Super Sportwin - 2011/06

20 MODEL AVIATION
cTaphteio nbasic fuselage components are laid out. This model uses caption
basic box-type construction with a turtledeck to keep it simple.
This airplane needs to be built straight. Use clamps to ensure
that nothing moves while the glue dries.
IN 2001, at the height of the “Speed 400” craze, I designed
my original Sportwin. Spanning 38 inches with simple,
all-balsa construction, it was an instant hit.
Many Sportwins were built around the world, and it gained quite a
following as a fun, fast, quick-building, slick little electric twin. This model
shocked (no pun intended!) many people with its great handling and good
performance on the meager power that was available at the time.
Brushless motors came into vogue shortly after, and they were soon followed
by Li-Poly batteries. Both of those developments were major leaps forward in
power plant design for electric models.
No longer was it necessary to watch every gram; an abundance of power was
at your service. Numerous Sportwins were built with brushless and Li-Poly
power, and some were extremely quick.
A sleek twin-motor
electric that is
built for speed
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:26 AM Page 20
June 2011 21
Half of the rear deck is glued and held in place with T-pins. The
other half is wet and ready to be glued in the same fashion.
The empennage uses simple sheet vertical and horizontal
stabilizers. The small filler pieces that are shown were added
to finish it off.
by Mark Rittinger Sportwin
Super
The Super Sportwin is elegant and
exciting in the air and on the ground.
06sig1x.QXD_00MSTA carved, drooped wingtip is worth the work. It helps with both
stability and efficiency.
The basic nacelle structure shows retracts, servo, and motor
installed.
Dowel pegs help align the nacelle on the wing and spread the load.
Use epoxy to adhere the nacelle to the wing.
Sand nacelles, if necessary, and confirm that both fit at 0°.
Above: Each nacelle has a hatch for easy access to
the motor and ESC. The author used E-flite
aluminum spinners for their clean look.
Left: Once all of the structures have been built, it’s
time to cover and then assemble the SST. MonoKote
and UltraCote covering were used on the prototypes.
Photos by the author
22 MODEL AVIATION
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:29 AM Page 22
RPG.QXD 4/21/11 9:25 AM Page 21
CLOSE
caption
June 2011 23
Super Sportwin
The completed and
temporarily assembled
model shows its Sportwin
heritage and clean lines.
The finished model is sexy and fast.
The 750 watts of power makes it move!
Type: RC sport
Skill level: Intermediate builder;
intermediate pilot
Wingspan: 50 inches
Wing area: 450 square inches
Length: 431/4 inches
Weight: 4 pounds, 7 ounces
Power: Two E-flite Power 10
outrunner motors; two E-flite 40-
Amp Pro ESCs; two 2600 mAh,
three-cell Li-Poly or one 5000
mAh, three-cell Li-Poly battery
Propeller: APC 9 x 9
Construction: Balsa-sheeted foam wing; balsa-andplywood
fuselage, empennage, nacelles
Finish: Iron-on covering
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:31 AM Page 23
24 MODEL AVIATION
Full-Size Plans Available—See Page 171
Super Sportwin
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:32 AM Page 24
June 2011 25
I Not long after the design hit, I was asked
to design a larger model with a landing gear
or possibly retractable undercarriage. I was
busy designing Scale aircraft, so I kept
pushing the request back, waiting for the right
time.
During the summer of 2009 I saw Denny
Sumner flying a Sportwin at the Mid-America
Electric Flies meet, and that reminded me
what a great little design it was. The bug bit
me again—and hard. I sat down and drew the
Super Sportwin a few days later.
I competed at thae 2010 Toledo Weak
Signals R/C Show with the new “SST.” It
placed second in Sport Plane category 30
years after my dad won the now-defunct 1/2A
category.
This is not merely a scaled-up rendering of
the Sportwin. It’s an entirely new model,
designed from the ground up, using the
general shapes of the Speed 400 version.
There are many differences.
