FOR THE PAST few years I’ve been
having a lot of modeling fun with
electric-powered aircraft, sheet foam and
built up, all park flyer size. I wanted to
try a larger .40-size electric-powered
airplane this time, and I wanted to build
my own.
There are many great ARFs available
these days, and I had a chance to fly two
of them during our last trip to California.
My grandson Matt flies a Cermark E-3D
Banchee and my son Rick flies a
Northeast Sailplane Products Samba.
Both are wonderful, and after flying
them I wanted a model in that size range.16 MODEL AVIATION
Lotsa Amps is a spirited performer that can do all the aerobatic maneuvers you can
think of. It could be converted to glow power, but why?
Power-system components: four-cell, 4400 mAh Poly-Quest Li-Poly battery pack; AXI
2826/12 brushless outrunner motor with radial mount kit; Jeti Advance PLUS 40
OPTO ESC; Ultimate BEC; APC 12 x 8 propeller.
A close-up showing the rudder control
horn and the steerable tail wheel.
ARFs make a great deal of economical
sense, but I like to make balsa sawdust and
wood chips when I build. I knew I couldn’t
make an airplane as light as most of the
ARFs, but I wanted one that was a bit more
rugged, to withstand those rough landings
and occasional tumbles. I also wanted good
aerobatic capability but not necessarily the
3-D stuff—a reflection of my flying style, I
guess. So I went to the drafting board.
For a long time .40 has been the bestselling
engine size; I’m sure because so
many trainers are powered by .40s and many
sport, aerobatic, and fun-fly aircraft are
made for this size engine. I was interested in
seeing how electric power compared to the
.40 glow engines I’d become accustomed to
while using for so many years.
I laid out a 54-inch-span wing with 675
square inches of wing area, a constant chord
for easy building, and a nice, thick
symmetrical airfoil. This is the size of
airplane I’d normally power with a good .40
or .45 glow engine.
For a lighter-weight wing I spaced the
ribs farther apart than usual and didn’t use
LE planking, but I did put in partial ribs
ahead of the spars. All the control surfaces
are built up, again to save weight. The
control surfaces are large but not huge.
The fuselage is a basic sheet-balsa box
with some lightening holes. I did use
plywood doublers in the forward section,
with lightening holes and a sturdy landinggear
mount. The one-piece wing bolts to the
fuselage. I left out the plastic canopy and
plastic nose cowl to keep things easy.
Using Electric Power: With modern
electric-power technology in mind, I knew I
wanted a brushless motor and Li-Poly
batteries for plenty of performance and the
lightest possible weight. Many power
systems could be used. I found the Hobby
Lobby Web site extremely helpful, with its
practical information about motors,
controllers, and batteries that the company
has used for electric conversions of many
glow-powered aircraft.
Reviewing the equipment Hobby Lobby
chose for the different airframes and the
practical information provided with the
motor specifications helped in my selections.
I could compare the size and weight of my
new project with a number of similar
Type: Aerobatic/sport aircraft. In addition, the company has
Wingspan: 54 inches
Wing area: 675 square inches
Weight: 4 pounds, 2 ounces
Wing loading: 14 ounces/square foot
Construction: Balsa and plywood
Covering/finish: MonoKote
Radio system: Four channels
Motor: AXI 2826/12 Outrunner
brushless, direct drive
ESC: Jeti Advance PLUS 40 OPTO
BEC: Ultimate
Propeller: APC 12 x 8E
Current: 40 amps
Voltage: 14.7
Motor power: 600 watts
rpm: 8,500
Watts/pound: 150
Battery: Four-cell, 4400 mAh Poly-
Quest 15C
Flight duration: 15 minutes or more,
depending on throttle usage
Power figures were taken on the
ground, at full throttle. Unloading in
the air is estimated at 15%-20%, and
full throttle is not used for most flying.
June 2006 17
knowledgeable people to answer questions
about your modeling projects; they sure
helped me.
How to select a motor, propeller, and
battery still seems mysterious to me. When
we pick a glow engine we don’t have to get
into dynamometer testing for horsepower
figures, so I prefer not to get into too much
volts, amps, and watts stuff.
I’d rather know that a motor will turn a
certain propeller at an rpm with a particular
battery-pack rating, and I can buy hardware
expecting it to fly my size of airplane. From
the Hobby Lobby data, and after talking with
Mike Hines for advice, I selected hardware
for this project.
With the airplane partially built I went
for the AXI 2826/12 Outrunner brushless
direct-drive motor, the Jeti Advance PLUS
40 OPTO ESC, and an APC 12 x 8E electric
propeller as the power setup. For battery
power I got the Poly-Quest 4S1P 4400 mAh
Li-Poly pack.
That is a newer-generation battery with
heavier discharge capability, and it is a
lightweight unit. I liked the idea of the
Transparent MonoKote finish reveals the lightweight wing, tail, and fuselage structure. It
adds up to performance!
A view into the fuselage, with wing removed, shows battery position with receiver wrapped in protective foam and the mounting of
the rudder and elevator servos.
Sporty-looking, isn’t it? Sturdy aluminum landing gear makes rough-field operation a cinch.
Photos courtesy the author
18 MODEL AVIATION
individual cell-monitoring device to ensure a
cell-balanced charged pack. A four-cell pack
is used for its higher voltage, keeping the
amp draw to a conservative level.
The OPTO ESC is made for highervoltage
operation. I also got the Jeti program
card for use with the ESC; that makes it easy
to set up the ESC for use by just plugging in
a few jumpers to choose the battery type,
cutoff voltage, cutoff type, brake on or off,
timing, and throttle curve. I like easy.
Since the ESCs for higher-voltage use
seldom provide a BEC output, I could have
carried a separate Ni-Cd pack for the radio;
instead I opted for an Ultimate BEC to
power the radio. All of that equipment is
available from Hobby Lobby.
For those of you who do get into volts,
amps, and watts, before I flew the airplane I
checked the power-system performance with
my handy AstroFlight Super Whattmeter.
Running on the ground, the AXI 2826/12
motor turned the APC 12 x 8E propeller at
8,500 rpm, drawing 39 amps from the fourcell
4400 mAh Poly-Quest Li-Poly battery
pack, for approximately 600 watts of power.
That’s roughly 150 watts per pound of
model—plenty for lively performance.
The current draw goes down when the
aircraft is flying, some estimate as much as
20%, and I found that full throttle isn’t
needed for most flying, so I think the
equipment is being used fairly
conservatively. I believe the airplane
performs at least as well as, if not better
than, it would with any hot .40 or .45 glow
engine for power.
Weight is important. I tried for a light
airframe figuring that the electric
components would be heavy. A .40 glow
engine, with muffler, could weigh 13-20
ounces, depending on the type. Add an
engine mount, throttle servo and linkage, a
10-ounce fuel tank, and the fuel in it. That
could be a total of 25-32 ounces flying
Looking at the bare framework you can see that there is no wing LE sheeting, but
partial ribs are used on the LE sections. Ailerons and all tail surfaces are built up.
The wing and tail surfaces are framed up, hinged, and ready for assembly to the
fuselage. This model is fun to build.
The fuselage parts are cut out and ready for assembly. There are few parts in this simple-to-construct aircraft.
weight. That surprised me.
For the electric hardware figure roughly 7
ounces for the motor, 3 ounces for the ESC
and BEC, and 14 ounces for the battery.
That’s approximately 24 ounces.
Okay, so maybe this .40-size electric stuff
isn’t so heavy. And maybe my figures aren’t
so accurate, but it seems that with modern
technology, brushless motors, and Li-Poly
batteries, electric power can weigh roughly
the same as glow-engine power.
The biggest difference between electric
and glow power is the speed the propeller is
turned and the propeller sizes used. An
average .40 engine would likely use a 10 x 6
propeller. With my AXI motor I’ve tried a
12 x 8, 13 x 8, and 13 x 6.5 so far, and I am
still experimenting. Sure, the motor turns
slower than a glow engine, but it turns a
bigger propeller.
The model doesn’t care too much. Many
of the glow-engine horsepower ratings are
made at higher speeds than these engines
will ever see in most sport-model usage, so
those high rpm and horsepower numbers
don’t mean much.
I used four Hitec HS-85BB servos. They
are small, light, and powerful.
The airplane at the completed-butuncovered-
framework stage without power
plant and radio equipment weighed
approximately 2 pounds. Covered and with
the motor, controller, battery pack, and radio
gear, the total weight was 4 pounds, 2
ounces, for a wing loading of 14 ounces per
square foot of wing area. I consider that a
great figure for a sport-flying, aerobatic
aircraft.
Test flights were uneventful except for
the large amount of power available. I was
immediately comfortable with the airplane—
well, at a lower throttle setting and after
adjusting the dual rate settings on the
transmitter to get the control response I liked
and could handle.
This model has plenty of power for easy
takeoffs from the grass fields I fly from and
ample power for all the aerobatics I can think
of. Most of the time I’m flying at
considerably less than full throttle, and I like
to make several shorter flights on one
charged pack. It looks as though 15-minuteplus
flights are no problem. You can
probably make them longer, depending on
your power usage.
I know I’ll be burning less glow fuel and
gas in the future. I’ll also be spending more
money on electric-power gear.
I charge my Li-Poly batteries with an
AstroFlight Lithium Charger (item 109) and
use a 10-amp DC power supply to run the
charger in my workshop. Since the Poly-
Quest Li-Poly battery packs are equipped
with a plug that has leads from each cell, I
use the Poly-Quest Protective Circuit
Module (PCM) Guards when charging them.
The PCM Guard is a protective device
that cuts off the charger when the first
cell in the pack reaches 4.2 volts; this
doesn’t balance all the cells, but it does
ensure that no particular cell will be
charged past the 4.2-volt safe upper limit.
It seems like a good idea.
For those of you who like to scratch-build
your airplanes, you can follow my plans or
incorporate your ideas for modifications as
you build. If you want to aim for more 3-D
flying, increase the aileron area by widening
their chord. If you think the tail control
surfaces could be larger, make them larger. If
you can put more lightening holes in the
structure, do it. If you want to use thinner
plywood doublers, go ahead.
An interesting modification would be to
move the wing location higher on the
fuselage and have separate wing panels
sliding onto an aluminum tube spar/joiner.
As scratch builders we can do what we want.
Following are some building notes.
CONSTRUCTION
I obtain an extra copy of the plans I can
cut up to get the parts patterns, along with
the wing and tail-surface layouts I use to
build the parts over. Paper parts patterns
aren’t bad to work with. I draw around them
on the plywood or balsa with a ballpoint pen
and then cut the pieces with a band saw or
scroll saw.
Wing: I usually start here, placing the lower
spar over the plans and using weights to keep
it in place, using waxed paper to protect the
plans and work surface. The ribs are placed
on the lower spar and held up off the table
with a balsa strip placed toward the rear of
the wing layout.with the top spar, LE, TE, TE sheeting, and
partial ribs. The TE has to be planed and
sanded to shape; it’s a pain, but there are
only two pieces needed.
I wait to add the center-section sheeting
until the wing halves are joined. I don’t
think the dihedral hurts the aerobatic
capability, but join the panels without
dihedral if you prefer a flat wing.
Don’t forget the cardboard tubes for the
aileron extension cables before you glue the
wing halves together with the plywood
joiner. I use a small amount of fiberglass
cloth and epoxy around the LE and TE
center areas.
Tail Surfaces: Build the ailerons, stabilizer,
fin, elevators, and rudder from 1/4 balsa strip
stock over the plans, using your choice of
glue. I do a great deal of building with fiveminute
epoxy; it seems like I’m always in a
hurry to get it done.
Join the elevator halves with a piece of
1/8-inch-diameter music wire. Plane and
block-sand the LEs of the elevators, rudder,
and ailerons to the beveled shape.
Use your choice of hinges. I employ the
pinned nylon variety or the cyanoacrylate
easy-hinge type.
Fuselage: Start the fuselage build-up by
gluing the plywood doublers to the balsa
side pieces. I put the lightening holes in the
plywood with a hole saw in a small drill
press. I glue the bulkheads at the LE and TE
positions to one of the sides, add the other
side, and then add the remaining bulkheads.
Cut the upper side pieces oversize, to
allow for the bevel that has to be sanded on
the bottom edge before gluing those pieces
in place. Because of the taper in the rear of
the fuselage, the upper pieces have to be
trimmed carefully to fit in place.
With the upper sides on I use a sanding
block to bevel the top edges for the top
sheeting. Add the top sheeting and round all
the edges well.
Final Assembly: Fit the fuselage to the
wing, align it, and get it bolted in place.
Add the horizontal stabilizer, aligning it
with the wing. The last step is to add the
vertical fin.
With the control surfaces hinged in
place, add the control horns and the linkage
from the servos. I use either fiberglass-tube
pushrods or flexible nylon-tube linkages.
Glue plywood mounts for the aileron servos
in place between the closely spaced ribs.
For easy access to the battery pack I
have a removable front hatch with dowels in
the rear for alignment and a nylon holddown
snap on the front end of the hatch. I
left the motor exposed for easy access and
mounted it to the firewall with 1-inch
standoffs. I did this so there would be room
for a geared motor setup if I ever want to try
that sort of power plant.
