that most canopies are made from and can cause the ABS
plastic that many cowls are made from to soften.

Epoxy

Great Planes has several Epoxy formulations available for
the modeler.The two most often used epoxies are 6-minute
and 30-minute. Both offer exceptional strength and good
working times. We recommend that you use epoxy when
the joint requires exceptional strength, such as when
installing the firewall, when joining the wing panels and
when installing wing hold-down blocks. As with most
epoxies, you mix equal parts of resin and hardener, stir
well, then apply a thin film to each part. Parts should be
clamped, pinned, taped or weighted in place until fully
cured. Before the epoxy cures, clean off any excess with a
paper towel. A word of caution about mixing epoxy – don't
use extra hardener in the hopes of making the mixture
harder or work faster. Just about all epoxies work best with
exactly a 50/50 mixture. When you increase the amount of
hardener you run the risk of causing the cured epoxy to
become either brittle or rubbery – neither being as strong as
a properly mixed batch.

A word about safety!

After applying CA, step back or look away from the work
to avoid the puff of vapors. All CA glues will bond skin
almost immediately.If this should happen, CA Debonder
(available from your hobby dealer) or acetone fingernail
polish remover will dissolve the CA if allowed to soak
into the bond for a few minutes. Don't use vigorous
means to separate a skin bond. Never point the CA
applicator tip toward your face and be especially careful
when opening a clogged tip. In case of eye contact,
flush thoroughly with water, then seek medical attention,

but don't panic. Please, keep CA (and all other
modeling chemicals) out of the reach of children.

8

Metric Conversion

6-Minute epoxy is used for simple,

small gluing operations where
elaborate alignment is not required.
Working time (before it's too gooey
to use) is about 5 minutes, handling
time 15 minutes and it's fully cured
in about 1 hour.

30-Minute epoxy is used for extra
strength (because it can penetrate
longer) and where several parts
must be aligned and checked
before it cures. Working time is
about 25 minutes, handling time 2
hours and it's fully cured in 8 hours.

45-Minute epoxy offers plenty of
responding time plus incredible
strength. It is ideal for sheeting
balsa wood to foam core wings
and other high stress areas.
Working time is about 45-50
minutes, handling time 2 hours and
it's fully cured overnight.

Great Planes Pro Wood Glue is an Aliphatic resin glue that
works well on all types of wood. It is non-toxic, virtually
odorless and dries clear. Some people are sensitive to the
fumes and sanding dust derived from CA, so this is a good
alternative for general modeling use. Its only drawback is
that it is slow to cure, requiring the parts to be securely
clamped, pinned or taped while the glue dries. In some
cases this is an advantage as it allows plenty of time for
accurate positioning of parts. For future reference, aliphatic
resin also sands easier than CA and is ideal for joining wing
sheeting planks.

Okay, you've got your work space ready, your tools are at
hand and you know how to choose and use the right glue
for the job. Let's get started!

❏ 1. Unroll the plan sheets. Reroll the plans inside out to

make them lie flat.

❏ 2. Remove all parts from the box. As you do, figure out

the name of each part by comparing it with the plans and
the parts list included with this kit. Using a felt-tip or
ballpoint pen, lightly write the part name or size on each
piece to avoid confusion later. Use the die-cut patterns
shown on pages 10 and 11 to identify the die-cut parts and
mark them before removing them from the sheet. Save all
scraps. If any of the die-cut parts are difficult to punch out,
do not force them! Instead, cut around the parts with a
hobby knife. After punching out the die-cut par ts, use your
bar sander or sanding block to lightly sand the edges to
remove any die-cutting irregularities or slivers.

❏3. As you identify and mark the parts, separate them into

groups, such as fuse (fuselage), wing, fin, stab (stabilizer)
and hardware.

Get Ready to Build

9

Zipper-top food storage bags are handy to store your
parts as you sort, identify and separate them into
subassemblies.

10

DIE-CUT PATTERNS FOR PT-20

11

DIE-CUT PATTERNS FOR PT-40

12

Work on a flat surface over the plans covered with waxed
paper. Frequently refer to the plans to identify the parts and
their locations.

❏1. Locate the shaped balsa forward and aft stab. Check

their fit and sand the mating edges if needed. Apply a light
bead of medium CA to the mating edges and glue them
together. Immediately wipe away any excess CA before it
cures.

