ARE YOU AN ARF flier or an airplane scratch builder? If you
haven’t tried scratch building, check out this story.
The project started with a discussion among a few members of
the Monmouth Model Airplane Club in New Jersey, to which I
belong, about selecting a particular aircraft, probably an ARF, that
many of our members could get and use for our club contests.
Some of these contests, such as limbo, quick takeoffs, aerobatic
maneuvers, and landings, several forms of spot landings, and
several types of Pylon Racing, tended to be pretty hard on the
aircraft. Many of our contest days ended with the loss of at least
several aircraft caused by hard contact with the ground or trees.
The thought was that if everyone used the same low-cost type of
aircraft, the competition would be more even and pilots wouldn’t
mind the crashes as much. Someone asked me about a building
project with a bunch of members scratch-building the same
airplane. It sounded like fun, and I had some ideas for such a
project.
Further discussion indicated that most fliers had a .40-, .45-, or
.46-size engine. The idea of a precut foam wing appealed to them.
A profile fuselage for quick and easy building didn’t raise any
objections.
Good flying characteristics were a must; some had tried the
plastic sign board and aluminum extrusion airframes but didn’t
care for the less than optimum handling. Ultra light weight
wasn’t high on the priority list; this wasn’t seen as a 3-D
airplane. And a low-cost but fairly rugged and easily reparable
airframe would be popular.
The glow version in the air. Control-surface deflections indicate
that the model is in the midst of an extreme fun-fly type
maneuver: its forte!
Design: I laid out the wing first, with a
thick, full symmetrical airfoil. It had a 48-
inch span and a 14-inch chord for 672
square inches of wing area.
The slab-profile fuselage length was
made 40 inches—compact overall, with
good proportions for lively flying. I used
large built-up control surfaces, but not
aimed at 3-D flying.
Weight was calculated to be
approximately 4 pounds, for a wing loading
of 14 ounces per square foot. That’s light,
and if the model came in slightly heavier it
would still be good.
A quick look shows that there is some
CL-type construction in this RC project.
The foam-core wings will not be sheeted
with balsa; the balsa top and bottom spars,
LE, TE, tip ribs, and plywood joiner will
provide plenty of strength, and a lowtemperature
iron-on plastic covering will
protect the foam a bit.
The fuselage is made from solid 1/2 balsa
with 1/8 plywood doublers on the nose
section. The fuselage is stronger than usual
because there is not a large cutout in it for
the wing to slide through; there is only a
vertical slot in the fuselage for the plywood
wing joiner. I got this idea from Phil Cartier,
who has considerable CL foam-core-wing
construction experience. The foam-core
wings butt up against either side of the
fuselage.
The wings and control surfaces are light
overall. The fuselage is somewhat heavy but
strong. This is not the lightest way to build
an airplane, but it’s a reasonable
compromise to get a model that is light
enough for good performance and can take a
little abuse without falling apart.
The fuselage should resist crashes, and
the wing panels can be fairly easily
replaced. The profile fuselage could be built
up or foam-cored for lighter weight, but it
would break more easily.
I constructed a prototype with my
amateur-cut foam wing cores and found that
it really was easy and quick to build. It came
out slightly heavier than I had hoped. I used
some hard wood and I used too much epoxy
glue, but even at almost 4.5 pounds with the
670 square inches of wing area, that’s a
wing loading of only 15 ounces per square
foot.
My prototype flew well! It had no bad
characteristics, did all the fun-fly aerobatic
stuff I could have it do, and withstood all
the snaps and spins I threw at it.
The SuperTigre GS-45 engine with an 11
x 5 propeller was more than enough power,
and I figured the model would also fly well
on electric power. To prove it I borrowed an
AXI 2826/10 brushless outrunner motor
turning an APC 11 x 7 electric propeller and
a Jeti 40-amp Opto ESC from a friend, and I
used my four-cell 4400 mAh Li-Poly battery
pack.
I mounted the AXI with a custommachined
aluminum adapter mount that Jim
Ehlen ([email protected]) manufactured,
which made it possible to retain the motor
on beam mounts set up for a glow engine. I
The 1/2-inch-thick balsa fuselage will be cut for the engine and mounts after the engine to
be used is chosen, to get the correct crankcase width.
The NJ One Design’s fuselage with the engine mounts and doublers assembled, with the
cut for the wing spar/joiner and built-up tail surfaces.
The wing panels are assembled using slow-cure epoxy to install the upper and lower
spars, LE, TE, and wingtip cap at the same time.
NJ One
Design
The 1/8 plywood servo mounts are epoxied into foam. The foam is
cut away for mounts and clearance for servos. Cavities ahead of
the spars are for the battery pack and receiver.
Aileron, elevator, and rudder servos in place. There is no throttle
servo; this is the electric-powered version of the model.
The wing panels with the ailerons built and hinges in place. The hinges will be
glued in after the airplane is assembled and covered.
Type: Easy-to-build RC sport
Wingspan: 49 inches
Wing area: 672 square inches
Weight: 4.0-4.5 pounds
Wing loading: Approximately 15 ounces/square foot
Length: 41 inches
Construction: Balsa, plywood, foam
Covering/finish: Iron-on plastic covering that can be
applied with a low-heat iron
Glow power: .40-.46 engine, 11 x 5 propeller
Electric power: AXI 2826/12 brushless outrunner
motor, Jeti Advance PLUS 40 Amp Opto ESC, 12
x 8 APC electric propeller, Poly-Quest four-cell
4400 mAh Li-Poly battery pack (600 watts)
NJ One Design Wood List
Fuselage
1/2 x 3 x 36 balsa Two pieces—fuselage
3/8 x 1/2 maple One piece—engine mounts
1/8 x 6 x 12 plywood Two pieces—nose doublers
Wings
3/8 x 1/2 x 36 balsa Four pieces—spars
1/4 x 1/2 x 36 balsa Two pieces—LE
3/8 x 1/2 x 36 balsa Two pieces—TE
1/8 x 6 x 12 plywood One piece—wing joiner
1/8 x 3 x 36 balsa One piece—wingtips
1/4 x 1/2 x 36 balsa Two pieces—ailerons
1/4 x 1/4 x 36 balsa Three pieces—ailerons
Tail Surfaces
1/4 x 4 x 36 balsa One piece—stabilizer, fin
1/4 x 1/2 x 36 balsa Two pieces—elevator,
rudder
1/4 x 1/4 x 36 balsa Two pieces—elevator,
rudder
Built-Up Wing, Ribs, and Sheeting
(or foam wing core by The Core House)
1/8 x 3 x 36 balsa Five pieces—ribs
3/32 x 4 x 36 Two pieces—sheeting MA
The fairly lightweight structure is rugged. Foam wing panels do not need to be sheeted
with balsa; they will be covered with low-temperature iron-on film.
Dick’s glow-powered model used a SuperTigre .45. The fuel
tank is held on with rubber bands. Note the muffler angle.
The electric version uses an AXI 2826/12 motor, Jeti 40-amp Opto ESC,
Ultimate BEC, and Poly-Quest four-cell 4400 mAh Li-Poly battery pack.
put the battery pack in place of the fuel
tank. I left the throttle servo and radio
battery in place; using a BEC would have
made the electric power installation even
lighter.
The airplane balanced roughly the same
as with the glow engine and flew well—
almost the same as with the SuperTigre. I
tried different propellers; with an APC 12 x
8 electric the AXI drew somewhat more
than 600 watts. I think the 2826/12 would
have been a better motor choice for this
application.
I figured that if I built this airplane
specifically for electric power, the plywood
nose doublers could be thinner, the maple
engine mounts would be eliminated, and a
firewall mount would be used, making that
version a good amount lighter than the
glow-powered version.
So I built a second model for electric
power. The results were great, and the glow
vs. electric comparison is discussed in more
detail in an accompanying sidebar.
Now that I knew the design worked, I
arranged to have Phil Cartier at The Core
House (34 Sweet Arrow Dr., Hummelstown
PA 17036) cut the foam wing cores using
his computer-controlled setup, which does
a great job. The cores are now
commercially available from The Core
House.
I worked up a wood materials list, and
with mail-order prices (I like Lone Star
Balsa) it would cost less than $20 for the
wood. I made the landing gear from 1/8 x 1-
inch 6061-T6 aluminum, but usable
commercial aluminum and composite gears
are available from several manufacturers.
I covered my airplane with Black Baron
Film because it’s applied with a low
temperature that will not harm the foam
wing cores. I found it extraordinarily easy
to use.
If you are used to buying ARFs, I can’t
say that building the NJ One Design will
save you a lot of money, and it would
certainly be more work than throwing an
ARF together. But if you feel that building
your airplane is part of the overall
modeling experience, if you want to know
how your model is built so you can easily
repair it, if you’d like knowing that you
built your airplane rather than just taking it
out of a box, or if you’re a do-it-yourselfer,
don’t hesitate to make some wood chips
and sawdust and scratch build your own
airplane!
The NJ One Design is an easy way to
try constructing a model from scratch, and I
think it adds to the fun of this hobby.
More than a dozen Monmouth club
members signed up to build this airplane as
a fun club project. And a half dozen guys
from the other local club, the Jersey Coast
Sport Fliers, got plans and foam wing cores
to try the project. So there are builders out
there!
Monmouth club member Ray Borden
digitized the plans from my pencils so
L-R: Ed Thieleman holds one of Dick’s models while Paul Gentile, Dick Sarpolus, Bob Serafin, and Pete Mularchuk Jr. show their NJ One
Designs. Another dozen airplanes are under construction by other members of the Monmouth Model Airplane Club.
I designed and built the NJ One Design for glow-engine
power with little thought for electric power. I really liked the
way the model flew with a SuperTigre .45 engine. Having
recently built my first .40-sized electric, I wondered about
powering the One Design with a motor.
I started by weighing my .45 glow engine, its muffler, the
fuel tank, the throttle servo, and the radio battery pack.
Those items weighed 26 ounces. Then I weighed an AXI
2826/12 motor, a Jeti 40-amp Opto ESC, an Ultimate BEC,
and a four-cell Poly-Quest 4400 mAh Li-Poly battery pack.
They weighed 23 ounces.
No glow fuel had to be added to fly. So if I put the
electric power system in the same airplane, it wouldn’t be
any heavier than it was with the glow engine. I did that,
using a light aluminum adapter mount to hold the AXI motor
in place. The aircraft’s balance point was unaffected.
I employed an APC 12 x 8 electric propeller, and the AXI
turned it approximately 8,500 rpm, drawing roughly 39 amps
for approximately 600 watts of power, measured on the
ground. The glow .45 was turning its 11 x 5 wooden
propeller at roughly 11,600 rpm.
I purchased the AXI brushless outrunner motor, Jeti ESC,
Ultimate BEC, and Poly-Quest Li-Poly from Hobby Lobby as
they were sold. I was familiar with that equipment, having had
some experience with it. There is a great deal of electric-power
equipment on the market to choose from, and I’m sure other
equipment could be used with results that wood be as good.
The NJ One Design flew almost the same! It jumped off
the ground quickly, climbed straight up, and did everything I
could do with the glow version in roughly the same way.
Thinking more about the weight-comparison issue, I had
left the 600 mAh Ni-Cd radio battery pack in the model and
the throttle servo in place to simplify the comparison flying.
If I built the airplane specifically for electric power, I’d use a
BEC and eliminate the Ni-Cd battery pack, leave out the
throttle servo, use thinner 1/16 plywood doublers on the nose
in place of the 1/8 plywood doublers, and leave out the
hardwood motor mounts. The electric-powered version
would be lighter.
So I did build another airplane—the same design—and
made no attempt to save airframe weight other than using
thinner plywood nose doublers and leaving out the hardwood
motor mounts. I made the nose 1/2 inch longer to make sure it
would balance properly. I used an Ultimate BEC so I would
not require a separate radio-system battery, and I didn’t need
a throttle servo.
The completed airplane was roughly 10 ounces lighter
than its glow-engine-powered twin.
Did it fly well? It sure did. I can’t honestly say there was
much difference in performance; I like the way both versions
fly.
Yes, the electric-power system components do cost more.
And I know that those who love the sound of a high-revving
glow engine and the smell and the feel of the exhaust may
never want to give those things up. The amount of money we
spend on our hobby is something each of us has to
determine.
If quiet operation, ease of operation, and cleanliness of
operation is important to us, and if the electric technology is
interesting to us, one thing is for sure: performance doesn’t
have to suffer when going from glow to electric power—at
least in this NJ One Design airplane. Options to suit each
person is what makes aeromodeling such a great hobby. MA
—Dick Sarpolus
NJ One Design: Glow Vs. Electric Power
This model likes to spend most of its time in the air in extreme positions! It’s aerobatic
and simple to build.
everyone would have good CAD plans
from which to work. We ordered a batch
of foam wing cores from The Core House,
made a bulk wood order from Lone Star,
cut some of the parts on my band saw, and
airplane production began. Within a
month or so some of the models began
showing up at our club flying field.
Practical experience has shown that
this airplane serves its purpose as a good
fun flier—particularly at our fairly small
field that can be tough on aircraft. This
model doesn’t survive all crashes, but it’s
pretty easy to repair after most of them.
I think pilots will be flying this design
for sometime. And the project has helped
our treasury; money made from this article
will go to the Monmouth Model Airplane
Club.
CONSTRUCTION
The following is for you who are new
to scratch-building.
You’ll need patterns for the parts that
have to be cut. Either cut the plans or trace
the parts outlines you need to make the
paper patterns.
Starting with the fuselage, epoxy two
pieces of 3-inch-wide 1/2 balsa together
and trace the fuselage outline for cutting.
A bit more balsa will be needed for the
canopy area of the fuselage; epoxy extra
wood together to make up what is needed.
Before you cut the nose area for the
engine mounts, make sure the spacing is
correct to suit the engine you’ll be using.
A slot needs to be cut through the fuselage
for the plywood wing joiner, and a hole
needs to be drilled for the TE dowel joiner
that ensures accurate positioning of the
wing panels.
The 1/8 plywood nose doublers, cut to
suit the engine being used, are epoxied on
both sides of the fuselage front end. The
plywood tail-wheel mount is epoxied to
the back end of the fuselage.
Moving on to the wing panels, a
vertical slot has to be cut into the foam
cores at their root ends for the 1/8 plywood
joiner. Sand the plywood joiner to make
sure it’s a good fit between the upper and
lower wing spars. The upper and lower
spars, LE, TE, and wingtip cap have to be
epoxied to the foam cores. If the spars are
too tight of a fit in the foam, sand the slots
a bit.
The TE pieces can be planed and
tapered to shape before or after they have
been glued to the foam cores—whichever
is easier for you. Round off the LEs after
the wood is glued into the foam.
At the root ends, sand the area ahead of
the spars to clear the fuselage plywood
doublers so the wing panels butt up flush
to the fuselage sides. Epoxy the plywood
joiner into one of the wing cores, and the
wing panels are ready for later assembly to
the fuselage.
Cut the horizontal and vertical
stabilizers to shape from 1/4 balsa, using
paper patterns. The ailerons, elevator
halves, and rudder are built up over the
plans from the 1/4 x 1/2 and 1/4 square balsa
strips. I use waxed paper over the plans
and small weights to hold the balsa strips
in place as I add and glue them to
complete the assemblies.
Bend a piece of 1/8-inch-diameter music
wire to shape as a joiner for the elevator
halves. At this point I cut the slots and fit
the nylon hinges in all the control surfaces;
they will be glued in place later, after the
airplane has been covered.
I glue the one wing panel with the
plywood joiner in place to the fuselage,
and then I glue the opposite panel in place.