Two washers on the left-side mounting
bolts provide some right thrust. I considered
22 MODEL AVIATION
shaping a foam or wood block for an
enclosed motor cowl, maybe with two
horizontal cheek-cowl shapes for styling,
and laying up a fiberglass cowl. In the end I
went with a simple sheet-balsa extension
on each side of the motor area.
I made the landing gear from a 1-inchwide,
1/8-inch-thick strip of 6061-T6
aluminum and used light foam wheels. The
gear is held in place with three 1/4-inch
nylon bolts. The mounting base is secure in
the fuselage; I’ve already ripped the gear
off on a poor landing, and the only damage
was the three broken nylon bolts.
A good source for aluminum landing
gear is TnT Landing Gear Products at
www.tntlandinggear.com. The steerable
tail-wheel bracket is a standard molded
nylon piece.
For final balancing of the airplane,
there’s enough room in the fuselage to
move the battery pack to the rear or
forward to get the balance point where you
want it. I like to start with the model
slightly nose-heavy and move the balance
point to the rear to get the response I want.
If you use a motor and/or battery pack
that is heavier than the equipment I used,
you might want to shorten the nose a bit—
maybe a half inch. Or you can install the
elevator and rudder servos back near the
tail surfaces.
Covering: I covered the airplane with
MonoKote; I’ve used this material for
many years. It took a lot of heating and
tugging to get the wingtips free of
wrinkles, so I might try some softer
material on the next project.
Flying: I like the way this aircraft
performs. It’s not a contest machine. I
wanted it to be a hot, fun flier—an
aerobatically capable airplane but one I
could relax with a bit. I notice that the older
I get, the better I used to fly.
I’m glad I tried this .40-size electric.
Although I won’t be getting rid of those
glow and gas burners, I expect to be
With the ribs glued in place, follow them
Edition: Model Aviation - 2006/06
Page Numbers: 15,16,17,18,19,20,22
Edition: Model Aviation - 2006/06
Page Numbers: 15,16,17,18,19,20,22
FOR THE PAST few years I’ve been
having a lot of modeling fun with
electric-powered aircraft, sheet foam and
built up, all park flyer size. I wanted to
try a larger .40-size electric-powered
airplane this time, and I wanted to build
my own.
There are many great ARFs available
these days, and I had a chance to fly two
of them during our last trip to California.
My grandson Matt flies a Cermark E-3D
Banchee and my son Rick flies a
Northeast Sailplane Products Samba.
Both are wonderful, and after flying
them I wanted a model in that size range.16 MODEL AVIATION
Lotsa Amps is a spirited performer that can do all the aerobatic maneuvers you can
think of. It could be converted to glow power, but why?
Power-system components: four-cell, 4400 mAh Poly-Quest Li-Poly battery pack; AXI
2826/12 brushless outrunner motor with radial mount kit; Jeti Advance PLUS 40
OPTO ESC; Ultimate BEC; APC 12 x 8 propeller.
A close-up showing the rudder control
horn and the steerable tail wheel.
ARFs make a great deal of economical
sense, but I like to make balsa sawdust and
wood chips when I build. I knew I couldn’t
make an airplane as light as most of the
ARFs, but I wanted one that was a bit more
rugged, to withstand those rough landings
and occasional tumbles. I also wanted good
aerobatic capability but not necessarily the
3-D stuff—a reflection of my flying style, I
guess. So I went to the drafting board.
For a long time .40 has been the bestselling
engine size; I’m sure because so
many trainers are powered by .40s and many
sport, aerobatic, and fun-fly aircraft are
made for this size engine. I was interested in
seeing how electric power compared to the
.40 glow engines I’d become accustomed to
while using for so many years.
I laid out a 54-inch-span wing with 675
square inches of wing area, a constant chord
for easy building, and a nice, thick
symmetrical airfoil. This is the size of
airplane I’d normally power with a good .40
or .45 glow engine.
For a lighter-weight wing I spaced the
ribs farther apart than usual and didn’t use
LE planking, but I did put in partial ribs
ahead of the spars. All the control surfaces
are built up, again to save weight. The
control surfaces are large but not huge.
The fuselage is a basic sheet-balsa box
with some lightening holes. I did use
plywood doublers in the forward section,
with lightening holes and a sturdy landinggear
mount. The one-piece wing bolts to the
fuselage. I left out the plastic canopy and
plastic nose cowl to keep things easy.
Using Electric Power: With modern
electric-power technology in mind, I knew I
wanted a brushless motor and Li-Poly
batteries for plenty of performance and the
lightest possible weight. Many power
systems could be used. I found the Hobby
Lobby Web site extremely helpful, with its
practical information about motors,
controllers, and batteries that the company
has used for electric conversions of many
glow-powered aircraft.
Reviewing the equipment Hobby Lobby
chose for the different airframes and the
practical information provided with the
motor specifications helped in my selections.
I could compare the size and weight of my
new project with a number of similar
Type: Aerobatic/sport aircraft. In addition, the company has
Wingspan: 54 inches
Wing area: 675 square inches
Weight: 4 pounds, 2 ounces
Wing loading: 14 ounces/square foot
Construction: Balsa and plywood
Covering/finish: MonoKote
Radio system: Four channels
Motor: AXI 2826/12 Outrunner
brushless, direct drive
ESC: Jeti Advance PLUS 40 OPTO
BEC: Ultimate
Propeller: APC 12 x 8E
Current: 40 amps
Voltage: 14.7
Motor power: 600 watts
rpm: 8,500
Watts/pound: 150
Battery: Four-cell, 4400 mAh Poly-
Quest 15C
Flight duration: 15 minutes or more,
depending on throttle usage
Power figures were taken on the
ground, at full throttle. Unloading in
the air is estimated at 15%-20%, and
full throttle is not used for most flying.
June 2006 17
knowledgeable people to answer questions
about your modeling projects; they sure
helped me.
How to select a motor, propeller, and
battery still seems mysterious to me. When
we pick a glow engine we don’t have to get
into dynamometer testing for horsepower
figures, so I prefer not to get into too much
volts, amps, and watts stuff.
I’d rather know that a motor will turn a
certain propeller at an rpm with a particular
battery-pack rating, and I can buy hardware
expecting it to fly my size of airplane. From
the Hobby Lobby data, and after talking with
Mike Hines for advice, I selected hardware
for this project.
With the airplane partially built I went
for the AXI 2826/12 Outrunner brushless
direct-drive motor, the Jeti Advance PLUS
40 OPTO ESC, and an APC 12 x 8E electric
propeller as the power setup. For battery
power I got the Poly-Quest 4S1P 4400 mAh
Li-Poly pack.
That is a newer-generation battery with
heavier discharge capability, and it is a
lightweight unit. I liked the idea of the
Transparent MonoKote finish reveals the lightweight wing, tail, and fuselage structure. It
adds up to performance!
A view into the fuselage, with wing removed, shows battery position with receiver wrapped in protective foam and the mounting of
the rudder and elevator servos.
Sporty-looking, isn’t it? Sturdy aluminum landing gear makes rough-field operation a cinch.
Photos courtesy the author
18 MODEL AVIATION
individual cell-monitoring device to ensure a
cell-balanced charged pack. A four-cell pack
is used for its higher voltage, keeping the
amp draw to a conservative level.
The OPTO ESC is made for highervoltage
operation. I also got the Jeti program
card for use with the ESC; that makes it easy
to set up the ESC for use by just plugging in
a few jumpers to choose the battery type,
cutoff voltage, cutoff type, brake on or off,
timing, and throttle curve. I like easy.
Since the ESCs for higher-voltage use
seldom provide a BEC output, I could have
carried a separate Ni-Cd pack for the radio;
instead I opted for an Ultimate BEC to
power the radio. All of that equipment is
available from Hobby Lobby.
For those of you who do get into volts,
amps, and watts, before I flew the airplane I
checked the power-system performance with
my handy AstroFlight Super Whattmeter.
Running on the ground, the AXI 2826/12
motor turned the APC 12 x 8E propeller at
8,500 rpm, drawing 39 amps from the fourcell
4400 mAh Poly-Quest Li-Poly battery
pack, for approximately 600 watts of power.
That’s roughly 150 watts per pound of
model—plenty for lively performance.
The current draw goes down when the
aircraft is flying, some estimate as much as
20%, and I found that full throttle isn’t
needed for most flying, so I think the
equipment is being used fairly
conservatively. I believe the airplane
performs at least as well as, if not better
than, it would with any hot .40 or .45 glow
engine for power.
Weight is important. I tried for a light
airframe figuring that the electric
components would be heavy. A .40 glow
engine, with muffler, could weigh 13-20
ounces, depending on the type. Add an
engine mount, throttle servo and linkage, a
10-ounce fuel tank, and the fuel in it. That
could be a total of 25-32 ounces flying
Looking at the bare framework you can see that there is no wing LE sheeting, but
partial ribs are used on the LE sections. Ailerons and all tail surfaces are built up.
The wing and tail surfaces are framed up, hinged, and ready for assembly to the
fuselage. This model is fun to build.
The fuselage parts are cut out and ready for assembly. There are few parts in this simple-to-construct aircraft.
weight. That surprised me.
For the electric hardware figure roughly 7
ounces for the motor, 3 ounces for the ESC
and BEC, and 14 ounces for the battery.
That’s approximately 24 ounces.
Okay, so maybe this .40-size electric stuff
isn’t so heavy. And maybe my figures aren’t
so accurate, but it seems that with modern
technology, brushless motors, and Li-Poly
batteries, electric power can weigh roughly
the same as glow-engine power.
The biggest difference between electric
and glow power is the speed the propeller is
turned and the propeller sizes used. An
average .40 engine would likely use a 10 x 6
propeller. With my AXI motor I’ve tried a
12 x 8, 13 x 8, and 13 x 6.5 so far, and I am
still experimenting. Sure, the motor turns
slower than a glow engine, but it turns a
bigger propeller.
The model doesn’t care too much. Many
of the glow-engine horsepower ratings are
made at higher speeds than these engines
will ever see in most sport-model usage, so
those high rpm and horsepower numbers
don’t mean much.
I used four Hitec HS-85BB servos. They
are small, light, and powerful.
The airplane at the completed-butuncovered-
framework stage without power
plant and radio equipment weighed
approximately 2 pounds. Covered and with
the motor, controller, battery pack, and radio
gear, the total weight was 4 pounds, 2
ounces, for a wing loading of 14 ounces per
square foot of wing area. I consider that a
great figure for a sport-flying, aerobatic
aircraft.
Test flights were uneventful except for
the large amount of power available. I was
immediately comfortable with the airplane—
well, at a lower throttle setting and after
adjusting the dual rate settings on the
transmitter to get the control response I liked
and could handle.
This model has plenty of power for easy
takeoffs from the grass fields I fly from and
ample power for all the aerobatics I can think
of. Most of the time I’m flying at
considerably less than full throttle, and I like
to make several shorter flights on one
charged pack. It looks as though 15-minuteplus
flights are no problem. You can
probably make them longer, depending on
your power usage.
I know I’ll be burning less glow fuel and
gas in the future. I’ll also be spending more
money on electric-power gear.
I charge my Li-Poly batteries with an
AstroFlight Lithium Charger (item 109) and
use a 10-amp DC power supply to run the
charger in my workshop. Since the Poly-
Quest Li-Poly battery packs are equipped
with a plug that has leads from each cell, I
use the Poly-Quest Protective Circuit
Module (PCM) Guards when charging them.
The PCM Guard is a protective device
that cuts off the charger when the first
cell in the pack reaches 4.2 volts; this
doesn’t balance all the cells, but it does
ensure that no particular cell will be
charged past the 4.2-volt safe upper limit.
It seems like a good idea.
For those of you who like to scratch-build
your airplanes, you can follow my plans or
incorporate your ideas for modifications as
you build. If you want to aim for more 3-D
flying, increase the aileron area by widening
their chord. If you think the tail control
surfaces could be larger, make them larger. If
you can put more lightening holes in the
structure, do it. If you want to use thinner
plywood doublers, go ahead.
An interesting modification would be to
move the wing location higher on the
fuselage and have separate wing panels
sliding onto an aluminum tube spar/joiner.
As scratch builders we can do what we want.
Following are some building notes.
CONSTRUCTION
I obtain an extra copy of the plans I can
cut up to get the parts patterns, along with
the wing and tail-surface layouts I use to
build the parts over. Paper parts patterns
aren’t bad to work with. I draw around them
on the plywood or balsa with a ballpoint pen
and then cut the pieces with a band saw or
scroll saw.
Wing: I usually start here, placing the lower
spar over the plans and using weights to keep
it in place, using waxed paper to protect the
plans and work surface. The ribs are placed
on the lower spar and held up off the table
with a balsa strip placed toward the rear of
the wing layout.with the top spar, LE, TE, TE sheeting, and
partial ribs. The TE has to be planed and
sanded to shape; it’s a pain, but there are
only two pieces needed.
I wait to add the center-section sheeting
until the wing halves are joined. I don’t
think the dihedral hurts the aerobatic
capability, but join the panels without
dihedral if you prefer a flat wing.
