Great Planes GPMA1975 User Manual

DIRTY BIRDY .60 ARF INSTRUCTION MANUAL

SPECIFICATIONS

Wingspan: 64.5 in [1640 mm]

2

Wing Area: 690 in

[44.5 dm2]

Wing Loading: 25−28 oz / ft

2

[76−85 g/dm2]

Weight: 7.5 − 8. 5 l b

Radio: 4-channel minimum

Length: 56 in [1420 mm]

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

[3400−3850 g]

with 5-7 servos and
standard size receiver

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:

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.

Engine: .60 – .65 cu in [10 –10.5cc]

two-stroke

Hobby Services

3002 N. Apollo Dr. Suite 1

Champaign IL 61822 USA

READ THROUGH THIS MANUAL BEFORE STARTING CONSTRUCTION. IT CONTAINS IMPORTANT

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

Entire Contents © 2011 Hobbico,® Inc. All rights reserved.

Champaign, Illinois

[phone], Ext 5

[e-mail]

GPMA1975

TABLE OF CONTENTS

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

Academy of Model Aeronautics . . . . . . . . . . . . . . . . . . 2

SAFETY PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . 3

DECISIONS YOU MUST MAKE . . . . . . . . . . . . . . . . . . . . 3

Radio Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Engine Recommendations. . . . . . . . . . . . . . . . . . . . . . 3

Optional Tuned Pipes. . . . . . . . . . . . . . . . . . . . . . . . . . 3

Optional Retracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

ADDITIONAL ITEMS REQUIRED. . . . . . . . . . . . . . . . . . . 4

Required Hardware & Accessories . . . . . . . . . . . . . . . 4

Adhesives and Building Supplies. . . . . . . . . . . . . . . . . 4

Optional Supplies and Tools . . . . . . . . . . . . . . . . . . . . 4

Building Stand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

IMPORTANT BUILDING NOTES . . . . . . . . . . . . . . . . . . . 5

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

ORDERING REPLACEMENT PARTS . . . . . . . . . . . . . . . 5

KIT CONTENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

PREPARATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

ASSEMBLE THE WINGS . . . . . . . . . . . . . . . . . . . . . . . . . 6

INSTALL THE FIXED LANDING GEAR . . . . . . . . . . . . . . 9

INSTALL THE OPTIONAL HOBBICO

MECHANICAL LANDING GEAR . . . . . . . . . . . . . . . 10

INSTALL THE OPTIONAL

PNEUMATIC LANDING GEAR. . . . . . . . . . . . . . . . . 14

MOUNT THE WING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

INSTALL THE STABILIZER AND TAIL SERVOS . . . . . 18

INSTALL THE POWER SYSTEM . . . . . . . . . . . . . . . . . . 20

INSTALL THE FIXED NOSE GEAR . . . . . . . . . . . . . . . . 23

INSTALL THE ELECTRONICS. . . . . . . . . . . . . . . . . . . . 24

INSTALL THE OPTIONAL

MECHANICAL NOSE GEAR RETRACT . . . . . . . . . 25

INSTALL THE OPTIONAL PNEUMATIC NOSE GEAR

RETRACT AND AIR CONTROL SYSTEM. . . . . . . . 29

OPTIONAL TUNED PIPE INSTALLATION. . . . . . . . . . . 33

FINISH THE MODEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Apply the Decals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

GET THE MODEL READY TO FLY. . . . . . . . . . . . . . . . . 35

Check the Control Directions. . . . . . . . . . . . . . . . . . . 35

Set the Control Throws . . . . . . . . . . . . . . . . . . . . . . . 35

Balance the Model (C.G.) . . . . . . . . . . . . . . . . . . . . . 36

Balance the Model Laterally . . . . . . . . . . . . . . . . . . .36

PREFLIGHT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Identify Your Model . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Charge the Batteries . . . . . . . . . . . . . . . . . . . . . . . . . 36

Balance Propellers. . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Ground Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Range Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

ENGINE SAFETY PRECAUTIONS. . . . . . . . . . . . . . . . . 37

AMA SAFETY CODE (excerpts) . . . . . . . . . . . . . . . . . . . 37

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Radio Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