The SST wing is made from foam and
removable, the airfoil is semisymmetrical, the
tail is longer, the stabilizer is larger, it has
retracts, rudder, and 1 horsepower (750 watts)
hauls it around the big blue!
Although this is not a beginner’s model in
the sense of construction or flying, anyone
who has scratch-built an airplane should have
no problems with it. My designs feature
hidden right angles or straight lines that might
not be readily apparent.
I have arranged for Bob Hunt, of CL
Aerobatics fame, to make wing cores
available, and they are perfect. Robart and Eflite
retracts fit in the nacelles with minor
trimming.
So if you are still interested, let’s get
building!
CONSTRUCTION
Fuselage: This part of the SST is fairly
straightforward; it’s a basic box type with a
turtledeck. All wood dimensions are inches.
Cut matching sides from medium 3/32
balsa. Cut the top turtledeck section oversize,
to allow for the curvature.
Add the 1/8 square spruce stringer, 3/32
balsa doubler from wing TE to nose, and 1/2
triangle stock along the bottom front and rear
of the fuselage. Glue in the stabilizer mount
doubler and small 3/16 sheet tripler in the nose.
Slice F2 from 1/8 plywood, and glue on the
1/8 square spruce and F2 doubler, also from 1/8
plywood. Glue to left side as shown on the
plans.
Cut F3 and F3B from two layers of crossgrain
1/16 balsa. Pay attention to the 45° angle
of the notches. Glue to the left fuselage side
against the doubler.
Carefully line up the left and right sides,
and adhere them at F2 and F3. Using the top
view, glue the tail together.
Cut F1 from layered 1/16 balsa and glue in
place in the nose. The fuselage side doubler
should stop 1/8 inch from the nose, to allow
for fitment of F1. Slide F4 and F5 into place
and glue. Install the three 1/4 square rear deck
stringers.
Wet one fuselage side on the turtledeck
with hot water on the outside only, and it will
begin to bend toward the center stringer. Mark
the center and cut to size. Glue to the top and
side stringer and repeat for the other side.
Sheet the bottom rear section with 1/16
balsa. Cut to rough shape and glue on the top
nose block and nose. Do not sheet the lower
nose at this time.
Add the hardwood wing hold-down blocks
and 1/8 plywood plates. By now the structure
looks like a submarine!
Build the hatch directly on top of the
fuselage. Using 1/16 with grain running side to
side, lay the hatch floor. Sand to match the
sides of the fuselage.
Glue on the 1/8 square, H1 through H5,
triangle braces, and stringers. Plank or sheet
the hatch with 3/32 balsa. On the underside of
the hatch, you can add hatch-alignment aids
from scrap balsa, magnet hold-downs, or
rubber band hooks.
Sand everything to be ultraslick, and set
aside to work on the wing.
Wing: This is a simple foam affair, sheeted
with 1/16 balsa, using a single aileron servo.
I’ve grown tired of seeing ugly servos
sticking out all over pretty models, so take a
few extra minutes to make a clean aileronservo
installation.
Using the templates on the plans, cut the
cores with 3/16 inch of washout per tip or order
them from Bob Hunt.
Lightly sand the cores to remove the
cutting fuzz. Assemble the core sheeting from
48-inch-long sheets of matched 1/16 balsa. I
used six pieces of 3 x 48 x 1/16.
Cut the core sheeting slightly oversized
using the core as a template. Spray the
sheeting with a light coat of plain hair spray,
to aid in adhesion.
To sheet the foam, I used finishing resin
and made a “wing press” from two 24-inchsquare
pieces of 11/2-inch-thick hardwood. I
drilled six holes through and inserted threaded
rods.
I spread a thin coat of resin on the cores,
placed them in their beds with the sheeting,
and put them in the press. Tightening the nuts
put even, firm pressure on the cores until they
were dry, which was approximately six hours.
If you have a flat workbench and heavy
weights, that will work just as well. Other
glues such as wood glue, contact cements, and
epoxy will also work to sheet the wings. The
key is a true surface. Uneven, warped wings
perform poorly.