Don’t forget the cardboard tubes for the
aileron extension cables before you glue the
wing halves together with the plywood
joiner. I use a small amount of fiberglass
cloth and epoxy around the LE and TE
center areas.
Tail Surfaces: Build the ailerons, stabilizer,
fin, elevators, and rudder from 1/4 balsa strip
stock over the plans, using your choice of
glue. I do a great deal of building with fiveminute
epoxy; it seems like I’m always in a
hurry to get it done.
Join the elevator halves with a piece of
1/8-inch-diameter music wire. Plane and
block-sand the LEs of the elevators, rudder,
and ailerons to the beveled shape.
Use your choice of hinges. I employ the
pinned nylon variety or the cyanoacrylate
easy-hinge type.
Fuselage: Start the fuselage build-up by
gluing the plywood doublers to the balsa
side pieces. I put the lightening holes in the
plywood with a hole saw in a small drill
press. I glue the bulkheads at the LE and TE
positions to one of the sides, add the other
side, and then add the remaining bulkheads.
Cut the upper side pieces oversize, to
allow for the bevel that has to be sanded on
the bottom edge before gluing those pieces
in place. Because of the taper in the rear of
the fuselage, the upper pieces have to be
trimmed carefully to fit in place.
With the upper sides on I use a sanding
block to bevel the top edges for the top
sheeting. Add the top sheeting and round all
the edges well.
Final Assembly: Fit the fuselage to the
wing, align it, and get it bolted in place.
Add the horizontal stabilizer, aligning it
with the wing. The last step is to add the
vertical fin.
With the control surfaces hinged in
place, add the control horns and the linkage
from the servos. I use either fiberglass-tube
pushrods or flexible nylon-tube linkages.
Glue plywood mounts for the aileron servos
in place between the closely spaced ribs.
For easy access to the battery pack I
have a removable front hatch with dowels in
the rear for alignment and a nylon holddown
snap on the front end of the hatch. I
left the motor exposed for easy access and
mounted it to the firewall with 1-inch
standoffs. I did this so there would be room
for a geared motor setup if I ever want to try
that sort of power plant.
Two washers on the left-side mounting
bolts provide some right thrust. I considered
22 MODEL AVIATION
shaping a foam or wood block for an
enclosed motor cowl, maybe with two
horizontal cheek-cowl shapes for styling,
and laying up a fiberglass cowl. In the end I
went with a simple sheet-balsa extension
on each side of the motor area.
I made the landing gear from a 1-inchwide,
1/8-inch-thick strip of 6061-T6
aluminum and used light foam wheels. The
gear is held in place with three 1/4-inch
nylon bolts. The mounting base is secure in
the fuselage; I’ve already ripped the gear
off on a poor landing, and the only damage
was the three broken nylon bolts.
A good source for aluminum landing
gear is TnT Landing Gear Products at
www.tntlandinggear.com. The steerable
tail-wheel bracket is a standard molded
nylon piece.
For final balancing of the airplane,
there’s enough room in the fuselage to
move the battery pack to the rear or
forward to get the balance point where you
want it. I like to start with the model
slightly nose-heavy and move the balance
point to the rear to get the response I want.
If you use a motor and/or battery pack
that is heavier than the equipment I used,
you might want to shorten the nose a bit—
maybe a half inch. Or you can install the
elevator and rudder servos back near the
tail surfaces.
Covering: I covered the airplane with
MonoKote; I’ve used this material for
many years. It took a lot of heating and
tugging to get the wingtips free of
wrinkles, so I might try some softer
material on the next project.
Flying: I like the way this aircraft
performs. It’s not a contest machine. I
wanted it to be a hot, fun flier—an
aerobatically capable airplane but one I
could relax with a bit. I notice that the older
I get, the better I used to fly.
I’m glad I tried this .40-size electric.
Although I won’t be getting rid of those
glow and gas burners, I expect to be
With the ribs glued in place, follow them
Edition: Model Aviation - 2006/06
Page Numbers: 15,16,17,18,19,20,22
FOR THE PAST few years I’ve been
having a lot of modeling fun with
electric-powered aircraft, sheet foam and
built up, all park flyer size. I wanted to
try a larger .40-size electric-powered
airplane this time, and I wanted to build
my own.
There are many great ARFs available
these days, and I had a chance to fly two
of them during our last trip to California.
My grandson Matt flies a Cermark E-3D
Banchee and my son Rick flies a
Northeast Sailplane Products Samba.
Both are wonderful, and after flying
them I wanted a model in that size range.16 MODEL AVIATION
Lotsa Amps is a spirited performer that can do all the aerobatic maneuvers you can
think of. It could be converted to glow power, but why?
Power-system components: four-cell, 4400 mAh Poly-Quest Li-Poly battery pack; AXI
2826/12 brushless outrunner motor with radial mount kit; Jeti Advance PLUS 40
OPTO ESC; Ultimate BEC; APC 12 x 8 propeller.
A close-up showing the rudder control
horn and the steerable tail wheel.
ARFs make a great deal of economical
sense, but I like to make balsa sawdust and
wood chips when I build. I knew I couldn’t
make an airplane as light as most of the
ARFs, but I wanted one that was a bit more
rugged, to withstand those rough landings
and occasional tumbles. I also wanted good
aerobatic capability but not necessarily the
3-D stuff—a reflection of my flying style, I
guess. So I went to the drafting board.
For a long time .40 has been the bestselling
engine size; I’m sure because so
many trainers are powered by .40s and many
sport, aerobatic, and fun-fly aircraft are
made for this size engine. I was interested in
seeing how electric power compared to the
.40 glow engines I’d become accustomed to
while using for so many years.
I laid out a 54-inch-span wing with 675
square inches of wing area, a constant chord
for easy building, and a nice, thick
symmetrical airfoil. This is the size of
airplane I’d normally power with a good .40
or .45 glow engine.
For a lighter-weight wing I spaced the
ribs farther apart than usual and didn’t use
LE planking, but I did put in partial ribs
ahead of the spars. All the control surfaces
are built up, again to save weight. The
control surfaces are large but not huge.
The fuselage is a basic sheet-balsa box
with some lightening holes. I did use
plywood doublers in the forward section,
with lightening holes and a sturdy landinggear
mount. The one-piece wing bolts to the
fuselage. I left out the plastic canopy and
plastic nose cowl to keep things easy.
Using Electric Power: With modern
electric-power technology in mind, I knew I
wanted a brushless motor and Li-Poly
batteries for plenty of performance and the
lightest possible weight. Many power
systems could be used. I found the Hobby
Lobby Web site extremely helpful, with its
practical information about motors,
controllers, and batteries that the company
has used for electric conversions of many
glow-powered aircraft.
Reviewing the equipment Hobby Lobby
chose for the different airframes and the
practical information provided with the
motor specifications helped in my selections.
I could compare the size and weight of my
new project with a number of similar
Type: Aerobatic/sport aircraft. In addition, the company has
Wingspan: 54 inches
Wing area: 675 square inches
Weight: 4 pounds, 2 ounces
Wing loading: 14 ounces/square foot
Construction: Balsa and plywood
Covering/finish: MonoKote
Radio system: Four channels
Motor: AXI 2826/12 Outrunner
brushless, direct drive
ESC: Jeti Advance PLUS 40 OPTO
BEC: Ultimate
Propeller: APC 12 x 8E
Current: 40 amps
Voltage: 14.7
Motor power: 600 watts
rpm: 8,500
Watts/pound: 150
Battery: Four-cell, 4400 mAh Poly-
Quest 15C
Flight duration: 15 minutes or more,
depending on throttle usage
Power figures were taken on the
ground, at full throttle. Unloading in
the air is estimated at 15%-20%, and
full throttle is not used for most flying.
June 2006 17
knowledgeable people to answer questions
about your modeling projects; they sure
helped me.
How to select a motor, propeller, and
battery still seems mysterious to me. When
we pick a glow engine we don’t have to get
into dynamometer testing for horsepower
figures, so I prefer not to get into too much
volts, amps, and watts stuff.
I’d rather know that a motor will turn a
certain propeller at an rpm with a particular
battery-pack rating, and I can buy hardware
expecting it to fly my size of airplane. From
the Hobby Lobby data, and after talking with
Mike Hines for advice, I selected hardware
for this project.
With the airplane partially built I went
for the AXI 2826/12 Outrunner brushless
direct-drive motor, the Jeti Advance PLUS
40 OPTO ESC, and an APC 12 x 8E electric
propeller as the power setup. For battery
power I got the Poly-Quest 4S1P 4400 mAh
Li-Poly pack.
That is a newer-generation battery with
heavier discharge capability, and it is a
lightweight unit. I liked the idea of the
Transparent MonoKote finish reveals the lightweight wing, tail, and fuselage structure. It
adds up to performance!
A view into the fuselage, with wing removed, shows battery position with receiver wrapped in protective foam and the mounting of
the rudder and elevator servos.
Sporty-looking, isn’t it? Sturdy aluminum landing gear makes rough-field operation a cinch.
Photos courtesy the author
18 MODEL AVIATION
individual cell-monitoring device to ensure a
cell-balanced charged pack. A four-cell pack
is used for its higher voltage, keeping the
amp draw to a conservative level.
The OPTO ESC is made for highervoltage
operation. I also got the Jeti program
card for use with the ESC; that makes it easy
to set up the ESC for use by just plugging in
a few jumpers to choose the battery type,
cutoff voltage, cutoff type, brake on or off,
timing, and throttle curve. I like easy.
Since the ESCs for higher-voltage use
seldom provide a BEC output, I could have
carried a separate Ni-Cd pack for the radio;
instead I opted for an Ultimate BEC to
power the radio. All of that equipment is
available from Hobby Lobby.
For those of you who do get into volts,
amps, and watts, before I flew the airplane I
checked the power-system performance with
my handy AstroFlight Super Whattmeter.
Running on the ground, the AXI 2826/12
motor turned the APC 12 x 8E propeller at
8,500 rpm, drawing 39 amps from the fourcell
4400 mAh Poly-Quest Li-Poly battery
pack, for approximately 600 watts of power.
That’s roughly 150 watts per pound of
model—plenty for lively performance.
The current draw goes down when the
aircraft is flying, some estimate as much as
20%, and I found that full throttle isn’t
needed for most flying, so I think the
equipment is being used fairly
conservatively. I believe the airplane
performs at least as well as, if not better
than, it would with any hot .40 or .45 glow
engine for power.
Weight is important. I tried for a light
airframe figuring that the electric
components would be heavy. A .40 glow
engine, with muffler, could weigh 13-20
ounces, depending on the type. Add an
engine mount, throttle servo and linkage, a
10-ounce fuel tank, and the fuel in it. That
could be a total of 25-32 ounces flying
Looking at the bare framework you can see that there is no wing LE sheeting, but
partial ribs are used on the LE sections. Ailerons and all tail surfaces are built up.
The wing and tail surfaces are framed up, hinged, and ready for assembly to the
fuselage. This model is fun to build.
The fuselage parts are cut out and ready for assembly. There are few parts in this simple-to-construct aircraft.
weight. That surprised me.
For the electric hardware figure roughly 7
ounces for the motor, 3 ounces for the ESC
and BEC, and 14 ounces for the battery.
That’s approximately 24 ounces.
Okay, so maybe this .40-size electric stuff
isn’t so heavy. And maybe my figures aren’t
so accurate, but it seems that with modern
technology, brushless motors, and Li-Poly
batteries, electric power can weigh roughly
the same as glow-engine power.
The biggest difference between electric
and glow power is the speed the propeller is
turned and the propeller sizes used. An
average .40 engine would likely use a 10 x 6
propeller. With my AXI motor I’ve tried a
12 x 8, 13 x 8, and 13 x 6.5 so far, and I am
still experimenting. Sure, the motor turns
slower than a glow engine, but it turns a
bigger propeller.
The model doesn’t care too much. Many
of the glow-engine horsepower ratings are
made at higher speeds than these engines
will ever see in most sport-model usage, so
those high rpm and horsepower numbers
don’t mean much.
I used four Hitec HS-85BB servos. They
are small, light, and powerful.
The airplane at the completed-butuncovered-
framework stage without power
plant and radio equipment weighed
approximately 2 pounds. Covered and with
the motor, controller, battery pack, and radio
gear, the total weight was 4 pounds, 2
ounces, for a wing loading of 14 ounces per
square foot of wing area. I consider that a
great figure for a sport-flying, aerobatic
aircraft.
Test flights were uneventful except for
the large amount of power available. I was
immediately comfortable with the airplane—
well, at a lower throttle setting and after
adjusting the dual rate settings on the
transmitter to get the control response I liked
and could handle.
This model has plenty of power for easy
takeoffs from the grass fields I fly from and
ample power for all the aerobatics I can think
of. Most of the time I’m flying at
considerably less than full throttle, and I like
to make several shorter flights on one
charged pack. It looks as though 15-minuteplus
flights are no problem. You can
probably make them longer, depending on
your power usage.
I know I’ll be burning less glow fuel and
gas in the future. I’ll also be spending more
money on electric-power gear.
I charge my Li-Poly batteries with an
AstroFlight Lithium Charger (item 109) and
use a 10-amp DC power supply to run the
charger in my workshop. Since the Poly-
Quest Li-Poly battery packs are equipped
with a plug that has leads from each cell, I
use the Poly-Quest Protective Circuit
Module (PCM) Guards when charging them.