The stabilizer can then be glued into the
fuselage, aligning it with the wing. Glue
the vertical fin to the fuselage, with its
dowel reinforcements.
All the control surfaces can be put into
place with their hinges, to check for proper
movement. The servos can be installed in
the top or bottom of the foam wing panels;
carve out recesses in the foam to clear the
servos, and epoxy plywood mounts into
the foam for mounting the servos.
Ahead of the spars hollow out an area
on one side of the fuselage for the battery
pack and on the other side for the receiver,
allowing enough room for some foam to
be wrapped around the battery and
receiver.
The servo leads can be routed through
the foam to reach the receiver. Thinplywood
removable hatches over the
receiver and battery areas are held in place
with small screws into plywood epoxied
into the foam.
Short wire linkages are used from the
30 MODEL AVIATION
aileron servos to the ailerons, and wire or
nylon tube pushrod setups to the elevator,
rudder, and throttle. I used a Du-Bro nylon
tail-wheel bracket. The aluminum or
composite landing gears are bolted to the
fuselage, and the fuel tank, or battery pack,
is held in place with rubber bands to eye
hooks. The whole model is finished with
an iron-on plastic covering; make sure to
use a material that can be applied with a
low-heat iron so the foam is not damaged.
My One Design balanced just behind
the wing-spars location, which suited me
fine. I set up the control surfaces, to start,
with aileron throw at 1/2 inch each way and
elevator throw approximately 3/4 inch each
way, on low rates, with much more
movement on high rates. I used all the
rudder throw I could get.
Airplane sensitivity is an individual
thing and should be adjusted to suit each
flier’s preference. Adjust the throws and
exponential if desired to get the airplane
feel that you prefer for your flying style
and comfort.
I’ve been asked why the hook in the
vertical fin. When the model goes into the
trees, it will hang up from a branch and be
easy to retrieve. I just thought it looked
different and not bad. I’m sure scratch
builders will eliminate that feature if they
don’t like its appearance.
If this is your first scratch-building
project, good! Make some sawdust and
wood chips, and, above all, have fun!
Enjoy the NJ One Design! MA
Dick Sarpolus
[email protected]
Edition: Model Aviation - 2007/02
Page Numbers: 25,26,27,28,29,30,31
Edition: Model Aviation - 2007/02
Page Numbers: 25,26,27,28,29,30,31
ARE YOU AN ARF flier or an airplane scratch builder? If you
haven’t tried scratch building, check out this story.
The project started with a discussion among a few members of
the Monmouth Model Airplane Club in New Jersey, to which I
belong, about selecting a particular aircraft, probably an ARF, that
many of our members could get and use for our club contests.
Some of these contests, such as limbo, quick takeoffs, aerobatic
maneuvers, and landings, several forms of spot landings, and
several types of Pylon Racing, tended to be pretty hard on the
aircraft. Many of our contest days ended with the loss of at least
several aircraft caused by hard contact with the ground or trees.
The thought was that if everyone used the same low-cost type of
aircraft, the competition would be more even and pilots wouldn’t
mind the crashes as much. Someone asked me about a building
project with a bunch of members scratch-building the same
airplane. It sounded like fun, and I had some ideas for such a
project.
Further discussion indicated that most fliers had a .40-, .45-, or
.46-size engine. The idea of a precut foam wing appealed to them.
A profile fuselage for quick and easy building didn’t raise any
objections.
Good flying characteristics were a must; some had tried the
plastic sign board and aluminum extrusion airframes but didn’t
care for the less than optimum handling. Ultra light weight
wasn’t high on the priority list; this wasn’t seen as a 3-D
airplane. And a low-cost but fairly rugged and easily reparable
airframe would be popular.
The glow version in the air. Control-surface deflections indicate
that the model is in the midst of an extreme fun-fly type
maneuver: its forte!
Design: I laid out the wing first, with a
thick, full symmetrical airfoil. It had a 48-
inch span and a 14-inch chord for 672
square inches of wing area.
The slab-profile fuselage length was
made 40 inches—compact overall, with
good proportions for lively flying. I used
large built-up control surfaces, but not
aimed at 3-D flying.
Weight was calculated to be
approximately 4 pounds, for a wing loading
of 14 ounces per square foot. That’s light,
and if the model came in slightly heavier it
would still be good.
A quick look shows that there is some
CL-type construction in this RC project.
The foam-core wings will not be sheeted
with balsa; the balsa top and bottom spars,
LE, TE, tip ribs, and plywood joiner will
provide plenty of strength, and a lowtemperature
iron-on plastic covering will
protect the foam a bit.
The fuselage is made from solid 1/2 balsa
with 1/8 plywood doublers on the nose
section. The fuselage is stronger than usual
because there is not a large cutout in it for
the wing to slide through; there is only a
vertical slot in the fuselage for the plywood
wing joiner. I got this idea from Phil Cartier,
who has considerable CL foam-core-wing
construction experience. The foam-core
wings butt up against either side of the
fuselage.
The wings and control surfaces are light
overall. The fuselage is somewhat heavy but
strong. This is not the lightest way to build
an airplane, but it’s a reasonable
compromise to get a model that is light
enough for good performance and can take a
little abuse without falling apart.
The fuselage should resist crashes, and
the wing panels can be fairly easily
replaced. The profile fuselage could be built
up or foam-cored for lighter weight, but it
would break more easily.
I constructed a prototype with my
amateur-cut foam wing cores and found that
it really was easy and quick to build. It came
out slightly heavier than I had hoped. I used
some hard wood and I used too much epoxy
glue, but even at almost 4.5 pounds with the
670 square inches of wing area, that’s a
wing loading of only 15 ounces per square
foot.
My prototype flew well! It had no bad
characteristics, did all the fun-fly aerobatic
stuff I could have it do, and withstood all
the snaps and spins I threw at it.
The SuperTigre GS-45 engine with an 11
x 5 propeller was more than enough power,
and I figured the model would also fly well
on electric power. To prove it I borrowed an
AXI 2826/10 brushless outrunner motor
turning an APC 11 x 7 electric propeller and
a Jeti 40-amp Opto ESC from a friend, and I
used my four-cell 4400 mAh Li-Poly battery
pack.
I mounted the AXI with a custommachined
aluminum adapter mount that Jim
Ehlen ([email protected]) manufactured,
which made it possible to retain the motor
on beam mounts set up for a glow engine. I
The 1/2-inch-thick balsa fuselage will be cut for the engine and mounts after the engine to
be used is chosen, to get the correct crankcase width.
The NJ One Design’s fuselage with the engine mounts and doublers assembled, with the
cut for the wing spar/joiner and built-up tail surfaces.
The wing panels are assembled using slow-cure epoxy to install the upper and lower
spars, LE, TE, and wingtip cap at the same time.
NJ One
Design
The 1/8 plywood servo mounts are epoxied into foam. The foam is
cut away for mounts and clearance for servos. Cavities ahead of
the spars are for the battery pack and receiver.
Aileron, elevator, and rudder servos in place. There is no throttle
servo; this is the electric-powered version of the model.
The wing panels with the ailerons built and hinges in place. The hinges will be
glued in after the airplane is assembled and covered.
Type: Easy-to-build RC sport
Wingspan: 49 inches
Wing area: 672 square inches
Weight: 4.0-4.5 pounds
Wing loading: Approximately 15 ounces/square foot
Length: 41 inches
Construction: Balsa, plywood, foam
Covering/finish: Iron-on plastic covering that can be
applied with a low-heat iron
Glow power: .40-.46 engine, 11 x 5 propeller
Electric power: AXI 2826/12 brushless outrunner
motor, Jeti Advance PLUS 40 Amp Opto ESC, 12
x 8 APC electric propeller, Poly-Quest four-cell
4400 mAh Li-Poly battery pack (600 watts)
NJ One Design Wood List
Fuselage
1/2 x 3 x 36 balsa Two pieces—fuselage
3/8 x 1/2 maple One piece—engine mounts
1/8 x 6 x 12 plywood Two pieces—nose doublers
Wings
3/8 x 1/2 x 36 balsa Four pieces—spars
1/4 x 1/2 x 36 balsa Two pieces—LE
3/8 x 1/2 x 36 balsa Two pieces—TE
1/8 x 6 x 12 plywood One piece—wing joiner
1/8 x 3 x 36 balsa One piece—wingtips
1/4 x 1/2 x 36 balsa Two pieces—ailerons
1/4 x 1/4 x 36 balsa Three pieces—ailerons
Tail Surfaces
1/4 x 4 x 36 balsa One piece—stabilizer, fin
1/4 x 1/2 x 36 balsa Two pieces—elevator,
rudder
1/4 x 1/4 x 36 balsa Two pieces—elevator,
rudder
Built-Up Wing, Ribs, and Sheeting
(or foam wing core by The Core House)
1/8 x 3 x 36 balsa Five pieces—ribs
3/32 x 4 x 36 Two pieces—sheeting MA
The fairly lightweight structure is rugged. Foam wing panels do not need to be sheeted
with balsa; they will be covered with low-temperature iron-on film.
Dick’s glow-powered model used a SuperTigre .45. The fuel
tank is held on with rubber bands. Note the muffler angle.
The electric version uses an AXI 2826/12 motor, Jeti 40-amp Opto ESC,
Ultimate BEC, and Poly-Quest four-cell 4400 mAh Li-Poly battery pack.
put the battery pack in place of the fuel
tank. I left the throttle servo and radio
battery in place; using a BEC would have
made the electric power installation even
lighter.
The airplane balanced roughly the same
as with the glow engine and flew well—
almost the same as with the SuperTigre. I
tried different propellers; with an APC 12 x
8 electric the AXI drew somewhat more
than 600 watts. I think the 2826/12 would
have been a better motor choice for this
application.
I figured that if I built this airplane
specifically for electric power, the plywood
nose doublers could be thinner, the maple
engine mounts would be eliminated, and a
firewall mount would be used, making that
version a good amount lighter than the
glow-powered version.
So I built a second model for electric
power. The results were great, and the glow
vs. electric comparison is discussed in more
detail in an accompanying sidebar.
Now that I knew the design worked, I
arranged to have Phil Cartier at The Core
House (34 Sweet Arrow Dr., Hummelstown
PA 17036) cut the foam wing cores using
his computer-controlled setup, which does
a great job. The cores are now
commercially available from The Core
House.
I worked up a wood materials list, and
with mail-order prices (I like Lone Star
Balsa) it would cost less than $20 for the
wood. I made the landing gear from 1/8 x 1-
inch 6061-T6 aluminum, but usable
commercial aluminum and composite gears
are available from several manufacturers.
I covered my airplane with Black Baron
Film because it’s applied with a low
temperature that will not harm the foam
wing cores. I found it extraordinarily easy
to use.
If you are used to buying ARFs, I can’t
say that building the NJ One Design will
save you a lot of money, and it would
certainly be more work than throwing an
ARF together. But if you feel that building
your airplane is part of the overall
modeling experience, if you want to know
how your model is built so you can easily
repair it, if you’d like knowing that you
built your airplane rather than just taking it
out of a box, or if you’re a do-it-yourselfer,
don’t hesitate to make some wood chips
and sawdust and scratch build your own
airplane!
The NJ One Design is an easy way to
try constructing a model from scratch, and I
think it adds to the fun of this hobby.
More than a dozen Monmouth club
members signed up to build this airplane as
a fun club project. And a half dozen guys
from the other local club, the Jersey Coast
Sport Fliers, got plans and foam wing cores
to try the project. So there are builders out
there!
Monmouth club member Ray Borden
digitized the plans from my pencils so
L-R: Ed Thieleman holds one of Dick’s models while Paul Gentile, Dick Sarpolus, Bob Serafin, and Pete Mularchuk Jr. show their NJ One
Designs. Another dozen airplanes are under construction by other members of the Monmouth Model Airplane Club.
I designed and built the NJ One Design for glow-engine
power with little thought for electric power. I really liked the
way the model flew with a SuperTigre .45 engine. Having
recently built my first .40-sized electric, I wondered about
powering the One Design with a motor.
I started by weighing my .45 glow engine, its muffler, the
fuel tank, the throttle servo, and the radio battery pack.
Those items weighed 26 ounces. Then I weighed an AXI
2826/12 motor, a Jeti 40-amp Opto ESC, an Ultimate BEC,
and a four-cell Poly-Quest 4400 mAh Li-Poly battery pack.
They weighed 23 ounces.
No glow fuel had to be added to fly. So if I put the
electric power system in the same airplane, it wouldn’t be
any heavier than it was with the glow engine. I did that,
using a light aluminum adapter mount to hold the AXI motor
in place. The aircraft’s balance point was unaffected.
I employed an APC 12 x 8 electric propeller, and the AXI
turned it approximately 8,500 rpm, drawing roughly 39 amps
for approximately 600 watts of power, measured on the
ground. The glow .45 was turning its 11 x 5 wooden
propeller at roughly 11,600 rpm.
I purchased the AXI brushless outrunner motor, Jeti ESC,
Ultimate BEC, and Poly-Quest Li-Poly from Hobby Lobby as
they were sold. I was familiar with that equipment, having had
some experience with it. There is a great deal of electric-power
equipment on the market to choose from, and I’m sure other
equipment could be used with results that wood be as good.
The NJ One Design flew almost the same! It jumped off
the ground quickly, climbed straight up, and did everything I
could do with the glow version in roughly the same way.
Thinking more about the weight-comparison issue, I had
left the 600 mAh Ni-Cd radio battery pack in the model and
the throttle servo in place to simplify the comparison flying.
If I built the airplane specifically for electric power, I’d use a
BEC and eliminate the Ni-Cd battery pack, leave out the
throttle servo, use thinner 1/16 plywood doublers on the nose
in place of the 1/8 plywood doublers, and leave out the
hardwood motor mounts. The electric-powered version
would be lighter.
So I did build another airplane—the same design—and
made no attempt to save airframe weight other than using
thinner plywood nose doublers and leaving out the hardwood
motor mounts. I made the nose 1/2 inch longer to make sure it
would balance properly. I used an Ultimate BEC so I would
not require a separate radio-system battery, and I didn’t need
a throttle servo.
The completed airplane was roughly 10 ounces lighter
than its glow-engine-powered twin.
Did it fly well? It sure did. I can’t honestly say there was
much difference in performance; I like the way both versions
fly.
Yes, the electric-power system components do cost more.
And I know that those who love the sound of a high-revving
glow engine and the smell and the feel of the exhaust may
never want to give those things up. The amount of money we
spend on our hobby is something each of us has to
determine.
If quiet operation, ease of operation, and cleanliness of
operation is important to us, and if the electric technology is
interesting to us, one thing is for sure: performance doesn’t
have to suffer when going from glow to electric power—at
least in this NJ One Design airplane. Options to suit each
person is what makes aeromodeling such a great hobby. MA
—Dick Sarpolus
NJ One Design: Glow Vs. Electric Power
This model likes to spend most of its time in the air in extreme positions! It’s aerobatic
and simple to build.
everyone would have good CAD plans
from which to work. We ordered a batch
of foam wing cores from The Core House,
made a bulk wood order from Lone Star,
cut some of the parts on my band saw, and
airplane production began. Within a
month or so some of the models began
showing up at our club flying field.
Practical experience has shown that
this airplane serves its purpose as a good
fun flier—particularly at our fairly small
field that can be tough on aircraft. This
model doesn’t survive all crashes, but it’s
pretty easy to repair after most of them.
I think pilots will be flying this design
for sometime. And the project has helped
our treasury; money made from this article
will go to the Monmouth Model Airplane
Club.
