Building From Scratch

WE ARE GETTING close to a wrap for
my portion of the “From the Ground Up”
series. In the past eight months you have
learned about Radio Control (RC) systems,
electric-power systems, assembling an
Almost Ready-to-Fly (ARF) model, flying
that model, and last month you learned the
A to Z of batteries.
The next step could have gone in either
of two directions: building a model from a
kit or building a model from raw
materials—from scratch! I chose the latter
and came up with a new RC trainer design
that I call the “Scratch-One.”
The idea was to utilize the RC system
and the electric power system from the
Aero Craft Pogo ARF. The Scratch-One RC
trainer design is slightly larger and slightly
heavier than the Pogo. Specifically, the
wing area is 247 square inches, the
wingspan is 45 inches, and the all-up weight
is 16.9 ounces (approximately an ounce
heavier than the Pogo).
The Scratch-One design can be
classified as an RC electric-powered trainer
sailplane. It has proven to be one of the
most forgiving designs to fly and perfect for
the RC beginner, but keep in mind that the
thrust of this article is to get you to build
your first model from scratch. The pieces
won’t be fabricated or preassembled; it is
all going to be strictly up to you. As part of
the process you will also cover all or part of
your model.
Obtaining the necessary balsa, plywood,
and spruce pieces to construct this model
took at least three visits to local hobby
shops; not every hobby dealer will have
every stick you need. I thought this might
be an initial point of frustration, so I came
up with an idea.
Craig Wagner, who owns Aero Craft,
agreed to make a box of wood for the
Scratch-One. It will have all of the wood
material you need, and in the correct sizes.
The only things you will have to purchase
on your own are the cements, covering
material, and hardware such as control rods,
control horns, and control-surface hinges.
You can reach Craig at Aero Craft Ltd., 432
Hallett Ave., Riverhead NY 11901; Tel.:
(631) 369-9319; Web site: www.aerocraft
rc.com.
(Editor’s note: Since this article was
written, we have received pricing and
shipping information from Aero Craft Ltd.
for the materials to build the Scratch-One.
The “kit” of materials is $19.95 plus $6
shipping and handling. This kit will come
packed in a 4 x 4 x 36-inch mailer box.)
About the Design: Before I get into the
construction, I want to point out some of the
Scratch-One’s design features. Cutting out
wing ribs can be a tedious job, especially
for a beginner. So in this design I
eliminated all wing ribs and substituted
balsa sticks.
The bottom stick is 1⁄8 x 1⁄4 balsa. Next
come three different-size wing spars, then
1⁄16 x 1⁄4 balsa sticks are bent over the spars
to provide the necessary airfoil shape. The
leading edge is common 3⁄16-inch-diameter
hardwood dowel. You won’t likely
experience much damage on rough landings
with this kind of construction.
I also made the wing’s center-section
flat so that no center joiner or brace is
necessary. Both tips are raised 41⁄2 inches
for what we call “polyhedral.” These raised
tips provide overall stability in flight.
Many models have what I call “internal”
battery compartments; to access the battery
pack for charging purposes, you must
remove the wing. I find that annoying and
time-consuming, so in this design the
battery compartment is on the bottom of the
fuselage where it can be accessed directly
without touching the wing.
Probably the most difficult task for the
beginner is to mount the servos and hook up
the control rods that operate the rudder and
elevator. To keep it simple I placed the two
servos on top of the fuselage, just aft of the
wing trailing edge. It’s kind of like “letting
it all hang out”!
The control rods are run externally from
the servo output arms back to the control
horns on the rudder and elevator. This
makes for easy control throw adjustments
and easy centering of the controls. These
few ideas made the Scratch-One extremely
simple to build and fly!
CONSTRUCTION
I like to make my own “kit” of parts
before starting the assembly. On this model
you must make two fuselage sides and all of
the tail pieces from 3⁄32 balsa. You also have
to cut out four fuselage formers from 1⁄16
plywood and a fifth former from 3⁄32 balsa.
The last items are two 1⁄16 plywood wingpanel
joiners—one for each tip panel.
To cut out these parts I take the plans to
a copying store, such as Kinko’s, and have
photocopies made of the parts to be cut out.
I paste these copies to manila-folder stock
34 MODEL AVIATION
Building From
To prepare templates, make copies from plans and cement them
to manila-folder stock. Use rubber cement and 3M Magic Tape. Templates after having been cut from manila-folder stock.
(file folders opened up) using rubber
cement and 3M Magic Tape.
After the cement dries I cut out the
pieces, which make handy templates. Then it
is just a matter of transcribing the outline of
the parts onto the balsa and plywood sheet
material with a ballpoint pen. Since you
made copies of the full-size plans, the parts
you cut out should fit perfectly.