The PCM Guard is a protective device
that cuts off the charger when the first
cell in the pack reaches 4.2 volts; this
doesn’t balance all the cells, but it does
ensure that no particular cell will be
charged past the 4.2-volt safe upper limit.
It seems like a good idea.
For those of you who like to scratch-build
your airplanes, you can follow my plans or
incorporate your ideas for modifications as
you build. If you want to aim for more 3-D
flying, increase the aileron area by widening
their chord. If you think the tail control
surfaces could be larger, make them larger. If
you can put more lightening holes in the
structure, do it. If you want to use thinner
plywood doublers, go ahead.
An interesting modification would be to
move the wing location higher on the
fuselage and have separate wing panels
sliding onto an aluminum tube spar/joiner.
As scratch builders we can do what we want.
Following are some building notes.
CONSTRUCTION
I obtain an extra copy of the plans I can
cut up to get the parts patterns, along with
the wing and tail-surface layouts I use to
build the parts over. Paper parts patterns
aren’t bad to work with. I draw around them
on the plywood or balsa with a ballpoint pen
and then cut the pieces with a band saw or
scroll saw.
Wing: I usually start here, placing the lower
spar over the plans and using weights to keep
it in place, using waxed paper to protect the
plans and work surface. The ribs are placed
on the lower spar and held up off the table
with a balsa strip placed toward the rear of
the wing layout.with the top spar, LE, TE, TE sheeting, and
partial ribs. The TE has to be planed and
sanded to shape; it’s a pain, but there are
only two pieces needed.
I wait to add the center-section sheeting
until the wing halves are joined. I don’t
think the dihedral hurts the aerobatic
capability, but join the panels without
dihedral if you prefer a flat wing.
Don’t forget the cardboard tubes for the
aileron extension cables before you glue the
wing halves together with the plywood
joiner. I use a small amount of fiberglass
cloth and epoxy around the LE and TE
center areas.
Tail Surfaces: Build the ailerons, stabilizer,
fin, elevators, and rudder from 1/4 balsa strip
stock over the plans, using your choice of
glue. I do a great deal of building with fiveminute
epoxy; it seems like I’m always in a
hurry to get it done.
Join the elevator halves with a piece of
1/8-inch-diameter music wire. Plane and
block-sand the LEs of the elevators, rudder,
and ailerons to the beveled shape.
Use your choice of hinges. I employ the
pinned nylon variety or the cyanoacrylate
easy-hinge type.
Fuselage: Start the fuselage build-up by
gluing the plywood doublers to the balsa
side pieces. I put the lightening holes in the
plywood with a hole saw in a small drill
press. I glue the bulkheads at the LE and TE
positions to one of the sides, add the other
side, and then add the remaining bulkheads.
Cut the upper side pieces oversize, to
allow for the bevel that has to be sanded on
the bottom edge before gluing those pieces
in place. Because of the taper in the rear of
the fuselage, the upper pieces have to be
trimmed carefully to fit in place.
With the upper sides on I use a sanding
block to bevel the top edges for the top
sheeting. Add the top sheeting and round all
the edges well.
Final Assembly: Fit the fuselage to the
wing, align it, and get it bolted in place.
Add the horizontal stabilizer, aligning it
with the wing. The last step is to add the
vertical fin.
With the control surfaces hinged in
place, add the control horns and the linkage
from the servos. I use either fiberglass-tube
pushrods or flexible nylon-tube linkages.
Glue plywood mounts for the aileron servos
in place between the closely spaced ribs.
For easy access to the battery pack I
have a removable front hatch with dowels in
the rear for alignment and a nylon holddown
snap on the front end of the hatch. I
left the motor exposed for easy access and
mounted it to the firewall with 1-inch
standoffs. I did this so there would be room
for a geared motor setup if I ever want to try
that sort of power plant.
Two washers on the left-side mounting
bolts provide some right thrust. I considered
22 MODEL AVIATION
shaping a foam or wood block for an
enclosed motor cowl, maybe with two
horizontal cheek-cowl shapes for styling,
and laying up a fiberglass cowl. In the end I
went with a simple sheet-balsa extension
on each side of the motor area.
I made the landing gear from a 1-inchwide,
1/8-inch-thick strip of 6061-T6
aluminum and used light foam wheels. The
gear is held in place with three 1/4-inch
nylon bolts. The mounting base is secure in
the fuselage; I’ve already ripped the gear
off on a poor landing, and the only damage
was the three broken nylon bolts.
A good source for aluminum landing
gear is TnT Landing Gear Products at
www.tntlandinggear.com. The steerable
tail-wheel bracket is a standard molded
nylon piece.
For final balancing of the airplane,
there’s enough room in the fuselage to
move the battery pack to the rear or
forward to get the balance point where you
want it. I like to start with the model
slightly nose-heavy and move the balance
point to the rear to get the response I want.
If you use a motor and/or battery pack
that is heavier than the equipment I used,
you might want to shorten the nose a bit—
maybe a half inch. Or you can install the
elevator and rudder servos back near the
tail surfaces.
Covering: I covered the airplane with
MonoKote; I’ve used this material for
many years. It took a lot of heating and
tugging to get the wingtips free of
wrinkles, so I might try some softer
material on the next project.
Flying: I like the way this aircraft
performs. It’s not a contest machine. I
wanted it to be a hot, fun flier—an
aerobatically capable airplane but one I
could relax with a bit. I notice that the older
I get, the better I used to fly.
I’m glad I tried this .40-size electric.
Although I won’t be getting rid of those
glow and gas burners, I expect to be
With the ribs glued in place, follow them
Edition: Model Aviation - 2006/06
Page Numbers: 15,16,17,18,19,20,22
FOR THE PAST few years I’ve been
having a lot of modeling fun with
electric-powered aircraft, sheet foam and
built up, all park flyer size. I wanted to
try a larger .40-size electric-powered
airplane this time, and I wanted to build
my own.
There are many great ARFs available
these days, and I had a chance to fly two
of them during our last trip to California.
My grandson Matt flies a Cermark E-3D
Banchee and my son Rick flies a
Northeast Sailplane Products Samba.
Both are wonderful, and after flying
them I wanted a model in that size range.16 MODEL AVIATION
Lotsa Amps is a spirited performer that can do all the aerobatic maneuvers you can
think of. It could be converted to glow power, but why?
Power-system components: four-cell, 4400 mAh Poly-Quest Li-Poly battery pack; AXI
2826/12 brushless outrunner motor with radial mount kit; Jeti Advance PLUS 40
OPTO ESC; Ultimate BEC; APC 12 x 8 propeller.
A close-up showing the rudder control
horn and the steerable tail wheel.
ARFs make a great deal of economical
sense, but I like to make balsa sawdust and
wood chips when I build. I knew I couldn’t
make an airplane as light as most of the
ARFs, but I wanted one that was a bit more
rugged, to withstand those rough landings
and occasional tumbles. I also wanted good
aerobatic capability but not necessarily the
3-D stuff—a reflection of my flying style, I
guess. So I went to the drafting board.
For a long time .40 has been the bestselling
engine size; I’m sure because so
many trainers are powered by .40s and many
sport, aerobatic, and fun-fly aircraft are
made for this size engine. I was interested in
seeing how electric power compared to the
.40 glow engines I’d become accustomed to
while using for so many years.
I laid out a 54-inch-span wing with 675
square inches of wing area, a constant chord
for easy building, and a nice, thick
symmetrical airfoil. This is the size of
airplane I’d normally power with a good .40
or .45 glow engine.
For a lighter-weight wing I spaced the
ribs farther apart than usual and didn’t use
LE planking, but I did put in partial ribs
ahead of the spars. All the control surfaces
are built up, again to save weight. The
control surfaces are large but not huge.
The fuselage is a basic sheet-balsa box
with some lightening holes. I did use
plywood doublers in the forward section,
with lightening holes and a sturdy landinggear
mount. The one-piece wing bolts to the
fuselage. I left out the plastic canopy and
plastic nose cowl to keep things easy.
Using Electric Power: With modern
electric-power technology in mind, I knew I
wanted a brushless motor and Li-Poly
batteries for plenty of performance and the
lightest possible weight. Many power
systems could be used. I found the Hobby
Lobby Web site extremely helpful, with its
practical information about motors,
controllers, and batteries that the company
has used for electric conversions of many
glow-powered aircraft.
Reviewing the equipment Hobby Lobby
chose for the different airframes and the
practical information provided with the
motor specifications helped in my selections.
I could compare the size and weight of my
new project with a number of similar
Type: Aerobatic/sport aircraft. In addition, the company has
Wingspan: 54 inches
Wing area: 675 square inches
Weight: 4 pounds, 2 ounces
Wing loading: 14 ounces/square foot
Construction: Balsa and plywood
Covering/finish: MonoKote
Radio system: Four channels
Motor: AXI 2826/12 Outrunner
brushless, direct drive
ESC: Jeti Advance PLUS 40 OPTO
BEC: Ultimate
Propeller: APC 12 x 8E
Current: 40 amps
Voltage: 14.7
Motor power: 600 watts
rpm: 8,500
Watts/pound: 150
Battery: Four-cell, 4400 mAh Poly-
Quest 15C
Flight duration: 15 minutes or more,
depending on throttle usage
Power figures were taken on the
ground, at full throttle. Unloading in
the air is estimated at 15%-20%, and
full throttle is not used for most flying.
June 2006 17
knowledgeable people to answer questions
about your modeling projects; they sure
helped me.
How to select a motor, propeller, and
battery still seems mysterious to me. When
we pick a glow engine we don’t have to get
into dynamometer testing for horsepower
figures, so I prefer not to get into too much
volts, amps, and watts stuff.
I’d rather know that a motor will turn a
certain propeller at an rpm with a particular
battery-pack rating, and I can buy hardware
expecting it to fly my size of airplane. From
the Hobby Lobby data, and after talking with
Mike Hines for advice, I selected hardware
for this project.
With the airplane partially built I went
for the AXI 2826/12 Outrunner brushless
direct-drive motor, the Jeti Advance PLUS
40 OPTO ESC, and an APC 12 x 8E electric
propeller as the power setup. For battery
power I got the Poly-Quest 4S1P 4400 mAh
Li-Poly pack.
That is a newer-generation battery with
heavier discharge capability, and it is a
lightweight unit. I liked the idea of the
Transparent MonoKote finish reveals the lightweight wing, tail, and fuselage structure. It
adds up to performance!
A view into the fuselage, with wing removed, shows battery position with receiver wrapped in protective foam and the mounting of
the rudder and elevator servos.
Sporty-looking, isn’t it? Sturdy aluminum landing gear makes rough-field operation a cinch.
Photos courtesy the author
18 MODEL AVIATION
individual cell-monitoring device to ensure a
cell-balanced charged pack. A four-cell pack
is used for its higher voltage, keeping the
amp draw to a conservative level.
The OPTO ESC is made for highervoltage
operation. I also got the Jeti program
card for use with the ESC; that makes it easy
to set up the ESC for use by just plugging in
a few jumpers to choose the battery type,
cutoff voltage, cutoff type, brake on or off,
timing, and throttle curve. I like easy.
Since the ESCs for higher-voltage use
seldom provide a BEC output, I could have
carried a separate Ni-Cd pack for the radio;
instead I opted for an Ultimate BEC to
power the radio. All of that equipment is
available from Hobby Lobby.
For those of you who do get into volts,
amps, and watts, before I flew the airplane I
checked the power-system performance with
my handy AstroFlight Super Whattmeter.
Running on the ground, the AXI 2826/12
motor turned the APC 12 x 8E propeller at
8,500 rpm, drawing 39 amps from the fourcell
4400 mAh Poly-Quest Li-Poly battery
pack, for approximately 600 watts of power.
That’s roughly 150 watts per pound of
model—plenty for lively performance.
The current draw goes down when the
aircraft is flying, some estimate as much as
20%, and I found that full throttle isn’t
needed for most flying, so I think the
equipment is being used fairly
conservatively. I believe the airplane
performs at least as well as, if not better
than, it would with any hot .40 or .45 glow
engine for power.
Weight is important. I tried for a light
airframe figuring that the electric
components would be heavy. A .40 glow
engine, with muffler, could weigh 13-20
ounces, depending on the type. Add an
engine mount, throttle servo and linkage, a
10-ounce fuel tank, and the fuel in it. That
could be a total of 25-32 ounces flying
Looking at the bare framework you can see that there is no wing LE sheeting, but
partial ribs are used on the LE sections. Ailerons and all tail surfaces are built up.
The wing and tail surfaces are framed up, hinged, and ready for assembly to the
fuselage. This model is fun to build.
The fuselage parts are cut out and ready for assembly. There are few parts in this simple-to-construct aircraft.
weight. That surprised me.
For the electric hardware figure roughly 7
ounces for the motor, 3 ounces for the ESC
and BEC, and 14 ounces for the battery.
That’s approximately 24 ounces.