After the wings are sheeted, add the 1/4
hard balsa LE and the 1/8 balsa rear cap. Sand
to shape. Sand the root to match 4° (13/4
inches) per panel dihedral, and epoxy them
together, ensuring that they are aligned.
Decide on the wingtip shape you will use,
and add them to the tips. Add the center TE
section, plywood wing mount, and torque
rods.
Cut the hole for the aileron servo. Sand the
LE flat to match the opening in the fuselage,
and sand the wing to perfectly fit the fuselage
opening.
Cut ailerons to fit, and drill holes for the
torque rods. I used floppy disk material for
hinges, after covering.
Mark locations for the ESC, retract (if
used), and power wires to run through the
06sig1x.QXD_00MSTRPG.QXD 4/20/11 11:21 AM Page 25
26 MODEL AVIATION
wing from the center fuselage area to the
nacelles.
Use an X-Acto knife to slice a “V” in the
sheeting where the wires will run. I run the
motor power wires approximately 1 inch or
more from the ESC signal wires, and I twist
the positive and negative power wires to
reduce radio frequency interference issues.
Remove the foam from the V piece cut
from the wing, install the wires, and glue the
piece back on. Wrap the center-section with
two layers of fiberglass or nylon cloth and 30-
minute epoxy.
Carefully align the wing in the fuselage,
and clamp in place. Use a long 1/4-inch drill to
make a hole through F2 and its doubler into
the wing for two wing-alignment dowels.
Screw an old nylon wing screw, ground to
a point, through from inside the fuselage to
mark the wing hold-down-screw locations.
Remove the clamps, and install two 1/4-
inch dowels in the wing with epoxy. Drill
holes through the wing for the nylon screws.
Attach the wing to the fuselage and
double-check alignment. It should be straight
and fit tight to the fuselage. If it isn’t find out
what is off and adjust it.
Now you can build, from scrap balsa, the
lower center-section under the wing, and sand
it to fit. You can also sheet the lower fuselage
nose and sand it to a nice contour—something
similar to a cross between a P-38 and a de
Havilland Comet.
Empennage: The SST uses simple sheet
vertical and horizontal stabilizers. Cut the
horizontal stabilizer from 3/8 light balsa, add
the tips, and sand to an airfoil shape as shown.
Cut the elevators from 1/4 balsa, and taper
to match the stabilizer. Make a joiner from 3/32
music or piano wire, and fit to the elevator
halves.
Using an incidence meter, set the wing to
0°, make it immobile with weights or
sandbags, and sand the fuselage to get -1/2° in
the stabilizer.
Cut the fin, rudder, dorsal, and skeg from
3/16 balsa, and sand to fit the fuselage. The fin
is glued to the top of the fuselage and the top
of the stabilizer, and small filler pieces are
added to finish it.
I do not install the fin and stabilizer until
after covering. I find it much easier to cover
this way.
The tail wheel wire runs through a tube
and into the fin. Denny built the second
prototype, and he elected to make the rudder
run all the way to the bottom of the model;
you can do that too.
Nacelles: The nacelles are built around a
frame of plywood and balsa. Use aircraftgrade
plywood in this area; light plywood
won’t hold up.
At this point you must decide what motors
you will use and what type of retracts, if any.
This model can be simplified significantly by
making it hand-launchable or with fixed gear.
Firewall location and servo/retract location are
much easier to adjust now than later.
If you plan on employing inrunner motors,
use a 3/16 plywood front mount firewall. For
rear-mounted outrunner types, use the rear 3/16
plywood firewall. Pylon racers who use glow
engines taught me that a solid firewall is
essential for reducing rpm-robbing vibration.
Cut N1 and N2 from 1/8 plywood. Make
the opening on the rear of N2 the required size
to clear the retracts. The plans fit the Robart
600 series.