CHECK LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

FLYING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Takeoff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Flight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Landing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

INTRODUCTION

Congratulations on your purchase of the Dirty Birdy .60
ARF! For 35 years Joe Bridi’s design has been known for its
capabilities of precision pattern fl ying and was revolutionary at
the time of its introduction. Great Planes offered a fi berglass
kit version of the Dirty Birdy in the 1980’s, and now it has
fi nally been revived as a fi berglass ARF. Accommodations for
mechanical retracts, pneumatic retracts, and a tuned pipe are
provided for drop-in installation. Fixed landing gear is provided
in the box for those budget-minded modelers as well. With
pre-hinged control surfaces and stab halves that mount onto
two carbon tubes, assembly couldn’t be easier. If you were
one of the fi rst to build this fantastic plane in 1975 and want
to relive the experience, or this is your very fi rst pattern ship,
you have made the right choice as the Dirty Birdy will surely
deliver the performance you expect.

For the latest technical updates or manual corrections to
the Great Planes Dirty Birdy .60 ARF visit the Great Planes
web site at www.greatplanes.com. Open the “Airplanes” link,
then select the Dirt Birdy .60 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.

Academy of Model Aeronautics

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 47302-9252

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.

2

SAFETY PRE CAUTION S

DECISI ONS YOU MUST MAKE

Protect Your Model, Yourself & Others…

Follow These Important Safety Precautions

1. Your Dirty Birdy .60 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 Dirty Birdy, 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 use an R/C radio system that is in fi rst-class
condition, and a correctly sized engine and components (fuel
tank, wheels, etc.) 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

fl ight to ensure 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 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.

8. While this kit has been fl ight tested to exceed normal use,
if the plane will be used for extremely high stress fl ying, such
as racing, or if an engine 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.

9. WARNING: The fuselage and cowl included in this kit

are made of fi berglass, the fi bers of which may cause eye,
skin and respiratory tract irritation. Never blow into a part to
remove fi berglass dust, as the dust will blow back into your
eyes. Always wear safety goggles, a particle mask and rubber
gloves when grinding, drilling and sanding fi berglass parts.

Vacuum the parts and the work area thoroughly after working

with fi berglass parts.

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 y our time and follo w the instructions to
end up with a well-built model that is straight and true.

This is a partial list of items required to fi nish the Dirty Birdy

ARF that may require planning or decision making before
starting to build. Order numbers are provided in parentheses.

Radio Equipment

The Dirty Birdy requires a minimum 4-channel radio system

with a minimum of fi ve 44 oz.-in. [3.2 kg-cm] standard sized
servos. If you are installing mechanical retracts, two retract
servos are also required. If you are installing pneumatic retracts,
one additional standard servo is required.

In addition, two 12" [305mm] servo extensions are required for
the aileron servos. If you are using a radio system that does
not support mixing functions, a Y-harness will also be required
to connect the aileron servos to the receiver. If you plan to
connect the aileron servos to separate channels, you will also
need two 6" [152mm] servo extensions to connect directly to
the receiver to provide easy access when mounting the wing
(these are not needed if you will be using the Y-harness).

Another Y-harness will also be needed if you are installing
mechanical retracts. There is no advantage in connecting the
retract servos to separate channels because you cannot alter
the endpoints or travel volume.

Recommended part numbers for the radio components are
provided below:

❍ Futaba

(FUTM0004)

❍ Hobbico® CS-63 Servo Low Profi le Retract BB U

(HCAM1060)

❍ Hobbico 12" Extension Futaba J (HCAM2100)

❍ Futaba Dual Servo Extension 6" J (FUTM4130)
❍ Ernst Charge Receptacle Futaba J FM (ERNM3001)
❍ Hobbico HydriMax™ 4C 4.8V 2000mAh NiMH Square

AA Rx U (HCAM6322)

®

S3004 Standard Ball Bearing Servo

Engine Recommendations

The recommended engine/motor size for the Dirty

Birdy is a .60 –.65 cu in [10–10.5cc ] two-stroke engine.
Choose a propeller based on the engine manufacturer’s
recommendation. The order number for the recommended
engine is provided below:

®

❍ O.S.