CONSTRUCTION
The following is for you who are new
to scratch-building.
You’ll need patterns for the parts that
have to be cut. Either cut the plans or trace
the parts outlines you need to make the
paper patterns.
Starting with the fuselage, epoxy two
pieces of 3-inch-wide 1/2 balsa together
and trace the fuselage outline for cutting.
A bit more balsa will be needed for the
canopy area of the fuselage; epoxy extra
wood together to make up what is needed.
Before you cut the nose area for the
engine mounts, make sure the spacing is
correct to suit the engine you’ll be using.
A slot needs to be cut through the fuselage
for the plywood wing joiner, and a hole
needs to be drilled for the TE dowel joiner
that ensures accurate positioning of the
wing panels.
The 1/8 plywood nose doublers, cut to
suit the engine being used, are epoxied on
both sides of the fuselage front end. The
plywood tail-wheel mount is epoxied to
the back end of the fuselage.
Moving on to the wing panels, a
vertical slot has to be cut into the foam
cores at their root ends for the 1/8 plywood
joiner. Sand the plywood joiner to make
sure it’s a good fit between the upper and
lower wing spars. The upper and lower
spars, LE, TE, and wingtip cap have to be
epoxied to the foam cores. If the spars are
too tight of a fit in the foam, sand the slots
a bit.
The TE pieces can be planed and
tapered to shape before or after they have
been glued to the foam cores—whichever
is easier for you. Round off the LEs after
the wood is glued into the foam.
At the root ends, sand the area ahead of
the spars to clear the fuselage plywood
doublers so the wing panels butt up flush
to the fuselage sides. Epoxy the plywood
joiner into one of the wing cores, and the
wing panels are ready for later assembly to
the fuselage.
Cut the horizontal and vertical
stabilizers to shape from 1/4 balsa, using
paper patterns. The ailerons, elevator
halves, and rudder are built up over the
plans from the 1/4 x 1/2 and 1/4 square balsa
strips. I use waxed paper over the plans
and small weights to hold the balsa strips
in place as I add and glue them to
complete the assemblies.
Bend a piece of 1/8-inch-diameter music
wire to shape as a joiner for the elevator
halves. At this point I cut the slots and fit
the nylon hinges in all the control surfaces;
they will be glued in place later, after the
airplane has been covered.
I glue the one wing panel with the
plywood joiner in place to the fuselage,
and then I glue the opposite panel in place.
The stabilizer can then be glued into the
fuselage, aligning it with the wing. Glue
the vertical fin to the fuselage, with its
dowel reinforcements.
All the control surfaces can be put into
place with their hinges, to check for proper
movement. The servos can be installed in
the top or bottom of the foam wing panels;
carve out recesses in the foam to clear the
servos, and epoxy plywood mounts into
the foam for mounting the servos.
Ahead of the spars hollow out an area
on one side of the fuselage for the battery
pack and on the other side for the receiver,
allowing enough room for some foam to
be wrapped around the battery and
receiver.
The servo leads can be routed through
the foam to reach the receiver. Thinplywood
removable hatches over the
receiver and battery areas are held in place
with small screws into plywood epoxied
into the foam.
Short wire linkages are used from the
30 MODEL AVIATION
aileron servos to the ailerons, and wire or
nylon tube pushrod setups to the elevator,
rudder, and throttle. I used a Du-Bro nylon
tail-wheel bracket. The aluminum or
composite landing gears are bolted to the
fuselage, and the fuel tank, or battery pack,
is held in place with rubber bands to eye
hooks. The whole model is finished with
an iron-on plastic covering; make sure to
use a material that can be applied with a
low-heat iron so the foam is not damaged.
My One Design balanced just behind
the wing-spars location, which suited me
fine. I set up the control surfaces, to start,
with aileron throw at 1/2 inch each way and
elevator throw approximately 3/4 inch each
way, on low rates, with much more
movement on high rates. I used all the
rudder throw I could get.
Airplane sensitivity is an individual
thing and should be adjusted to suit each
flier’s preference. Adjust the throws and
exponential if desired to get the airplane
feel that you prefer for your flying style
and comfort.
I’ve been asked why the hook in the
vertical fin. When the model goes into the
trees, it will hang up from a branch and be
easy to retrieve. I just thought it looked
different and not bad. I’m sure scratch
builders will eliminate that feature if they
don’t like its appearance.
If this is your first scratch-building
project, good! Make some sawdust and
wood chips, and, above all, have fun!
Enjoy the NJ One Design! MA
Dick Sarpolus
[email protected]
Edition: Model Aviation - 2007/02
Page Numbers: 25,26,27,28,29,30,31
ARE YOU AN ARF flier or an airplane scratch builder? If you
haven’t tried scratch building, check out this story.
The project started with a discussion among a few members of
the Monmouth Model Airplane Club in New Jersey, to which I
belong, about selecting a particular aircraft, probably an ARF, that
many of our members could get and use for our club contests.
Some of these contests, such as limbo, quick takeoffs, aerobatic
maneuvers, and landings, several forms of spot landings, and
several types of Pylon Racing, tended to be pretty hard on the
aircraft. Many of our contest days ended with the loss of at least
several aircraft caused by hard contact with the ground or trees.
The thought was that if everyone used the same low-cost type of
aircraft, the competition would be more even and pilots wouldn’t
mind the crashes as much. Someone asked me about a building
project with a bunch of members scratch-building the same
airplane. It sounded like fun, and I had some ideas for such a
project.
Further discussion indicated that most fliers had a .40-, .45-, or
.46-size engine. The idea of a precut foam wing appealed to them.
A profile fuselage for quick and easy building didn’t raise any
objections.
Good flying characteristics were a must; some had tried the
plastic sign board and aluminum extrusion airframes but didn’t
care for the less than optimum handling. Ultra light weight
wasn’t high on the priority list; this wasn’t seen as a 3-D
airplane. And a low-cost but fairly rugged and easily reparable
airframe would be popular.
The glow version in the air. Control-surface deflections indicate
that the model is in the midst of an extreme fun-fly type
maneuver: its forte!
Design: I laid out the wing first, with a
thick, full symmetrical airfoil. It had a 48-
inch span and a 14-inch chord for 672
square inches of wing area.
The slab-profile fuselage length was
made 40 inches—compact overall, with
good proportions for lively flying. I used
large built-up control surfaces, but not
aimed at 3-D flying.
Weight was calculated to be
approximately 4 pounds, for a wing loading
of 14 ounces per square foot. That’s light,
and if the model came in slightly heavier it
would still be good.
A quick look shows that there is some
CL-type construction in this RC project.
The foam-core wings will not be sheeted
with balsa; the balsa top and bottom spars,
LE, TE, tip ribs, and plywood joiner will
provide plenty of strength, and a lowtemperature
iron-on plastic covering will
protect the foam a bit.
The fuselage is made from solid 1/2 balsa
with 1/8 plywood doublers on the nose
section. The fuselage is stronger than usual
because there is not a large cutout in it for
the wing to slide through; there is only a
vertical slot in the fuselage for the plywood
wing joiner. I got this idea from Phil Cartier,
who has considerable CL foam-core-wing
construction experience. The foam-core
wings butt up against either side of the
fuselage.
The wings and control surfaces are light
overall. The fuselage is somewhat heavy but
strong. This is not the lightest way to build
an airplane, but it’s a reasonable
compromise to get a model that is light
enough for good performance and can take a
little abuse without falling apart.
The fuselage should resist crashes, and
the wing panels can be fairly easily
replaced. The profile fuselage could be built
up or foam-cored for lighter weight, but it
would break more easily.
I constructed a prototype with my
amateur-cut foam wing cores and found that
it really was easy and quick to build. It came
out slightly heavier than I had hoped. I used
some hard wood and I used too much epoxy
glue, but even at almost 4.5 pounds with the
670 square inches of wing area, that’s a
wing loading of only 15 ounces per square
foot.
My prototype flew well! It had no bad
characteristics, did all the fun-fly aerobatic
stuff I could have it do, and withstood all
the snaps and spins I threw at it.
The SuperTigre GS-45 engine with an 11
x 5 propeller was more than enough power,
and I figured the model would also fly well
on electric power. To prove it I borrowed an
AXI 2826/10 brushless outrunner motor
turning an APC 11 x 7 electric propeller and
a Jeti 40-amp Opto ESC from a friend, and I
used my four-cell 4400 mAh Li-Poly battery
pack.
I mounted the AXI with a custommachined
aluminum adapter mount that Jim
Ehlen ([email protected]) manufactured,
which made it possible to retain the motor
on beam mounts set up for a glow engine. I
The 1/2-inch-thick balsa fuselage will be cut for the engine and mounts after the engine to
be used is chosen, to get the correct crankcase width.
The NJ One Design’s fuselage with the engine mounts and doublers assembled, with the
cut for the wing spar/joiner and built-up tail surfaces.
The wing panels are assembled using slow-cure epoxy to install the upper and lower
spars, LE, TE, and wingtip cap at the same time.
NJ One
Design
The 1/8 plywood servo mounts are epoxied into foam. The foam is
cut away for mounts and clearance for servos. Cavities ahead of
the spars are for the battery pack and receiver.
Aileron, elevator, and rudder servos in place. There is no throttle
servo; this is the electric-powered version of the model.
The wing panels with the ailerons built and hinges in place. The hinges will be
glued in after the airplane is assembled and covered.
Type: Easy-to-build RC sport
Wingspan: 49 inches
Wing area: 672 square inches
Weight: 4.0-4.5 pounds
Wing loading: Approximately 15 ounces/square foot
Length: 41 inches
Construction: Balsa, plywood, foam
Covering/finish: Iron-on plastic covering that can be
applied with a low-heat iron
Glow power: .40-.46 engine, 11 x 5 propeller
Electric power: AXI 2826/12 brushless outrunner
motor, Jeti Advance PLUS 40 Amp Opto ESC, 12
x 8 APC electric propeller, Poly-Quest four-cell
4400 mAh Li-Poly battery pack (600 watts)
NJ One Design Wood List
Fuselage
1/2 x 3 x 36 balsa Two pieces—fuselage
3/8 x 1/2 maple One piece—engine mounts
1/8 x 6 x 12 plywood Two pieces—nose doublers
Wings
3/8 x 1/2 x 36 balsa Four pieces—spars
1/4 x 1/2 x 36 balsa Two pieces—LE
3/8 x 1/2 x 36 balsa Two pieces—TE
1/8 x 6 x 12 plywood One piece—wing joiner
1/8 x 3 x 36 balsa One piece—wingtips
1/4 x 1/2 x 36 balsa Two pieces—ailerons
1/4 x 1/4 x 36 balsa Three pieces—ailerons
Tail Surfaces
1/4 x 4 x 36 balsa One piece—stabilizer, fin
1/4 x 1/2 x 36 balsa Two pieces—elevator,
rudder
1/4 x 1/4 x 36 balsa Two pieces—elevator,
rudder
Built-Up Wing, Ribs, and Sheeting
(or foam wing core by The Core House)
1/8 x 3 x 36 balsa Five pieces—ribs
3/32 x 4 x 36 Two pieces—sheeting MA
The fairly lightweight structure is rugged. Foam wing panels do not need to be sheeted
with balsa; they will be covered with low-temperature iron-on film.
Dick’s glow-powered model used a SuperTigre .45. The fuel
tank is held on with rubber bands. Note the muffler angle.
The electric version uses an AXI 2826/12 motor, Jeti 40-amp Opto ESC,
Ultimate BEC, and Poly-Quest four-cell 4400 mAh Li-Poly battery pack.
put the battery pack in place of the fuel
tank. I left the throttle servo and radio
battery in place; using a BEC would have
made the electric power installation even
lighter.
The airplane balanced roughly the same
as with the glow engine and flew well—
almost the same as with the SuperTigre. I
tried different propellers; with an APC 12 x
8 electric the AXI drew somewhat more
than 600 watts. I think the 2826/12 would
have been a better motor choice for this
application.
I figured that if I built this airplane
specifically for electric power, the plywood
nose doublers could be thinner, the maple
engine mounts would be eliminated, and a
firewall mount would be used, making that
version a good amount lighter than the
glow-powered version.
So I built a second model for electric
power. The results were great, and the glow
vs. electric comparison is discussed in more
detail in an accompanying sidebar.
Now that I knew the design worked, I
arranged to have Phil Cartier at The Core
House (34 Sweet Arrow Dr., Hummelstown
PA 17036) cut the foam wing cores using
his computer-controlled setup, which does
a great job. The cores are now
commercially available from The Core
House.
I worked up a wood materials list, and
with mail-order prices (I like Lone Star
Balsa) it would cost less than $20 for the
wood. I made the landing gear from 1/8 x 1-
inch 6061-T6 aluminum, but usable
commercial aluminum and composite gears
are available from several manufacturers.
I covered my airplane with Black Baron
Film because it’s applied with a low
temperature that will not harm the foam
wing cores. I found it extraordinarily easy
to use.
If you are used to buying ARFs, I can’t
say that building the NJ One Design will
save you a lot of money, and it would
certainly be more work than throwing an
ARF together. But if you feel that building
your airplane is part of the overall
modeling experience, if you want to know
how your model is built so you can easily
repair it, if you’d like knowing that you
built your airplane rather than just taking it
out of a box, or if you’re a do-it-yourselfer,
don’t hesitate to make some wood chips
and sawdust and scratch build your own
airplane!
The NJ One Design is an easy way to
try constructing a model from scratch, and I
think it adds to the fun of this hobby.
More than a dozen Monmouth club
members signed up to build this airplane as
a fun club project. And a half dozen guys
from the other local club, the Jersey Coast
Sport Fliers, got plans and foam wing cores
to try the project. So there are builders out
there!
Monmouth club member Ray Borden
digitized the plans from my pencils so
L-R: Ed Thieleman holds one of Dick’s models while Paul Gentile, Dick Sarpolus, Bob Serafin, and Pete Mularchuk Jr. show their NJ One
Designs. Another dozen airplanes are under construction by other members of the Monmouth Model Airplane Club.
I designed and built the NJ One Design for glow-engine
power with little thought for electric power. I really liked the
way the model flew with a SuperTigre .45 engine. Having
recently built my first .40-sized electric, I wondered about
powering the One Design with a motor.
I started by weighing my .45 glow engine, its muffler, the
fuel tank, the throttle servo, and the radio battery pack.
Those items weighed 26 ounces. Then I weighed an AXI
2826/12 motor, a Jeti 40-amp Opto ESC, an Ultimate BEC,
and a four-cell Poly-Quest 4400 mAh Li-Poly battery pack.
They weighed 23 ounces.
No glow fuel had to be added to fly. So if I put the
electric power system in the same airplane, it wouldn’t be
any heavier than it was with the glow engine. I did that,
using a light aluminum adapter mount to hold the AXI motor
in place. The aircraft’s balance point was unaffected.
I employed an APC 12 x 8 electric propeller, and the AXI
turned it approximately 8,500 rpm, drawing roughly 39 amps
for approximately 600 watts of power, measured on the
ground. The glow .45 was turning its 11 x 5 wooden
propeller at roughly 11,600 rpm.
I purchased the AXI brushless outrunner motor, Jeti ESC,
Ultimate BEC, and Poly-Quest Li-Poly from Hobby Lobby as
they were sold. I was familiar with that equipment, having had
some experience with it. There is a great deal of electric-power
equipment on the market to choose from, and I’m sure other
equipment could be used with results that wood be as good.
The NJ One Design flew almost the same! It jumped off
the ground quickly, climbed straight up, and did everything I
could do with the glow version in roughly the same way.
