Hobbico Viper User Manual

TM

© Copyright 1993, Hobbico, Inc.

• Comes 70% prebuilt, requiring very little sanding.

• Control surfaces are preshaped and ready for covering.

• Wing features balsa sheeting over foam core.

• Meets all requirements for Quickie 500 racing.

• Can be customized with
three different tail
configurations

Stock tail design

V-tail design

(optional)

Mid-tail design

(optional)

C ongratulations upon purchasing your

new Viper RTC kit. The Viper RTC is
assembled with only the finest materials
and workmanship so you can enjoy the
fun of flying more quickly and easily than
ever before. We have completed 70% of
the assembly. All that needs to be done is
final assembly and covering - you can
customize. This airplane is a joy to fly and
promises hours of pure enjoyment. If
Quickie 500 racing is your goal., you will

find the Viper to be a very competitive
performer in the racing circles. For more
information on Quickie 500 racing,
contact the Academy of Model
Aeronautics at the address shown below.

Two decisions must be made before construction of this
airplane can begin.

1. What size engine will be used?

2. What style of tail will be used?

1. Engine Size:

If a .25 size engine is to be used for powering your Viper, no
additional reinforcement is required to the nose. You may
skip the steps with the checkered flag ( ). If a .40 size
engine is going to be used, complete the steps marked with
a checkered flag ( ).

2. Tail Configuration:

Conventional Tail:

This is a normal tail and all of the wood
required to build this version is included with this kit. This is
the easiest of the three versions to build and is highly
recommended for flyers/builders with limited building
experience.

Mid-Tail:

The mid-tail offers a very unique appearance to
the Viper as well as offering better elevator response. This is
due to the fact the stabilizer and elevator are out of the wing
slip stream. Although the mid-tail is not difficult to build, it
will require careful attention to insure the stabilizer and fin
are square.This can be either an aerobatic or racing
configuration and requires some additional 3/16" balsa to
complete.

V-Tail:

The V-tail version is slightly more difficult to build
than the other two versions. Extra care must be taken to
make sure the tail assembly is square, level and at zero
incidence. V-tail airplanes theoretically reduce drag
because there is only two control surfaces. This is primarily
a racing configuration and 3/16" balsa is required for
completion. This configuration is not recommended for
beginners. This also requires a radio that mixes V-tails or an
electronic mixer for elevator/rudder.

90-Day Limited Warranty

If you, as the original owner of this model, discover defects in
parts or workmanship within 90 days of purchase, Hobbico will
repair or replace it—at the option of our authorized U.S. repair
facility, Hobby Services— without charge. Our liability does not
include cost of shipping to us. However, Hobby Services will pay
shipping expenses to return your model to you.

You must provide proof of purchase, such as your original
purchase invoice or receipt, for your model’s warranty to be
honored.

This warranty does not apply to damage or defects caused by
misuse or improper assembly, service or shipment. Modifications,
alterations or repair by anyone other than Hobby Services voids
this warranty. We are sorry, but we cannot be responsible for crash
damage and/or resulting loss of kits, engines, accessories, etc.

Repair Service

Your Viper must be returned directly to Hobby Services for
warranty work. The address is:

Hobby Services

Attn: Service Department

1610 Interstate Drive

Champaign, IL 61821-1067

Phone: [phone]

Hours: 9:00-5:00 CST Mon. thru Fri.

Please follow the instructions below when returning your model.
This will help our experienced technicians to repair and return it as
quickly as possible.

1. ALWAYS return your entire kit.

2. Include a list of all items returned and a THOROUGH, written

explanation of the problem and service needed. If you expect the
repair to be covered under warranty, also include your proof of
purchase.

3. Include your full return address and a phone number where you

can be reached during the day.

If your model is past the 90-day warranty period or is excluded
from warranty coverage, you can still receive repair service
through Hobby Services at a nominal cost. Repair charges and
postage may be prepaid or billed COD. Additional postage charges
will be applied for non-warranty returns. All repairs shipped
outside the United States must be prepaid in U.S. funds only.

All pictures, descriptions and specifications found in this
instruction manual and on the product package are subject to
change without notice. Hobbico maintains no responsibility for
inadvertent errors.

Academy of Model Aeronautics

5151 E. Memorial Drive

Muncie, IN. 47302
Tel. [phone]

JOIN THE AMA

About this manual:

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Other items you’ll need:

Glues

Choose any 5- or 6-minute epoxy, such as Hobbico Bullet, which has been formulated
especially for R/C model building. Epoxies offer a strong bond and a variety of curing
times suited for every step of assembly. You’ll also need an instant-setting CA
(cyanoacrylate), a thicker CA+, and a 30-minute epoxy, plus rubbing alcohol for easy
epoxy cleanup.

Hardware

Tools and accessories required for assembly include
a hobby knife; flat tip screwdriver; file; needle nose
pliers; drill bits; ruler; and 3 feet of medium fuel
tubing.