65AX ABL w/Muffl er (OSMG0558)

Optional Tuned Pipes

The following parts are recommended for an optional tuned

pipe system for the O.S. .65AX engine:

❍ .60 – .75 cu in Quiet Tuned Pipe 1060 (MACG1060)

❍ Macs Long Tuned Pipe Adapter O.S. .61 SF/FX/FP

(MACG2861)

❍ Macs Tuned Pipe Mount (MACG9231)

3

Optional Retracts

Optional Supplies and Tools

The Dirty Birdy is designed to accept both mechanical and

pneumatic retracts. If you plan to use mechanical retracts you
only need to purchase the mechanical retract set:

❍ Hobbico Mechanical Retracts 3-Gear (HCAP4000)

If you plan to install pneumatic retracts, you will need to
purchase the following items:

❍ Robart 90 Degree Nose 5/32" Wire (ROBQ1807)

❍ Robart 90 Degree Mains w/3/16" Wire (ROBQ0005)

❍ Robart Standard Deluxe Air Control Kit (ROBQ2307)

❍ Great Planes Wire Axle 2x3/16" (2) (GPMQ4282)

❍ Great Planes Plated Wheel Collars 3/16" (4)

(GPMQ4308)

ADD ITIONAL ITEMS R EQ UI RE D

Required Hardware & Accessories

This is the list of hardware and accessories required to fi nish

the Dirty Birdy. Order numbers are provided in parentheses:

❍ R/C foam rubber 1/4" [6mm] (HCAQ1000)

❍ 3' [900mm] standard silicone fuel tubing (GPMQ4131)

Adhesives and Building Supplies

This is the list of Adhesives and Building Supplies that are

required to fi nish the Dirty Birdy:

❍ 1/2 oz. [15g] Thin Pro™ CA (GPMR6001)

❍ Pro 30-minute epoxy (GPMR6047)

❍ Threadlocker thread locking cement (GPMR6060)

❍ Denatured alcohol (for epoxy clean up)

❍ Drill bits: 1/16" [1.6mm], 5/64" [2mm], 3/32" [2.4mm],

(13/64" [5.2mm] pneumatic retracts only)

❍ Great Planes Tap & Drill Set 6-32 (GPMR8102)

❍ Tap handle (GPMR8120)

❍ Rotary tool with cutting bit

❍ Revell® Premium Soft Handle Knife w/Blades (5)

(RMXR6900)

❍ Top Flite® MonoKote® sealing iron (TOPR2100)

❍ Top Flite Hot Sock™ iron cover (TOPR2175)

❍ Panel Line Pen (TOPQ2510)

❍ Hobbico Steel T-Pins 1" (100) (HCAR5100)

❍ Harry Higley’s 3/16" Extended Drill (HIGR1020)

❍ Small clamps

❍ Masking tape

❍ Household oil

Here is a list of optional tools that will help you build the Dirty
Birdy .60 ARF:

❍ 1/2 oz. [15g] Thick Pro CA- (GPMR6013)

❍ 1/2 oz. [15g] Medium Pro CA+ (GPMR6007)

❍ Great Planes Pro Foam Safe CA- Thick Glue 20g

(GPMR6072)

❍ 2 oz. [57g] spray CA activator (GPMR6035)

❍ 4 oz. [113g] aerosol CA activator (GPMR6034)

❍ CA applicator tips (HCAR3780)

❍ CA debonder (GPMR6039)

❍ Great Planes Pro Epoxy 6-Minute Formula 4 oz

(GPMR6042)

❍ Epoxy brushes 6, (GPMR8060)

❍ Mixing sticks (GPMR8055)

❍ Mixing cups (GPMR8056)

❍ Pliers with wire cutter (HCAR0630)

❍ T.A. Emerald Performance Duster Compressed Air

(TAEC1060)

❍ Servo horn drill (HCAR0698)

❍ Hobby Heat™ Micro Torch II (HCAR0755)

❍ Dead Center™ Engine Mount Hole Locator

(GPMR8130)

❍ DuraTrax® Ultimate Body Reamer (DTXR1157)