Okay, so maybe this .40-size electric stuff
isn’t so heavy. And maybe my figures aren’t
so accurate, but it seems that with modern
technology, brushless motors, and Li-Poly
batteries, electric power can weigh roughly
the same as glow-engine power.
The biggest difference between electric
and glow power is the speed the propeller is
turned and the propeller sizes used. An
average .40 engine would likely use a 10 x 6
propeller. With my AXI motor I’ve tried a
12 x 8, 13 x 8, and 13 x 6.5 so far, and I am
still experimenting. Sure, the motor turns
slower than a glow engine, but it turns a
bigger propeller.
The model doesn’t care too much. Many
of the glow-engine horsepower ratings are
made at higher speeds than these engines
will ever see in most sport-model usage, so
those high rpm and horsepower numbers
don’t mean much.
I used four Hitec HS-85BB servos. They
are small, light, and powerful.
The airplane at the completed-butuncovered-
framework stage without power
plant and radio equipment weighed
approximately 2 pounds. Covered and with
the motor, controller, battery pack, and radio
gear, the total weight was 4 pounds, 2
ounces, for a wing loading of 14 ounces per
square foot of wing area. I consider that a
great figure for a sport-flying, aerobatic
aircraft.
Test flights were uneventful except for
the large amount of power available. I was
immediately comfortable with the airplane—
well, at a lower throttle setting and after
adjusting the dual rate settings on the
transmitter to get the control response I liked
and could handle.
This model has plenty of power for easy
takeoffs from the grass fields I fly from and
ample power for all the aerobatics I can think
of. Most of the time I’m flying at
considerably less than full throttle, and I like
to make several shorter flights on one
charged pack. It looks as though 15-minuteplus
flights are no problem. You can
probably make them longer, depending on
your power usage.
I know I’ll be burning less glow fuel and
gas in the future. I’ll also be spending more
money on electric-power gear.
I charge my Li-Poly batteries with an
AstroFlight Lithium Charger (item 109) and
use a 10-amp DC power supply to run the
charger in my workshop. Since the Poly-
Quest Li-Poly battery packs are equipped
with a plug that has leads from each cell, I
use the Poly-Quest Protective Circuit
Module (PCM) Guards when charging them.
The PCM Guard is a protective device
that cuts off the charger when the first
cell in the pack reaches 4.2 volts; this
doesn’t balance all the cells, but it does
ensure that no particular cell will be
charged past the 4.2-volt safe upper limit.
It seems like a good idea.
For those of you who like to scratch-build
your airplanes, you can follow my plans or
incorporate your ideas for modifications as
you build. If you want to aim for more 3-D
flying, increase the aileron area by widening
their chord. If you think the tail control
surfaces could be larger, make them larger. If
you can put more lightening holes in the
structure, do it. If you want to use thinner
plywood doublers, go ahead.
An interesting modification would be to
move the wing location higher on the
fuselage and have separate wing panels
sliding onto an aluminum tube spar/joiner.
As scratch builders we can do what we want.
Following are some building notes.
CONSTRUCTION
I obtain an extra copy of the plans I can
cut up to get the parts patterns, along with
the wing and tail-surface layouts I use to
build the parts over. Paper parts patterns
aren’t bad to work with. I draw around them
on the plywood or balsa with a ballpoint pen
and then cut the pieces with a band saw or
scroll saw.
Wing: I usually start here, placing the lower
spar over the plans and using weights to keep
it in place, using waxed paper to protect the
plans and work surface. The ribs are placed
on the lower spar and held up off the table
with a balsa strip placed toward the rear of
the wing layout.with the top spar, LE, TE, TE sheeting, and
partial ribs. The TE has to be planed and
sanded to shape; it’s a pain, but there are
only two pieces needed.
I wait to add the center-section sheeting
until the wing halves are joined. I don’t
think the dihedral hurts the aerobatic
capability, but join the panels without
dihedral if you prefer a flat wing.
Don’t forget the cardboard tubes for the
aileron extension cables before you glue the
wing halves together with the plywood
joiner. I use a small amount of fiberglass
cloth and epoxy around the LE and TE
center areas.
Tail Surfaces: Build the ailerons, stabilizer,
fin, elevators, and rudder from 1/4 balsa strip
stock over the plans, using your choice of
glue. I do a great deal of building with fiveminute
epoxy; it seems like I’m always in a
hurry to get it done.
Join the elevator halves with a piece of
1/8-inch-diameter music wire. Plane and
block-sand the LEs of the elevators, rudder,
and ailerons to the beveled shape.
Use your choice of hinges. I employ the
pinned nylon variety or the cyanoacrylate
easy-hinge type.
Fuselage: Start the fuselage build-up by
gluing the plywood doublers to the balsa
side pieces. I put the lightening holes in the
plywood with a hole saw in a small drill
press. I glue the bulkheads at the LE and TE
positions to one of the sides, add the other
side, and then add the remaining bulkheads.
Cut the upper side pieces oversize, to
allow for the bevel that has to be sanded on
the bottom edge before gluing those pieces
in place. Because of the taper in the rear of
the fuselage, the upper pieces have to be
trimmed carefully to fit in place.
With the upper sides on I use a sanding
block to bevel the top edges for the top
sheeting. Add the top sheeting and round all
the edges well.
Final Assembly: Fit the fuselage to the
wing, align it, and get it bolted in place.
Add the horizontal stabilizer, aligning it
with the wing. The last step is to add the
vertical fin.
With the control surfaces hinged in
place, add the control horns and the linkage
from the servos. I use either fiberglass-tube
pushrods or flexible nylon-tube linkages.
Glue plywood mounts for the aileron servos
in place between the closely spaced ribs.
For easy access to the battery pack I
have a removable front hatch with dowels in
the rear for alignment and a nylon holddown
snap on the front end of the hatch. I
left the motor exposed for easy access and
mounted it to the firewall with 1-inch
standoffs. I did this so there would be room
for a geared motor setup if I ever want to try
that sort of power plant.
Two washers on the left-side mounting
bolts provide some right thrust. I considered
22 MODEL AVIATION
shaping a foam or wood block for an
enclosed motor cowl, maybe with two
horizontal cheek-cowl shapes for styling,
and laying up a fiberglass cowl. In the end I
went with a simple sheet-balsa extension
on each side of the motor area.
I made the landing gear from a 1-inchwide,
1/8-inch-thick strip of 6061-T6
aluminum and used light foam wheels. The
gear is held in place with three 1/4-inch
nylon bolts. The mounting base is secure in
the fuselage; I’ve already ripped the gear
off on a poor landing, and the only damage
was the three broken nylon bolts.
A good source for aluminum landing
gear is TnT Landing Gear Products at
www.tntlandinggear.com. The steerable
tail-wheel bracket is a standard molded
nylon piece.
For final balancing of the airplane,
there’s enough room in the fuselage to
move the battery pack to the rear or
forward to get the balance point where you
want it. I like to start with the model
slightly nose-heavy and move the balance
point to the rear to get the response I want.
If you use a motor and/or battery pack
that is heavier than the equipment I used,
you might want to shorten the nose a bit—
maybe a half inch. Or you can install the
elevator and rudder servos back near the
tail surfaces.
Covering: I covered the airplane with
MonoKote; I’ve used this material for
many years. It took a lot of heating and
tugging to get the wingtips free of
wrinkles, so I might try some softer
material on the next project.
Flying: I like the way this aircraft
performs. It’s not a contest machine. I
wanted it to be a hot, fun flier—an
aerobatically capable airplane but one I
could relax with a bit. I notice that the older
I get, the better I used to fly.
I’m glad I tried this .40-size electric.
Although I won’t be getting rid of those
glow and gas burners, I expect to be
With the ribs glued in place, follow them
Edition: Model Aviation - 2006/06
Page Numbers: 15,16,17,18,19,20,22
FOR THE PAST few years I’ve been
having a lot of modeling fun with
electric-powered aircraft, sheet foam and
built up, all park flyer size. I wanted to
try a larger .40-size electric-powered
airplane this time, and I wanted to build
my own.
There are many great ARFs available
these days, and I had a chance to fly two
of them during our last trip to California.
My grandson Matt flies a Cermark E-3D
Banchee and my son Rick flies a
Northeast Sailplane Products Samba.
Both are wonderful, and after flying
them I wanted a model in that size range.16 MODEL AVIATION
Lotsa Amps is a spirited performer that can do all the aerobatic maneuvers you can
think of. It could be converted to glow power, but why?
Power-system components: four-cell, 4400 mAh Poly-Quest Li-Poly battery pack; AXI
2826/12 brushless outrunner motor with radial mount kit; Jeti Advance PLUS 40
OPTO ESC; Ultimate BEC; APC 12 x 8 propeller.
A close-up showing the rudder control
horn and the steerable tail wheel.
ARFs make a great deal of economical
sense, but I like to make balsa sawdust and
wood chips when I build. I knew I couldn’t
make an airplane as light as most of the
ARFs, but I wanted one that was a bit more
rugged, to withstand those rough landings
and occasional tumbles. I also wanted good
aerobatic capability but not necessarily the
3-D stuff—a reflection of my flying style, I
guess. So I went to the drafting board.
For a long time .40 has been the bestselling
engine size; I’m sure because so
many trainers are powered by .40s and many
sport, aerobatic, and fun-fly aircraft are
made for this size engine. I was interested in
seeing how electric power compared to the
.40 glow engines I’d become accustomed to
while using for so many years.
I laid out a 54-inch-span wing with 675
square inches of wing area, a constant chord
for easy building, and a nice, thick
symmetrical airfoil. This is the size of
airplane I’d normally power with a good .40
or .45 glow engine.
For a lighter-weight wing I spaced the
ribs farther apart than usual and didn’t use
LE planking, but I did put in partial ribs
ahead of the spars. All the control surfaces
are built up, again to save weight. The
control surfaces are large but not huge.
The fuselage is a basic sheet-balsa box
with some lightening holes. I did use
plywood doublers in the forward section,
with lightening holes and a sturdy landinggear
mount. The one-piece wing bolts to the
fuselage. I left out the plastic canopy and
plastic nose cowl to keep things easy.
Using Electric Power: With modern
electric-power technology in mind, I knew I
wanted a brushless motor and Li-Poly
batteries for plenty of performance and the
lightest possible weight. Many power
systems could be used. I found the Hobby
Lobby Web site extremely helpful, with its
practical information about motors,
controllers, and batteries that the company
has used for electric conversions of many
glow-powered aircraft.
Reviewing the equipment Hobby Lobby
chose for the different airframes and the
practical information provided with the
motor specifications helped in my selections.
I could compare the size and weight of my
new project with a number of similar
Type: Aerobatic/sport aircraft. In addition, the company has
Wingspan: 54 inches
Wing area: 675 square inches
Weight: 4 pounds, 2 ounces
Wing loading: 14 ounces/square foot
Construction: Balsa and plywood
Covering/finish: MonoKote
Radio system: Four channels
Motor: AXI 2826/12 Outrunner
brushless, direct drive
ESC: Jeti Advance PLUS 40 OPTO
BEC: Ultimate
Propeller: APC 12 x 8E
Current: 40 amps
Voltage: 14.7
Motor power: 600 watts
rpm: 8,500
Watts/pound: 150
Battery: Four-cell, 4400 mAh Poly-
Quest 15C
Flight duration: 15 minutes or more,
depending on throttle usage
Power figures were taken on the
ground, at full throttle. Unloading in
the air is estimated at 15%-20%, and
full throttle is not used for most flying.
June 2006 17
knowledgeable people to answer questions
about your modeling projects; they sure
helped me.
How to select a motor, propeller, and
battery still seems mysterious to me. When
we pick a glow engine we don’t have to get
into dynamometer testing for horsepower
figures, so I prefer not to get into too much
volts, amps, and watts stuff.
I’d rather know that a motor will turn a
certain propeller at an rpm with a particular
battery-pack rating, and I can buy hardware
expecting it to fly my size of airplane. From
the Hobby Lobby data, and after talking with
Mike Hines for advice, I selected hardware
for this project.
With the airplane partially built I went
for the AXI 2826/12 Outrunner brushless
direct-drive motor, the Jeti Advance PLUS
40 OPTO ESC, and an APC 12 x 8E electric
propeller as the power setup. For battery
power I got the Poly-Quest 4S1P 4400 mAh
Li-Poly pack.
That is a newer-generation battery with
heavier discharge capability, and it is a
lightweight unit. I liked the idea of the
Transparent MonoKote finish reveals the lightweight wing, tail, and fuselage structure. It
adds up to performance!
A view into the fuselage, with wing removed, shows battery position with receiver wrapped in protective foam and the mounting of
the rudder and elevator servos.
Sporty-looking, isn’t it? Sturdy aluminum landing gear makes rough-field operation a cinch.
Photos courtesy the author
18 MODEL AVIATION
individual cell-monitoring device to ensure a
cell-balanced charged pack. A four-cell pack
is used for its higher voltage, keeping the
amp draw to a conservative level.
The OPTO ESC is made for highervoltage
operation. I also got the Jeti program
card for use with the ESC; that makes it easy
to set up the ESC for use by just plugging in
a few jumpers to choose the battery type,
cutoff voltage, cutoff type, brake on or off,
timing, and throttle curve. I like easy.