You will be using the same cements that
you used to assemble the Pogo. I purchase
all of mine from Balsa Products Inc. in
Iselin, New Jersey, but there are many
supply sources. You will need thin and thick
cyanoacrylate glue (CyA) with an
accelerator (in a spray bottle) and fiveminute
epoxy cement for the high-stress
areas such as the firewall, wing-panel joints,
and stabilizer/vertical fin attachment to the
fuselage.
Because the wing requires no ribs, all
you need is a bunch of balsa sticks. The
bottom of the airfoil is made from 1⁄8 balsa
sticks. Add the three spars, and the last step
is to bend 1⁄16-inch-thick strips over the
spars, forming the airfoil shape of the wing.
You may find that briefly soaking these
strips in water will make them bend easier.
When assembling the wing, take note
that the middle spar in the center panel is
1⁄8 x 3⁄8 spruce (a hardwood); that is for
extra strength. On the tip panels, to
maintain a gradually thinning airfoil shape
it is necessary to taper the spars from the
panel joint out to the tip. For that reason
all of the tip-panel spars are made from
balsa so that they can be easily tapered
(cut). Each wingtip is simply capped off
with 3⁄32 balsa and sanded to blend in.
Fuselage: Trial-mount your Speed 400
motor to the plywood firewall F1. You will
need to drill a clearance hole in the center
along with two screw holes. The screws are
2.6 millimeter, which you can obtain from
Kirk Massey at New Creations R/C. Leave
the motor off until after F1 is cemented to
the fuselage sides.
Add 1⁄16 x 1⁄4 spruce stiffeners to the
wing-mount and battery-compartment areas.
This provides extra strength and should not
be omitted. When you cement the stiffeners
in place, remember that you are making one
left fuselage side and one right side.
Now you can cement the formers in
place, first to one side using a square or
triangle to make sure that they are aligned
properly. You can use thin CyA to spot the
formers in place, then follow up with thick
CyA, which adds more strength.
Attach the firewall (F1) with five-minute
epoxy cement. Once formers F1 through F4
are in place, add the other fuselage side. Try
to eyeball-align the two sides. The last thing
you do is join the two fuselage sides at the
rear. Hold them temporarily with a
clothespin and cement them in place (with
thick CyA).
Add the two 1⁄8 x 1⁄4 spruce servomounting
rails which are located on top of
the fuselage, just aft of the wing trailing
edge. The Hitec HS-81 servos are mounted
to these rails using the supplied wood
screws (two for each servo). Run the cables
coming from these servos through the hole
in former F4 and into the receiver
compartment, just below the wing.
Mount the Speed 400 motor in place with
the two screws, and install the Jeti JES 110
Electronic Speed Control (ESC). The motor
cables run through the hole in former F2.
Then the ESC servo cable passes through
the hole in former F3. I used double-stick
tape to hold the ESC to the fuselage side.
Install the ESC switch on the left side of the
fuselage. Before adding the sheeting, install
the battery-compartment floor, which is
made from 3⁄32 balsa.
With this done, you can apply the 1⁄16
sheet top and bottom to most of the model.
For example, do the fuselage top from the
servos to the leading edge of the stabilizer,
November 2003 35
Part One
Use cut-out templates to trace patterns onto raw balsa sheeting. Cut parts from sheeting using sharp X-Acto #11 knife blade.
■ Bob Aberle
36 MODEL AVIATION
All of the balsa-sheet pieces are ready for assembly. The wing
parts are literally a bunch of balsa sticks.
Leading-edge material, at top, is common 3⁄16-inch-diameter
hardwood dowel. Spar material is in center. The main, center
spar is made from spruce—a hardwood—for extra strength.
Starting wing construction. Leading edge is pinned in place, then
bottom 1⁄8 x 1⁄4 balsa sticks are set in place. Triangular-shaped
trailing-edge stock is at other end.
The three wing spars are added on top of 1⁄8-inch-thick balsa
strips. Remember that these spars on both tip panels taper as
they go out to the tips.
Notice how the spars taper going out to the tip. You cut this taper
with the help of a long, steel straightedge.
Complete airfoil by placing 1⁄16-inch-thick balsa strips on top of
spars. Soak strips in water so they will bend easier.
Photos courtesy the author Graphic Design by Lydia Whitehead
then sheet the entire bottom of the fuselage. With all of this
sheeting, the grain runs across or at right angles to the fuselage
sides. The only sheeting you leave open at this point is the top
from the firewall to the wing leading edge.
At this point I am going to break for this month. Since this is a
beginner’s first-time scratch-built model, the final tally came to
more than 50 photographs to support the article. Not wanting to
cut anything out, the editors decided to divide the Scratch-One
construction article into two parts. I chose the start of covering as
the logical point to make the break.