Model Engine

Power your Viper with any high-quality, .25-size
model engine. The O.S. ..25 FP, SuperTigre G-34 and
Irvine .25 RC are just a few examples. Look for
features such as easy break-in, easy starting, efficient
carburetion and low maintenance. Check the
manufacturer’s recommendations for propellers to
use with your engine. For Quickie 500 racing you will
want to choose a high performance, .40 size engine.

Radio Equipment

To let you send the commands that control your Viper’s
“flight path,” you’ll need a 4-channel aircraft radio system
with four standard servos. Many 4-channel radios include
just three servos. You may need to purchase the fourth
separately. The servos and radio receiver will be mounted
on-board your model and need to be cushioned from jolts
and vibration. One-quarter inch thick foam rubber sheets
are available for this purpose.

Getting Ready for Flight

Your Hobbico Viper is ready for takeoff in as little as 15-20 hours. Your
hobby dealer can help you decide what accessories you’ll need for flight.
You will need glow fuel with a 10-15% nitro blend to keep your engine
performing at its peak...and your Viper will have the power to perform the
impressive aerobatic maneuvers.

Other General Items Required

Masking Tape

Fine Line Felt Tip Pen

A Wooden Match

Balsa Filler

Covering Material

Sealing Iron

1/4"-20 Tap

Engine Mount

Hex Wrench for #6-32 Bolt

3M "77" Spray Adhesive

90Þ Triangle

Sand Paper (220 grit)

Drill and Drill Bits:

1/16", 1/8", 9/64", 5/32", #7

or 3/16", 1/4"

Additional Items Required for Optional Quickie Racer, V-Tail or Mid Tail

1 sq. Yard 2oz. Fiberglass
3/16 Hard Balsa (V-Tail and Mid Tail)
Wire and Tube Pushrod
Cable Pushrod (for throttle)

6 oz. Hayes Fuel Tank
Candle Wax
45 Minute Epoxy

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FUSELAGE PREPARATION

Marking firewall for engine mount

1. With a straight edge, draw lines from corner to corner

on the firewall. This will help you position the engine mount.

Drilling holes for engine mount

2. Center the engine mount on the firewall using the lines

as a reference. Mark and drill 5/32" (4mm) holes according to
the motor mount you plan to use.

Installation of blind nuts

3. Using a file or a Moto-Tool™, remove the triangle stock

around the holes drilled through the firewall. This creates a flat
surface to mount the blind nuts against. Install #6-32 blind
nuts into the holes and apply thick CA to secure them in place.

Hardening blind nut holes

4. Apply thin CA to the outside of the holes to harden the

firewall around the blind nuts.

Protecting blind nut threads

5. Pack wax into each of the blind nuts to protect the

threads from being clogged by epoxy.

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Cutting fiberglass cloth

6. Cut (5) pieces of 2 oz. fiberglass cloth as shown. Mark

the center of pieces A, B, and D.

Installing the fiberglass cloth

7. Apply a very light coat of 3M "77" spray adhesive to the

nose of the fuselage. Place the center of piece "A", cut in the
previous step, at the center of the firewall and wrap the
remainder around the left and right sides of the fuselage. Wrap
piece "C" starting at the bottom of the firewall up over the top of
the fuselage. Wrap piece "B" starting at the center of the
firewall over pieces A and C and around the sides of the
fuselage. Coat the fiberglass cloth with 45 minute epoxy and
remove all excess epoxy with a squeegee.

Fuel proofing the
fuel compartment

8. Install piece "D" of the fiberglass cloth on the inside,

wrapping from one side over the firewall to the other. Install
the other piece "D" from the bottom of the firewall to the top
of the fuselage. Completely coat the entire fuel tank
compartment, making sure all of the fiberglass is saturated
and the fuel compartment is fuel proof.

Opening the blind nuts

9. Using a hobby knife, remove the fiberglass covering the

bolt holes. Pick the wax out of each of the blind nuts.

Drilling hole for throttle rod tube

10. Using a 5/32" (4mm) drill bit, drill a hole through the

firewall directly behind the throttle arm. This will be the hole
for the throttle rod tube. Drill another hole through the second
bulkhead and in the most direct path to the throttle servo.
Make sure it does not interfere with the wing saddle. Note: A
long drill bit is shown but not nexessary.

Installation of throttle servo tray

11. Using a file, enlarge the throttle servo tray hole to

accommodate the servo being used. Then, with thick CA,
install the throttle servo tray as shown. Make sure that
enough room is left under the servo tray to accommodate the
throttle servo you'll use. Also make sure the throttle servo will
not interfere with the aileron servo. Install the servo tray 2" to
3" from the second bulkhead. Locate the triangle brace and
install it under the front portion of the servo tray using thin
CA. Mount the throttle servo according to the manufacturer's
recommendations.