Since the ESCs for higher-voltage use
seldom provide a BEC output, I could have
carried a separate Ni-Cd pack for the radio;
instead I opted for an Ultimate BEC to
power the radio. All of that equipment is
available from Hobby Lobby.
For those of you who do get into volts,
amps, and watts, before I flew the airplane I
checked the power-system performance with
my handy AstroFlight Super Whattmeter.
Running on the ground, the AXI 2826/12
motor turned the APC 12 x 8E propeller at
8,500 rpm, drawing 39 amps from the fourcell
4400 mAh Poly-Quest Li-Poly battery
pack, for approximately 600 watts of power.
That’s roughly 150 watts per pound of
model—plenty for lively performance.
The current draw goes down when the
aircraft is flying, some estimate as much as
20%, and I found that full throttle isn’t
needed for most flying, so I think the
equipment is being used fairly
conservatively. I believe the airplane
performs at least as well as, if not better
than, it would with any hot .40 or .45 glow
engine for power.
Weight is important. I tried for a light
airframe figuring that the electric
components would be heavy. A .40 glow
engine, with muffler, could weigh 13-20
ounces, depending on the type. Add an
engine mount, throttle servo and linkage, a
10-ounce fuel tank, and the fuel in it. That
could be a total of 25-32 ounces flying
Looking at the bare framework you can see that there is no wing LE sheeting, but
partial ribs are used on the LE sections. Ailerons and all tail surfaces are built up.
The wing and tail surfaces are framed up, hinged, and ready for assembly to the
fuselage. This model is fun to build.
The fuselage parts are cut out and ready for assembly. There are few parts in this simple-to-construct aircraft.
weight. That surprised me.
For the electric hardware figure roughly 7
ounces for the motor, 3 ounces for the ESC
and BEC, and 14 ounces for the battery.
That’s approximately 24 ounces.
Okay, so maybe this .40-size electric stuff
isn’t so heavy. And maybe my figures aren’t
so accurate, but it seems that with modern
technology, brushless motors, and Li-Poly
batteries, electric power can weigh roughly
the same as glow-engine power.
The biggest difference between electric
and glow power is the speed the propeller is
turned and the propeller sizes used. An
average .40 engine would likely use a 10 x 6
propeller. With my AXI motor I’ve tried a
12 x 8, 13 x 8, and 13 x 6.5 so far, and I am
still experimenting. Sure, the motor turns
slower than a glow engine, but it turns a
bigger propeller.
The model doesn’t care too much. Many
of the glow-engine horsepower ratings are
made at higher speeds than these engines
will ever see in most sport-model usage, so
those high rpm and horsepower numbers
don’t mean much.
I used four Hitec HS-85BB servos. They
are small, light, and powerful.
The airplane at the completed-butuncovered-
framework stage without power
plant and radio equipment weighed
approximately 2 pounds. Covered and with
the motor, controller, battery pack, and radio
gear, the total weight was 4 pounds, 2
ounces, for a wing loading of 14 ounces per
square foot of wing area. I consider that a
great figure for a sport-flying, aerobatic
aircraft.
Test flights were uneventful except for
the large amount of power available. I was
immediately comfortable with the airplane—
well, at a lower throttle setting and after
adjusting the dual rate settings on the
transmitter to get the control response I liked
and could handle.
This model has plenty of power for easy
takeoffs from the grass fields I fly from and
ample power for all the aerobatics I can think
of. Most of the time I’m flying at
considerably less than full throttle, and I like
to make several shorter flights on one
charged pack. It looks as though 15-minuteplus
flights are no problem. You can
probably make them longer, depending on
your power usage.
I know I’ll be burning less glow fuel and
gas in the future. I’ll also be spending more
money on electric-power gear.
I charge my Li-Poly batteries with an
AstroFlight Lithium Charger (item 109) and
use a 10-amp DC power supply to run the
charger in my workshop. Since the Poly-
Quest Li-Poly battery packs are equipped
with a plug that has leads from each cell, I
use the Poly-Quest Protective Circuit
Module (PCM) Guards when charging them.
The PCM Guard is a protective device
that cuts off the charger when the first
cell in the pack reaches 4.2 volts; this
doesn’t balance all the cells, but it does
ensure that no particular cell will be
charged past the 4.2-volt safe upper limit.
It seems like a good idea.
For those of you who like to scratch-build
your airplanes, you can follow my plans or
incorporate your ideas for modifications as
you build. If you want to aim for more 3-D
flying, increase the aileron area by widening
their chord. If you think the tail control
surfaces could be larger, make them larger. If
you can put more lightening holes in the
structure, do it. If you want to use thinner
plywood doublers, go ahead.
An interesting modification would be to
move the wing location higher on the
fuselage and have separate wing panels
sliding onto an aluminum tube spar/joiner.
As scratch builders we can do what we want.
Following are some building notes.
CONSTRUCTION
I obtain an extra copy of the plans I can
cut up to get the parts patterns, along with
the wing and tail-surface layouts I use to
build the parts over. Paper parts patterns
aren’t bad to work with. I draw around them
on the plywood or balsa with a ballpoint pen
and then cut the pieces with a band saw or
scroll saw.
Wing: I usually start here, placing the lower
spar over the plans and using weights to keep
it in place, using waxed paper to protect the
plans and work surface. The ribs are placed
on the lower spar and held up off the table
with a balsa strip placed toward the rear of
the wing layout.with the top spar, LE, TE, TE sheeting, and
partial ribs. The TE has to be planed and
sanded to shape; it’s a pain, but there are
only two pieces needed.
I wait to add the center-section sheeting
until the wing halves are joined. I don’t
think the dihedral hurts the aerobatic
capability, but join the panels without
dihedral if you prefer a flat wing.
Don’t forget the cardboard tubes for the
aileron extension cables before you glue the
wing halves together with the plywood
joiner. I use a small amount of fiberglass
cloth and epoxy around the LE and TE
center areas.
Tail Surfaces: Build the ailerons, stabilizer,
fin, elevators, and rudder from 1/4 balsa strip
stock over the plans, using your choice of
glue. I do a great deal of building with fiveminute
epoxy; it seems like I’m always in a
hurry to get it done.
Join the elevator halves with a piece of
1/8-inch-diameter music wire. Plane and
block-sand the LEs of the elevators, rudder,
and ailerons to the beveled shape.
Use your choice of hinges. I employ the
pinned nylon variety or the cyanoacrylate
easy-hinge type.
Fuselage: Start the fuselage build-up by
gluing the plywood doublers to the balsa
side pieces. I put the lightening holes in the
plywood with a hole saw in a small drill
press. I glue the bulkheads at the LE and TE
positions to one of the sides, add the other
side, and then add the remaining bulkheads.
Cut the upper side pieces oversize, to
allow for the bevel that has to be sanded on
the bottom edge before gluing those pieces
in place. Because of the taper in the rear of
the fuselage, the upper pieces have to be
trimmed carefully to fit in place.
With the upper sides on I use a sanding
block to bevel the top edges for the top
sheeting. Add the top sheeting and round all
the edges well.
Final Assembly: Fit the fuselage to the
wing, align it, and get it bolted in place.
Add the horizontal stabilizer, aligning it
with the wing. The last step is to add the
vertical fin.
With the control surfaces hinged in
place, add the control horns and the linkage
from the servos. I use either fiberglass-tube
pushrods or flexible nylon-tube linkages.
Glue plywood mounts for the aileron servos
in place between the closely spaced ribs.
For easy access to the battery pack I
have a removable front hatch with dowels in
the rear for alignment and a nylon holddown
snap on the front end of the hatch. I
left the motor exposed for easy access and
mounted it to the firewall with 1-inch
standoffs. I did this so there would be room
for a geared motor setup if I ever want to try
that sort of power plant.
Two washers on the left-side mounting
bolts provide some right thrust. I considered
22 MODEL AVIATION
shaping a foam or wood block for an
enclosed motor cowl, maybe with two
horizontal cheek-cowl shapes for styling,
and laying up a fiberglass cowl. In the end I
went with a simple sheet-balsa extension
on each side of the motor area.
I made the landing gear from a 1-inchwide,
1/8-inch-thick strip of 6061-T6
aluminum and used light foam wheels. The
gear is held in place with three 1/4-inch
nylon bolts. The mounting base is secure in
the fuselage; I’ve already ripped the gear
off on a poor landing, and the only damage
was the three broken nylon bolts.
A good source for aluminum landing
gear is TnT Landing Gear Products at
www.tntlandinggear.com. The steerable
tail-wheel bracket is a standard molded
nylon piece.
For final balancing of the airplane,
there’s enough room in the fuselage to
move the battery pack to the rear or
forward to get the balance point where you
want it. I like to start with the model
slightly nose-heavy and move the balance
point to the rear to get the response I want.
If you use a motor and/or battery pack
that is heavier than the equipment I used,
you might want to shorten the nose a bit—
maybe a half inch. Or you can install the
elevator and rudder servos back near the
tail surfaces.
Covering: I covered the airplane with
MonoKote; I’ve used this material for
many years. It took a lot of heating and
tugging to get the wingtips free of
wrinkles, so I might try some softer
material on the next project.
Flying: I like the way this aircraft
performs. It’s not a contest machine. I
wanted it to be a hot, fun flier—an
aerobatically capable airplane but one I
could relax with a bit. I notice that the older
I get, the better I used to fly.
I’m glad I tried this .40-size electric.
Although I won’t be getting rid of those
glow and gas burners, I expect to be
With the ribs glued in place, follow them
Edition: Model Aviation - 2006/06
Page Numbers: 15,16,17,18,19,20,22
FOR THE PAST few years I’ve been
having a lot of modeling fun with
electric-powered aircraft, sheet foam and
built up, all park flyer size. I wanted to
try a larger .40-size electric-powered
airplane this time, and I wanted to build
my own.
There are many great ARFs available
these days, and I had a chance to fly two
of them during our last trip to California.
My grandson Matt flies a Cermark E-3D
Banchee and my son Rick flies a
Northeast Sailplane Products Samba.
Both are wonderful, and after flying
them I wanted a model in that size range.16 MODEL AVIATION
Lotsa Amps is a spirited performer that can do all the aerobatic maneuvers you can
think of. It could be converted to glow power, but why?
Power-system components: four-cell, 4400 mAh Poly-Quest Li-Poly battery pack; AXI
2826/12 brushless outrunner motor with radial mount kit; Jeti Advance PLUS 40
OPTO ESC; Ultimate BEC; APC 12 x 8 propeller.
A close-up showing the rudder control
horn and the steerable tail wheel.
ARFs make a great deal of economical
sense, but I like to make balsa sawdust and
wood chips when I build. I knew I couldn’t
make an airplane as light as most of the
ARFs, but I wanted one that was a bit more
rugged, to withstand those rough landings
and occasional tumbles. I also wanted good
aerobatic capability but not necessarily the
3-D stuff—a reflection of my flying style, I
guess. So I went to the drafting board.
For a long time .40 has been the bestselling
engine size; I’m sure because so
many trainers are powered by .40s and many
sport, aerobatic, and fun-fly aircraft are
made for this size engine. I was interested in
seeing how electric power compared to the
.40 glow engines I’d become accustomed to
while using for so many years.
I laid out a 54-inch-span wing with 675
square inches of wing area, a constant chord
for easy building, and a nice, thick
symmetrical airfoil. This is the size of
airplane I’d normally power with a good .40
or .45 glow engine.
For a lighter-weight wing I spaced the
ribs farther apart than usual and didn’t use
LE planking, but I did put in partial ribs
ahead of the spars. All the control surfaces
are built up, again to save weight. The
control surfaces are large but not huge.
The fuselage is a basic sheet-balsa box
with some lightening holes. I did use
plywood doublers in the forward section,
with lightening holes and a sturdy landinggear
mount. The one-piece wing bolts to the
fuselage. I left out the plastic canopy and
plastic nose cowl to keep things easy.
Using Electric Power: With modern
electric-power technology in mind, I knew I
wanted a brushless motor and Li-Poly
batteries for plenty of performance and the
lightest possible weight. Many power
systems could be used. I found the Hobby
Lobby Web site extremely helpful, with its
practical information about motors,
controllers, and batteries that the company
has used for electric conversions of many
glow-powered aircraft.
Reviewing the equipment Hobby Lobby
chose for the different airframes and the
practical information provided with the
motor specifications helped in my selections.
I could compare the size and weight of my
new project with a number of similar
Type: Aerobatic/sport aircraft. In addition, the company has
Wingspan: 54 inches
Wing area: 675 square inches
Weight: 4 pounds, 2 ounces
Wing loading: 14 ounces/square foot
Construction: Balsa and plywood
Covering/finish: MonoKote
Radio system: Four channels
Motor: AXI 2826/12 Outrunner
brushless, direct drive
ESC: Jeti Advance PLUS 40 OPTO
BEC: Ultimate
Propeller: APC 12 x 8E
Current: 40 amps
Voltage: 14.7
Motor power: 600 watts
rpm: 8,500
Watts/pound: 150
Battery: Four-cell, 4400 mAh Poly-
Quest 15C
Flight duration: 15 minutes or more,
depending on throttle usage
Power figures were taken on the
ground, at full throttle. Unloading in
the air is estimated at 15%-20%, and
full throttle is not used for most flying.