Next month is the Nationals-coverage issue, but in the January
issue I will start with control-surface hinging and proceed all the
way through the Scratch-One’s first flights. For your
convenience, the plans and specifications are included with Part
One. With this information you can purchase the balsa, cut out
the parts, and do the assembly work. Thank you for your
patience. MA
Manufacturers:
Du-Bro Products (control rods, control horns, keepers)
Box 815
Wauconda IL 60084
(800) 848-9411
www.dubro.com
Hitec RCD (Neon RC system)
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
Hobby Lobby International (propellers)
5614 Franklin Pike Cir.
Brentwood TN 37027
(615) 373-1444
E-mail sales: [email protected]
www.hobby-lobby.com
New Creations R/C (electric power system)
Box 497
Willis TX 77378
(936) 856-4630 (telephone calls are preferred)
SR Batteries Inc. (Gapless Hinge Tape, R/C Techniques on covering
application)
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
November 2003 37
Make wingtip-panel joints at proper polyhedral angle of 41⁄2
inches off of building board. Clothespin holds plywood wing
Shown are the plywood wing-panel joiners or braces. You will brace in position until five-minute epoxy sets.
need two: one for each wingtip panel.
You can see the wingtip detail. Fashion each tip from scrap
pieces of 3⁄32 balsa, sanded to a smooth contour. Looking from wingtip toward center of wing. Neat construction!
Balsa and plywood raw-material suppliers
(in addition to Aero Craft Inc.):
Lone Star Models
115 Industrial St.
Lancaster TX 75134
(800) 687-5555
www.lonestar-models.com
National Balsa Co.
97 Cherokee Dr.
Springfield MA 01109
(413) 796-1925
www.nationalbalsa.com
Superior Balsa & Hobby Supplies
12020-G Centralia
Hawaiian Gardens CA 90716
(800) 488-9525
www.superiorbalsa.com
38 MODEL AVIATION
This photo shows the mounting of the Speed 400 electric motor to the plywood former
F1 using two 2.6-millimeter machine screws.
Add 1⁄16 x 1⁄4 spruce stiffeners as shown to wing-mounting area (top) and edges of
battery compartment. Be sure to make one right and one left fuselage side.
Begin cementing the formers in position on one fuselage side. The triangle helps to
keep the formers at a right angle to the fuselage side.
Scratch-One
Specifications
Type: Electric-powered RC
sailplane/basic three-channel trainer
Wingspan: 45 inches
Wing area: 247 square inches
Weight: 16.9 ounces (with a 78-cell
1100 mAh NiMH battery)
Wing loading: 9.8 ounces per square
foot
Length: 29 inches
Motor: Speed 400 direct drive
Propeller: Gunther 5 x 4
Motor current: 12 amps (at start of
run on full charge)
Motor power: 90 watts
rpm: 13,900
Watts per ounce: 5.32
Battery: Eight-cell 1100 mAh NiMH
Radio used: Hitec RCD Neon threechannel
transmitter (with control
options installed), Hitec Electron 6
micro dual-conversion receiver, two
Hitec HS-81 servos, Jeti JES 110 ESC
Flight duration: Almost six minutes
at full throttle. Close to 10-minute
motor-run time at half throttle.
November 2003 39
The overall framework is pinned together so the author can check everything before covering.
Both fuselage sides are shown cemented to the formers. Apply five-minute epoxy to the plywood firewall F1 for extra
strength since it supports the electric motor.
The two Hitec HS-81 servos are in place on top of the fuselage.
Join the fuselage sides at the rear and hold them together with a
clothespin until the cement dries.

WE ARE GETTING close to a wrap for
my portion of the “From the Ground Up”
series. In the past eight months you have
learned about Radio Control (RC) systems,
electric-power systems, assembling an
Almost Ready-to-Fly (ARF) model, flying
that model, and last month you learned the
A to Z of batteries.
The next step could have gone in either
of two directions: building a model from a
kit or building a model from raw
materials—from scratch! I chose the latter
and came up with a new RC trainer design
that I call the “Scratch-One.”
The idea was to utilize the RC system
and the electric power system from the
Aero Craft Pogo ARF. The Scratch-One RC
trainer design is slightly larger and slightly
heavier than the Pogo. Specifically, the
wing area is 247 square inches, the
wingspan is 45 inches, and the all-up weight
is 16.9 ounces (approximately an ounce
heavier than the Pogo).
The Scratch-One design can be
classified as an RC electric-powered trainer
sailplane. It has proven to be one of the
most forgiving designs to fly and perfect for
the RC beginner, but keep in mind that the
thrust of this article is to get you to build
your first model from scratch. The pieces
won’t be fabricated or preassembled; it is
all going to be strictly up to you. As part of
the process you will also cover all or part of
your model.
Obtaining the necessary balsa, plywood,
and spruce pieces to construct this model
took at least three visits to local hobby
shops; not every hobby dealer will have
every stick you need. I thought this might
be an initial point of frustration, so I came
up with an idea.
Craig Wagner, who owns Aero Craft,
agreed to make a box of wood for the
Scratch-One. It will have all of the wood
material you need, and in the correct sizes.
The only things you will have to purchase
on your own are the cements, covering
material, and hardware such as control rods,
control horns, and control-surface hinges.