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Installation of throttle rod

12. Roughen the entire throttle rod tube using sandpaper.

Slide the tube through the hole in the firewall and the first
bulkhead. Slide the rod into the tube and direct the rod
straight to the servo arm with as little bending as possible.
Apply epoxy to the tube where it goes through the firewall
and the first bulkhead. Also attach the tube securely to the
side of the fuselage. Thread a clevis onto the throttle
pushrod. Slide the pushrod into the tube and out past the
servo. Mark the pushrod where the pushrod crosses the
outside hole of the throttle servo arm. Place a "Z" bend at this
mark. Connect the "Z" bend to the throttle servo arm. Adjust
the pushrod using the clevis. Note: It may be necessary to
replace the pushrod with a cable in some engine positioning
situations.

ASSEMBLY OF WING

Making an alignment peg

1. Cut about 1/4" (6mm) off the end of a wooden match or

similar piece of wood.

Installation of alignment peg

2. Using thick CA, glue the piece of match into the hole in

the aileron torque rod slot in the trailing edge of one of the
wing panels. This will serve as an alignment peg.

Trial fitting wing halves

3. Position the two wing halves together and check their fit.

Adjust the angle of root center section using a sanding block.
This should be done with the wing on a flat surface and one
of the wing panels blocked up to the proper dihedral angle. It
is 5/8" (16mm) for Quickie 500 racing or aerobatics and 1"
(25mm) for beginners.

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Setting wing dihedral

4. Use a piece of 5/8" (16mm) or 1" (25mm) scrap balsa to

block up one wing panel. This will account for the dihedral
required for the wing. If this is your first low wing airplane,
increase the dihedral from 5/8" (16mm) to 1" (25mm). Place
a piece of wax paper on your building surface to prevent the
wing from sticking to the surface.

Applying epoxy to wing panel

5. Using 30- or 45-minute epoxy, apply a liberal amount of

epoxy to each wing panel as shown, making sure that epoxy
is applied to the balsa sheeting as well as the foam core.

Wing panel assembly

6. Assemble the wing panels together and remove any

epoxy that may have squeezed out. Block up the trailing
edge using a piece of 5/8" (16mm) balsa. Masking tape
should be used to hold the panels tightly together until the
epoxy has fully cured. Note: Wax paper was used to prevent
the wing from sticking to the building surface.

Fiberglassing the wing joint

7. Apply 30- or 45-minute epoxy and thoroughly saturate

the fiberglass cloth. Once saturated, squeegee off as much
epoxy as possible. Remember, this is excess weight. Once
the epoxy has cured, repeat this procedure for the top of the
wing. Hobbylite filler should be used to smooth the transition
from the fiberglass to the wood skin. Make sure a cut out is
made to fit around the aileron torque rods and that no epoxy
is allowed into the torque rod openings.

Cutting the fiberglass cloth

8. Cut 2 oz. fiberglass cloth into the panel dimensions

shown above. Cut two of each panel.

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Applying the fiberglass cloth

9. Start with the bottom of the wing first. Mark the center of

the fiberglass panels cut in the previous step. Apply the 24"
(610mm) wide piece first and then the 18" (460mm) wide
piece over the top of it, making sure that the center marks
line up on the center section of the wing. Apply 30- or 45­minute epoxy and thoroughly saturate the fiberglass cloth.
Once saturated, squeegee off as much epoxy as possible.
Remember, this is excess weight. Once the epoxy has cured,
repeat this procedure for the top of the wing. Hobbylite filler
should be used to smooth the transition from the fiberglass to
the wood skin. Note: The fiberglass goes right over the
landing gear blocks. Once the epoxy cures, use a hobby
knife to remove the fiberglass from the wire slots.

Cutting holes for hold down dowels

10. Using the photo as a reference, draw 2 boxes as

shown and then 2 ovals inside the boxes. Using a hobby
knife, cut through the fiberglass and balsa and remove only
the oval portions drawn.

Drill holes for hold down dowels

11. With a 1/4" (6mm) drill bit, drill holes into the foam core

at approximately the angle shown, 3" deep. Note: A long drill
bit is shown, but is not required.

Trimming the hold down dowels

12. Cut (2) wing hold down dowels to 3-1/2" (89mm).

Round one end of each of the dowels. Insert the round end of
each of the dowels into the holes in the wing. Trial fit the wing
onto the fuselage, checking the fit with the first bulkhead. If
necessary, adjust the bulkhead grooves or oblong the holes
in the wing to achieve a good, snug fit between the bulkhead
and the dowels. If necessary, adjust the wing saddle until the
wing fits perfectly to the fuselage.

Installation of hold down dowels

13. Apply a generous amount of 30-minute epoxy both to

the wing hold down dowels and to the holes in the wing for
the dowels. Insert the dowels, with the flat end out, into the
wing. Leave 5/8" (16mm) of the dowels protruding past the
leading edge of the wing. Install the wing onto the fuselage
and hold the dowels snug against the bulkhead until the
epoxy cures. Make sure the 30-minute epoxy does not
contact the fuselage.

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