June 2006 17
knowledgeable people to answer questions
about your modeling projects; they sure
helped me.
How to select a motor, propeller, and
battery still seems mysterious to me. When
we pick a glow engine we don’t have to get
into dynamometer testing for horsepower
figures, so I prefer not to get into too much
volts, amps, and watts stuff.
I’d rather know that a motor will turn a
certain propeller at an rpm with a particular
battery-pack rating, and I can buy hardware
expecting it to fly my size of airplane. From
the Hobby Lobby data, and after talking with
Mike Hines for advice, I selected hardware
for this project.
With the airplane partially built I went
for the AXI 2826/12 Outrunner brushless
direct-drive motor, the Jeti Advance PLUS
40 OPTO ESC, and an APC 12 x 8E electric
propeller as the power setup. For battery
power I got the Poly-Quest 4S1P 4400 mAh
Li-Poly pack.
That is a newer-generation battery with
heavier discharge capability, and it is a
lightweight unit. I liked the idea of the
Transparent MonoKote finish reveals the lightweight wing, tail, and fuselage structure. It
adds up to performance!
A view into the fuselage, with wing removed, shows battery position with receiver wrapped in protective foam and the mounting of
the rudder and elevator servos.
Sporty-looking, isn’t it? Sturdy aluminum landing gear makes rough-field operation a cinch.
Photos courtesy the author
18 MODEL AVIATION
individual cell-monitoring device to ensure a
cell-balanced charged pack. A four-cell pack
is used for its higher voltage, keeping the
amp draw to a conservative level.
The OPTO ESC is made for highervoltage
operation. I also got the Jeti program
card for use with the ESC; that makes it easy
to set up the ESC for use by just plugging in
a few jumpers to choose the battery type,
cutoff voltage, cutoff type, brake on or off,
timing, and throttle curve. I like easy.
Since the ESCs for higher-voltage use
seldom provide a BEC output, I could have
carried a separate Ni-Cd pack for the radio;
instead I opted for an Ultimate BEC to
power the radio. All of that equipment is
available from Hobby Lobby.
For those of you who do get into volts,
amps, and watts, before I flew the airplane I
checked the power-system performance with
my handy AstroFlight Super Whattmeter.
Running on the ground, the AXI 2826/12
motor turned the APC 12 x 8E propeller at
8,500 rpm, drawing 39 amps from the fourcell
4400 mAh Poly-Quest Li-Poly battery
pack, for approximately 600 watts of power.
That’s roughly 150 watts per pound of
model—plenty for lively performance.
The current draw goes down when the
aircraft is flying, some estimate as much as
20%, and I found that full throttle isn’t
needed for most flying, so I think the
equipment is being used fairly
conservatively. I believe the airplane
performs at least as well as, if not better
than, it would with any hot .40 or .45 glow
engine for power.
Weight is important. I tried for a light
airframe figuring that the electric
components would be heavy. A .40 glow
engine, with muffler, could weigh 13-20
ounces, depending on the type. Add an
engine mount, throttle servo and linkage, a
10-ounce fuel tank, and the fuel in it. That
could be a total of 25-32 ounces flying
Looking at the bare framework you can see that there is no wing LE sheeting, but
partial ribs are used on the LE sections. Ailerons and all tail surfaces are built up.
The wing and tail surfaces are framed up, hinged, and ready for assembly to the
fuselage. This model is fun to build.
The fuselage parts are cut out and ready for assembly. There are few parts in this simple-to-construct aircraft.
weight. That surprised me.
For the electric hardware figure roughly 7
ounces for the motor, 3 ounces for the ESC
and BEC, and 14 ounces for the battery.
That’s approximately 24 ounces.
Okay, so maybe this .40-size electric stuff
isn’t so heavy. And maybe my figures aren’t
so accurate, but it seems that with modern
technology, brushless motors, and Li-Poly
batteries, electric power can weigh roughly
the same as glow-engine power.
The biggest difference between electric
and glow power is the speed the propeller is
turned and the propeller sizes used. An
average .40 engine would likely use a 10 x 6
propeller. With my AXI motor I’ve tried a
12 x 8, 13 x 8, and 13 x 6.5 so far, and I am
still experimenting. Sure, the motor turns
slower than a glow engine, but it turns a
bigger propeller.
The model doesn’t care too much. Many
of the glow-engine horsepower ratings are
made at higher speeds than these engines
will ever see in most sport-model usage, so
those high rpm and horsepower numbers
don’t mean much.
I used four Hitec HS-85BB servos. They
are small, light, and powerful.
The airplane at the completed-butuncovered-
framework stage without power
plant and radio equipment weighed
approximately 2 pounds. Covered and with
the motor, controller, battery pack, and radio
gear, the total weight was 4 pounds, 2
ounces, for a wing loading of 14 ounces per
square foot of wing area. I consider that a
great figure for a sport-flying, aerobatic
aircraft.
Test flights were uneventful except for
the large amount of power available. I was
immediately comfortable with the airplane—
well, at a lower throttle setting and after
adjusting the dual rate settings on the
transmitter to get the control response I liked
and could handle.
This model has plenty of power for easy
takeoffs from the grass fields I fly from and
ample power for all the aerobatics I can think
of. Most of the time I’m flying at
considerably less than full throttle, and I like
to make several shorter flights on one
charged pack. It looks as though 15-minuteplus
flights are no problem. You can
probably make them longer, depending on
your power usage.
I know I’ll be burning less glow fuel and
gas in the future. I’ll also be spending more
money on electric-power gear.
I charge my Li-Poly batteries with an
AstroFlight Lithium Charger (item 109) and
use a 10-amp DC power supply to run the
charger in my workshop. Since the Poly-
Quest Li-Poly battery packs are equipped
with a plug that has leads from each cell, I
use the Poly-Quest Protective Circuit
Module (PCM) Guards when charging them.
The PCM Guard is a protective device
that cuts off the charger when the first
cell in the pack reaches 4.2 volts; this
doesn’t balance all the cells, but it does
ensure that no particular cell will be
charged past the 4.2-volt safe upper limit.
It seems like a good idea.
For those of you who like to scratch-build
your airplanes, you can follow my plans or
incorporate your ideas for modifications as
you build. If you want to aim for more 3-D
flying, increase the aileron area by widening
their chord. If you think the tail control
surfaces could be larger, make them larger. If
you can put more lightening holes in the
structure, do it. If you want to use thinner
plywood doublers, go ahead.
An interesting modification would be to
move the wing location higher on the
fuselage and have separate wing panels
sliding onto an aluminum tube spar/joiner.
As scratch builders we can do what we want.
Following are some building notes.
CONSTRUCTION
I obtain an extra copy of the plans I can
cut up to get the parts patterns, along with
the wing and tail-surface layouts I use to
build the parts over. Paper parts patterns
aren’t bad to work with. I draw around them
on the plywood or balsa with a ballpoint pen
and then cut the pieces with a band saw or
scroll saw.
Wing: I usually start here, placing the lower
spar over the plans and using weights to keep
it in place, using waxed paper to protect the
plans and work surface. The ribs are placed
on the lower spar and held up off the table
with a balsa strip placed toward the rear of
the wing layout.with the top spar, LE, TE, TE sheeting, and
partial ribs. The TE has to be planed and
sanded to shape; it’s a pain, but there are
only two pieces needed.
I wait to add the center-section sheeting
until the wing halves are joined. I don’t
think the dihedral hurts the aerobatic
capability, but join the panels without
dihedral if you prefer a flat wing.
Don’t forget the cardboard tubes for the
aileron extension cables before you glue the
wing halves together with the plywood
joiner. I use a small amount of fiberglass
cloth and epoxy around the LE and TE
center areas.
Tail Surfaces: Build the ailerons, stabilizer,
fin, elevators, and rudder from 1/4 balsa strip
stock over the plans, using your choice of
glue. I do a great deal of building with fiveminute
epoxy; it seems like I’m always in a
hurry to get it done.
Join the elevator halves with a piece of
1/8-inch-diameter music wire. Plane and
block-sand the LEs of the elevators, rudder,
and ailerons to the beveled shape.
Use your choice of hinges. I employ the
pinned nylon variety or the cyanoacrylate
easy-hinge type.
Fuselage: Start the fuselage build-up by
gluing the plywood doublers to the balsa
side pieces. I put the lightening holes in the
plywood with a hole saw in a small drill
press. I glue the bulkheads at the LE and TE
positions to one of the sides, add the other
side, and then add the remaining bulkheads.
Cut the upper side pieces oversize, to
allow for the bevel that has to be sanded on
the bottom edge before gluing those pieces
in place. Because of the taper in the rear of
the fuselage, the upper pieces have to be
trimmed carefully to fit in place.
With the upper sides on I use a sanding
block to bevel the top edges for the top
sheeting. Add the top sheeting and round all
the edges well.
Final Assembly: Fit the fuselage to the
wing, align it, and get it bolted in place.
Add the horizontal stabilizer, aligning it
with the wing. The last step is to add the
vertical fin.
With the control surfaces hinged in
place, add the control horns and the linkage
from the servos. I use either fiberglass-tube
pushrods or flexible nylon-tube linkages.
Glue plywood mounts for the aileron servos
in place between the closely spaced ribs.
For easy access to the battery pack I
have a removable front hatch with dowels in
the rear for alignment and a nylon holddown
snap on the front end of the hatch. I
left the motor exposed for easy access and
mounted it to the firewall with 1-inch
standoffs. I did this so there would be room
for a geared motor setup if I ever want to try
that sort of power plant.
Two washers on the left-side mounting
bolts provide some right thrust. I considered
22 MODEL AVIATION
shaping a foam or wood block for an
enclosed motor cowl, maybe with two
horizontal cheek-cowl shapes for styling,
and laying up a fiberglass cowl. In the end I
went with a simple sheet-balsa extension
on each side of the motor area.
I made the landing gear from a 1-inchwide,
1/8-inch-thick strip of 6061-T6
aluminum and used light foam wheels. The
gear is held in place with three 1/4-inch
nylon bolts. The mounting base is secure in
the fuselage; I’ve already ripped the gear
off on a poor landing, and the only damage
was the three broken nylon bolts.
A good source for aluminum landing
gear is TnT Landing Gear Products at
www.tntlandinggear.com. The steerable
tail-wheel bracket is a standard molded
nylon piece.
For final balancing of the airplane,
there’s enough room in the fuselage to
move the battery pack to the rear or
forward to get the balance point where you
want it. I like to start with the model
slightly nose-heavy and move the balance
point to the rear to get the response I want.
If you use a motor and/or battery pack
that is heavier than the equipment I used,
you might want to shorten the nose a bit—
maybe a half inch. Or you can install the
elevator and rudder servos back near the
tail surfaces.
Covering: I covered the airplane with
MonoKote; I’ve used this material for
many years. It took a lot of heating and
tugging to get the wingtips free of
wrinkles, so I might try some softer
material on the next project.
Flying: I like the way this aircraft
performs. It’s not a contest machine. I
wanted it to be a hot, fun flier—an
aerobatically capable airplane but one I
could relax with a bit. I notice that the older
I get, the better I used to fly.
I’m glad I tried this .40-size electric.
Although I won’t be getting rid of those
glow and gas burners, I expect to be
With the ribs glued in place, follow them
Edition: Model Aviation - 2006/06
Page Numbers: 15,16,17,18,19,20,22
FOR THE PAST few years I’ve been
having a lot of modeling fun with
electric-powered aircraft, sheet foam and
built up, all park flyer size. I wanted to
try a larger .40-size electric-powered
airplane this time, and I wanted to build
my own.
There are many great ARFs available
these days, and I had a chance to fly two
of them during our last trip to California.
My grandson Matt flies a Cermark E-3D
Banchee and my son Rick flies a
Northeast Sailplane Products Samba.
Both are wonderful, and after flying
them I wanted a model in that size range.16 MODEL AVIATION
Lotsa Amps is a spirited performer that can do all the aerobatic maneuvers you can
think of. It could be converted to glow power, but why?
Power-system components: four-cell, 4400 mAh Poly-Quest Li-Poly battery pack; AXI
2826/12 brushless outrunner motor with radial mount kit; Jeti Advance PLUS 40
OPTO ESC; Ultimate BEC; APC 12 x 8 propeller.
A close-up showing the rudder control
horn and the steerable tail wheel.
ARFs make a great deal of economical
sense, but I like to make balsa sawdust and
wood chips when I build. I knew I couldn’t
make an airplane as light as most of the
ARFs, but I wanted one that was a bit more
rugged, to withstand those rough landings
and occasional tumbles. I also wanted good
aerobatic capability but not necessarily the
3-D stuff—a reflection of my flying style, I
guess. So I went to the drafting board.
For a long time .40 has been the bestselling
engine size; I’m sure because so
many trainers are powered by .40s and many
sport, aerobatic, and fun-fly aircraft are
made for this size engine. I was interested in
seeing how electric power compared to the
.40 glow engines I’d become accustomed to
while using for so many years.
I laid out a 54-inch-span wing with 675
square inches of wing area, a constant chord
for easy building, and a nice, thick
symmetrical airfoil. This is the size of
airplane I’d normally power with a good .40
or .45 glow engine.