❍ Precision Magnetic Prop Balancer (TOPQ5700)

❍ AccuThrow™ Defl ection Gauge (GPMR2405)

❍ CG Machine™ (GPMR2400)

❍ Hobbico Flexible 18" Ruler Stainless Steel

(HCAR0460)

❍ Top Flite MonoKote trim seal iron (TOPR2200)

❍ Top Flite MonoKote heat gun (TOPR2000)

❍ Hobbico Pin Vise 1/16 Collet w/6 Bits (HCAR0696)

❍ Hobbico 8-Piece Ball Tip Hex L Wrench SAE

(HCAR0520)

❍ Hobbico 7-Piece Ball Tip Hex L Wrench Metric

(HCAR0521)

❍ Great Planes Clevis Installation Tool (GPMR8030)

4

Building Stand

KIT IN SPE CTION

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 Pr oduct 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 Ph: [phone], ext. 5

Champaign, IL 61822 Fax: [phone]

E-mail: [e-mail]

ORDERING REPLAC EMENT PARTS

A building stand or cradle comes in handy during the build. We

use the Robart Super Stand II (ROBP1402) for all our projects
in R&D, and it can be seen in pictures throughout this manual.

IMPORTANT BUILDI NG 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.

● The stabilizer and wing incidences and engine thrust angles

have been factory-built into this model. However, some

technically-minded modelers may wish to check these

measurements anyway. To view this information visit the web

site at www.greatplanes.com and click on “Technical Data.”
Due to manufacturing tolerances which will have little or no
effect on the way your model will fl y, please expect slight

deviations between your model and the published values.

Replacement parts for the Great Planes Dirty Birdy 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 Great Planes web site at

www.greatplanes.com. Select “Where to Buy” in the menu
across the top of the page and follow the instructions provided
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 Hobby Services

and payments by 3002 N Apollo Drive, Suite 1
personal check to: 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 productsupport@greatplanes.
com, or by telephone at [phone].

REPLACEMENT PARTS LIST

Order No. Description

GPMA2160
GPMA2161
GPMA2162
GPMA2163
GPMA2164
GPMA2165
GPMA2166

WING
FUSELAGE
HORIZONTAL STABILIZER SET
COWL
SPINNER
LANDING GEAR SET
DECALS

5

Cut Off

Unused Arms

5/64" [2mm]

KIT CONTENTS

1

5

8

15

7

1. Fuselage

2. Wing Panels

3. Horizontal Stabilizer & Elevators

4. Wing Joiner

5. Cowl

6. Fuel Tank

6

10

9

2 2

7. Fixed Landing Gear

8. Spinner

9. Belly Pan

10. Nose Gear Cover

11. Retract Servo Tray

12. Air Valve Mount

13

16

12

11

4

3

14

13. Pushrods

14. Horizontal Stabilizer Tubes

15. Engine Mount

16. Outer Pushrod Tubes

PREPARATIONS

1. If you have not done so already, remove the major

❏

parts of the kit from the box and inspect for damage. If any
parts are damaged or missing, contact Product Support at
the address or telephone number listed in the “Kit Inspection”
section on page 5.

2. Use a covering iron with a covering sock on high heat

❏

(350°F) to tighten the covering if necessary. Apply pressure

over sheeted areas to thoroughly bond the covering to

the wood.

ASSEMBLE THE WI NGS

1. Center your aileron servos and trims with your radio

❏

system. Test fi t four-armed servo arms onto the servos to
determine their best orientation so that the arms are closest

6

to being perpendicular with the servo case with the transmitter

Hinge Line Hinge Line

CORRECT INCORRECT

trims centered. Cut three arms from each servo arm leaving
one arm on each servo that matches the photo. Enlarge the
outer hole of each remaining arm with a 5/64" [2mm] drill bit.
Install the rubber grommets and eyelets.

2. Attach a 12" [305mm] servo extension to each servo.

❏

Secure the connection using tape, heat shrink tubing (not
included) or special clips designed for that purpose.