Thinking more about the weight-comparison issue, I had
left the 600 mAh Ni-Cd radio battery pack in the model and
the throttle servo in place to simplify the comparison flying.
If I built the airplane specifically for electric power, I’d use a
BEC and eliminate the Ni-Cd battery pack, leave out the
throttle servo, use thinner 1/16 plywood doublers on the nose
in place of the 1/8 plywood doublers, and leave out the
hardwood motor mounts. The electric-powered version
would be lighter.
So I did build another airplane—the same design—and
made no attempt to save airframe weight other than using
thinner plywood nose doublers and leaving out the hardwood
motor mounts. I made the nose 1/2 inch longer to make sure it
would balance properly. I used an Ultimate BEC so I would
not require a separate radio-system battery, and I didn’t need
a throttle servo.
The completed airplane was roughly 10 ounces lighter
than its glow-engine-powered twin.
Did it fly well? It sure did. I can’t honestly say there was
much difference in performance; I like the way both versions
fly.
Yes, the electric-power system components do cost more.
And I know that those who love the sound of a high-revving
glow engine and the smell and the feel of the exhaust may
never want to give those things up. The amount of money we
spend on our hobby is something each of us has to
determine.
If quiet operation, ease of operation, and cleanliness of
operation is important to us, and if the electric technology is
interesting to us, one thing is for sure: performance doesn’t
have to suffer when going from glow to electric power—at
least in this NJ One Design airplane. Options to suit each
person is what makes aeromodeling such a great hobby. MA
—Dick Sarpolus
NJ One Design: Glow Vs. Electric Power
This model likes to spend most of its time in the air in extreme positions! It’s aerobatic
and simple to build.
everyone would have good CAD plans
from which to work. We ordered a batch
of foam wing cores from The Core House,
made a bulk wood order from Lone Star,
cut some of the parts on my band saw, and
airplane production began. Within a
month or so some of the models began
showing up at our club flying field.
Practical experience has shown that
this airplane serves its purpose as a good
fun flier—particularly at our fairly small
field that can be tough on aircraft. This
model doesn’t survive all crashes, but it’s
pretty easy to repair after most of them.
I think pilots will be flying this design
for sometime. And the project has helped
our treasury; money made from this article
will go to the Monmouth Model Airplane
Club.
CONSTRUCTION
The following is for you who are new
to scratch-building.
You’ll need patterns for the parts that
have to be cut. Either cut the plans or trace
the parts outlines you need to make the
paper patterns.
Starting with the fuselage, epoxy two
pieces of 3-inch-wide 1/2 balsa together
and trace the fuselage outline for cutting.
A bit more balsa will be needed for the
canopy area of the fuselage; epoxy extra
wood together to make up what is needed.
Before you cut the nose area for the
engine mounts, make sure the spacing is
correct to suit the engine you’ll be using.
A slot needs to be cut through the fuselage
for the plywood wing joiner, and a hole
needs to be drilled for the TE dowel joiner
that ensures accurate positioning of the
wing panels.
The 1/8 plywood nose doublers, cut to
suit the engine being used, are epoxied on
both sides of the fuselage front end. The
plywood tail-wheel mount is epoxied to
the back end of the fuselage.
Moving on to the wing panels, a
vertical slot has to be cut into the foam
cores at their root ends for the 1/8 plywood
joiner. Sand the plywood joiner to make
sure it’s a good fit between the upper and
lower wing spars. The upper and lower
spars, LE, TE, and wingtip cap have to be
epoxied to the foam cores. If the spars are
too tight of a fit in the foam, sand the slots
a bit.
The TE pieces can be planed and
tapered to shape before or after they have
been glued to the foam cores—whichever
is easier for you. Round off the LEs after
the wood is glued into the foam.
At the root ends, sand the area ahead of
the spars to clear the fuselage plywood
doublers so the wing panels butt up flush
to the fuselage sides. Epoxy the plywood
joiner into one of the wing cores, and the
wing panels are ready for later assembly to
the fuselage.
Cut the horizontal and vertical
stabilizers to shape from 1/4 balsa, using
paper patterns. The ailerons, elevator
halves, and rudder are built up over the
plans from the 1/4 x 1/2 and 1/4 square balsa
strips. I use waxed paper over the plans
and small weights to hold the balsa strips
in place as I add and glue them to
complete the assemblies.
Bend a piece of 1/8-inch-diameter music
wire to shape as a joiner for the elevator
halves. At this point I cut the slots and fit
the nylon hinges in all the control surfaces;
they will be glued in place later, after the
airplane has been covered.
I glue the one wing panel with the
plywood joiner in place to the fuselage,
and then I glue the opposite panel in place.
The stabilizer can then be glued into the
fuselage, aligning it with the wing. Glue
the vertical fin to the fuselage, with its
dowel reinforcements.
All the control surfaces can be put into
place with their hinges, to check for proper
movement. The servos can be installed in
the top or bottom of the foam wing panels;
carve out recesses in the foam to clear the
servos, and epoxy plywood mounts into
the foam for mounting the servos.
Ahead of the spars hollow out an area
on one side of the fuselage for the battery
pack and on the other side for the receiver,
allowing enough room for some foam to
be wrapped around the battery and
receiver.
The servo leads can be routed through
the foam to reach the receiver. Thinplywood
removable hatches over the
receiver and battery areas are held in place
with small screws into plywood epoxied
into the foam.
Short wire linkages are used from the
30 MODEL AVIATION
aileron servos to the ailerons, and wire or
nylon tube pushrod setups to the elevator,
rudder, and throttle. I used a Du-Bro nylon
tail-wheel bracket. The aluminum or
composite landing gears are bolted to the
fuselage, and the fuel tank, or battery pack,
is held in place with rubber bands to eye
hooks. The whole model is finished with
an iron-on plastic covering; make sure to
use a material that can be applied with a
low-heat iron so the foam is not damaged.
My One Design balanced just behind
the wing-spars location, which suited me
fine. I set up the control surfaces, to start,
with aileron throw at 1/2 inch each way and
elevator throw approximately 3/4 inch each
way, on low rates, with much more
movement on high rates. I used all the
rudder throw I could get.
Airplane sensitivity is an individual
thing and should be adjusted to suit each
flier’s preference. Adjust the throws and
exponential if desired to get the airplane
feel that you prefer for your flying style
and comfort.
I’ve been asked why the hook in the
vertical fin. When the model goes into the
trees, it will hang up from a branch and be
easy to retrieve. I just thought it looked
different and not bad. I’m sure scratch
builders will eliminate that feature if they
don’t like its appearance.
If this is your first scratch-building
project, good! Make some sawdust and
wood chips, and, above all, have fun!
Enjoy the NJ One Design! MA
Dick Sarpolus
[email protected]
Edition: Model Aviation - 2007/02
Page Numbers: 25,26,27,28,29,30,31
ARE YOU AN ARF flier or an airplane scratch builder? If you
haven’t tried scratch building, check out this story.
The project started with a discussion among a few members of
the Monmouth Model Airplane Club in New Jersey, to which I
belong, about selecting a particular aircraft, probably an ARF, that
many of our members could get and use for our club contests.
Some of these contests, such as limbo, quick takeoffs, aerobatic
maneuvers, and landings, several forms of spot landings, and
several types of Pylon Racing, tended to be pretty hard on the
aircraft. Many of our contest days ended with the loss of at least
several aircraft caused by hard contact with the ground or trees.
The thought was that if everyone used the same low-cost type of
aircraft, the competition would be more even and pilots wouldn’t
mind the crashes as much. Someone asked me about a building
project with a bunch of members scratch-building the same
airplane. It sounded like fun, and I had some ideas for such a
project.
Further discussion indicated that most fliers had a .40-, .45-, or
.46-size engine. The idea of a precut foam wing appealed to them.
A profile fuselage for quick and easy building didn’t raise any
objections.
Good flying characteristics were a must; some had tried the
plastic sign board and aluminum extrusion airframes but didn’t
care for the less than optimum handling. Ultra light weight
wasn’t high on the priority list; this wasn’t seen as a 3-D
airplane. And a low-cost but fairly rugged and easily reparable
airframe would be popular.
The glow version in the air. Control-surface deflections indicate
that the model is in the midst of an extreme fun-fly type
maneuver: its forte!
Design: I laid out the wing first, with a
thick, full symmetrical airfoil. It had a 48-
inch span and a 14-inch chord for 672
square inches of wing area.
The slab-profile fuselage length was
made 40 inches—compact overall, with
good proportions for lively flying. I used
large built-up control surfaces, but not
aimed at 3-D flying.
Weight was calculated to be
approximately 4 pounds, for a wing loading
of 14 ounces per square foot. That’s light,
and if the model came in slightly heavier it
would still be good.
A quick look shows that there is some
CL-type construction in this RC project.
The foam-core wings will not be sheeted
with balsa; the balsa top and bottom spars,
LE, TE, tip ribs, and plywood joiner will
provide plenty of strength, and a lowtemperature
iron-on plastic covering will
protect the foam a bit.
The fuselage is made from solid 1/2 balsa
with 1/8 plywood doublers on the nose
section. The fuselage is stronger than usual
because there is not a large cutout in it for
the wing to slide through; there is only a
vertical slot in the fuselage for the plywood
wing joiner. I got this idea from Phil Cartier,
who has considerable CL foam-core-wing
construction experience. The foam-core
wings butt up against either side of the
fuselage.
The wings and control surfaces are light
overall. The fuselage is somewhat heavy but
strong. This is not the lightest way to build
an airplane, but it’s a reasonable
compromise to get a model that is light
enough for good performance and can take a
little abuse without falling apart.
The fuselage should resist crashes, and
the wing panels can be fairly easily
replaced. The profile fuselage could be built
up or foam-cored for lighter weight, but it
would break more easily.
I constructed a prototype with my
amateur-cut foam wing cores and found that
it really was easy and quick to build. It came
out slightly heavier than I had hoped. I used
some hard wood and I used too much epoxy
glue, but even at almost 4.5 pounds with the
670 square inches of wing area, that’s a
wing loading of only 15 ounces per square
foot.
My prototype flew well! It had no bad
characteristics, did all the fun-fly aerobatic
stuff I could have it do, and withstood all
the snaps and spins I threw at it.
The SuperTigre GS-45 engine with an 11
x 5 propeller was more than enough power,
and I figured the model would also fly well
on electric power. To prove it I borrowed an
AXI 2826/10 brushless outrunner motor
turning an APC 11 x 7 electric propeller and
a Jeti 40-amp Opto ESC from a friend, and I
used my four-cell 4400 mAh Li-Poly battery
pack.
I mounted the AXI with a custommachined
aluminum adapter mount that Jim
Ehlen ([email protected]) manufactured,
which made it possible to retain the motor
on beam mounts set up for a glow engine. I
The 1/2-inch-thick balsa fuselage will be cut for the engine and mounts after the engine to
be used is chosen, to get the correct crankcase width.
The NJ One Design’s fuselage with the engine mounts and doublers assembled, with the
cut for the wing spar/joiner and built-up tail surfaces.
The wing panels are assembled using slow-cure epoxy to install the upper and lower
spars, LE, TE, and wingtip cap at the same time.
NJ One
Design
The 1/8 plywood servo mounts are epoxied into foam. The foam is
cut away for mounts and clearance for servos. Cavities ahead of
the spars are for the battery pack and receiver.
Aileron, elevator, and rudder servos in place. There is no throttle
servo; this is the electric-powered version of the model.
The wing panels with the ailerons built and hinges in place. The hinges will be
glued in after the airplane is assembled and covered.
Type: Easy-to-build RC sport
Wingspan: 49 inches
Wing area: 672 square inches
Weight: 4.0-4.5 pounds
Wing loading: Approximately 15 ounces/square foot
Length: 41 inches
Construction: Balsa, plywood, foam
Covering/finish: Iron-on plastic covering that can be
applied with a low-heat iron
Glow power: .40-.46 engine, 11 x 5 propeller
Electric power: AXI 2826/12 brushless outrunner
motor, Jeti Advance PLUS 40 Amp Opto ESC, 12
x 8 APC electric propeller, Poly-Quest four-cell
4400 mAh Li-Poly battery pack (600 watts)
NJ One Design Wood List
Fuselage
1/2 x 3 x 36 balsa Two pieces—fuselage
3/8 x 1/2 maple One piece—engine mounts
1/8 x 6 x 12 plywood Two pieces—nose doublers
Wings
3/8 x 1/2 x 36 balsa Four pieces—spars
1/4 x 1/2 x 36 balsa Two pieces—LE
3/8 x 1/2 x 36 balsa Two pieces—TE
1/8 x 6 x 12 plywood One piece—wing joiner
1/8 x 3 x 36 balsa One piece—wingtips
1/4 x 1/2 x 36 balsa Two pieces—ailerons
1/4 x 1/4 x 36 balsa Three pieces—ailerons
Tail Surfaces
1/4 x 4 x 36 balsa One piece—stabilizer, fin
1/4 x 1/2 x 36 balsa Two pieces—elevator,
rudder
1/4 x 1/4 x 36 balsa Two pieces—elevator,
rudder
Built-Up Wing, Ribs, and Sheeting
(or foam wing core by The Core House)
1/8 x 3 x 36 balsa Five pieces—ribs
3/32 x 4 x 36 Two pieces—sheeting MA
The fairly lightweight structure is rugged. Foam wing panels do not need to be sheeted
with balsa; they will be covered with low-temperature iron-on film.
Dick’s glow-powered model used a SuperTigre .45. The fuel
tank is held on with rubber bands. Note the muffler angle.
The electric version uses an AXI 2826/12 motor, Jeti 40-amp Opto ESC,
Ultimate BEC, and Poly-Quest four-cell 4400 mAh Li-Poly battery pack.
put the battery pack in place of the fuel
tank. I left the throttle servo and radio
battery in place; using a BEC would have
made the electric power installation even
lighter.
The airplane balanced roughly the same
as with the glow engine and flew well—
almost the same as with the SuperTigre. I
tried different propellers; with an APC 12 x
8 electric the AXI drew somewhat more
than 600 watts. I think the 2826/12 would
have been a better motor choice for this
application.
I figured that if I built this airplane
specifically for electric power, the plywood
nose doublers could be thinner, the maple
engine mounts would be eliminated, and a
firewall mount would be used, making that
version a good amount lighter than the
glow-powered version.
So I built a second model for electric
power. The results were great, and the glow
vs. electric comparison is discussed in more
detail in an accompanying sidebar.
Now that I knew the design worked, I
arranged to have Phil Cartier at The Core
House (34 Sweet Arrow Dr., Hummelstown
PA 17036) cut the foam wing cores using
his computer-controlled setup, which does
a great job. The cores are now
commercially available from The Core
House.
I worked up a wood materials list, and
with mail-order prices (I like Lone Star
Balsa) it would cost less than $20 for the
wood. I made the landing gear from 1/8 x 1-
inch 6061-T6 aluminum, but usable
commercial aluminum and composite gears
are available from several manufacturers.
I covered my airplane with Black Baron
Film because it’s applied with a low
temperature that will not harm the foam
wing cores. I found it extraordinarily easy
to use.
If you are used to buying ARFs, I can’t
say that building the NJ One Design will
save you a lot of money, and it would
certainly be more work than throwing an
ARF together. But if you feel that building
your airplane is part of the overall
modeling experience, if you want to know
how your model is built so you can easily
repair it, if you’d like knowing that you
built your airplane rather than just taking it
out of a box, or if you’re a do-it-yourselfer,
don’t hesitate to make some wood chips
and sawdust and scratch build your own
airplane!