Epoxy N1 to N2 and add N3, made from
1/8 balsa. These are right-angle pieces. Add the
maple or spruce hardwood retract bearing
rails. Glue on the 1/4 stringers and the nose
firewall. The 1/4 square stringers can be used
as datum.
If you’re using the rear firewall, cut it from
3/16 plywood. Depending on your motors, you
can move it forward or rearward and it is still
on the datum thrustline. Neat, huh?
You might need to trim or add slightly to
the firewall bottom to fit it in place. Mark and
drill for the motor mounts and epoxy in place.
Fit the retract servo, or retract unit if using
electric units. Bend the legs to match the plans
or to fit your application. Test operation,
because things are better to fix now rather
than later. I used mini ball links with metalgear
servos to operate the retracts.
The inner and outer referred to on the
nacelle sides relates to wing orientation; inner
is toward the root and outer is toward the tip.
Cut an “inner” and an “outer” side from 1/16
balsa and glue one on each side. Be positive
that these are on straight.
Cut a second side of each, and glue to the
nacelles back to N3, but no farther than that.
You should now have 1/8-inch-thick nacelle
sides. Glue the 1/8 top and bottom fillers in
place.
Wet the rear sides of the nacelles, and pin
or clamp together along the rear edge. Let dry
and then remove pins and glue together.
That’s how you make 1/8-inch wood bend that
tight; do it in layers.
Add the lower front and rear blocks, and
make the gear doors or center filler block with
retract gear hole. I initially made clamshell
gear doors, but after much fuss I decided that
holes to clear the gear were much more
simple and lighter.
Denny made removable pieces, with
dowels and magnets to hold them on. This
way he can still remove them for
maintenance. Add the 1/4-inch-diameter
dowels that go up into the wing cores.
Build the hatches directly on the nacelles
by gluing NH1, NH2, and NH3 on top of two
strips of 1/8 x 1/4 balsa and planking with 1/8 x
1/4 balsa strips. I used clothing snaps in the
front and a magnet on the rear to hold them in
place. You might find that the hatches are
easier to assemble after the nacelles are glued
to the wing.
Repeat construction for the second nacelle,
being sure not to build two left or right ones!
Final Assembly/Covering: If you stand the
wing on its TE, you can mark 9 inches from
the centerline of the wing to each nacelle
centerline, and mark them with a triangle on
the wing bottom sheeting.
Mark the holes and drill for the 1/4-inchdiameter
dowels in the nacelles. Fit all wiring
through the nacelle opening, and trial-fit the
nacelles. Use an incidence meter and/or
06sig1x.QXD_00MSTRPG.QXD 4/20/11 11:21 AM Page 26
levels and draw sand for perfect fitment.
Epoxy the nacelles to the wing bottom.
Since there are many hidden right angles in
this design, they come in handy. If you have a
long triangle, use it to ensure that the nacelles
are glued on aligned. They can also easily be
measured as 18 inches from center to center at
the front and at the rear.
A good-performing model must be
assembled straight. Trimming in the air can
correct for only so much, and a straight
airplane flies much better than one with
something that is off and corrected for with
trim.
Trial-fit the fin/rudder and double-check to
make sure that the stabilizer has -1/2°.
I cover the SST at this point. I used white
and Metallic Wine MonoKote on mine, and
Denny used red UltraCote. I strongly suggest
employing a vibrant color scheme with large
panels of bright colors; it makes this aircraft
much easier to see in the air.
After covering, hinge the surfaces using
pieces cut from floppy disk material. I use thin
CA to adhere them in place and have yet to
have one break. Stock up if you see floppy
disks in a store; they are becoming rare.
Glue on the stabilizer, making sure that it’s
aligned, and then glue on the fin with the
dorsal.
Glue on the canopy. I used a Great Planes
Spirit glider unit, trimmed to fit. I’m sure that
others will fit as well, so don’t be afraid to
look around.