4. Fit the servos into the servo openings and drill 1/16"

❏

[1.6mm] holes through the mounting tabs on the servo cases
into the rails. Thread a servo mounting screw (included with
the servo) into each hole and back it out. Apply a drop of thin
CA to each hole to harden the wood surrounding the wood.
When the CA has dried, install the servos into the openings
as shown using the screws supplied with the servos.

5. Thread a nylon clevis onto each of the two 6" [152mm]

❏

pushrods 20 complete turns. Slide a silicone clevis retainer
onto the base of each clevis. Attach each clevis to the outer
hole of a large control horn.

3. Use the strings taped inside the aileron servo openings

❏

to pull the servo leads through the wing panels.

6. Position a control horn onto the aileron aligning the

❏

pushrod with the outer hole of the aileron servo arm. Position
the control horns over the plywood plates in the ailerons (if
you cannot see them, hold the aileron at a shallow angle in

7

good lighting or use a small pin to puncture the covering).

FasLink

2-56 (.074") Pushrod Wire

Servo Horn

1/16"

When satisfi ed, use a felt-tip pen to mark the location of the
control horn mounting holes onto the aileron. Repeat this step
for the other wing panel.

7. Drill 5/64" [2mm] holes through the aileron at the marks

❏

you made. Install the control horns onto the ailerons using 2-56
x 5/8" [16mm] machine screws and control horn backplates.
With the ailerons in the neutral position (use tape or small
clamps to hold them in place), mark the pushrod wires where
they cross the outer hole in the servo arms.

9. Prepare the aluminum wing joiner piece by roughening

❏

both sides of it with 180-220 grit sandpaper. Clean the piece
with denatured alcohol. Use epoxy to laminate the three wing
joiner pieces together with the aluminum piece in the center.
Wipe away any excess epoxy using a paper towel dampened
with denatured alcohol and use small clamps to hold the parts
together while the epoxy cures. Be sure that the edges of each
piece are fl ush with the others.

8. Make a 90 degree bend at the mark on each pushrod

❏

and cut off the excess pushrod 1/4" [6mm] beyond the bends.
Attach the pushrods to the servo arms using nylon FasLinks.
Thread the clevises up or down on the pushrods as necessary

to center the ailerons with the servo arms still perpendicular

to the servo cases. When satisfi ed, slide the silicone clevis

retainers to the ends of the clevises to secure them.

10. Route the aileron servo leads through the holes in the

❏

top of the wing panels.

11. When the epoxy from step 9 has cured completely, test

❏

fi t the joiner into each wing panel. Make sure that the joiner
can be inserted halfway into each joiner pocket (the point of
the “v” shape of the joiner should point towards the underside
of the wing. Drawing a line down the center of the joiner is
helpful.) The joiner should be a slightly loose fi t in each panel
to allow space for epoxy. Sand the sides or edges of the joiner
until the proper fi t is achieved. Insert the nylon anti-rotation
pin halfway into the hole in one wing panel and test fi t the
two panels together.

8

12. When satisfi ed with the fi t of the panels, mix up

❏

approximately 20cc [20ml] of 30-minute epoxy and thoroughly

coat the insides of the wing joiner pockets. Coat one half of the

joiner and insert it into one of the panels. Coat the anti-rotation

pin and insert it into the pin hole. Coat the other halves of the

joiner and pin as well as the root ribs of the panels. Join the

two panels together, taking care to wipe away excess epoxy

as it squeezes out of the joint. Use masking tape to hold the

panels together while the epoxy cures.

INSTALL THE FIXED LANDING GEAR

If you will be installing mechanical or pneumatic main gear

retracts, skip this section.

3. Fit the main landing gear wires into the blocks as shown.

❏

Use four landing gear straps and eight #2 x 3/8" [9.5mm] self­tapping screws to secure them to the blocks.

1. Insert the fi xed landing gear blocks into the openings

❏

in the wing (use the other photos in this section to determine

the correct orientation of the blocks). Drill through the four

mounting holes on each block and into the wood rails in the

wing using a 5/64" [2mm] bit.

2. Remove the blocks from the wing. Thread a #4 x 5/8"

❏

[16mm] self-tapping screw into each hole and back it out.
Apply a drop of thin CA to each hole and allow the glue to

harden. Reinstall the blocks into the wing and secure them

using eight #4 x 5/8" [16mm] self-tapping screws.