❏ 2. Locate the shaped balsa forward and aft fin. Check

their fit and sand the mating edges if needed.Work over the
plans (don’t forget the waxed paper), then glue the two
parts together as you did the stab parts. Immediately wipe
away any excess CA from the surface before it cures.

❏3. See the Expert Tip that follows, then sand the stab and

fin flat and smooth with sharp 220-gr it sandpaper and your
bar sander or a sanding block.

Note: One of the best ways to enhance the finish and
appearance of your model is to do a good hinging job.
Properly aligned hinge slots and secure hinges will
eliminate problems at the flying field. Follow these
instructions and take your time in order to avoid crooked or
misaligned hinge slots that can lead to tight control
surfaces or loose hinges.

❏ 1. Locate the balsa elevator (refer to the plan for size

and shape). Use a ballpoint pen to lightly mark the location
of the hinges on the stab and the elevator where they are
shown on the plan.

❏ 2. Refer to the Expert Tip below and mark the location

of each hinge slot on the trailing edge of the stab.

Hinge The Elevator and Rudder

Build The Stabilizer and Fin

BUILD THE T AIL SURFACES

It is more important to keep the thickness of the entire
stab and fin constant than it is to completely eliminate
the glue joint. Don’t spend too much time sanding in
one particular spot where the seam might not be
perfect – otherwise that area of the stab or fin will
become thinner than the rest. This is a little more
important on the PT-20.

HOW TO DRAW A CENTERLINE

A. Place the part on a flat surface and draw a line
approximately 1" long with a ballpoint pen (a Bic Stik
works well).

❏3. Use the same procedure to mark the centerline on the

entire length of the leading edge of the elevator.

❏ 4. Cut the hinge slots in the elevator and stabilizer using

a #11 blade. Begin by carefully cutting a very shallow slit
at the hinge location. This first cut will establish the
location of the hinge slot, so concentrate on staying on the
centerline and don’t cut too deep!

❏ 5. Make three or four more cuts on the same line, going

slightly deeper each time. As you make these additional

cuts, go straight into the wood. Continue this process while
“wiggling” the knife handle from side to side until the
blade has reached the proper depth for the hinge.

❏ 6. Refer to the Expert Tip below and sand the LE of the

elevator and rudder to a “V” as shown on the plans. Leave

the TE of the stab and fin squared off.

13

B. Confirm that the line you have drawn is on center by
flipping the part over and drawing a second line over the
first. If the line is on center, you will see only one line.
Draw a centerline at each hinge location. If you see two
lines (as in the photo) go to step C.

HOW TO BEVEL THE LEADING EDGES

A. Place the leading edge of the elevator on your work
surface and use your ballpoint pen to mark a “bevel to”
line on both sides about 3/32" high. Note: You will
probably have to shim the elevator (similar to the way
you did for drawing the hinging centerlines) so your bevel
to line is not too far away from the leading edge.

C. Place shims such as business cards or playing cards
under the stab until you can mark the centerline.

CUT HINGE SLOT
WITH HOBBY KNIFE
AND #11 BLADE

❏ 7. Cut the hinges for the elevator and the rudder from

the supplied 2" x 9" hinge material, then snip off the
corners so they go into the slot easier. Note: If you are
building the PT-20, make the hinge for the bottom of the
rudder 3/8" wide.

❏ 8. Temporarily join the elevator to the stab with the

hinges and widen any slots if required so they all match up.

❏ 9.Return to step 1 and use the same procedures to

hinge the rudder and fin. Note: If you are building the
PT-20, make the bottom hinge slot in the rudder 3/8" wide.

❏ 10. Use the same “centerline technique” you used when

you made the hinge slots to mark the perimeter of the
stabilizer and elevator.Round the perimeter of the stab and
elevator with your bar sander and 220-grit sandpaper using
the centerline as a guide. On the stab, keep the trailing
edge and the “flattened-off” center portion of the leading
edge square. Finish-sand the stab and elevator with 320-grit
sandpaper. Hint: Leave the elevator attached to the stab
during sanding so the ends will be rounded off the same.

Congratulations! You’ve made it through the first stage
and if this is your first model you should be proud of
yourself.You should also have learned a few “tricks of the
trade” used by the guys that designed this kit. Remember,
all of these helpful tips are the same methods that we use
to build our award winning models and are tips that you can
use and refine for future, more ambitious building projects!