You can reach Craig at Aero Craft Ltd., 432
Hallett Ave., Riverhead NY 11901; Tel.:
(631) 369-9319; Web site: www.aerocraft
rc.com.
(Editor’s note: Since this article was
written, we have received pricing and
shipping information from Aero Craft Ltd.
for the materials to build the Scratch-One.
The “kit” of materials is $19.95 plus $6
shipping and handling. This kit will come
packed in a 4 x 4 x 36-inch mailer box.)
About the Design: Before I get into the
construction, I want to point out some of the
Scratch-One’s design features. Cutting out
wing ribs can be a tedious job, especially
for a beginner. So in this design I
eliminated all wing ribs and substituted
balsa sticks.
The bottom stick is 1⁄8 x 1⁄4 balsa. Next
come three different-size wing spars, then
1⁄16 x 1⁄4 balsa sticks are bent over the spars
to provide the necessary airfoil shape. The
leading edge is common 3⁄16-inch-diameter
hardwood dowel. You won’t likely
experience much damage on rough landings
with this kind of construction.
I also made the wing’s center-section
flat so that no center joiner or brace is
necessary. Both tips are raised 41⁄2 inches
for what we call “polyhedral.” These raised
tips provide overall stability in flight.
Many models have what I call “internal”
battery compartments; to access the battery
pack for charging purposes, you must
remove the wing. I find that annoying and
time-consuming, so in this design the
battery compartment is on the bottom of the
fuselage where it can be accessed directly
without touching the wing.
Probably the most difficult task for the
beginner is to mount the servos and hook up
the control rods that operate the rudder and
elevator. To keep it simple I placed the two
servos on top of the fuselage, just aft of the
wing trailing edge. It’s kind of like “letting
it all hang out”!
The control rods are run externally from
the servo output arms back to the control
horns on the rudder and elevator. This
makes for easy control throw adjustments
and easy centering of the controls. These
few ideas made the Scratch-One extremely
simple to build and fly!
CONSTRUCTION
I like to make my own “kit” of parts
before starting the assembly. On this model
you must make two fuselage sides and all of
the tail pieces from 3⁄32 balsa. You also have
to cut out four fuselage formers from 1⁄16
plywood and a fifth former from 3⁄32 balsa.
The last items are two 1⁄16 plywood wingpanel
joiners—one for each tip panel.
To cut out these parts I take the plans to
a copying store, such as Kinko’s, and have
photocopies made of the parts to be cut out.
I paste these copies to manila-folder stock
34 MODEL AVIATION
Building From
To prepare templates, make copies from plans and cement them
to manila-folder stock. Use rubber cement and 3M Magic Tape. Templates after having been cut from manila-folder stock.
(file folders opened up) using rubber
cement and 3M Magic Tape.
After the cement dries I cut out the
pieces, which make handy templates. Then it
is just a matter of transcribing the outline of
the parts onto the balsa and plywood sheet
material with a ballpoint pen. Since you
made copies of the full-size plans, the parts
you cut out should fit perfectly.
You will be using the same cements that
you used to assemble the Pogo. I purchase
all of mine from Balsa Products Inc. in
Iselin, New Jersey, but there are many
supply sources. You will need thin and thick
cyanoacrylate glue (CyA) with an
accelerator (in a spray bottle) and fiveminute
epoxy cement for the high-stress
areas such as the firewall, wing-panel joints,
and stabilizer/vertical fin attachment to the
fuselage.
Because the wing requires no ribs, all
you need is a bunch of balsa sticks. The
bottom of the airfoil is made from 1⁄8 balsa
sticks. Add the three spars, and the last step
is to bend 1⁄16-inch-thick strips over the
spars, forming the airfoil shape of the wing.
You may find that briefly soaking these
strips in water will make them bend easier.
When assembling the wing, take note
that the middle spar in the center panel is
1⁄8 x 3⁄8 spruce (a hardwood); that is for
extra strength. On the tip panels, to
maintain a gradually thinning airfoil shape
it is necessary to taper the spars from the
panel joint out to the tip. For that reason
all of the tip-panel spars are made from
balsa so that they can be easily tapered
(cut). Each wingtip is simply capped off
with 3⁄32 balsa and sanded to blend in.
Fuselage: Trial-mount your Speed 400
motor to the plywood firewall F1. You will
need to drill a clearance hole in the center
along with two screw holes. The screws are
2.6 millimeter, which you can obtain from
Kirk Massey at New Creations R/C. Leave
the motor off until after F1 is cemented to
the fuselage sides.
Add 1⁄16 x 1⁄4 spruce stiffeners to the
wing-mount and battery-compartment areas.
This provides extra strength and should not
be omitted. When you cement the stiffeners
in place, remember that you are making one
left fuselage side and one right side.
Now you can cement the formers in
place, first to one side using a square or
triangle to make sure that they are aligned
properly. You can use thin CyA to spot the
formers in place, then follow up with thick
CyA, which adds more strength.