4. Slide a 5/32" [4mm] wheel collar followed by a main

❏

wheel then another 5/32" [4mm] collar onto the axles of the
landing gear wires. Mark the location of the collar screw holes
onto the axles using a felt-tip pen.

5. Use a fi le or rotary tool to grind fl at spots onto the axles

❏

at the spots that you marked.

9

6. Apply a drop of oil (household oil or bearing oil are

❏

acceptable) to each axle. Reinstall the collars and wheels

onto the axles. Secure the collars to the axles with 6-32 x
1/4" [6.4mm] SHCS and thread locking compound. Ensure

that the wheels rotate freely on the axles.

INSTALL THE OPTIONAL HOBBICO

MECHANICAL LANDING GEAR

If you have installed the fi xed main gear, skip this section.

3. Cut the landing gear struts to 4-11/16" [119mm] as

❏

shown. File a small bevel onto the ends of the struts to ease
the installation of the axles.

4. Set the retracts into position on the rails. Trace the outline

❏

of the coils (the portion that overlaps the sheeting) onto the
underside of the wing as shown.

1. Trim the covering from the main wheel wells on the

❏

underside of the wing. There are small pieces of wood

supporting the covering that must also be removed.

2. Prepare the mechanical retracts by adjusting the up

❏

and down lock set screws as described in the instructions

that came with the retract set (with tool in hand, adjust the

nose retract as well). Removing the free play ensures that

the plane will taxi straight and smoothly down the runway. Do

not skip this step.

5. Cut out a small section using your marks as a guide.

❏

The cutouts should be just deep enough to accommodate

the coils when the retracts are in the up position. Test fi t the
retracts onto the rails to ensure the coils fi t into your cutouts.
When satisfi ed, coat the exposed foam and sheeting edge
with epoxy or foam safe CA.

10

6. Temporarily slide the axle shown in step 7 onto the end

❏

of the gear struts to ensure they are centered in the wheel

wells. Mark the locations of the retract mounting holes onto

the rails. Drill 3/32" [2.4mm] holes at your marks. Thread a

#4 x 5/8" [16mm] self-tapping screw into each hole and then

back it out. Apply a drop of thin CA to each hole and let the

glue harden. Install the retracts using eight #4 x 5/8" [16mm]

self-tapping screws.

7. Cut three 5/32" x 1-1/4" [4mm x 32mm] bolt-on wheel

❏

axle to 1" [25mm] long (the third one will be used for the nose

gear in a later section). Grind a fl at spot at the end of each

axle using a fl at spot or rotary tool.

8. Slide a wheel onto each axle and secure them with

❏

a 5/32" [4mm] wheel collar, 6-32 x 1/4" [6mm] SHCS and
thread locking compound. A drop or two of oil on the axles
will ensure that the wheels rotate freely. Loosely thread a
6-32 x 1/4" [6mm] SHCS into each axle. Slide the axles onto
the ends of the struts and move the retracts to the locked up
position. Position the axles on the struts so that the wheels
are centered in the wheel wells. Tighten the SHCS in the axles
just tight enough to hold them in place on the struts. Move the
retracts to the down position. Rotate the axles on the struts
so the wheels point straight ahead. Thoroughly tighten the
SHCS in the axle.

11

9. Remove the axles from the struts. A mark will be left

❏

on the struts from tightening the screws in the previous step.

Grind a fl at spot at each mark. Reinstall the axles onto the

struts and tighten the SHCS against the fl at spots with thread

locking compound.

11. Cut out a section of the wing for the retract servo tray

❏

using your lines as a guide. The depth of the cutout is defi ned
by the slot that you aligned the tray over in the previous step.
A variety of tools could be used to remove the foam and balsa
material. We suggest fi rst using a hobby knife to cut around
the perimeter of your lines as deep as the knife blade will allow.
Use a small fl at blade screw driver to work out the portion that
you have so far cut away. Use a rotary tool with a sanding drum
bit to remove most of the remaining material. Work carefully
as the sanding drum will cut aggressively through the foam.
Once you get near the bottom of the plywood slot, switch to
a 1/8" [3mm] (or a similar bit size) drill bit in your rotary tool
and use the fl utes of the bit to clean up the walls of the cutout.
Make several zigzagging passes to clean up the bottom of
the cutout. There will be a plywood ledge at the bottom of the
cutout at both the forward and aft ends. The notches in the
servo tray fi t onto these ledges.