❏ 1. Test fit the die-cut balsa fuse side pieces as shown in

the photo. Sand the edges as necessar y for a good fit.
When satisfied with the fit, make a fuse side using thin CA
to glue the parts together over waxed paper. Make a
second fuse side in the same manner.Note: It is easiest to
first glue the aft fuse side to the upper fuse side, then
glue the lower fuse side.

Preparation

BUILD THE FUSELAGE

14

B. Use a razor plane or your bar sander with 150-grit
sandpaper to make the “V” on the rudder and elevator.
Use the “bevel to” lines and the previously drawn
centerline as a guide to keep the angle of the “V”
constant and centered.

1"
1"

3/4"

❏ 2. Examine the two fuse sides for blemishes, then

position them on your workbench exactly as shown in the
photo with the best-looking sides facing down. You must
build a right and a left side so be sure that the sides are
mirrored as you look at them. Mark the inside surfaces as
“right” and “left.”

❏ 3. Lightly sand the edges of the die-cut 1/8" plywood

upper and lower fuse doublers to remove any slivers or
die-cutting irregularities.

Work especially carefully during the following two
steps. You must accurately position the fuse doublers on

the fuselage sides as this is the most critical step in building
a straight fuselage.

❏❏4. Still working over waxed paper, test fit, then glue a

die-cut 1/8" plywood upper fuse doubler to the inside of
the right fuselage side with medium CA. See the photo at
step 6. The top edge of the doubler should align with the

top of the fuse side at the wing saddle. The balsa side
behind the wing saddle protr udes above the doubler

by 3/32".

❏❏5. Test fit the lower fuse doubler in the notch of the

top doubler with 3/32" of the balsa fuselage side showing
below the doubler when it’s properly aligned. Glue the lower
doubler in position with medium CA the same way as you
did the upper doubler. See the photo at step 6.

❏ 6. Repeat steps 4 and 5 to glue the doublers to the

inside of left fuse side. Be sure you are building a right
and a left.

❏❏7. Test fit the die-cut balsa aft fuse doubler on the

inside of the right fuselage side.The “steps” in the front and
rear of the doubler should align with the fuselage side and
the aft end of the doubler and the fuselage side should also
align. Apply medium CA to the doubler, then glue it in
position. Repeat for the other fuselage side.

Skip step #8 if you will be using bolts to mount
your wing.

❏ 8. If you will be installing the dowels for rubber band

wing attachment, drill 1/4" holes through the fuse sides at
each punch mark in the upper doublers. Use a backup
block of scrap wood under the fuse side to prevent splitting
the balsa as the drill bit goes through (and to keep from
drilling into your table).

❏ 9. Locate the three die-cut 1/8" plywood firewall formers

F-1A, F-1B and F-1C and the three die-cut 1/8" plywood
wing bolt plates. Note: You need the wing bolt plates for

strength even if you will be using rubber bands to attach
the wing.

15

❏ 10. Notice that two pieces of the wing bolt plate

assembly have grain running in one direction while the third
piece has grain running opposite to the first two. The odd
one goes in the center of the “sandwich.” Mix about 1/4 oz.
of 30-minute epoxy and glue the bolt plates together as
shown (the extra epoxy will be used in the next step). This
assembly must be clamped together with C-clamps or
weighted down while the epoxy cures. If you use weights,
be sure the pieces do not slide and shift when you add
the weights.

❏ 11. Use the remaining 30-minute epoxy to glue F-1A,

F-1B and F-1C together. Be sure that F-1A (the one with
the punch marks) is on top of the stack with the punch
marks facing outward, the locking tabs are aligned, and
that F-1C is flush with the top edge of the assembly (see
the fuse plan). This assembly must be held together with
clamps, or weighted down while the epoxy cures. Note: If
the three formers are wrapped, simply clamping them
together may not necessarily “cancel out” the warps. It is
best to clamp the assembly over waxed paper to a flat
board or table. Allow the epoxy to fully cure before
removing the clamps.

❏ 12. Position the die-cut 1/8" plywood formers F-2

through F-5 over a piece of scrap wood, then drill a 3/16"

hole through each of the punch marks (former F-4 on the
PT-20 is balsa). Do not drill the F-1 assembly during this
step. Note: When punching out former F-2 from the die
sheet, don’t accidentally throw away the plywood hatch
retainer as it may be easily mistaken for scrap. Refer to the
die drawings.