Equipment Installation: I am using a Hitec
Eclipse 7 radio system with a 2.4 GHz
module, also from Hitec. This combo has
worked flawlessly, with no interference from
any of the wiring or motors.
The radio install is rather straightforward,
having one aileron servo (HS-65MG) with
torque rods, one elevator servo (HS-82MG),
one rudder servo (HS-82MG), and retract
servos in the nacelles.
I mounted the rudder and elevator servos
directly behind the wing, on hardwood rails.
The receiver is mounted on the fuselage side
with double-stick tape.
Make pushrods using 1/4 spruce and
threaded ends. For the best in precision, you
can use ball links on the pushrods.
My SST has 750 watts of power on tap
from two incredibly reliable E-flite Power 10
1100 Kv motors. I also equipped it with 9 x 9
APC propellers and E-flite aluminum
spinners.
These motors have big, sturdy shafts and
bearings, and they really put out the power
while staying cool. Mount your motors to the
firewall, and hook up the ESCs.
I’m using the E-flite 40-Amp Pro heatsinked
speed controller and one BEC, by
disconnecting the red wire on one of the
ESCs. These are capable of handling up to
seven servos each and have performed well as
set up. You can use a separate BEC if you
prefer, but I see no need.
I’ve been flying with two 2600 mAh, 11.1-
volt 30C Li-Poly packs—one for each
individual ESC. You can set yours up this way
or as Denny has done, with one 5000 mAh,
11.1-volt pack powering both ESCs. Whatever
June 2011 27
you choose, make sure that the battery and the
connector(s) can handle the amperage draw.
Use a hook-and-loop fastener to hold your
battery in place, and make sure that it has
adequate cooling air going over it.
Balance at the forward point shown on the
plans for the model’s first flights, and then
move it rearward. Don’t go past 33%, or it
gets a bit “twitchy.”
Initial control throws are:
Low:
Aileron: 3/16 up/down
Elevator: 1/4 up/down
Rudder: 1/2 left/right (at bottom)
High:
Aileron: 1/4 up/down
Elevator: 3/8 up/down
Rudder: 1 left/right (at bottom)
Flying: As you always should, double- and
triple-check the throws on low and high rates
and for the proper direction of surface travel.
You might prefer to add exponential.
Have a buddy hold the model at least a
foot off of the ground and do a motor-running
range check. Never skip this step! Just
because you have 2.4 GHz capability does not
mean there might not be issues.
If everything seems good to go, install
fully charged batteries and get a feeling for the
SST’s ground handling. I’ve learned that a
few degrees of toe-in on the main gear helps
greatly. I tend to get a good feel for a model
before just jumping it off the ground.
Line up the airplane into the wind and
smoothly apply power. You’ll find that it likes
heavy right rudder until the tail lifts, and then
you can let off slightly. I use high-rate rudder
until flying and then switch to low.
Once the aircraft is up on the mains, apply
more power and it will smoothly lift off. Gain
some altitude and trim it out.
Test the stall and glide ratio. You’ll see
that the SST is fast and glides well. Line up
for landing with a great deal of ground in front
of it, to allow for that flat, fast glide.
Once back on the ground, give it a
thorough examination. Make sure that there
are no loose parts or equipment.
Now you can take this model up and wring
it out! Put a fresh pack or packs in and go up
again. You can do all of the RC Aerobatics
(Pattern) moves with it and outrun some glow
racers. The SST tracks like a Pattern model
with the speed of a racer.
Huge loops and vertical moves are easy,
and this airplane will do well inverted with
some practice. It also does good four-point
rolls and slow rolls.
I hope you enjoy your Super Sportwin as
much as I do! I’ll bet you’ll turn a few heads
at the flying field and swell with pride when
flying it. MA
Mark Rittinger
[email protected]
Sources:
Bob Hunt
(610) 746-0106
[email protected]
E-flite
(800) 338-4639
www.e-fliterc.com
Hitec RCD
(858) 748-6948
www.hitecrcd.com
APC
(530) 661-0399
www.apcprop.com
Robart
(630) 584-7616
www.robart.com
Why Pay a Dollar
for just 4 Screws?