The NJ One Design is an easy way to
try constructing a model from scratch, and I
think it adds to the fun of this hobby.
More than a dozen Monmouth club
members signed up to build this airplane as
a fun club project. And a half dozen guys
from the other local club, the Jersey Coast
Sport Fliers, got plans and foam wing cores
to try the project. So there are builders out
there!
Monmouth club member Ray Borden
digitized the plans from my pencils so
L-R: Ed Thieleman holds one of Dick’s models while Paul Gentile, Dick Sarpolus, Bob Serafin, and Pete Mularchuk Jr. show their NJ One
Designs. Another dozen airplanes are under construction by other members of the Monmouth Model Airplane Club.
I designed and built the NJ One Design for glow-engine
power with little thought for electric power. I really liked the
way the model flew with a SuperTigre .45 engine. Having
recently built my first .40-sized electric, I wondered about
powering the One Design with a motor.
I started by weighing my .45 glow engine, its muffler, the
fuel tank, the throttle servo, and the radio battery pack.
Those items weighed 26 ounces. Then I weighed an AXI
2826/12 motor, a Jeti 40-amp Opto ESC, an Ultimate BEC,
and a four-cell Poly-Quest 4400 mAh Li-Poly battery pack.
They weighed 23 ounces.
No glow fuel had to be added to fly. So if I put the
electric power system in the same airplane, it wouldn’t be
any heavier than it was with the glow engine. I did that,
using a light aluminum adapter mount to hold the AXI motor
in place. The aircraft’s balance point was unaffected.
I employed an APC 12 x 8 electric propeller, and the AXI
turned it approximately 8,500 rpm, drawing roughly 39 amps
for approximately 600 watts of power, measured on the
ground. The glow .45 was turning its 11 x 5 wooden
propeller at roughly 11,600 rpm.
I purchased the AXI brushless outrunner motor, Jeti ESC,
Ultimate BEC, and Poly-Quest Li-Poly from Hobby Lobby as
they were sold. I was familiar with that equipment, having had
some experience with it. There is a great deal of electric-power
equipment on the market to choose from, and I’m sure other
equipment could be used with results that wood be as good.
The NJ One Design flew almost the same! It jumped off
the ground quickly, climbed straight up, and did everything I
could do with the glow version in roughly the same way.
Thinking more about the weight-comparison issue, I had
left the 600 mAh Ni-Cd radio battery pack in the model and
the throttle servo in place to simplify the comparison flying.
If I built the airplane specifically for electric power, I’d use a
BEC and eliminate the Ni-Cd battery pack, leave out the
throttle servo, use thinner 1/16 plywood doublers on the nose
in place of the 1/8 plywood doublers, and leave out the
hardwood motor mounts. The electric-powered version
would be lighter.
So I did build another airplane—the same design—and
made no attempt to save airframe weight other than using
thinner plywood nose doublers and leaving out the hardwood
motor mounts. I made the nose 1/2 inch longer to make sure it
would balance properly. I used an Ultimate BEC so I would
not require a separate radio-system battery, and I didn’t need
a throttle servo.
The completed airplane was roughly 10 ounces lighter
than its glow-engine-powered twin.
Did it fly well? It sure did. I can’t honestly say there was
much difference in performance; I like the way both versions
fly.
Yes, the electric-power system components do cost more.
And I know that those who love the sound of a high-revving
glow engine and the smell and the feel of the exhaust may
never want to give those things up. The amount of money we
spend on our hobby is something each of us has to
determine.
If quiet operation, ease of operation, and cleanliness of
operation is important to us, and if the electric technology is
interesting to us, one thing is for sure: performance doesn’t
have to suffer when going from glow to electric power—at
least in this NJ One Design airplane. Options to suit each
person is what makes aeromodeling such a great hobby. MA
—Dick Sarpolus
NJ One Design: Glow Vs. Electric Power
This model likes to spend most of its time in the air in extreme positions! It’s aerobatic
and simple to build.
everyone would have good CAD plans
from which to work. We ordered a batch
of foam wing cores from The Core House,
made a bulk wood order from Lone Star,
cut some of the parts on my band saw, and
airplane production began. Within a
month or so some of the models began
showing up at our club flying field.
Practical experience has shown that
this airplane serves its purpose as a good
fun flier—particularly at our fairly small
field that can be tough on aircraft. This
model doesn’t survive all crashes, but it’s
pretty easy to repair after most of them.
I think pilots will be flying this design
for sometime. And the project has helped
our treasury; money made from this article
will go to the Monmouth Model Airplane
Club.
CONSTRUCTION
The following is for you who are new
to scratch-building.
You’ll need patterns for the parts that
have to be cut. Either cut the plans or trace
the parts outlines you need to make the
paper patterns.
Starting with the fuselage, epoxy two
pieces of 3-inch-wide 1/2 balsa together
and trace the fuselage outline for cutting.
A bit more balsa will be needed for the
canopy area of the fuselage; epoxy extra
wood together to make up what is needed.
Before you cut the nose area for the
engine mounts, make sure the spacing is
correct to suit the engine you’ll be using.
A slot needs to be cut through the fuselage
for the plywood wing joiner, and a hole
needs to be drilled for the TE dowel joiner
that ensures accurate positioning of the
wing panels.
The 1/8 plywood nose doublers, cut to
suit the engine being used, are epoxied on
both sides of the fuselage front end. The
plywood tail-wheel mount is epoxied to
the back end of the fuselage.
Moving on to the wing panels, a
vertical slot has to be cut into the foam
cores at their root ends for the 1/8 plywood
joiner. Sand the plywood joiner to make
sure it’s a good fit between the upper and
lower wing spars. The upper and lower
spars, LE, TE, and wingtip cap have to be
epoxied to the foam cores. If the spars are
too tight of a fit in the foam, sand the slots
a bit.
The TE pieces can be planed and
tapered to shape before or after they have
been glued to the foam cores—whichever
is easier for you. Round off the LEs after
the wood is glued into the foam.
At the root ends, sand the area ahead of
the spars to clear the fuselage plywood
doublers so the wing panels butt up flush
to the fuselage sides. Epoxy the plywood
joiner into one of the wing cores, and the
wing panels are ready for later assembly to
the fuselage.
Cut the horizontal and vertical
stabilizers to shape from 1/4 balsa, using
paper patterns. The ailerons, elevator
halves, and rudder are built up over the
plans from the 1/4 x 1/2 and 1/4 square balsa
strips. I use waxed paper over the plans
and small weights to hold the balsa strips
in place as I add and glue them to
complete the assemblies.
Bend a piece of 1/8-inch-diameter music
wire to shape as a joiner for the elevator
halves. At this point I cut the slots and fit
the nylon hinges in all the control surfaces;
they will be glued in place later, after the
airplane has been covered.
I glue the one wing panel with the
plywood joiner in place to the fuselage,
and then I glue the opposite panel in place.
The stabilizer can then be glued into the
fuselage, aligning it with the wing. Glue
the vertical fin to the fuselage, with its
dowel reinforcements.
All the control surfaces can be put into
place with their hinges, to check for proper
movement. The servos can be installed in
the top or bottom of the foam wing panels;
carve out recesses in the foam to clear the
servos, and epoxy plywood mounts into
the foam for mounting the servos.
Ahead of the spars hollow out an area
on one side of the fuselage for the battery
pack and on the other side for the receiver,
allowing enough room for some foam to
be wrapped around the battery and
receiver.
The servo leads can be routed through
the foam to reach the receiver. Thinplywood
removable hatches over the
receiver and battery areas are held in place
with small screws into plywood epoxied
into the foam.
Short wire linkages are used from the
30 MODEL AVIATION
aileron servos to the ailerons, and wire or
nylon tube pushrod setups to the elevator,
rudder, and throttle. I used a Du-Bro nylon
tail-wheel bracket. The aluminum or
composite landing gears are bolted to the
fuselage, and the fuel tank, or battery pack,
is held in place with rubber bands to eye
hooks. The whole model is finished with
an iron-on plastic covering; make sure to
use a material that can be applied with a
low-heat iron so the foam is not damaged.
My One Design balanced just behind
the wing-spars location, which suited me
fine. I set up the control surfaces, to start,
with aileron throw at 1/2 inch each way and
elevator throw approximately 3/4 inch each
way, on low rates, with much more
movement on high rates. I used all the
rudder throw I could get.
Airplane sensitivity is an individual
thing and should be adjusted to suit each
flier’s preference. Adjust the throws and
exponential if desired to get the airplane
feel that you prefer for your flying style
and comfort.
I’ve been asked why the hook in the
vertical fin. When the model goes into the
trees, it will hang up from a branch and be
easy to retrieve. I just thought it looked
different and not bad. I’m sure scratch
builders will eliminate that feature if they
don’t like its appearance.
If this is your first scratch-building
project, good! Make some sawdust and
wood chips, and, above all, have fun!
Enjoy the NJ One Design! MA
Dick Sarpolus
[email protected]
Edition: Model Aviation - 2007/02
Page Numbers: 25,26,27,28,29,30,31
ARE YOU AN ARF flier or an airplane scratch builder? If you
haven’t tried scratch building, check out this story.
The project started with a discussion among a few members of
the Monmouth Model Airplane Club in New Jersey, to which I
belong, about selecting a particular aircraft, probably an ARF, that
many of our members could get and use for our club contests.
Some of these contests, such as limbo, quick takeoffs, aerobatic
maneuvers, and landings, several forms of spot landings, and
several types of Pylon Racing, tended to be pretty hard on the
aircraft. Many of our contest days ended with the loss of at least
several aircraft caused by hard contact with the ground or trees.
The thought was that if everyone used the same low-cost type of
aircraft, the competition would be more even and pilots wouldn’t
mind the crashes as much. Someone asked me about a building
project with a bunch of members scratch-building the same
airplane. It sounded like fun, and I had some ideas for such a
project.
Further discussion indicated that most fliers had a .40-, .45-, or
.46-size engine. The idea of a precut foam wing appealed to them.
A profile fuselage for quick and easy building didn’t raise any
objections.
Good flying characteristics were a must; some had tried the
plastic sign board and aluminum extrusion airframes but didn’t
care for the less than optimum handling. Ultra light weight
wasn’t high on the priority list; this wasn’t seen as a 3-D
airplane. And a low-cost but fairly rugged and easily reparable
airframe would be popular.
The glow version in the air. Control-surface deflections indicate
that the model is in the midst of an extreme fun-fly type
maneuver: its forte!
Design: I laid out the wing first, with a
thick, full symmetrical airfoil. It had a 48-
inch span and a 14-inch chord for 672
square inches of wing area.
The slab-profile fuselage length was
made 40 inches—compact overall, with
good proportions for lively flying. I used
large built-up control surfaces, but not
aimed at 3-D flying.
Weight was calculated to be
approximately 4 pounds, for a wing loading
of 14 ounces per square foot. That’s light,
and if the model came in slightly heavier it
would still be good.
A quick look shows that there is some
CL-type construction in this RC project.
The foam-core wings will not be sheeted
with balsa; the balsa top and bottom spars,
LE, TE, tip ribs, and plywood joiner will
provide plenty of strength, and a lowtemperature
iron-on plastic covering will
protect the foam a bit.
The fuselage is made from solid 1/2 balsa
with 1/8 plywood doublers on the nose
section. The fuselage is stronger than usual
because there is not a large cutout in it for
the wing to slide through; there is only a
vertical slot in the fuselage for the plywood
wing joiner. I got this idea from Phil Cartier,
who has considerable CL foam-core-wing
construction experience. The foam-core
wings butt up against either side of the
fuselage.
The wings and control surfaces are light
overall. The fuselage is somewhat heavy but
strong. This is not the lightest way to build
an airplane, but it’s a reasonable
compromise to get a model that is light
enough for good performance and can take a
little abuse without falling apart.
The fuselage should resist crashes, and
the wing panels can be fairly easily
replaced. The profile fuselage could be built
up or foam-cored for lighter weight, but it
would break more easily.
I constructed a prototype with my
amateur-cut foam wing cores and found that
it really was easy and quick to build. It came
out slightly heavier than I had hoped. I used
some hard wood and I used too much epoxy
glue, but even at almost 4.5 pounds with the
670 square inches of wing area, that’s a
wing loading of only 15 ounces per square
foot.
My prototype flew well! It had no bad
characteristics, did all the fun-fly aerobatic
stuff I could have it do, and withstood all
the snaps and spins I threw at it.
The SuperTigre GS-45 engine with an 11
x 5 propeller was more than enough power,
and I figured the model would also fly well
on electric power. To prove it I borrowed an
AXI 2826/10 brushless outrunner motor
turning an APC 11 x 7 electric propeller and
a Jeti 40-amp Opto ESC from a friend, and I
used my four-cell 4400 mAh Li-Poly battery
pack.
I mounted the AXI with a custommachined
aluminum adapter mount that Jim
Ehlen ([email protected]) manufactured,
which made it possible to retain the motor
on beam mounts set up for a glow engine. I
The 1/2-inch-thick balsa fuselage will be cut for the engine and mounts after the engine to
be used is chosen, to get the correct crankcase width.
The NJ One Design’s fuselage with the engine mounts and doublers assembled, with the
cut for the wing spar/joiner and built-up tail surfaces.
The wing panels are assembled using slow-cure epoxy to install the upper and lower
spars, LE, TE, and wingtip cap at the same time.
NJ One
Design
The 1/8 plywood servo mounts are epoxied into foam. The foam is
cut away for mounts and clearance for servos. Cavities ahead of
the spars are for the battery pack and receiver.
Aileron, elevator, and rudder servos in place. There is no throttle
servo; this is the electric-powered version of the model.
The wing panels with the ailerons built and hinges in place. The hinges will be
glued in after the airplane is assembled and covered.
Type: Easy-to-build RC sport
Wingspan: 49 inches
Wing area: 672 square inches
Weight: 4.0-4.5 pounds
Wing loading: Approximately 15 ounces/square foot
Length: 41 inches
Construction: Balsa, plywood, foam
Covering/finish: Iron-on plastic covering that can be
applied with a low-heat iron
Glow power: .40-.46 engine, 11 x 5 propeller
Electric power: AXI 2826/12 brushless outrunner
motor, Jeti Advance PLUS 40 Amp Opto ESC, 12
x 8 APC electric propeller, Poly-Quest four-cell
4400 mAh Li-Poly battery pack (600 watts)
NJ One Design Wood List
Fuselage
1/2 x 3 x 36 balsa Two pieces—fuselage
3/8 x 1/2 maple One piece—engine mounts
1/8 x 6 x 12 plywood Two pieces—nose doublers
Wings
3/8 x 1/2 x 36 balsa Four pieces—spars
1/4 x 1/2 x 36 balsa Two pieces—LE
3/8 x 1/2 x 36 balsa Two pieces—TE
1/8 x 6 x 12 plywood One piece—wing joiner
1/8 x 3 x 36 balsa One piece—wingtips
1/4 x 1/2 x 36 balsa Two pieces—ailerons
1/4 x 1/4 x 36 balsa Three pieces—ailerons
Tail Surfaces
1/4 x 4 x 36 balsa One piece—stabilizer, fin
1/4 x 1/2 x 36 balsa Two pieces—elevator,
rudder
1/4 x 1/4 x 36 balsa Two pieces—elevator,
rudder
Built-Up Wing, Ribs, and Sheeting
(or foam wing core by The Core House)
1/8 x 3 x 36 balsa Five pieces—ribs
3/32 x 4 x 36 Two pieces—sheeting MA
The fairly lightweight structure is rugged. Foam wing panels do not need to be sheeted
with balsa; they will be covered with low-temperature iron-on film.