Attach the firewall (F1) with five-minute
epoxy cement. Once formers F1 through F4
are in place, add the other fuselage side. Try
to eyeball-align the two sides. The last thing
you do is join the two fuselage sides at the
rear. Hold them temporarily with a
clothespin and cement them in place (with
thick CyA).
Add the two 1⁄8 x 1⁄4 spruce servomounting
rails which are located on top of
the fuselage, just aft of the wing trailing
edge. The Hitec HS-81 servos are mounted
to these rails using the supplied wood
screws (two for each servo). Run the cables
coming from these servos through the hole
in former F4 and into the receiver
compartment, just below the wing.
Mount the Speed 400 motor in place with
the two screws, and install the Jeti JES 110
Electronic Speed Control (ESC). The motor
cables run through the hole in former F2.
Then the ESC servo cable passes through
the hole in former F3. I used double-stick
tape to hold the ESC to the fuselage side.
Install the ESC switch on the left side of the
fuselage. Before adding the sheeting, install
the battery-compartment floor, which is
made from 3⁄32 balsa.
With this done, you can apply the 1⁄16
sheet top and bottom to most of the model.
For example, do the fuselage top from the
servos to the leading edge of the stabilizer,
November 2003 35
Part One
Use cut-out templates to trace patterns onto raw balsa sheeting. Cut parts from sheeting using sharp X-Acto #11 knife blade.
■ Bob Aberle
36 MODEL AVIATION
All of the balsa-sheet pieces are ready for assembly. The wing
parts are literally a bunch of balsa sticks.
Leading-edge material, at top, is common 3⁄16-inch-diameter
hardwood dowel. Spar material is in center. The main, center
spar is made from spruce—a hardwood—for extra strength.
Starting wing construction. Leading edge is pinned in place, then
bottom 1⁄8 x 1⁄4 balsa sticks are set in place. Triangular-shaped
trailing-edge stock is at other end.
The three wing spars are added on top of 1⁄8-inch-thick balsa
strips. Remember that these spars on both tip panels taper as
they go out to the tips.
Notice how the spars taper going out to the tip. You cut this taper
with the help of a long, steel straightedge.
Complete airfoil by placing 1⁄16-inch-thick balsa strips on top of
spars. Soak strips in water so they will bend easier.
Photos courtesy the author Graphic Design by Lydia Whitehead
then sheet the entire bottom of the fuselage. With all of this
sheeting, the grain runs across or at right angles to the fuselage
sides. The only sheeting you leave open at this point is the top
from the firewall to the wing leading edge.
At this point I am going to break for this month. Since this is a
beginner’s first-time scratch-built model, the final tally came to
more than 50 photographs to support the article. Not wanting to
cut anything out, the editors decided to divide the Scratch-One
construction article into two parts. I chose the start of covering as
the logical point to make the break.
Next month is the Nationals-coverage issue, but in the January
issue I will start with control-surface hinging and proceed all the
way through the Scratch-One’s first flights. For your
convenience, the plans and specifications are included with Part
One. With this information you can purchase the balsa, cut out
the parts, and do the assembly work. Thank you for your
patience. MA
Manufacturers:
Du-Bro Products (control rods, control horns, keepers)
Box 815
Wauconda IL 60084
(800) 848-9411
www.dubro.com
Hitec RCD (Neon RC system)
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
Hobby Lobby International (propellers)
5614 Franklin Pike Cir.
Brentwood TN 37027
(615) 373-1444
E-mail sales: [email protected]
www.hobby-lobby.com
New Creations R/C (electric power system)
Box 497
Willis TX 77378
(936) 856-4630 (telephone calls are preferred)
SR Batteries Inc. (Gapless Hinge Tape, R/C Techniques on covering
application)
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
November 2003 37
Make wingtip-panel joints at proper polyhedral angle of 41⁄2
inches off of building board. Clothespin holds plywood wing
Shown are the plywood wing-panel joiners or braces. You will brace in position until five-minute epoxy sets.
need two: one for each wingtip panel.
You can see the wingtip detail. Fashion each tip from scrap
pieces of 3⁄32 balsa, sanded to a smooth contour. Looking from wingtip toward center of wing. Neat construction!
Balsa and plywood raw-material suppliers
(in addition to Aero Craft Inc.):
Lone Star Models
115 Industrial St.
Lancaster TX 75134
(800) 687-5555
www.lonestar-models.com
National Balsa Co.
97 Cherokee Dr.
Springfield MA 01109
(413) 796-1925
www.nationalbalsa.com
Superior Balsa & Hobby Supplies
12020-G Centralia
Hawaiian Gardens CA 90716
(800) 488-9525
www.superiorbalsa.com
38 MODEL AVIATION
This photo shows the mounting of the Speed 400 electric motor to the plywood former
F1 using two 2.6-millimeter machine screws.