❏ 13. Refer to the sketch, then drill two 3/16" pushrod tube

holes through the firewall where indicated. Change your bit
size to 7/32" (or 15/64" for perfection) and drill the two fuel
tube holes where indicated. Finally, drill four 5/32" holes
(1/8" if you’re building the PT-20) for the engine mount blind
nuts. Note: The remaining four punch marks around the
perimeter of the firewall could be used for locating the
center of the firewall should you choose to use a different
engine mount.

❏ 14. Clean up any slivers from around the holes you

drilled and also the edges of the formers with a bar sander
and 220-grit sandpaper.

❏ 15. Press a 6-32 blind nut (4-40 if you’re building the

PT-20) into one of the holes in the back of the firewall
(F-1C), then tap it gently with a hammer until it is fully
seated. Put a few drops of thin CA on the outer edge of the
flange to secure the blind nut. Install the remaining three
blind nuts the same way.

16

IMPORTANT: Position all of the formers with the embossed
numbers facing the front of the model.

❏1.Test fit the die-cut 1/8" plywood formers F-2 and F-3 in

position on the right and left fuse sides. Be sure the
bottoms of the formers line up with the bottom of the
doublers on both fuselage sides.

For the bolt-on wing
version, the F-2A former must face toward the front of the
model.

Glue F-2 and F-3 to the right fuse side as shown
with medium CA. Hold F-2 and F-3 vertical with a triangle
or building square while the CA cures.

❏ 2. Glue the left fuse side to formers F-2 and F-3,

making sure the fuse sides are aligned and the bottoms of
the formers are flush with the bottom of the doublers.

❏3.Test fit, but do not glue, the die-cut 1/8" plywood tank

floor and the firewall assembly between the fuse sides.The

tab at the rear end of the tank floor should fit into the notch
at the bottom of F-2 and the front of the tank floor should fit
under F-1C on the back of the firewall assembly. Make any
adjustments if required to the firewall sides or the tank floor.

❏ 4. With the tank floor installed (but not yet glued), glue

the firewall assembly in position with 30-minute epoxy.
Use rubber bands and/or masking tape to clamp the
fuselage sides together while the epoxy cures. After the
epoxy has cured, glue the tank floor in position with
medium CA.

❏ 5. Test fit the die-cut 3/32" balsa front fuse bottom into

the notches and recess on the bottom of the fuse. If you
have your battery pack handy, simulate installing it under
the tank floor as you would if the model was completed. A
500 mAh flat pack wrapped in foam will fit but if you have a
larger battery pack you may wish to enlarge the opening in
the tank floor. Make modifications before you glue the front
fuse bottom in position. When satisfied with the fit, glue the
front fuse bottom in position with thin CA along both outside
edges.Turn the fuse over, then wick thin CA into the inside
joints between the bottom and the formers. Follow with
medium or thick CA in any open joints.

Join the Fuselage Sides

17

❏ 16. Glue the die-cut 1/8" plywood former doubler

F-2A to the front of former F-2 (that’s the side with the
punched number) so the top edges are even.

❏ 6. Test fit the die-cut 3/32" balsa rear fuse bottom

between the fuse sides. Temporarily hold the bottom in
position with a few strips of masking tape.

❏ 7. Install the die-cut 1/8" formers F-4 and F-5 in the

notches of the fuse sides and bottom. Be sure that the
antenna tube hole is toward the bottom of the fuse. Use
more masking tape to hold the formers tightly in position.
When you are satisfied that everything is square and true,
place the fuse on waxed paper, then wick thin CA into the
joints (from the inside) between the fuse sides, bottom and
the formers. As you apply glue, press down on the fuselage
to hold it square.

❏ 8. Apply medium CA along all of the inside joints to

permanently secure the framework.Remove the masking tape.

❏ 9. Cut the two 36" plastic outer pushrod tubes to 26"

for the PT 40 (24-1/4" for the PT 20). One tube will be used
as the elevator pushrod guide tube and the other will be
used as the rudder pushrod guide tube. Make the
antenna tube (optional) from any type of 3/16" pushrod
tube (not included). We recommend purchasing a Great
Planes 36" flexible pushrod set (GPMQ3710) and using
one of the outer tubes from the set. Save the scrap pieces

from the elevator and rudder tubes for use later.

❏ 10. Sand the outside of each tube with 150-grit

sandpaper so glue will stick to them. Slide the antenna
tube (if used) through the bottom hole in formers F-3, F-4

and F-5 and through the exit slot in the bottom of the fuse.
Slide the pushrod tubes through the upper holes in the
formers and out through the exit slots at the rear of the
fuse. All of the tubes should protrude about 1/2" past the
rear end of the slots. Use medium CA to glue the pushrod
tubes to each former and the exit slots.