W e h a v e t h e h a r d w a r e y o u n e e d
at a fraction of retail!
Order today at:
www.rtlfasteners.com
or call 800-239-6010
708 Battlefield Blvd South #107
Chesapeake, VA 23322
06sig1x.QXD_00MSTRPG.QXD 4/20/11 11:21 AM Page 27

20 MODEL AVIATION
cTaphteio nbasic fuselage components are laid out. This model uses caption
basic box-type construction with a turtledeck to keep it simple.
This airplane needs to be built straight. Use clamps to ensure
that nothing moves while the glue dries.
IN 2001, at the height of the “Speed 400” craze, I designed
my original Sportwin. Spanning 38 inches with simple,
all-balsa construction, it was an instant hit.
Many Sportwins were built around the world, and it gained quite a
following as a fun, fast, quick-building, slick little electric twin. This model
shocked (no pun intended!) many people with its great handling and good
performance on the meager power that was available at the time.
Brushless motors came into vogue shortly after, and they were soon followed
by Li-Poly batteries. Both of those developments were major leaps forward in
power plant design for electric models.
No longer was it necessary to watch every gram; an abundance of power was
at your service. Numerous Sportwins were built with brushless and Li-Poly
power, and some were extremely quick.
A sleek twin-motor
electric that is
built for speed
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:26 AM Page 20
June 2011 21
Half of the rear deck is glued and held in place with T-pins. The
other half is wet and ready to be glued in the same fashion.
The empennage uses simple sheet vertical and horizontal
stabilizers. The small filler pieces that are shown were added
to finish it off.
by Mark Rittinger Sportwin
Super
The Super Sportwin is elegant and
exciting in the air and on the ground.
06sig1x.QXD_00MSTA carved, drooped wingtip is worth the work. It helps with both
stability and efficiency.
The basic nacelle structure shows retracts, servo, and motor
installed.
Dowel pegs help align the nacelle on the wing and spread the load.
Use epoxy to adhere the nacelle to the wing.
Sand nacelles, if necessary, and confirm that both fit at 0°.
Above: Each nacelle has a hatch for easy access to
the motor and ESC. The author used E-flite
aluminum spinners for their clean look.
Left: Once all of the structures have been built, it’s
time to cover and then assemble the SST. MonoKote
and UltraCote covering were used on the prototypes.
Photos by the author
22 MODEL AVIATION
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:29 AM Page 22
RPG.QXD 4/21/11 9:25 AM Page 21
CLOSE
caption
June 2011 23
Super Sportwin
The completed and
temporarily assembled
model shows its Sportwin
heritage and clean lines.
The finished model is sexy and fast.
The 750 watts of power makes it move!
Type: RC sport
Skill level: Intermediate builder;
intermediate pilot
Wingspan: 50 inches
Wing area: 450 square inches
Length: 431/4 inches
Weight: 4 pounds, 7 ounces
Power: Two E-flite Power 10
outrunner motors; two E-flite 40-
Amp Pro ESCs; two 2600 mAh,
three-cell Li-Poly or one 5000
mAh, three-cell Li-Poly battery
Propeller: APC 9 x 9
Construction: Balsa-sheeted foam wing; balsa-andplywood
fuselage, empennage, nacelles
Finish: Iron-on covering
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:31 AM Page 23
24 MODEL AVIATION
Full-Size Plans Available—See Page 171
Super Sportwin
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:32 AM Page 24
June 2011 25
I Not long after the design hit, I was asked
to design a larger model with a landing gear
or possibly retractable undercarriage. I was
busy designing Scale aircraft, so I kept
pushing the request back, waiting for the right
time.
During the summer of 2009 I saw Denny
Sumner flying a Sportwin at the Mid-America
Electric Flies meet, and that reminded me
what a great little design it was. The bug bit
me again—and hard. I sat down and drew the
Super Sportwin a few days later.
