Hobbico SUKHOI SU31 .50-.91 ARF Assembly Instructions Manual

ASSEMBLY INSTRUCTIONS

Entire Contents © Copyright 2004 HCAZ3047 for HCAA2090 V1.0

Wingspan: 61 in [1550mm]
Wing Area: 708 sq in [45.7 dm2]
Weight: 7.5 - 8.5 lb [3400 - 3850g]
Wing Loading: 24 - 28oz/sq ft [73 - 85 g/dm2]
Length: 51.5 in [1310mm]
Radio: Four-channel with 5 servos
Engine: .50 - .75 cu in [8 - 12cc] two-stroke,

.70 - .91 cu in [11. 5 - 15cc] four-stroke

Hobbico®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

Hobbico’s liability exceed the original cost of the
purchased kit. Further, Hobbico reserves the right to

change or modify this warranty without notice.

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

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

To make a warranty
claim, send the defective
part or item to Hobby
Services at this address.

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 THIS MANUAL BEFORE

STARTING CONSTRUCTION.

IT CONTAINS IMPORTANT

INSTRUCTIONS AND WARNINGS

CONCERNING THE ASSEMBLY

AND USE OF THIS MODEL.

WARRANTY

Hobby Services

3002 N. Apollo Dr. Suite 1

Champaign IL 61822

USA

1610 Interstate Drive
Champaign, Illinois

[phone] ext. 2

[e-mail]

SUKHOI SU31

SUKHOI SU31

.50 - .91

.50 - .91

ARF

ARF

™

2

TECHNICAL UPDATES . . . . . . . . . . . . . . . . . . .2

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

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

HARDWARE AND ACCESSORIES . . . . . . . . . . .3

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

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

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

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

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

ORDERING REPLACEMENT PARTS . . . . . . . . .6

REPLACEMENT PARTS LIST . . . . . . . . . . . . . . .6

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

ASSEMBLE THE WING . . . . . . . . . . . . . . . . . . .7

Install the Ailerons . . . . . . . . . . . . . . . . . . . .7

Install the Aileron Servos and Pushrods . . . . .7

Join the Wings . . . . . . . . . . . . . . . . . . . . . . .9

ASSEMBLE THE FUSELAGE . . . . . . . . . . . . . . .11

Install the Stab, Elevators and Rudder . . . . .11

Install the Landing Gear . . . . . . . . . . . . . . .12

Install Engine, Fuel Tank & Throttle Servo . . .13

Mount the Cowl . . . . . . . . . . . . . . . . . . . . .15

Install the Radio System . . . . . . . . . . . . . . .17

FINISHING TOUCHES . . . . . . . . . . . . . . . . . .19

GET THE MODEL READY TO FLY . . . . . . . . . .19

Check the Control Directions . . . . . . . . . . .19

Set the Control Throws . . . . . . . . . . . . . . . .19

Balance the Model (C.G.) . . . . . . . . . . . . . .20

Balance the Model Laterally . . . . . . . . . . . .20

PREFLIGHT . . . . . . . . . . . . . . . . . . . . . . . . . .21

Identify Your Model . . . . . . . . . . . . . . . . . .21

Charge the Batteries . . . . . . . . . . . . . . . . . .21

Balance Propellers . . . . . . . . . . . . . . . . . . .21

Ground Check . . . . . . . . . . . . . . . . . . . . . .21

Range Check . . . . . . . . . . . . . . . . . . . . . . .21

ENGINE SAFETY PRECAUTIONS . . . . . . . . . .22

AMA SAFETY CODE . . . . . . . . . . . . . . . . . . .22

CHECK LIST . . . . . . . . . . . . . . . . . . . . . . . . .23

FLYING . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Takeoff . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Flight . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Landing . . . . . . . . . . . . . . . . . . . . . . . . . . .24

For the latest technical updates or manual
corrections to the Hobbico Sukhoi SU31 visit the
Hobbico web site at www.hobbico.com. Open the
“Airplanes” link, then select the Hobbico Sukhoi
SU31 .50 -.91 ARF. If there is new technical
information or changes to this model a “tech
notice” box will appear in the upper left corner of
the page.

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

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 flying near full-scale aircraft and avoid flying
near or over groups of people.

1. Your Hobbico Sukhoi SU31 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 Hobbico
Sukhoi SU31, if not assembled and operated correctly,
could possibly cause injury to yourself or spectators
and damage to property.