10. Center the retract servo tray over the slot in the wing as

❏

shown. Use a felt-tip pen to trace around the tray onto the wing.

12. When satisfi ed with your cutout, test fi t the servo tray

❏

in the cutout. Be sure it can be fully seated onto the plywood
ledges. If not, use a hobby knife to scrape away any remaining
balsa or glue that may be preventing the tray from fully seating.

12

13. Use the hardware included with the retract servo to

❏

mount it to the servo tray. Be sure to harden the servo mounting

holes with thin CA glue. Coat the notches of the tray with

epoxy as well as the plywood ledges in the cutout. Glue the

tray into the cutout.

the actuator link on the retract when the retract is in the down
(landing) position. Make a mark on the wire just beyond the
hole in the wheel well.

16. Make a shallow bend in the wire at your mark and

❏

another bend just behind the threaded portion of the pushrod
(you may need to adjust the angles of the bends after you test
fi t the pushrod into the wing.

14. Check the rotation of your retract servo using your

❏

radio. The servo shown in the picture will rotate clockwise to

raise the wheels into the wells. Attach two brass screw lock

connectors to a servo wheel (a two-armed servo arm would

also work) so that they are 1" [25mm] apart and positioned

slightly angled from being perpendicular to the servo case. To

ensure that the retracts open from lock to lock we recommend

setting the screw-lock connectors close to 1" [25mm] apart.

Loosely install two 4-40 set screws in the screw lock connectors.

17. Reinsert the pushrod into the wing and connect the

❏

clevis to the actuator link on the retract. Rotate the link so it
is closest to the leading edge of the wing as shown. Make
any adjustments to the bends in the pushrod so that the wire
lays as close to the bottom of the wheel well as possible. The
pushrod must not interfere with the wheel going up into the
wheel well.

15. Thread a nylon clevis 20 complete turns onto a 12"

❏

[305mm] pushrod. Insert the pushrod through the hole at the

inboard side of a wheel well. Align the pin in the clevis over

18. Mark the pushrod where it meets the opposite edge

❏

of the retract servo cutout in the wing (with the gear in the
landing position.) Cut off the excess pushrod at this mark.

13

19. Fit the end of the pushrod into the screw lock connector

❏

on the opposite side of the servo as the retract. Repeat steps
15-18 for the other retract. Tighten the set screws in the screw

lock connectors and test the operation of the retracts. The gear

must raise and lower lock to lock. If the gear is not locking in

position, adjust the positions of the pushrods in the connectors.

INSTALL THE OPTIONAL ROBART

PNEUMATIC LANDI NG GEAR

If you have installed the fi xed or mechanical main gear, skip

this section. Additional hardw are is required that is not included
with the Dirty Birdy ARF to install pneumatic retracts. See

the beginning sections of this manual for a detailed list of the

required hardware.

2. Open the pneumatic retract cases and fl ip the positions

❏

of the valves to the opposite side as shown in the photo.

3. Cut the retract struts to 5" [127mm] as shown in the

❏

photo using a rotary tool and cutoff wheel. File a small bevel
onto the ends of the struts to ease the installation of the axles.
Loosen the set screws that holds the struts in the retract
assemblies. Rotate the struts so that the coils in the wires are
inline with the rolling direction of the wheels. Tighten the set
screws against the wire in order to make marks on the wires.
Remove the struts completely from the retracts, fi le fl at spots
at the marks from the set screw, and then reinstall the struts
using thread locking compound on the set screws.

1. Trim the covering from the main wheel wells on the

❏

underside of the wing. There are small pieces of wood

supporting the covering that must also be removed.

4. Trim the hardwood landing gear mounting rails as

❏

necessary in order to fi t the retract assemblies in place.

14