I competed at thae 2010 Toledo Weak
Signals R/C Show with the new “SST.” It
placed second in Sport Plane category 30
years after my dad won the now-defunct 1/2A
category.
This is not merely a scaled-up rendering of
the Sportwin. It’s an entirely new model,
designed from the ground up, using the
general shapes of the Speed 400 version.
There are many differences.
The SST wing is made from foam and
removable, the airfoil is semisymmetrical, the
tail is longer, the stabilizer is larger, it has
retracts, rudder, and 1 horsepower (750 watts)
hauls it around the big blue!
Although this is not a beginner’s model in
the sense of construction or flying, anyone
who has scratch-built an airplane should have
no problems with it. My designs feature
hidden right angles or straight lines that might
not be readily apparent.
I have arranged for Bob Hunt, of CL
Aerobatics fame, to make wing cores
available, and they are perfect. Robart and Eflite
retracts fit in the nacelles with minor
trimming.
So if you are still interested, let’s get
building!
CONSTRUCTION
Fuselage: This part of the SST is fairly
straightforward; it’s a basic box type with a
turtledeck. All wood dimensions are inches.
Cut matching sides from medium 3/32
balsa. Cut the top turtledeck section oversize,
to allow for the curvature.
Add the 1/8 square spruce stringer, 3/32
balsa doubler from wing TE to nose, and 1/2
triangle stock along the bottom front and rear
of the fuselage. Glue in the stabilizer mount
doubler and small 3/16 sheet tripler in the nose.
Slice F2 from 1/8 plywood, and glue on the
1/8 square spruce and F2 doubler, also from 1/8
plywood. Glue to left side as shown on the
plans.
Cut F3 and F3B from two layers of crossgrain
1/16 balsa. Pay attention to the 45° angle
of the notches. Glue to the left fuselage side
against the doubler.
Carefully line up the left and right sides,
and adhere them at F2 and F3. Using the top
view, glue the tail together.
Cut F1 from layered 1/16 balsa and glue in
place in the nose. The fuselage side doubler
should stop 1/8 inch from the nose, to allow
for fitment of F1. Slide F4 and F5 into place
and glue. Install the three 1/4 square rear deck
stringers.
Wet one fuselage side on the turtledeck
with hot water on the outside only, and it will
begin to bend toward the center stringer. Mark
the center and cut to size. Glue to the top and
side stringer and repeat for the other side.
Sheet the bottom rear section with 1/16
balsa. Cut to rough shape and glue on the top
nose block and nose. Do not sheet the lower
nose at this time.
Add the hardwood wing hold-down blocks
and 1/8 plywood plates. By now the structure
looks like a submarine!
Build the hatch directly on top of the
fuselage. Using 1/16 with grain running side to
side, lay the hatch floor. Sand to match the
sides of the fuselage.
Glue on the 1/8 square, H1 through H5,
triangle braces, and stringers. Plank or sheet
the hatch with 3/32 balsa. On the underside of
the hatch, you can add hatch-alignment aids
from scrap balsa, magnet hold-downs, or
rubber band hooks.
Sand everything to be ultraslick, and set
aside to work on the wing.
Wing: This is a simple foam affair, sheeted
with 1/16 balsa, using a single aileron servo.
I’ve grown tired of seeing ugly servos
sticking out all over pretty models, so take a
few extra minutes to make a clean aileronservo
installation.
Using the templates on the plans, cut the
cores with 3/16 inch of washout per tip or order
them from Bob Hunt.
Lightly sand the cores to remove the
cutting fuzz. Assemble the core sheeting from
48-inch-long sheets of matched 1/16 balsa. I
used six pieces of 3 x 48 x 1/16.
Cut the core sheeting slightly oversized
using the core as a template. Spray the
sheeting with a light coat of plain hair spray,
to aid in adhesion.