2. You must assemble the model according to the
instructions. Do not alter or modify the model, as
doing so may result in an unsafe or unflyable model. In
a few cases the instructions may differ slightly from the
photos. In those instances the written instructions
should be considered as correct.

Protect your model, yourself &

others... Follow these Important

Safety Precautions

AMA

TECHNICAL UPDATES

TABLE OF CONTENTS

3

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

4. You must use an R/C radio system that is in first­class 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 flight to insure that all equipment is operating and
that the model has remained structurally sound. Be
sure to check clevises or other connectors often and
replace them if they show any signs of wear or fatigue.

7. If you are not an experienced pilot or have not
flown this type of model before, we recommend
that you get the assistance of an experienced pilot
in your R/C club for your first flights.

8. While this kit has been flight tested to exceed
normal use, if the plane will be used for extremely
high stress flying, the modeler is responsible for
taking steps to reinforce the high stress points.

9. WARNING: The cowl included in this kit is made
of fiberglass, the fibers of which may cause eye,
skin and respiratory tract irritation. Never blow into
the cowl to remove fiberglass 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 fiberglass parts.
Vacuum the parts and the work area thoroughly
after working with fiberglass parts.

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

This is a partial list of items required to finish the
Hobbico Sukhoi SU31 that may require planning or
decision making before starting to build. Order
numbers are provided in parentheses.

RADIO EQUIPMENT

❏ Four channel radio
❏ Four 54 oz-in servos and one 30 oz-in servo
❏ Two 6” [150mm] servo extensions

(HCAM2701 for Futaba)

❏ Y-harness (HCAM2751 for Futaba)
❏ 500 mAh battery or greater

ENGINE RECOMMENDATIONS

We have installed both a two-and a four-stroke engine
in our prototypes. The two-stroke engine with a
standard muffler or with most Pitts style mufflers
requires much of the cowl to be cut away, while the
four-stroke maintains most of the integrity of the cowl.
If a more “scale“ look is desired we recommend the
four-stroke engine over the two-stroke.

50 - .75 cu in [8 - 12cc] two-stroke,

.70 - .91 [11. 5 - 15cc] four-stroke

❏ R/C foam rubber (1/4” [6mm] - HCAQ1000,

or 1/2” [13mm] - HCAQ1050)

❏ 1/2 oz. [15g] Thin Pro

™

CA (GPMR6001)

❏ 1 oz. [30g] Medium Pro CA+ (GPMR6008)
❏ Pro 30-minute epoxy (GPMR6047)
❏ Pro 6-minute epoxy (GPMR6045)
❏ Drill bits: 1/16” [1.6mm], 5/64” [2mm], 1/8”

[3.2mm], 3/16” [4.8mm].

❏ #1 Hobby knife (HCAR0105)
❏ #11 blades (5-pack, HCAR0211)
❏ Top Flite

®

MonoKote®sealing iron (TOPR2100)

❏ CA applicator tips (HCAR3780)
❏ R/C-56 canopy glue (JOZR5007)
❏ Threadlocker thread locking cement

(GPMR6060)

ADDITIONAL ITEMS REQUIRED

HARDWARE & ACCESSORIES

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

OPTIONAL SUPPLIES AND TOOLS

Here is a list of optional tools mentioned in the
manual that will help you build the Hobbico
Sukhoi SU31.

❏ 2 oz. [57g] spray CA activator (GPMR6035)
❏ CA debonder (GPMR6039)
❏ Epoxy brushes (6, GPMR8060)
❏ Mixing sticks (50, GPMR8055)
❏ Mixing cups (GPMR8056)
❏ Curved-tip canopy scissors for trimming plastic

parts (HCAR0667)

❏ Robart Super Stand II (ROBP1402)
❏ 18” x 24” [460 x 610mm] Builder’s Cutting

Mat (HCAR0455)

❏ Hobbico Duster

™

can of compressed air

(HCAR5500)

❏ Masking tape (TOPR8018)
❏ Denatured alcohol (for epoxy clean up)
❏ Switch & Charge Jack Mounting Set

(GPMM1000)

❏ Rotary tool such as Dremel

®

❏ Rotary tool reinforced cut-off wheel

(GPMR8200)

❏ Servo horn drill (HCAR0698)
❏ AccuThrow

™

Deflection Gauge (GPMR2405)

❏ CG Machine

™

(GPMR2400)

❏ Precision Magnetic Prop Balancer

™

(TOPQ5700)

·

When you see the term test fit in the

instructions, it means that you should first
position the part on the assembly without using
any glue, then slightly modify or custom fit the
part as necessary for the best fit.