Dick’s glow-powered model used a SuperTigre .45. The fuel
tank is held on with rubber bands. Note the muffler angle.
The electric version uses an AXI 2826/12 motor, Jeti 40-amp Opto ESC,
Ultimate BEC, and Poly-Quest four-cell 4400 mAh Li-Poly battery pack.
put the battery pack in place of the fuel
tank. I left the throttle servo and radio
battery in place; using a BEC would have
made the electric power installation even
lighter.
The airplane balanced roughly the same
as with the glow engine and flew well—
almost the same as with the SuperTigre. I
tried different propellers; with an APC 12 x
8 electric the AXI drew somewhat more
than 600 watts. I think the 2826/12 would
have been a better motor choice for this
application.
I figured that if I built this airplane
specifically for electric power, the plywood
nose doublers could be thinner, the maple
engine mounts would be eliminated, and a
firewall mount would be used, making that
version a good amount lighter than the
glow-powered version.
So I built a second model for electric
power. The results were great, and the glow
vs. electric comparison is discussed in more
detail in an accompanying sidebar.
Now that I knew the design worked, I
arranged to have Phil Cartier at The Core
House (34 Sweet Arrow Dr., Hummelstown
PA 17036) cut the foam wing cores using
his computer-controlled setup, which does
a great job. The cores are now
commercially available from The Core
House.
I worked up a wood materials list, and
with mail-order prices (I like Lone Star
Balsa) it would cost less than $20 for the
wood. I made the landing gear from 1/8 x 1-
inch 6061-T6 aluminum, but usable
commercial aluminum and composite gears
are available from several manufacturers.
I covered my airplane with Black Baron
Film because it’s applied with a low
temperature that will not harm the foam
wing cores. I found it extraordinarily easy
to use.
If you are used to buying ARFs, I can’t
say that building the NJ One Design will
save you a lot of money, and it would
certainly be more work than throwing an
ARF together. But if you feel that building
your airplane is part of the overall
modeling experience, if you want to know
how your model is built so you can easily
repair it, if you’d like knowing that you
built your airplane rather than just taking it
out of a box, or if you’re a do-it-yourselfer,
don’t hesitate to make some wood chips
and sawdust and scratch build your own
airplane!
The NJ One Design is an easy way to
try constructing a model from scratch, and I
think it adds to the fun of this hobby.
More than a dozen Monmouth club
members signed up to build this airplane as
a fun club project. And a half dozen guys
from the other local club, the Jersey Coast
Sport Fliers, got plans and foam wing cores
to try the project. So there are builders out
there!
Monmouth club member Ray Borden
digitized the plans from my pencils so
L-R: Ed Thieleman holds one of Dick’s models while Paul Gentile, Dick Sarpolus, Bob Serafin, and Pete Mularchuk Jr. show their NJ One
Designs. Another dozen airplanes are under construction by other members of the Monmouth Model Airplane Club.
I designed and built the NJ One Design for glow-engine
power with little thought for electric power. I really liked the
way the model flew with a SuperTigre .45 engine. Having
recently built my first .40-sized electric, I wondered about
powering the One Design with a motor.
I started by weighing my .45 glow engine, its muffler, the
fuel tank, the throttle servo, and the radio battery pack.
Those items weighed 26 ounces. Then I weighed an AXI
2826/12 motor, a Jeti 40-amp Opto ESC, an Ultimate BEC,
and a four-cell Poly-Quest 4400 mAh Li-Poly battery pack.
They weighed 23 ounces.
No glow fuel had to be added to fly. So if I put the
electric power system in the same airplane, it wouldn’t be
any heavier than it was with the glow engine. I did that,
using a light aluminum adapter mount to hold the AXI motor
in place. The aircraft’s balance point was unaffected.
I employed an APC 12 x 8 electric propeller, and the AXI
turned it approximately 8,500 rpm, drawing roughly 39 amps
for approximately 600 watts of power, measured on the
ground. The glow .45 was turning its 11 x 5 wooden
propeller at roughly 11,600 rpm.
I purchased the AXI brushless outrunner motor, Jeti ESC,
Ultimate BEC, and Poly-Quest Li-Poly from Hobby Lobby as
they were sold. I was familiar with that equipment, having had
some experience with it. There is a great deal of electric-power
equipment on the market to choose from, and I’m sure other
equipment could be used with results that wood be as good.
The NJ One Design flew almost the same! It jumped off
the ground quickly, climbed straight up, and did everything I
could do with the glow version in roughly the same way.
Thinking more about the weight-comparison issue, I had
left the 600 mAh Ni-Cd radio battery pack in the model and
the throttle servo in place to simplify the comparison flying.
If I built the airplane specifically for electric power, I’d use a
BEC and eliminate the Ni-Cd battery pack, leave out the
throttle servo, use thinner 1/16 plywood doublers on the nose
in place of the 1/8 plywood doublers, and leave out the
hardwood motor mounts. The electric-powered version
would be lighter.
So I did build another airplane—the same design—and
made no attempt to save airframe weight other than using
thinner plywood nose doublers and leaving out the hardwood
motor mounts. I made the nose 1/2 inch longer to make sure it
would balance properly. I used an Ultimate BEC so I would
not require a separate radio-system battery, and I didn’t need
a throttle servo.
The completed airplane was roughly 10 ounces lighter
than its glow-engine-powered twin.
Did it fly well? It sure did. I can’t honestly say there was
much difference in performance; I like the way both versions
fly.
Yes, the electric-power system components do cost more.
And I know that those who love the sound of a high-revving
glow engine and the smell and the feel of the exhaust may
never want to give those things up. The amount of money we
spend on our hobby is something each of us has to
determine.
If quiet operation, ease of operation, and cleanliness of
operation is important to us, and if the electric technology is
interesting to us, one thing is for sure: performance doesn’t
have to suffer when going from glow to electric power—at
least in this NJ One Design airplane. Options to suit each
person is what makes aeromodeling such a great hobby. MA
—Dick Sarpolus
NJ One Design: Glow Vs. Electric Power
This model likes to spend most of its time in the air in extreme positions! It’s aerobatic
and simple to build.
everyone would have good CAD plans
from which to work. We ordered a batch
of foam wing cores from The Core House,
made a bulk wood order from Lone Star,
cut some of the parts on my band saw, and
airplane production began. Within a
month or so some of the models began
showing up at our club flying field.
Practical experience has shown that
this airplane serves its purpose as a good
fun flier—particularly at our fairly small
field that can be tough on aircraft. This
model doesn’t survive all crashes, but it’s
pretty easy to repair after most of them.
I think pilots will be flying this design
for sometime. And the project has helped
our treasury; money made from this article
will go to the Monmouth Model Airplane
Club.
CONSTRUCTION
The following is for you who are new
to scratch-building.
You’ll need patterns for the parts that
have to be cut. Either cut the plans or trace
the parts outlines you need to make the
paper patterns.
Starting with the fuselage, epoxy two
pieces of 3-inch-wide 1/2 balsa together
and trace the fuselage outline for cutting.
A bit more balsa will be needed for the
canopy area of the fuselage; epoxy extra
wood together to make up what is needed.
Before you cut the nose area for the
engine mounts, make sure the spacing is
correct to suit the engine you’ll be using.
A slot needs to be cut through the fuselage
for the plywood wing joiner, and a hole
needs to be drilled for the TE dowel joiner
that ensures accurate positioning of the
wing panels.
The 1/8 plywood nose doublers, cut to
suit the engine being used, are epoxied on
both sides of the fuselage front end. The
plywood tail-wheel mount is epoxied to
the back end of the fuselage.
Moving on to the wing panels, a
vertical slot has to be cut into the foam
cores at their root ends for the 1/8 plywood
joiner. Sand the plywood joiner to make
sure it’s a good fit between the upper and
lower wing spars. The upper and lower
spars, LE, TE, and wingtip cap have to be
epoxied to the foam cores. If the spars are
too tight of a fit in the foam, sand the slots
a bit.
The TE pieces can be planed and
tapered to shape before or after they have
been glued to the foam cores—whichever
is easier for you. Round off the LEs after
the wood is glued into the foam.
At the root ends, sand the area ahead of
the spars to clear the fuselage plywood
doublers so the wing panels butt up flush
to the fuselage sides. Epoxy the plywood
joiner into one of the wing cores, and the
wing panels are ready for later assembly to
the fuselage.
Cut the horizontal and vertical
stabilizers to shape from 1/4 balsa, using
paper patterns. The ailerons, elevator
halves, and rudder are built up over the
plans from the 1/4 x 1/2 and 1/4 square balsa
strips. I use waxed paper over the plans
and small weights to hold the balsa strips
in place as I add and glue them to
complete the assemblies.
Bend a piece of 1/8-inch-diameter music
wire to shape as a joiner for the elevator
halves. At this point I cut the slots and fit
the nylon hinges in all the control surfaces;
they will be glued in place later, after the
airplane has been covered.
I glue the one wing panel with the
plywood joiner in place to the fuselage,
and then I glue the opposite panel in place.
The stabilizer can then be glued into the
fuselage, aligning it with the wing. Glue
the vertical fin to the fuselage, with its
dowel reinforcements.
All the control surfaces can be put into
place with their hinges, to check for proper
movement. The servos can be installed in
the top or bottom of the foam wing panels;
carve out recesses in the foam to clear the
servos, and epoxy plywood mounts into
the foam for mounting the servos.
Ahead of the spars hollow out an area
on one side of the fuselage for the battery
pack and on the other side for the receiver,
allowing enough room for some foam to
be wrapped around the battery and
receiver.
The servo leads can be routed through
the foam to reach the receiver. Thinplywood
removable hatches over the
receiver and battery areas are held in place
with small screws into plywood epoxied
into the foam.
Short wire linkages are used from the
30 MODEL AVIATION
aileron servos to the ailerons, and wire or
nylon tube pushrod setups to the elevator,
rudder, and throttle. I used a Du-Bro nylon
tail-wheel bracket. The aluminum or
composite landing gears are bolted to the
fuselage, and the fuel tank, or battery pack,
is held in place with rubber bands to eye
hooks. The whole model is finished with
an iron-on plastic covering; make sure to
use a material that can be applied with a
low-heat iron so the foam is not damaged.
My One Design balanced just behind
the wing-spars location, which suited me
fine. I set up the control surfaces, to start,
with aileron throw at 1/2 inch each way and
elevator throw approximately 3/4 inch each
way, on low rates, with much more
movement on high rates. I used all the
rudder throw I could get.
Airplane sensitivity is an individual
thing and should be adjusted to suit each
flier’s preference. Adjust the throws and
exponential if desired to get the airplane
feel that you prefer for your flying style
and comfort.
I’ve been asked why the hook in the
vertical fin. When the model goes into the
trees, it will hang up from a branch and be
easy to retrieve. I just thought it looked
different and not bad. I’m sure scratch
builders will eliminate that feature if they
don’t like its appearance.
If this is your first scratch-building
project, good! Make some sawdust and
wood chips, and, above all, have fun!
Enjoy the NJ One Design! MA
Dick Sarpolus
[email protected]
Edition: Model Aviation - 2007/02
Page Numbers: 25,26,27,28,29,30,31
ARE YOU AN ARF flier or an airplane scratch builder? If you
haven’t tried scratch building, check out this story.
The project started with a discussion among a few members of
the Monmouth Model Airplane Club in New Jersey, to which I
belong, about selecting a particular aircraft, probably an ARF, that
many of our members could get and use for our club contests.
Some of these contests, such as limbo, quick takeoffs, aerobatic
maneuvers, and landings, several forms of spot landings, and
several types of Pylon Racing, tended to be pretty hard on the
aircraft. Many of our contest days ended with the loss of at least
several aircraft caused by hard contact with the ground or trees.
The thought was that if everyone used the same low-cost type of
aircraft, the competition would be more even and pilots wouldn’t
mind the crashes as much. Someone asked me about a building
project with a bunch of members scratch-building the same
airplane. It sounded like fun, and I had some ideas for such a
project.
Further discussion indicated that most fliers had a .40-, .45-, or
.46-size engine. The idea of a precut foam wing appealed to them.
A profile fuselage for quick and easy building didn’t raise any
objections.
Good flying characteristics were a must; some had tried the
plastic sign board and aluminum extrusion airframes but didn’t
care for the less than optimum handling. Ultra light weight
wasn’t high on the priority list; this wasn’t seen as a 3-D
airplane. And a low-cost but fairly rugged and easily reparable
airframe would be popular.
The glow version in the air. Control-surface deflections indicate
that the model is in the midst of an extreme fun-fly type
maneuver: its forte!
Design: I laid out the wing first, with a
thick, full symmetrical airfoil. It had a 48-
inch span and a 14-inch chord for 672
square inches of wing area.
The slab-profile fuselage length was
made 40 inches—compact overall, with
good proportions for lively flying. I used
large built-up control surfaces, but not
aimed at 3-D flying.
Weight was calculated to be
approximately 4 pounds, for a wing loading
of 14 ounces per square foot. That’s light,
and if the model came in slightly heavier it
would still be good.
A quick look shows that there is some
CL-type construction in this RC project.
The foam-core wings will not be sheeted
with balsa; the balsa top and bottom spars,
LE, TE, tip ribs, and plywood joiner will
provide plenty of strength, and a lowtemperature
iron-on plastic covering will
protect the foam a bit.
The fuselage is made from solid 1/2 balsa
with 1/8 plywood doublers on the nose
section. The fuselage is stronger than usual
because there is not a large cutout in it for
the wing to slide through; there is only a
vertical slot in the fuselage for the plywood
wing joiner. I got this idea from Phil Cartier,
who has considerable CL foam-core-wing
construction experience. The foam-core
wings butt up against either side of the
fuselage.
The wings and control surfaces are light
overall. The fuselage is somewhat heavy but
strong. This is not the lightest way to build
an airplane, but it’s a reasonable
compromise to get a model that is light
enough for good performance and can take a
little abuse without falling apart.
The fuselage should resist crashes, and
the wing panels can be fairly easily
replaced. The profile fuselage could be built
up or foam-cored for lighter weight, but it
would break more easily.
I constructed a prototype with my
amateur-cut foam wing cores and found that
it really was easy and quick to build. It came
out slightly heavier than I had hoped. I used
some hard wood and I used too much epoxy
glue, but even at almost 4.5 pounds with the
670 square inches of wing area, that’s a
wing loading of only 15 ounces per square
foot.
My prototype flew well! It had no bad
characteristics, did all the fun-fly aerobatic
stuff I could have it do, and withstood all
the snaps and spins I threw at it.
The SuperTigre GS-45 engine with an 11
x 5 propeller was more than enough power,
and I figured the model would also fly well
on electric power. To prove it I borrowed an
AXI 2826/10 brushless outrunner motor
turning an APC 11 x 7 electric propeller and
a Jeti 40-amp Opto ESC from a friend, and I
used my four-cell 4400 mAh Li-Poly battery
pack.
I mounted the AXI with a custommachined
aluminum adapter mount that Jim
Ehlen ([email protected]) manufactured,
which made it possible to retain the motor
on beam mounts set up for a glow engine. I
The 1/2-inch-thick balsa fuselage will be cut for the engine and mounts after the engine to
be used is chosen, to get the correct crankcase width.
The NJ One Design’s fuselage with the engine mounts and doublers assembled, with the
cut for the wing spar/joiner and built-up tail surfaces.
The wing panels are assembled using slow-cure epoxy to install the upper and lower
spars, LE, TE, and wingtip cap at the same time.