Add 1⁄16 x 1⁄4 spruce stiffeners as shown to wing-mounting area (top) and edges of
battery compartment. Be sure to make one right and one left fuselage side.
Begin cementing the formers in position on one fuselage side. The triangle helps to
keep the formers at a right angle to the fuselage side.
Scratch-One
Specifications
Type: Electric-powered RC
sailplane/basic three-channel trainer
Wingspan: 45 inches
Wing area: 247 square inches
Weight: 16.9 ounces (with a 78-cell
1100 mAh NiMH battery)
Wing loading: 9.8 ounces per square
foot
Length: 29 inches
Motor: Speed 400 direct drive
Propeller: Gunther 5 x 4
Motor current: 12 amps (at start of
run on full charge)
Motor power: 90 watts
rpm: 13,900
Watts per ounce: 5.32
Battery: Eight-cell 1100 mAh NiMH
Radio used: Hitec RCD Neon threechannel
transmitter (with control
options installed), Hitec Electron 6
micro dual-conversion receiver, two
Hitec HS-81 servos, Jeti JES 110 ESC
Flight duration: Almost six minutes
at full throttle. Close to 10-minute
motor-run time at half throttle.
November 2003 39
The overall framework is pinned together so the author can check everything before covering.
Both fuselage sides are shown cemented to the formers. Apply five-minute epoxy to the plywood firewall F1 for extra
strength since it supports the electric motor.
The two Hitec HS-81 servos are in place on top of the fuselage.
Join the fuselage sides at the rear and hold them together with a
clothespin until the cement dries.

WE ARE GETTING close to a wrap for
my portion of the “From the Ground Up”
series. In the past eight months you have
learned about Radio Control (RC) systems,
electric-power systems, assembling an
Almost Ready-to-Fly (ARF) model, flying
that model, and last month you learned the
A to Z of batteries.
The next step could have gone in either
of two directions: building a model from a
kit or building a model from raw
materials—from scratch! I chose the latter
and came up with a new RC trainer design
that I call the “Scratch-One.”
The idea was to utilize the RC system
and the electric power system from the
Aero Craft Pogo ARF. The Scratch-One RC
trainer design is slightly larger and slightly
heavier than the Pogo. Specifically, the
wing area is 247 square inches, the
wingspan is 45 inches, and the all-up weight
is 16.9 ounces (approximately an ounce
heavier than the Pogo).
The Scratch-One design can be
classified as an RC electric-powered trainer
sailplane. It has proven to be one of the
most forgiving designs to fly and perfect for
the RC beginner, but keep in mind that the
thrust of this article is to get you to build
your first model from scratch. The pieces
won’t be fabricated or preassembled; it is
all going to be strictly up to you. As part of
the process you will also cover all or part of
your model.
Obtaining the necessary balsa, plywood,
and spruce pieces to construct this model
took at least three visits to local hobby
shops; not every hobby dealer will have
every stick you need. I thought this might
be an initial point of frustration, so I came
up with an idea.
Craig Wagner, who owns Aero Craft,
agreed to make a box of wood for the
Scratch-One. It will have all of the wood
material you need, and in the correct sizes.
The only things you will have to purchase
on your own are the cements, covering
material, and hardware such as control rods,
control horns, and control-surface hinges.
You can reach Craig at Aero Craft Ltd., 432
Hallett Ave., Riverhead NY 11901; Tel.:
(631) 369-9319; Web site: www.aerocraft
rc.com.
(Editor’s note: Since this article was
written, we have received pricing and
shipping information from Aero Craft Ltd.
for the materials to build the Scratch-One.
The “kit” of materials is $19.95 plus $6
shipping and handling. This kit will come
packed in a 4 x 4 x 36-inch mailer box.)
About the Design: Before I get into the
construction, I want to point out some of the
Scratch-One’s design features. Cutting out
wing ribs can be a tedious job, especially
for a beginner. So in this design I
eliminated all wing ribs and substituted
balsa sticks.
The bottom stick is 1⁄8 x 1⁄4 balsa. Next
come three different-size wing spars, then
1⁄16 x 1⁄4 balsa sticks are bent over the spars
to provide the necessary airfoil shape. The
leading edge is common 3⁄16-inch-diameter
hardwood dowel. You won’t likely
experience much damage on rough landings
with this kind of construction.
I also made the wing’s center-section
flat so that no center joiner or brace is
necessary. Both tips are raised 41⁄2 inches
for what we call “polyhedral.” These raised
tips provide overall stability in flight.
Many models have what I call “internal”
battery compartments; to access the battery
pack for charging purposes, you must
remove the wing. I find that annoying and
time-consuming, so in this design the
battery compartment is on the bottom of the
fuselage where it can be accessed directly
without touching the wing.
Probably the most difficult task for the
beginner is to mount the servos and hook up
the control rods that operate the rudder and
elevator. To keep it simple I placed the two
servos on top of the fuselage, just aft of the
wing trailing edge. It’s kind of like “letting
it all hang out”!