·

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

·

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

·

Photos and sketches are placed before the step

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

·

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.hobbico.com and click on “Technical
Data.” Due to manufacturing tolerances which
will have little or no effect on the way your
model will fly, please expect slight deviations
between your model and the published values.

METRIC CONVERSIONS

COMMON ABBREVIATIONS

Fuse = Fuselage

Stab = Horizontal Stabilizer

Fin = Ver tical Fin

LE = Leading Edge
TE = Trailing Edge

LG = Landing Gear

Ply = Plywood

" = Inches

mm = Millimeters

SHCS = Socket Head Cap Screw

1/64" = .4mm
1/32" = .8mm
1/16" = 1.6mm
3/32" = 2.4mm

1/8" = 3.2mm
5/32" = 4mm
3/16" = 4.8mm

1/4" = 6.4mm

3/8" = 9.5mm

1/2" = 12.7mm

5/8" = 15.9mm

3/4" = 19mm

1" = 25.4mm
2" = 50.8mm
3" = 76.2mm

6" = 152.4mm
12" = 304.8mm
15" = 381mm
18" = 457.2mm
21" = 533.4mm
24" = 609.6mm
30" = 762mm
36" = 914.4mm

To convert inches to millimeters,

multiply inches by 25.4 (25.4mm = 1")

IMPORTANT BUILDING NOTES

4

5

11

12

13

14

1

2

3

4

5

6

7

8

9

10

KIT INSPECTION

KIT CONTENTS

Before starting to build, take an inventory of this kit to make sure it is complete, and inspect the parts to
make sure they are of acceptable quality. If any parts are missing or are not of acceptable quality, or if you
need assistance with assembly, contact Product Support. When reporting defective or missing parts, use
the part names exactly as they are written in the Kit Contents list.

Hobbico Product Support • 3002 N Apollo Drive, Suite 1 • Champaign, IL 61822

Telephone: [phone], ext. 2 • Fax: [phone]

E-mail: [e-mail]

Items photographed

1. Fuselage & Cowl

2. Fuel tank

3. Dummy engine

4. Left wing

5. Landing gear

6. Wheels

7. Wheel pants

8. Tail wheel assembly

9. Belly pan

10. Canopy

11. Right wing

12. Stab & elevators

13. Fin & Rudder

14. Engine Mount

Qty
2 15x15x15mm hardwood block
2 15x15x10mm hardwood block
2 155mm length of Velcro

®

2 3mm plywood wing joiner
1 Plywood wing bolt plate
5 Nylon control horns and plates
17 Hinges
5 Nylon clevises
4 Faslinks
2 4 x 40mm machine screw
2 4 x 35mm machine screw
4 4 x 25mm machine screw
4 4 x 19mm machine screw
4 4 x 15mm machine screw
10 4mm flat washer
8 4mm lock washers
2 4mm nuts
3 3 x 5mm machine screw
2 4mm wheel collar
4 2 x 20mm machine screw

Qty
6 2 x 15mm machine screw
3 2 x 7mm sheet metal screw
1 screw lock connector
1 2mm thumb nut
1 2mm washer for screw-lock

connector

1 300mm nylon pushrod
3 2 x 710 mm pushrod wire
1 1mm wire
4 4mm blind nuts
4 3 x 12mm cowl mounting bolts
1 6 x 6 x 127mm balsa stick
1 2.5” (approximately 64mm)

red plastic spinner

1 400mm fuel tubing
6 4mm lock nuts
5 Silicone clevis retainers
2 2 x 80mm pushrod wire

Parts not photographed

Replacement parts for the Sukhoi SU 31 ARF are
available using the order numbers in the
Replacement Parts List that follows. The fastest,
most economical service can be provided by your
hobby dealer or mail-order company.

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

www.hobbico.com. Choose “Where to Buy” at the

bottom of the menu on the left side of the page. Follow
the instructions provided on the page to locate a U.S.,
Canadian or International dealer. If a hobby shop is not
available, replacement parts may also be ordered from
Tower Hobbies at www.towerhobbies.com or by
calling toll free [phone].

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.