❏ 11. Use HobbyLite filler to fill the gap around the

pushrod tubes on the outside of the fuselage.

❏ 12. After the filler has fully cured, sand the protruding

pushrod tubes and the filler so it is flush with the fuselage.

Skip step #13 if you will be using bolts to mount
your wing.

❏ 13. Glue the die-cut 1/8" plywood front and rear dowel

triplers in position with medium CA.

18

❏ 14. Hold the die-cut 3/32" balsa fuse top at the edge of

your work table, then gently “crack” the wood along the die­cut score line. Do not break the part in two. Hint: Bend
the fuse top away from the side that has the score
on it.

❏15. Use a straightedge and a ballpoint pen to draw a line

across the notches on the fuse top at the score line. Cut
two 1/4" wide strips from 3/32" scrap balsa and glue them
to the inside of the fuse top on either side of the score line
between the lines you marked. Note: If building the PT-20,
the 3/32" balsa strips must be shorter than the ones shown
in the photo to fit between the fuselage doublers.

❏ 16. Test fit the fuse top to the fuselage. Glue it in position

by wicking thin CA into the joint between the top, former tabs,
and the sides.Follow with medium CA to fill in any gaps.

❏ 17. Use epoxy to glue the wing bolt plate assembly into

the notches of the plywood doublers and F-3.

We
recommend that you perform this step even if you are not
going to use the bolt-on wing option.

❏ 19. Carefully sand or cut a bevel along the bottom of the

notch in the windshield. This bevel will allow the windshield
to fit flush against F-2.

❏ 20. When the windshield fits properly, glue it in position

with medium CA. Sand the top of former F-2 (A) flush with
the front surface of the windshield. Sand the rear of the
windshield overhang flush with the back of F-2.

Skip step #21 if you are building the PT-20.

❏ 21. Test fit the die-cut 1/8" balsa nose blocks in the

engine compartment, then glue them in position with epoxy.
After the epoxy has cured, sand the outside edges flush
with the fuse.

19

❏ 18. Increase the depth of the notch in the die-cut 1/8"

windshield by 1/8" to allow for F-2A (the windshield for
the PT-20 is balsa). See the following photo.

❏ 22. Locate the die-cut 1/8" plywood hatch retainer

(HR). Center the hatch retainer on the bottom (unpunched
surface) of the die-cut 1/8" plywood tank compartment
hatch with approximately 3/8" protruding from the rear,

then glue it in position.

❏ 23. Position the hatch on the fuselage and drill 1/16"

holes through the punch marks in the hatch into the firewall.
Remove the hatch, then enlarge the holes in the hatch
only with a 3/32" drill bit. Temporarily mount the hatch to
the fuselage with #2 x 3/8" screws.

❏ 24. Glue the two die-cut balsa cabin top fillers in the

notches on both sides of the windshield.

❏ 25. Test fit, then glue the die-cut stab base and the

tapered balsa tail wedge into the aft end of the fuselage.
Trim the tail wedge as necessary for a good fit.

Skip step #26 if you are building the bolt-on wing version.

❏ 26. Slightly chamfer the ends of the two wing dowels,

then test fit them through the holes in the fuse. Hint: Run a
1/4" drill through the fuse sides to make sure the holes are
all lined up. Remove the dowels until the model is
covered. You will be instructed when to glue the dowels in.

❏ 1. Test fit, but do not glue, the grooved hardwood

landing gear (LG) rail in the slot on the bottom of the fuse.

It should fit snugly in the space between the ends of the
bottom sheeting and the notches in the fuse sides.

❏ 2. See the following photo at step 4. While the rail is in

position (but not yet glued) test fit the two die-cut 1/8"
plywood landing gear doublers (LGD) and the hardwood
landing gear blocks. Note: The grain direction of the LG
blocks is vertical (as shown on the plan).

❏ 3. Remove all the landing gear parts, then mix enough

30-minute epoxy to glue the LG rail and the LG blocks.Glue
the LG rail to the fuse sides and fuse doublers with epoxy,
then glue the LG doublers in position with medium CA.
Immediately proceed to the next step.

Install the Main Landing Gear

20

Trim to fit bottom

of fuselage