The control rods are run externally from
the servo output arms back to the control
horns on the rudder and elevator. This
makes for easy control throw adjustments
and easy centering of the controls. These
few ideas made the Scratch-One extremely
simple to build and fly!
CONSTRUCTION
I like to make my own “kit” of parts
before starting the assembly. On this model
you must make two fuselage sides and all of
the tail pieces from 3⁄32 balsa. You also have
to cut out four fuselage formers from 1⁄16
plywood and a fifth former from 3⁄32 balsa.
The last items are two 1⁄16 plywood wingpanel
joiners—one for each tip panel.
To cut out these parts I take the plans to
a copying store, such as Kinko’s, and have
photocopies made of the parts to be cut out.
I paste these copies to manila-folder stock
34 MODEL AVIATION
Building From
To prepare templates, make copies from plans and cement them
to manila-folder stock. Use rubber cement and 3M Magic Tape. Templates after having been cut from manila-folder stock.
(file folders opened up) using rubber
cement and 3M Magic Tape.
After the cement dries I cut out the
pieces, which make handy templates. Then it
is just a matter of transcribing the outline of
the parts onto the balsa and plywood sheet
material with a ballpoint pen. Since you
made copies of the full-size plans, the parts
you cut out should fit perfectly.
You will be using the same cements that
you used to assemble the Pogo. I purchase
all of mine from Balsa Products Inc. in
Iselin, New Jersey, but there are many
supply sources. You will need thin and thick
cyanoacrylate glue (CyA) with an
accelerator (in a spray bottle) and fiveminute
epoxy cement for the high-stress
areas such as the firewall, wing-panel joints,
and stabilizer/vertical fin attachment to the
fuselage.
Because the wing requires no ribs, all
you need is a bunch of balsa sticks. The
bottom of the airfoil is made from 1⁄8 balsa
sticks. Add the three spars, and the last step
is to bend 1⁄16-inch-thick strips over the
spars, forming the airfoil shape of the wing.
You may find that briefly soaking these
strips in water will make them bend easier.
When assembling the wing, take note
that the middle spar in the center panel is
1⁄8 x 3⁄8 spruce (a hardwood); that is for
extra strength. On the tip panels, to
maintain a gradually thinning airfoil shape
it is necessary to taper the spars from the
panel joint out to the tip. For that reason
all of the tip-panel spars are made from
balsa so that they can be easily tapered
(cut). Each wingtip is simply capped off
with 3⁄32 balsa and sanded to blend in.
Fuselage: Trial-mount your Speed 400
motor to the plywood firewall F1. You will
need to drill a clearance hole in the center
along with two screw holes. The screws are
2.6 millimeter, which you can obtain from
Kirk Massey at New Creations R/C. Leave
the motor off until after F1 is cemented to
the fuselage sides.
Add 1⁄16 x 1⁄4 spruce stiffeners to the
wing-mount and battery-compartment areas.
This provides extra strength and should not
be omitted. When you cement the stiffeners
in place, remember that you are making one
left fuselage side and one right side.
Now you can cement the formers in
place, first to one side using a square or
triangle to make sure that they are aligned
properly. You can use thin CyA to spot the
formers in place, then follow up with thick
CyA, which adds more strength.
Attach the firewall (F1) with five-minute
epoxy cement. Once formers F1 through F4
are in place, add the other fuselage side. Try
to eyeball-align the two sides. The last thing
you do is join the two fuselage sides at the
rear. Hold them temporarily with a
clothespin and cement them in place (with
thick CyA).
Add the two 1⁄8 x 1⁄4 spruce servomounting
rails which are located on top of
the fuselage, just aft of the wing trailing
edge. The Hitec HS-81 servos are mounted
to these rails using the supplied wood
screws (two for each servo). Run the cables
coming from these servos through the hole
in former F4 and into the receiver
compartment, just below the wing.
Mount the Speed 400 motor in place with
the two screws, and install the Jeti JES 110
Electronic Speed Control (ESC). The motor
cables run through the hole in former F2.
Then the ESC servo cable passes through
the hole in former F3. I used double-stick
tape to hold the ESC to the fuselage side.
Install the ESC switch on the left side of the
fuselage. Before adding the sheeting, install
the battery-compartment floor, which is
made from 3⁄32 balsa.
With this done, you can apply the 1⁄16
sheet top and bottom to most of the model.
For example, do the fuselage top from the
servos to the leading edge of the stabilizer,
November 2003 35
Part One
Use cut-out templates to trace patterns onto raw balsa sheeting. Cut parts from sheeting using sharp X-Acto #11 knife blade.
■ Bob Aberle
36 MODEL AVIATION
All of the balsa-sheet pieces are ready for assembly. The wing
parts are literally a bunch of balsa sticks.
Leading-edge material, at top, is common 3⁄16-inch-diameter
hardwood dowel. Spar material is in center. The main, center
spar is made from spruce—a hardwood—for extra strength.