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

Order
Number Description How to purchase

HCAA3630 . . . . . Wing . . . . . . Hobby Supplier

HCAA3631 . . Fuse/belly pan . . . Hobby Supplier
HCAA3633 . . . Tail Surfaces . . . Hobby Supplier

HCAA3632. . . . . . Cowl . . . . . . Hobby Supplier

HCAA3635. . . . . Canopy . . . . . Hobby Supplier

HCAA3636 . . Landing Gear . . . Hobby Supplier
HCAA3634 . . Wheel Fairings. . . Hobby Supplier
HCAA3637. . Dummy Engine . . Hobby Supplier

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

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

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

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. Remove the tape and separate the ailerons and
flaps from the wing and the elevators from the stab.
Use a covering iron with a covering sock on high
heat to tighten the covering if necessary. Apply
pressure over sheeted areas to thoroughly bond the
covering to the wood.

When ready to fly, you'll need some additional
equipment to fuel the plane and start the engine.
The most important items include an electric starter,
12 volt battery, or chicken stick, fuel pump (electric
or hand-crank), fueling lines and fittings and a 1.5
volt glow plug igniter. Your flight instructor will
probably let you share his equipment for a while,
but eventually you'll need your own. Visit your local
hobby dealer or see the Hobbico catalog for a full
selection, descriptions and pricing.

PREPARATIONS

REPLACEMENT PARTS LIST

ORDERING REPLACEMENT PARTS

6

INSTALL THE AILERONS

Do the right wing first so your work matches the
photos the first time through.

❏❏1. Install a hinge into each of the four hinge

slots in the aileron. Be sure the slit in the hinge is
perpendicular to the leading edge of the aileron.

❏❏2. Apply six drops of thin CA to the top and

bottom of each hinge waiting a few seconds
between drops to allow the CA to soak in. Do not
use CA accelerator. After the CA has fully hardened,
test the hinges by pulling on the aileron.

❏❏3. Locate the opening for the servo on the bottom

of the wing. Cut the covering from the opening.

❏❏4. On the top of the wing locate the 1/2”

[13mm] hole and cut the covering away.

❏ 5. Repeat steps 1 - 4 for the left wing.

INSTALL THE AILERON SERVOS AND PUSHRODS

❏ 1. Installing the servos in the wing will require

the use of one 6” [152mm] servo extension for each
aileron. One Y-harness connector is required and is
used to allow the aileron servos to plug into one slot
in your receiver. You may have a computer radio
that allows you to plug the servos into separate slots
and mix them together through the radio transmitter.
If you choose to mix them with the radio rather than
the Y-harness, refer to the instructions with your
particular brand of radio. Attach the servo extension
to the aileron servo. Secure the connectors together
using a large piece of heat shrink tubing or tape.

❏❏2. Located in the wing in the servo compartment,

a string is taped to the wing skin. Tie the string to the end
of the servo wire. Pull the servo wire through the wing
with the string. Feed the servo wire out the hole in the
top of the wing center section. Tape the servo wire to
the wing to prevent it from falling back into the wing.

ASSEMBLE THE WING

7

❏❏3. Install the servo into the wing. Center the

servo and install a servo arm as shown.

❏❏4. Position a nylon control horn on the aileron as

shown in the sketch, aligning it with the servo. Mark the
location for the screw holes. Drill through the marks you
made with a 1/16” [1.6mm] drill bit, drilling through the
aileron. Secure the control horn to the aileron with two
2 x 20mm [3/4”] machine screws and the nylon
mounting plate.

❏❏5. Locate a 2 x 102mm [4”] pushrod wire

threaded on one end. Screw a nylon clevis onto the
threaded end of the wire 20 full turns. Install a
silicone clevis keeper onto the clevis and then install
the clevis in the second hole from the end of the
aileron control horn.

❏❏6. Be sure the aileron servo is centered.

Enlarge the second outermost hole in the servo arm
with a Hobbico Servo Horn Drill (or a #48 or 5/64”
[2mm] drill bit). Center the aileron and align the wire
pushrod with the hole in the end of the servo arm.
Using a marker, mark the location where the wire
aligns with the hole in the servo arm. On that mark
make a 90 degree bend. From the bend measure an
additional 3/16” [4.8mm], then cut off the excess
pushrod wire.

❏❏7. Install the wire into the hole in the servo

arm using a nylon FasLink as shown in the sketch.

❏ 8. Repeat steps I - 7 for the left wing panel.

Correct Incorrect

8