For a lighter-weight wing I spaced the
ribs farther apart than usual and didn’t use
LE planking, but I did put in partial ribs
ahead of the spars. All the control surfaces
are built up, again to save weight. The
control surfaces are large but not huge.
The fuselage is a basic sheet-balsa box
with some lightening holes. I did use
plywood doublers in the forward section,
with lightening holes and a sturdy landinggear
mount. The one-piece wing bolts to the
fuselage. I left out the plastic canopy and
plastic nose cowl to keep things easy.
Using Electric Power: With modern
electric-power technology in mind, I knew I
wanted a brushless motor and Li-Poly
batteries for plenty of performance and the
lightest possible weight. Many power
systems could be used. I found the Hobby
Lobby Web site extremely helpful, with its
practical information about motors,
controllers, and batteries that the company
has used for electric conversions of many
glow-powered aircraft.
Reviewing the equipment Hobby Lobby
chose for the different airframes and the
practical information provided with the
motor specifications helped in my selections.
I could compare the size and weight of my
new project with a number of similar
Type: Aerobatic/sport aircraft. In addition, the company has
Wingspan: 54 inches
Wing area: 675 square inches
Weight: 4 pounds, 2 ounces
Wing loading: 14 ounces/square foot
Construction: Balsa and plywood
Covering/finish: MonoKote
Radio system: Four channels
Motor: AXI 2826/12 Outrunner
brushless, direct drive
ESC: Jeti Advance PLUS 40 OPTO
BEC: Ultimate
Propeller: APC 12 x 8E
Current: 40 amps
Voltage: 14.7
Motor power: 600 watts
rpm: 8,500
Watts/pound: 150
Battery: Four-cell, 4400 mAh Poly-
Quest 15C
Flight duration: 15 minutes or more,
depending on throttle usage
Power figures were taken on the
ground, at full throttle. Unloading in
the air is estimated at 15%-20%, and
full throttle is not used for most flying.
June 2006 17
knowledgeable people to answer questions
about your modeling projects; they sure
helped me.
How to select a motor, propeller, and
battery still seems mysterious to me. When
we pick a glow engine we don’t have to get
into dynamometer testing for horsepower
figures, so I prefer not to get into too much
volts, amps, and watts stuff.
I’d rather know that a motor will turn a
certain propeller at an rpm with a particular
battery-pack rating, and I can buy hardware
expecting it to fly my size of airplane. From
the Hobby Lobby data, and after talking with
Mike Hines for advice, I selected hardware
for this project.
With the airplane partially built I went
for the AXI 2826/12 Outrunner brushless
direct-drive motor, the Jeti Advance PLUS
40 OPTO ESC, and an APC 12 x 8E electric
propeller as the power setup. For battery
power I got the Poly-Quest 4S1P 4400 mAh
Li-Poly pack.
That is a newer-generation battery with
heavier discharge capability, and it is a
lightweight unit. I liked the idea of the
Transparent MonoKote finish reveals the lightweight wing, tail, and fuselage structure. It
adds up to performance!
A view into the fuselage, with wing removed, shows battery position with receiver wrapped in protective foam and the mounting of
the rudder and elevator servos.
Sporty-looking, isn’t it? Sturdy aluminum landing gear makes rough-field operation a cinch.
Photos courtesy the author
18 MODEL AVIATION
individual cell-monitoring device to ensure a
cell-balanced charged pack. A four-cell pack
is used for its higher voltage, keeping the
amp draw to a conservative level.
The OPTO ESC is made for highervoltage
operation. I also got the Jeti program
card for use with the ESC; that makes it easy
to set up the ESC for use by just plugging in
a few jumpers to choose the battery type,
cutoff voltage, cutoff type, brake on or off,
timing, and throttle curve. I like easy.
Since the ESCs for higher-voltage use
seldom provide a BEC output, I could have
carried a separate Ni-Cd pack for the radio;
instead I opted for an Ultimate BEC to
power the radio. All of that equipment is
available from Hobby Lobby.
For those of you who do get into volts,
amps, and watts, before I flew the airplane I
checked the power-system performance with
my handy AstroFlight Super Whattmeter.
Running on the ground, the AXI 2826/12
motor turned the APC 12 x 8E propeller at
8,500 rpm, drawing 39 amps from the fourcell
4400 mAh Poly-Quest Li-Poly battery
pack, for approximately 600 watts of power.
That’s roughly 150 watts per pound of
model—plenty for lively performance.
The current draw goes down when the
aircraft is flying, some estimate as much as
20%, and I found that full throttle isn’t
needed for most flying, so I think the
equipment is being used fairly
conservatively. I believe the airplane
performs at least as well as, if not better
than, it would with any hot .40 or .45 glow
engine for power.
Weight is important. I tried for a light
airframe figuring that the electric
components would be heavy. A .40 glow
engine, with muffler, could weigh 13-20
ounces, depending on the type. Add an
engine mount, throttle servo and linkage, a
10-ounce fuel tank, and the fuel in it. That
could be a total of 25-32 ounces flying
Looking at the bare framework you can see that there is no wing LE sheeting, but
partial ribs are used on the LE sections. Ailerons and all tail surfaces are built up.
The wing and tail surfaces are framed up, hinged, and ready for assembly to the
fuselage. This model is fun to build.
The fuselage parts are cut out and ready for assembly. There are few parts in this simple-to-construct aircraft.
weight. That surprised me.
For the electric hardware figure roughly 7
ounces for the motor, 3 ounces for the ESC
and BEC, and 14 ounces for the battery.
That’s approximately 24 ounces.
Okay, so maybe this .40-size electric stuff
isn’t so heavy. And maybe my figures aren’t
so accurate, but it seems that with modern
technology, brushless motors, and Li-Poly
batteries, electric power can weigh roughly
the same as glow-engine power.
The biggest difference between electric
and glow power is the speed the propeller is
turned and the propeller sizes used. An
average .40 engine would likely use a 10 x 6
propeller. With my AXI motor I’ve tried a
12 x 8, 13 x 8, and 13 x 6.5 so far, and I am
still experimenting. Sure, the motor turns
slower than a glow engine, but it turns a
bigger propeller.
The model doesn’t care too much. Many
of the glow-engine horsepower ratings are
made at higher speeds than these engines
will ever see in most sport-model usage, so
those high rpm and horsepower numbers
don’t mean much.
I used four Hitec HS-85BB servos. They
are small, light, and powerful.
The airplane at the completed-butuncovered-
framework stage without power
plant and radio equipment weighed
approximately 2 pounds. Covered and with
the motor, controller, battery pack, and radio
gear, the total weight was 4 pounds, 2
ounces, for a wing loading of 14 ounces per
square foot of wing area. I consider that a
great figure for a sport-flying, aerobatic
aircraft.
Test flights were uneventful except for
the large amount of power available. I was
immediately comfortable with the airplane—
well, at a lower throttle setting and after
adjusting the dual rate settings on the
transmitter to get the control response I liked
and could handle.
This model has plenty of power for easy
takeoffs from the grass fields I fly from and
ample power for all the aerobatics I can think
of. Most of the time I’m flying at
considerably less than full throttle, and I like
to make several shorter flights on one
charged pack. It looks as though 15-minuteplus
flights are no problem. You can
probably make them longer, depending on
your power usage.
I know I’ll be burning less glow fuel and
gas in the future. I’ll also be spending more
money on electric-power gear.
I charge my Li-Poly batteries with an
AstroFlight Lithium Charger (item 109) and
use a 10-amp DC power supply to run the
charger in my workshop. Since the Poly-
Quest Li-Poly battery packs are equipped
with a plug that has leads from each cell, I
use the Poly-Quest Protective Circuit
Module (PCM) Guards when charging them.
The PCM Guard is a protective device
that cuts off the charger when the first
cell in the pack reaches 4.2 volts; this
doesn’t balance all the cells, but it does
ensure that no particular cell will be
charged past the 4.2-volt safe upper limit.
It seems like a good idea.
For those of you who like to scratch-build
your airplanes, you can follow my plans or
incorporate your ideas for modifications as
you build. If you want to aim for more 3-D
flying, increase the aileron area by widening
their chord. If you think the tail control
surfaces could be larger, make them larger. If
you can put more lightening holes in the
structure, do it. If you want to use thinner
plywood doublers, go ahead.
An interesting modification would be to
move the wing location higher on the
fuselage and have separate wing panels
sliding onto an aluminum tube spar/joiner.
As scratch builders we can do what we want.
Following are some building notes.
CONSTRUCTION
I obtain an extra copy of the plans I can
cut up to get the parts patterns, along with
the wing and tail-surface layouts I use to
build the parts over. Paper parts patterns
aren’t bad to work with. I draw around them
on the plywood or balsa with a ballpoint pen
and then cut the pieces with a band saw or
scroll saw.
Wing: I usually start here, placing the lower
spar over the plans and using weights to keep
it in place, using waxed paper to protect the
plans and work surface. The ribs are placed
on the lower spar and held up off the table
with a balsa strip placed toward the rear of
the wing layout.with the top spar, LE, TE, TE sheeting, and
partial ribs. The TE has to be planed and
sanded to shape; it’s a pain, but there are
only two pieces needed.
I wait to add the center-section sheeting
until the wing halves are joined. I don’t
think the dihedral hurts the aerobatic
capability, but join the panels without
dihedral if you prefer a flat wing.
Don’t forget the cardboard tubes for the
aileron extension cables before you glue the
wing halves together with the plywood
joiner. I use a small amount of fiberglass
cloth and epoxy around the LE and TE
center areas.
Tail Surfaces: Build the ailerons, stabilizer,
fin, elevators, and rudder from 1/4 balsa strip
stock over the plans, using your choice of
glue. I do a great deal of building with fiveminute
epoxy; it seems like I’m always in a
hurry to get it done.
Join the elevator halves with a piece of
1/8-inch-diameter music wire. Plane and
block-sand the LEs of the elevators, rudder,
and ailerons to the beveled shape.
Use your choice of hinges. I employ the
pinned nylon variety or the cyanoacrylate
easy-hinge type.
Fuselage: Start the fuselage build-up by
gluing the plywood doublers to the balsa
side pieces. I put the lightening holes in the
plywood with a hole saw in a small drill
press. I glue the bulkheads at the LE and TE
positions to one of the sides, add the other
side, and then add the remaining bulkheads.
Cut the upper side pieces oversize, to
allow for the bevel that has to be sanded on
the bottom edge before gluing those pieces
in place. Because of the taper in the rear of
the fuselage, the upper pieces have to be
trimmed carefully to fit in place.
With the upper sides on I use a sanding
block to bevel the top edges for the top
sheeting. Add the top sheeting and round all
the edges well.
Final Assembly: Fit the fuselage to the
wing, align it, and get it bolted in place.
Add the horizontal stabilizer, aligning it
with the wing. The last step is to add the
vertical fin.
With the control surfaces hinged in
place, add the control horns and the linkage
from the servos. I use either fiberglass-tube
pushrods or flexible nylon-tube linkages.
Glue plywood mounts for the aileron servos
in place between the closely spaced ribs.
For easy access to the battery pack I
have a removable front hatch with dowels in
the rear for alignment and a nylon holddown
snap on the front end of the hatch. I
left the motor exposed for easy access and
mounted it to the firewall with 1-inch
standoffs. I did this so there would be room
for a geared motor setup if I ever want to try
that sort of power plant.
Two washers on the left-side mounting
bolts provide some right thrust. I considered
22 MODEL AVIATION
shaping a foam or wood block for an
enclosed motor cowl, maybe with two
horizontal cheek-cowl shapes for styling,
and laying up a fiberglass cowl. In the end I
went with a simple sheet-balsa extension
on each side of the motor area.
I made the landing gear from a 1-inchwide,
1/8-inch-thick strip of 6061-T6
aluminum and used light foam wheels. The
gear is held in place with three 1/4-inch
nylon bolts. The mounting base is secure in
the fuselage; I’ve already ripped the gear
off on a poor landing, and the only damage
was the three broken nylon bolts.
A good source for aluminum landing
gear is TnT Landing Gear Products at
www.tntlandinggear.com. The steerable
tail-wheel bracket is a standard molded
nylon piece.
For final balancing of the airplane,
there’s enough room in the fuselage to
move the battery pack to the rear or
forward to get the balance point where you
want it. I like to start with the model
slightly nose-heavy and move the balance
point to the rear to get the response I want.
If you use a motor and/or battery pack
that is heavier than the equipment I used,
you might want to shorten the nose a bit—
maybe a half inch. Or you can install the
elevator and rudder servos back near the
tail surfaces.
Covering: I covered the airplane with
MonoKote; I’ve used this material for
many years. It took a lot of heating and
tugging to get the wingtips free of
wrinkles, so I might try some softer
material on the next project.
Flying: I like the way this aircraft
performs. It’s not a contest machine. I
wanted it to be a hot, fun flier—an
aerobatically capable airplane but one I
could relax with a bit. I notice that the older
I get, the better I used to fly.
I’m glad I tried this .40-size electric.
Although I won’t be getting rid of those
glow and gas burners, I expect to be
With the ribs glued in place, follow them