Starting wing construction. Leading edge is pinned in place, then
bottom 1⁄8 x 1⁄4 balsa sticks are set in place. Triangular-shaped
trailing-edge stock is at other end.
The three wing spars are added on top of 1⁄8-inch-thick balsa
strips. Remember that these spars on both tip panels taper as
they go out to the tips.
Notice how the spars taper going out to the tip. You cut this taper
with the help of a long, steel straightedge.
Complete airfoil by placing 1⁄16-inch-thick balsa strips on top of
spars. Soak strips in water so they will bend easier.
Photos courtesy the author Graphic Design by Lydia Whitehead
then sheet the entire bottom of the fuselage. With all of this
sheeting, the grain runs across or at right angles to the fuselage
sides. The only sheeting you leave open at this point is the top
from the firewall to the wing leading edge.
At this point I am going to break for this month. Since this is a
beginner’s first-time scratch-built model, the final tally came to
more than 50 photographs to support the article. Not wanting to
cut anything out, the editors decided to divide the Scratch-One
construction article into two parts. I chose the start of covering as
the logical point to make the break.
Next month is the Nationals-coverage issue, but in the January
issue I will start with control-surface hinging and proceed all the
way through the Scratch-One’s first flights. For your
convenience, the plans and specifications are included with Part
One. With this information you can purchase the balsa, cut out
the parts, and do the assembly work. Thank you for your
patience. MA
Manufacturers:
Du-Bro Products (control rods, control horns, keepers)
Box 815
Wauconda IL 60084
(800) 848-9411
www.dubro.com
Hitec RCD (Neon RC system)
12115 Paine St.
Poway CA 92064
(858) 748-6948
www.hitecrcd.com
Hobby Lobby International (propellers)
5614 Franklin Pike Cir.
Brentwood TN 37027
(615) 373-1444
E-mail sales: [email protected]
www.hobby-lobby.com
New Creations R/C (electric power system)
Box 497
Willis TX 77378
(936) 856-4630 (telephone calls are preferred)
SR Batteries Inc. (Gapless Hinge Tape, R/C Techniques on covering
application)
Box 287
Bellport NY 11713
(631) 286-0079
Fax: (631) 286-0901
[email protected]
www.srbatteries.com
November 2003 37
Make wingtip-panel joints at proper polyhedral angle of 41⁄2
inches off of building board. Clothespin holds plywood wing
Shown are the plywood wing-panel joiners or braces. You will brace in position until five-minute epoxy sets.
need two: one for each wingtip panel.
You can see the wingtip detail. Fashion each tip from scrap
pieces of 3⁄32 balsa, sanded to a smooth contour. Looking from wingtip toward center of wing. Neat construction!
Balsa and plywood raw-material suppliers
(in addition to Aero Craft Inc.):
Lone Star Models
115 Industrial St.
Lancaster TX 75134
(800) 687-5555
www.lonestar-models.com
National Balsa Co.
97 Cherokee Dr.
Springfield MA 01109
(413) 796-1925
www.nationalbalsa.com
Superior Balsa & Hobby Supplies
12020-G Centralia
Hawaiian Gardens CA 90716
(800) 488-9525
www.superiorbalsa.com
38 MODEL AVIATION
This photo shows the mounting of the Speed 400 electric motor to the plywood former
F1 using two 2.6-millimeter machine screws.
Add 1⁄16 x 1⁄4 spruce stiffeners as shown to wing-mounting area (top) and edges of
battery compartment. Be sure to make one right and one left fuselage side.
Begin cementing the formers in position on one fuselage side. The triangle helps to
keep the formers at a right angle to the fuselage side.
Scratch-One
Specifications
Type: Electric-powered RC
sailplane/basic three-channel trainer
Wingspan: 45 inches
Wing area: 247 square inches
Weight: 16.9 ounces (with a 78-cell
1100 mAh NiMH battery)
Wing loading: 9.8 ounces per square
foot
Length: 29 inches
Motor: Speed 400 direct drive
Propeller: Gunther 5 x 4
Motor current: 12 amps (at start of
run on full charge)
Motor power: 90 watts
rpm: 13,900
Watts per ounce: 5.32
Battery: Eight-cell 1100 mAh NiMH
Radio used: Hitec RCD Neon threechannel
transmitter (with control
options installed), Hitec Electron 6
micro dual-conversion receiver, two
Hitec HS-81 servos, Jeti JES 110 ESC
Flight duration: Almost six minutes
at full throttle. Close to 10-minute
motor-run time at half throttle.
November 2003 39
The overall framework is pinned together so the author can check everything before covering.
Both fuselage sides are shown cemented to the formers. Apply five-minute epoxy to the plywood firewall F1 for extra
strength since it supports the electric motor.
The two Hitec HS-81 servos are in place on top of the fuselage.
Join the fuselage sides at the rear and hold them together with a
clothespin until the cement dries.