NJ One
Design
The 1/8 plywood servo mounts are epoxied into foam. The foam is
cut away for mounts and clearance for servos. Cavities ahead of
the spars are for the battery pack and receiver.
Aileron, elevator, and rudder servos in place. There is no throttle
servo; this is the electric-powered version of the model.
The wing panels with the ailerons built and hinges in place. The hinges will be
glued in after the airplane is assembled and covered.
Type: Easy-to-build RC sport
Wingspan: 49 inches
Wing area: 672 square inches
Weight: 4.0-4.5 pounds
Wing loading: Approximately 15 ounces/square foot
Length: 41 inches
Construction: Balsa, plywood, foam
Covering/finish: Iron-on plastic covering that can be
applied with a low-heat iron
Glow power: .40-.46 engine, 11 x 5 propeller
Electric power: AXI 2826/12 brushless outrunner
motor, Jeti Advance PLUS 40 Amp Opto ESC, 12
x 8 APC electric propeller, Poly-Quest four-cell
4400 mAh Li-Poly battery pack (600 watts)
NJ One Design Wood List
Fuselage
1/2 x 3 x 36 balsa Two pieces—fuselage
3/8 x 1/2 maple One piece—engine mounts
1/8 x 6 x 12 plywood Two pieces—nose doublers
Wings
3/8 x 1/2 x 36 balsa Four pieces—spars
1/4 x 1/2 x 36 balsa Two pieces—LE
3/8 x 1/2 x 36 balsa Two pieces—TE
1/8 x 6 x 12 plywood One piece—wing joiner
1/8 x 3 x 36 balsa One piece—wingtips
1/4 x 1/2 x 36 balsa Two pieces—ailerons
1/4 x 1/4 x 36 balsa Three pieces—ailerons
Tail Surfaces
1/4 x 4 x 36 balsa One piece—stabilizer, fin
1/4 x 1/2 x 36 balsa Two pieces—elevator,
rudder
1/4 x 1/4 x 36 balsa Two pieces—elevator,
rudder
Built-Up Wing, Ribs, and Sheeting
(or foam wing core by The Core House)
1/8 x 3 x 36 balsa Five pieces—ribs
3/32 x 4 x 36 Two pieces—sheeting MA
The fairly lightweight structure is rugged. Foam wing panels do not need to be sheeted
with balsa; they will be covered with low-temperature iron-on film.
Dick’s glow-powered model used a SuperTigre .45. The fuel
tank is held on with rubber bands. Note the muffler angle.
The electric version uses an AXI 2826/12 motor, Jeti 40-amp Opto ESC,
Ultimate BEC, and Poly-Quest four-cell 4400 mAh Li-Poly battery pack.
put the battery pack in place of the fuel
tank. I left the throttle servo and radio
battery in place; using a BEC would have
made the electric power installation even
lighter.
The airplane balanced roughly the same
as with the glow engine and flew well—
almost the same as with the SuperTigre. I
tried different propellers; with an APC 12 x
8 electric the AXI drew somewhat more
than 600 watts. I think the 2826/12 would
have been a better motor choice for this
application.
I figured that if I built this airplane
specifically for electric power, the plywood
nose doublers could be thinner, the maple
engine mounts would be eliminated, and a
firewall mount would be used, making that
version a good amount lighter than the
glow-powered version.
So I built a second model for electric
power. The results were great, and the glow
vs. electric comparison is discussed in more
detail in an accompanying sidebar.
Now that I knew the design worked, I
arranged to have Phil Cartier at The Core
House (34 Sweet Arrow Dr., Hummelstown
PA 17036) cut the foam wing cores using
his computer-controlled setup, which does
a great job. The cores are now
commercially available from The Core
House.
I worked up a wood materials list, and
with mail-order prices (I like Lone Star
Balsa) it would cost less than $20 for the
wood. I made the landing gear from 1/8 x 1-
inch 6061-T6 aluminum, but usable
commercial aluminum and composite gears
are available from several manufacturers.
I covered my airplane with Black Baron
Film because it’s applied with a low
temperature that will not harm the foam
wing cores. I found it extraordinarily easy
to use.
If you are used to buying ARFs, I can’t
say that building the NJ One Design will
save you a lot of money, and it would
certainly be more work than throwing an
ARF together. But if you feel that building
your airplane is part of the overall
modeling experience, if you want to know
how your model is built so you can easily
repair it, if you’d like knowing that you
built your airplane rather than just taking it
out of a box, or if you’re a do-it-yourselfer,
don’t hesitate to make some wood chips
and sawdust and scratch build your own
airplane!
The NJ One Design is an easy way to
try constructing a model from scratch, and I
think it adds to the fun of this hobby.
More than a dozen Monmouth club
members signed up to build this airplane as
a fun club project. And a half dozen guys
from the other local club, the Jersey Coast
Sport Fliers, got plans and foam wing cores
to try the project. So there are builders out
there!
Monmouth club member Ray Borden
digitized the plans from my pencils so
L-R: Ed Thieleman holds one of Dick’s models while Paul Gentile, Dick Sarpolus, Bob Serafin, and Pete Mularchuk Jr. show their NJ One
Designs. Another dozen airplanes are under construction by other members of the Monmouth Model Airplane Club.
I designed and built the NJ One Design for glow-engine
power with little thought for electric power. I really liked the
way the model flew with a SuperTigre .45 engine. Having
recently built my first .40-sized electric, I wondered about
powering the One Design with a motor.
I started by weighing my .45 glow engine, its muffler, the
fuel tank, the throttle servo, and the radio battery pack.
Those items weighed 26 ounces. Then I weighed an AXI
2826/12 motor, a Jeti 40-amp Opto ESC, an Ultimate BEC,
and a four-cell Poly-Quest 4400 mAh Li-Poly battery pack.
They weighed 23 ounces.
No glow fuel had to be added to fly. So if I put the
electric power system in the same airplane, it wouldn’t be
any heavier than it was with the glow engine. I did that,
using a light aluminum adapter mount to hold the AXI motor
in place. The aircraft’s balance point was unaffected.
I employed an APC 12 x 8 electric propeller, and the AXI
turned it approximately 8,500 rpm, drawing roughly 39 amps
for approximately 600 watts of power, measured on the
ground. The glow .45 was turning its 11 x 5 wooden
propeller at roughly 11,600 rpm.
I purchased the AXI brushless outrunner motor, Jeti ESC,
Ultimate BEC, and Poly-Quest Li-Poly from Hobby Lobby as
they were sold. I was familiar with that equipment, having had
some experience with it. There is a great deal of electric-power
equipment on the market to choose from, and I’m sure other
equipment could be used with results that wood be as good.
The NJ One Design flew almost the same! It jumped off
the ground quickly, climbed straight up, and did everything I
could do with the glow version in roughly the same way.
Thinking more about the weight-comparison issue, I had
left the 600 mAh Ni-Cd radio battery pack in the model and
the throttle servo in place to simplify the comparison flying.
If I built the airplane specifically for electric power, I’d use a
BEC and eliminate the Ni-Cd battery pack, leave out the
throttle servo, use thinner 1/16 plywood doublers on the nose
in place of the 1/8 plywood doublers, and leave out the
hardwood motor mounts. The electric-powered version
would be lighter.
So I did build another airplane—the same design—and
made no attempt to save airframe weight other than using
thinner plywood nose doublers and leaving out the hardwood
motor mounts. I made the nose 1/2 inch longer to make sure it
would balance properly. I used an Ultimate BEC so I would
not require a separate radio-system battery, and I didn’t need
a throttle servo.
The completed airplane was roughly 10 ounces lighter
than its glow-engine-powered twin.
Did it fly well? It sure did. I can’t honestly say there was
much difference in performance; I like the way both versions
fly.
Yes, the electric-power system components do cost more.
And I know that those who love the sound of a high-revving
glow engine and the smell and the feel of the exhaust may
never want to give those things up. The amount of money we
spend on our hobby is something each of us has to
determine.
If quiet operation, ease of operation, and cleanliness of
operation is important to us, and if the electric technology is
interesting to us, one thing is for sure: performance doesn’t
have to suffer when going from glow to electric power—at
least in this NJ One Design airplane. Options to suit each
person is what makes aeromodeling such a great hobby. MA
—Dick Sarpolus
NJ One Design: Glow Vs. Electric Power
This model likes to spend most of its time in the air in extreme positions! It’s aerobatic
and simple to build.
everyone would have good CAD plans
from which to work. We ordered a batch
of foam wing cores from The Core House,
made a bulk wood order from Lone Star,
cut some of the parts on my band saw, and
airplane production began. Within a
month or so some of the models began
showing up at our club flying field.
Practical experience has shown that
this airplane serves its purpose as a good
fun flier—particularly at our fairly small
field that can be tough on aircraft. This
model doesn’t survive all crashes, but it’s
pretty easy to repair after most of them.
I think pilots will be flying this design
for sometime. And the project has helped
our treasury; money made from this article
will go to the Monmouth Model Airplane
Club.
CONSTRUCTION
The following is for you who are new
to scratch-building.
You’ll need patterns for the parts that
have to be cut. Either cut the plans or trace
the parts outlines you need to make the
paper patterns.
Starting with the fuselage, epoxy two
pieces of 3-inch-wide 1/2 balsa together
and trace the fuselage outline for cutting.
A bit more balsa will be needed for the
canopy area of the fuselage; epoxy extra
wood together to make up what is needed.
Before you cut the nose area for the
engine mounts, make sure the spacing is
correct to suit the engine you’ll be using.
A slot needs to be cut through the fuselage
for the plywood wing joiner, and a hole
needs to be drilled for the TE dowel joiner
that ensures accurate positioning of the
wing panels.
The 1/8 plywood nose doublers, cut to
suit the engine being used, are epoxied on
both sides of the fuselage front end. The
plywood tail-wheel mount is epoxied to
the back end of the fuselage.
Moving on to the wing panels, a
vertical slot has to be cut into the foam
cores at their root ends for the 1/8 plywood
joiner. Sand the plywood joiner to make
sure it’s a good fit between the upper and
lower wing spars. The upper and lower
spars, LE, TE, and wingtip cap have to be
epoxied to the foam cores. If the spars are
too tight of a fit in the foam, sand the slots
a bit.
The TE pieces can be planed and
tapered to shape before or after they have
been glued to the foam cores—whichever
is easier for you. Round off the LEs after
the wood is glued into the foam.
At the root ends, sand the area ahead of
the spars to clear the fuselage plywood
doublers so the wing panels butt up flush
to the fuselage sides. Epoxy the plywood
joiner into one of the wing cores, and the
wing panels are ready for later assembly to
the fuselage.
Cut the horizontal and vertical
stabilizers to shape from 1/4 balsa, using
paper patterns. The ailerons, elevator
halves, and rudder are built up over the
plans from the 1/4 x 1/2 and 1/4 square balsa
strips. I use waxed paper over the plans
and small weights to hold the balsa strips
in place as I add and glue them to
complete the assemblies.
Bend a piece of 1/8-inch-diameter music
wire to shape as a joiner for the elevator
halves. At this point I cut the slots and fit
the nylon hinges in all the control surfaces;
they will be glued in place later, after the
airplane has been covered.
I glue the one wing panel with the
plywood joiner in place to the fuselage,
and then I glue the opposite panel in place.
The stabilizer can then be glued into the
fuselage, aligning it with the wing. Glue
the vertical fin to the fuselage, with its
dowel reinforcements.
All the control surfaces can be put into
place with their hinges, to check for proper
movement. The servos can be installed in
the top or bottom of the foam wing panels;
carve out recesses in the foam to clear the
servos, and epoxy plywood mounts into
the foam for mounting the servos.
Ahead of the spars hollow out an area
on one side of the fuselage for the battery
pack and on the other side for the receiver,
allowing enough room for some foam to
be wrapped around the battery and
receiver.
The servo leads can be routed through
the foam to reach the receiver. Thinplywood
removable hatches over the
receiver and battery areas are held in place
with small screws into plywood epoxied
into the foam.
Short wire linkages are used from the
30 MODEL AVIATION
aileron servos to the ailerons, and wire or
nylon tube pushrod setups to the elevator,
rudder, and throttle. I used a Du-Bro nylon
tail-wheel bracket. The aluminum or
composite landing gears are bolted to the
fuselage, and the fuel tank, or battery pack,
is held in place with rubber bands to eye
hooks. The whole model is finished with
an iron-on plastic covering; make sure to
use a material that can be applied with a
low-heat iron so the foam is not damaged.
My One Design balanced just behind
the wing-spars location, which suited me
fine. I set up the control surfaces, to start,
with aileron throw at 1/2 inch each way and
elevator throw approximately 3/4 inch each
way, on low rates, with much more
movement on high rates. I used all the
rudder throw I could get.
Airplane sensitivity is an individual
thing and should be adjusted to suit each
flier’s preference. Adjust the throws and
exponential if desired to get the airplane
feel that you prefer for your flying style
and comfort.
I’ve been asked why the hook in the
vertical fin. When the model goes into the
trees, it will hang up from a branch and be
easy to retrieve. I just thought it looked
different and not bad. I’m sure scratch
builders will eliminate that feature if they
don’t like its appearance.
If this is your first scratch-building
project, good! Make some sawdust and
wood chips, and, above all, have fun!
Enjoy the NJ One Design! MA
Dick Sarpolus
[email protected]
Edition: Model Aviation - 2007/02
Page Numbers: 25,26,27,28,29,30,31
ARE YOU AN ARF flier or an airplane scratch builder? If you
haven’t tried scratch building, check out this story.
The project started with a discussion among a few members of
the Monmouth Model Airplane Club in New Jersey, to which I
belong, about selecting a particular aircraft, probably an ARF, that
many of our members could get and use for our club contests.
Some of these contests, such as limbo, quick takeoffs, aerobatic
maneuvers, and landings, several forms of spot landings, and
several types of Pylon Racing, tended to be pretty hard on the
aircraft. Many of our contest days ended with the loss of at least
several aircraft caused by hard contact with the ground or trees.
The thought was that if everyone used the same low-cost type of
aircraft, the competition would be more even and pilots wouldn’t
mind the crashes as much. Someone asked me about a building
project with a bunch of members scratch-building the same
airplane. It sounded like fun, and I had some ideas for such a
project.
Further discussion indicated that most fliers had a .40-, .45-, or
.46-size engine. The idea of a precut foam wing appealed to them.
A profile fuselage for quick and easy building didn’t raise any
objections.
Good flying characteristics were a must; some had tried the
plastic sign board and aluminum extrusion airframes but didn’t
care for the less than optimum handling. Ultra light weight
wasn’t high on the priority list; this wasn’t seen as a 3-D
airplane. And a low-cost but fairly rugged and easily reparable
airframe would be popular.
The glow version in the air. Control-surface deflections indicate
that the model is in the midst of an extreme fun-fly type
maneuver: its forte!
Design: I laid out the wing first, with a
thick, full symmetrical airfoil. It had a 48-
inch span and a 14-inch chord for 672
square inches of wing area.
The slab-profile fuselage length was
made 40 inches—compact overall, with
good proportions for lively flying. I used
large built-up control surfaces, but not
aimed at 3-D flying.
Weight was calculated to be
approximately 4 pounds, for a wing loading
of 14 ounces per square foot. That’s light,
and if the model came in slightly heavier it
would still be good.
A quick look shows that there is some
CL-type construction in this RC project.
The foam-core wings will not be sheeted
with balsa; the balsa top and bottom spars,
LE, TE, tip ribs, and plywood joiner will
provide plenty of strength, and a lowtemperature
iron-on plastic covering will
protect the foam a bit.
The fuselage is made from solid 1/2 balsa
with 1/8 plywood doublers on the nose
section. The fuselage is stronger than usual
because there is not a large cutout in it for
the wing to slide through; there is only a
vertical slot in the fuselage for the plywood
wing joiner. I got this idea from Phil Cartier,
who has considerable CL foam-core-wing
construction experience. The foam-core
wings butt up against either side of the
fuselage.
The wings and control surfaces are light
overall. The fuselage is somewhat heavy but
strong. This is not the lightest way to build
an airplane, but it’s a reasonable
compromise to get a model that is light
enough for good performance and can take a
little abuse without falling apart.
The fuselage should resist crashes, and
the wing panels can be fairly easily
replaced. The profile fuselage could be built
up or foam-cored for lighter weight, but it
would break more easily.
I constructed a prototype with my
amateur-cut foam wing cores and found that
it really was easy and quick to build. It came
out slightly heavier than I had hoped. I used
some hard wood and I used too much epoxy
glue, but even at almost 4.5 pounds with the
670 square inches of wing area, that’s a
wing loading of only 15 ounces per square
foot.
My prototype flew well! It had no bad
characteristics, did all the fun-fly aerobatic
stuff I could have it do, and withstood all
the snaps and spins I threw at it.
The SuperTigre GS-45 engine with an 11
x 5 propeller was more than enough power,
and I figured the model would also fly well
on electric power. To prove it I borrowed an
AXI 2826/10 brushless outrunner motor
turning an APC 11 x 7 electric propeller and
a Jeti 40-amp Opto ESC from a friend, and I
used my four-cell 4400 mAh Li-Poly battery
pack.
I mounted the AXI with a custommachined
aluminum adapter mount that Jim
Ehlen ([email protected]) manufactured,
which made it possible to retain the motor
on beam mounts set up for a glow engine. I
The 1/2-inch-thick balsa fuselage will be cut for the engine and mounts after the engine to
be used is chosen, to get the correct crankcase width.
The NJ One Design’s fuselage with the engine mounts and doublers assembled, with the
cut for the wing spar/joiner and built-up tail surfaces.
The wing panels are assembled using slow-cure epoxy to install the upper and lower
spars, LE, TE, and wingtip cap at the same time.
NJ One
Design
The 1/8 plywood servo mounts are epoxied into foam. The foam is
cut away for mounts and clearance for servos. Cavities ahead of
the spars are for the battery pack and receiver.
Aileron, elevator, and rudder servos in place. There is no throttle
servo; this is the electric-powered version of the model.
The wing panels with the ailerons built and hinges in place. The hinges will be
glued in after the airplane is assembled and covered.
Type: Easy-to-build RC sport
Wingspan: 49 inches
Wing area: 672 square inches
Weight: 4.0-4.5 pounds
Wing loading: Approximately 15 ounces/square foot
Length: 41 inches
Construction: Balsa, plywood, foam
Covering/finish: Iron-on plastic covering that can be
applied with a low-heat iron
Glow power: .40-.46 engine, 11 x 5 propeller
Electric power: AXI 2826/12 brushless outrunner
motor, Jeti Advance PLUS 40 Amp Opto ESC, 12
x 8 APC electric propeller, Poly-Quest four-cell
4400 mAh Li-Poly battery pack (600 watts)
NJ One Design Wood List
Fuselage
1/2 x 3 x 36 balsa Two pieces—fuselage
3/8 x 1/2 maple One piece—engine mounts
1/8 x 6 x 12 plywood Two pieces—nose doublers
Wings
3/8 x 1/2 x 36 balsa Four pieces—spars
1/4 x 1/2 x 36 balsa Two pieces—LE
3/8 x 1/2 x 36 balsa Two pieces—TE
1/8 x 6 x 12 plywood One piece—wing joiner
1/8 x 3 x 36 balsa One piece—wingtips
1/4 x 1/2 x 36 balsa Two pieces—ailerons
1/4 x 1/4 x 36 balsa Three pieces—ailerons
Tail Surfaces
1/4 x 4 x 36 balsa One piece—stabilizer, fin
1/4 x 1/2 x 36 balsa Two pieces—elevator,
rudder
1/4 x 1/4 x 36 balsa Two pieces—elevator,
rudder
Built-Up Wing, Ribs, and Sheeting
(or foam wing core by The Core House)
1/8 x 3 x 36 balsa Five pieces—ribs
3/32 x 4 x 36 Two pieces—sheeting MA
The fairly lightweight structure is rugged. Foam wing panels do not need to be sheeted
with balsa; they will be covered with low-temperature iron-on film.
Dick’s glow-powered model used a SuperTigre .45. The fuel
tank is held on with rubber bands. Note the muffler angle.
The electric version uses an AXI 2826/12 motor, Jeti 40-amp Opto ESC,
Ultimate BEC, and Poly-Quest four-cell 4400 mAh Li-Poly battery pack.
put the battery pack in place of the fuel
tank. I left the throttle servo and radio
battery in place; using a BEC would have
made the electric power installation even
lighter.
The airplane balanced roughly the same
as with the glow engine and flew well—
almost the same as with the SuperTigre. I
tried different propellers; with an APC 12 x
8 electric the AXI drew somewhat more
than 600 watts. I think the 2826/12 would
have been a better motor choice for this
application.
I figured that if I built this airplane
specifically for electric power, the plywood
nose doublers could be thinner, the maple
engine mounts would be eliminated, and a
firewall mount would be used, making that
version a good amount lighter than the
glow-powered version.
So I built a second model for electric
power. The results were great, and the glow
vs. electric comparison is discussed in more
detail in an accompanying sidebar.
Now that I knew the design worked, I
arranged to have Phil Cartier at The Core
House (34 Sweet Arrow Dr., Hummelstown
PA 17036) cut the foam wing cores using
his computer-controlled setup, which does
a great job. The cores are now
commercially available from The Core
House.
I worked up a wood materials list, and
with mail-order prices (I like Lone Star
Balsa) it would cost less than $20 for the
wood. I made the landing gear from 1/8 x 1-
inch 6061-T6 aluminum, but usable
commercial aluminum and composite gears
are available from several manufacturers.
I covered my airplane with Black Baron
Film because it’s applied with a low
temperature that will not harm the foam
wing cores. I found it extraordinarily easy
to use.
If you are used to buying ARFs, I can’t
say that building the NJ One Design will
save you a lot of money, and it would
certainly be more work than throwing an
ARF together. But if you feel that building
your airplane is part of the overall
modeling experience, if you want to know
how your model is built so you can easily
repair it, if you’d like knowing that you
built your airplane rather than just taking it
out of a box, or if you’re a do-it-yourselfer,
don’t hesitate to make some wood chips
and sawdust and scratch build your own
airplane!
The NJ One Design is an easy way to
try constructing a model from scratch, and I
think it adds to the fun of this hobby.
More than a dozen Monmouth club
members signed up to build this airplane as
a fun club project. And a half dozen guys
from the other local club, the Jersey Coast
Sport Fliers, got plans and foam wing cores
to try the project. So there are builders out
there!
Monmouth club member Ray Borden
digitized the plans from my pencils so
L-R: Ed Thieleman holds one of Dick’s models while Paul Gentile, Dick Sarpolus, Bob Serafin, and Pete Mularchuk Jr. show their NJ One
Designs. Another dozen airplanes are under construction by other members of the Monmouth Model Airplane Club.
I designed and built the NJ One Design for glow-engine
power with little thought for electric power. I really liked the
way the model flew with a SuperTigre .45 engine. Having
recently built my first .40-sized electric, I wondered about
powering the One Design with a motor.
I started by weighing my .45 glow engine, its muffler, the
fuel tank, the throttle servo, and the radio battery pack.
Those items weighed 26 ounces. Then I weighed an AXI
2826/12 motor, a Jeti 40-amp Opto ESC, an Ultimate BEC,
and a four-cell Poly-Quest 4400 mAh Li-Poly battery pack.
They weighed 23 ounces.
No glow fuel had to be added to fly. So if I put the
electric power system in the same airplane, it wouldn’t be
any heavier than it was with the glow engine. I did that,
using a light aluminum adapter mount to hold the AXI motor
in place. The aircraft’s balance point was unaffected.
I employed an APC 12 x 8 electric propeller, and the AXI
turned it approximately 8,500 rpm, drawing roughly 39 amps
for approximately 600 watts of power, measured on the
ground. The glow .45 was turning its 11 x 5 wooden
propeller at roughly 11,600 rpm.
I purchased the AXI brushless outrunner motor, Jeti ESC,
Ultimate BEC, and Poly-Quest Li-Poly from Hobby Lobby as
they were sold. I was familiar with that equipment, having had
some experience with it. There is a great deal of electric-power
equipment on the market to choose from, and I’m sure other
equipment could be used with results that wood be as good.
The NJ One Design flew almost the same! It jumped off
the ground quickly, climbed straight up, and did everything I
could do with the glow version in roughly the same way.
Thinking more about the weight-comparison issue, I had
left the 600 mAh Ni-Cd radio battery pack in the model and
the throttle servo in place to simplify the comparison flying.
If I built the airplane specifically for electric power, I’d use a
BEC and eliminate the Ni-Cd battery pack, leave out the
throttle servo, use thinner 1/16 plywood doublers on the nose
in place of the 1/8 plywood doublers, and leave out the
hardwood motor mounts. The electric-powered version
would be lighter.
So I did build another airplane—the same design—and
made no attempt to save airframe weight other than using
thinner plywood nose doublers and leaving out the hardwood
motor mounts. I made the nose 1/2 inch longer to make sure it
would balance properly. I used an Ultimate BEC so I would
not require a separate radio-system battery, and I didn’t need
a throttle servo.
The completed airplane was roughly 10 ounces lighter
than its glow-engine-powered twin.
Did it fly well? It sure did. I can’t honestly say there was
much difference in performance; I like the way both versions
fly.
Yes, the electric-power system components do cost more.
And I know that those who love the sound of a high-revving
glow engine and the smell and the feel of the exhaust may
never want to give those things up. The amount of money we
spend on our hobby is something each of us has to
determine.
If quiet operation, ease of operation, and cleanliness of
operation is important to us, and if the electric technology is
interesting to us, one thing is for sure: performance doesn’t
have to suffer when going from glow to electric power—at
least in this NJ One Design airplane. Options to suit each
person is what makes aeromodeling such a great hobby. MA
—Dick Sarpolus
NJ One Design: Glow Vs. Electric Power
This model likes to spend most of its time in the air in extreme positions! It’s aerobatic
and simple to build.
everyone would have good CAD plans
from which to work. We ordered a batch
of foam wing cores from The Core House,
made a bulk wood order from Lone Star,
cut some of the parts on my band saw, and
airplane production began. Within a
month or so some of the models began
showing up at our club flying field.
Practical experience has shown that
this airplane serves its purpose as a good
fun flier—particularly at our fairly small
field that can be tough on aircraft. This
model doesn’t survive all crashes, but it’s
pretty easy to repair after most of them.
I think pilots will be flying this design
for sometime. And the project has helped
our treasury; money made from this article
will go to the Monmouth Model Airplane
Club.
CONSTRUCTION
The following is for you who are new
to scratch-building.
You’ll need patterns for the parts that
have to be cut. Either cut the plans or trace
the parts outlines you need to make the
paper patterns.
Starting with the fuselage, epoxy two
pieces of 3-inch-wide 1/2 balsa together
and trace the fuselage outline for cutting.
A bit more balsa will be needed for the
canopy area of the fuselage; epoxy extra
wood together to make up what is needed.
Before you cut the nose area for the
engine mounts, make sure the spacing is
correct to suit the engine you’ll be using.
A slot needs to be cut through the fuselage
for the plywood wing joiner, and a hole
needs to be drilled for the TE dowel joiner
that ensures accurate positioning of the
wing panels.
The 1/8 plywood nose doublers, cut to
suit the engine being used, are epoxied on
both sides of the fuselage front end. The
plywood tail-wheel mount is epoxied to
the back end of the fuselage.
Moving on to the wing panels, a
vertical slot has to be cut into the foam
cores at their root ends for the 1/8 plywood
joiner. Sand the plywood joiner to make
sure it’s a good fit between the upper and
lower wing spars. The upper and lower
spars, LE, TE, and wingtip cap have to be
epoxied to the foam cores. If the spars are
too tight of a fit in the foam, sand the slots
a bit.
The TE pieces can be planed and
tapered to shape before or after they have
been glued to the foam cores—whichever
is easier for you. Round off the LEs after
the wood is glued into the foam.
At the root ends, sand the area ahead of
the spars to clear the fuselage plywood
doublers so the wing panels butt up flush
to the fuselage sides. Epoxy the plywood
joiner into one of the wing cores, and the
wing panels are ready for later assembly to
the fuselage.
Cut the horizontal and vertical
stabilizers to shape from 1/4 balsa, using
paper patterns. The ailerons, elevator
halves, and rudder are built up over the
plans from the 1/4 x 1/2 and 1/4 square balsa
strips. I use waxed paper over the plans
and small weights to hold the balsa strips
in place as I add and glue them to
complete the assemblies.
Bend a piece of 1/8-inch-diameter music
wire to shape as a joiner for the elevator
halves. At this point I cut the slots and fit
the nylon hinges in all the control surfaces;
they will be glued in place later, after the
airplane has been covered.
I glue the one wing panel with the
plywood joiner in place to the fuselage,
and then I glue the opposite panel in place.
The stabilizer can then be glued into the
fuselage, aligning it with the wing. Glue
the vertical fin to the fuselage, with its
dowel reinforcements.
All the control surfaces can be put into
place with their hinges, to check for proper
movement. The servos can be installed in
the top or bottom of the foam wing panels;
carve out recesses in the foam to clear the
servos, and epoxy plywood mounts into
the foam for mounting the servos.
Ahead of the spars hollow out an area
on one side of the fuselage for the battery
pack and on the other side for the receiver,
allowing enough room for some foam to
be wrapped around the battery and
receiver.
The servo leads can be routed through
the foam to reach the receiver. Thinplywood
removable hatches over the
receiver and battery areas are held in place
with small screws into plywood epoxied
into the foam.
Short wire linkages are used from the
30 MODEL AVIATION
aileron servos to the ailerons, and wire or
nylon tube pushrod setups to the elevator,
rudder, and throttle. I used a Du-Bro nylon
tail-wheel bracket. The aluminum or
composite landing gears are bolted to the
fuselage, and the fuel tank, or battery pack,
is held in place with rubber bands to eye
hooks. The whole model is finished with
an iron-on plastic covering; make sure to
use a material that can be applied with a
low-heat iron so the foam is not damaged.
My One Design balanced just behind
the wing-spars location, which suited me
fine. I set up the control surfaces, to start,
with aileron throw at 1/2 inch each way and
elevator throw approximately 3/4 inch each
way, on low rates, with much more
movement on high rates. I used all the
rudder throw I could get.
Airplane sensitivity is an individual
thing and should be adjusted to suit each
flier’s preference. Adjust the throws and
exponential if desired to get the airplane
feel that you prefer for your flying style
and comfort.
I’ve been asked why the hook in the
vertical fin. When the model goes into the
trees, it will hang up from a branch and be
easy to retrieve. I just thought it looked
different and not bad. I’m sure scratch
builders will eliminate that feature if they
don’t like its appearance.
If this is your first scratch-building
project, good! Make some sawdust and
wood chips, and, above all, have fun!
Enjoy the NJ One Design! MA
Dick Sarpolus
[email protected]