To sheet the foam, I used finishing resin
and made a “wing press” from two 24-inchsquare
pieces of 11/2-inch-thick hardwood. I
drilled six holes through and inserted threaded
rods.
I spread a thin coat of resin on the cores,
placed them in their beds with the sheeting,
and put them in the press. Tightening the nuts
put even, firm pressure on the cores until they
were dry, which was approximately six hours.
If you have a flat workbench and heavy
weights, that will work just as well. Other
glues such as wood glue, contact cements, and
epoxy will also work to sheet the wings. The
key is a true surface. Uneven, warped wings
perform poorly.
After the wings are sheeted, add the 1/4
hard balsa LE and the 1/8 balsa rear cap. Sand
to shape. Sand the root to match 4° (13/4
inches) per panel dihedral, and epoxy them
together, ensuring that they are aligned.
Decide on the wingtip shape you will use,
and add them to the tips. Add the center TE
section, plywood wing mount, and torque
rods.
Cut the hole for the aileron servo. Sand the
LE flat to match the opening in the fuselage,
and sand the wing to perfectly fit the fuselage
opening.
Cut ailerons to fit, and drill holes for the
torque rods. I used floppy disk material for
hinges, after covering.
Mark locations for the ESC, retract (if
used), and power wires to run through the
06sig1x.QXD_00MSTRPG.QXD 4/20/11 11:21 AM Page 25
26 MODEL AVIATION
wing from the center fuselage area to the
nacelles.
Use an X-Acto knife to slice a “V” in the
sheeting where the wires will run. I run the
motor power wires approximately 1 inch or
more from the ESC signal wires, and I twist
the positive and negative power wires to
reduce radio frequency interference issues.
Remove the foam from the V piece cut
from the wing, install the wires, and glue the
piece back on. Wrap the center-section with
two layers of fiberglass or nylon cloth and 30-
minute epoxy.
Carefully align the wing in the fuselage,
and clamp in place. Use a long 1/4-inch drill to
make a hole through F2 and its doubler into
the wing for two wing-alignment dowels.
Screw an old nylon wing screw, ground to
a point, through from inside the fuselage to
mark the wing hold-down-screw locations.
Remove the clamps, and install two 1/4-
inch dowels in the wing with epoxy. Drill
holes through the wing for the nylon screws.
Attach the wing to the fuselage and
double-check alignment. It should be straight
and fit tight to the fuselage. If it isn’t find out
what is off and adjust it.
Now you can build, from scrap balsa, the
lower center-section under the wing, and sand
it to fit. You can also sheet the lower fuselage
nose and sand it to a nice contour—something
similar to a cross between a P-38 and a de
Havilland Comet.
Empennage: The SST uses simple sheet
vertical and horizontal stabilizers. Cut the
horizontal stabilizer from 3/8 light balsa, add
the tips, and sand to an airfoil shape as shown.
Cut the elevators from 1/4 balsa, and taper
to match the stabilizer. Make a joiner from 3/32
music or piano wire, and fit to the elevator
halves.
Using an incidence meter, set the wing to
0°, make it immobile with weights or
sandbags, and sand the fuselage to get -1/2° in
the stabilizer.
Cut the fin, rudder, dorsal, and skeg from
3/16 balsa, and sand to fit the fuselage. The fin
is glued to the top of the fuselage and the top
of the stabilizer, and small filler pieces are
added to finish it.
I do not install the fin and stabilizer until
after covering. I find it much easier to cover
this way.
The tail wheel wire runs through a tube
and into the fin. Denny built the second
prototype, and he elected to make the rudder
run all the way to the bottom of the model;
you can do that too.
Nacelles: The nacelles are built around a
frame of plywood and balsa. Use aircraftgrade
plywood in this area; light plywood
won’t hold up.
At this point you must decide what motors
you will use and what type of retracts, if any.
This model can be simplified significantly by
making it hand-launchable or with fixed gear.
Firewall location and servo/retract location are
much easier to adjust now than later.
If you plan on employing inrunner motors,
use a 3/16 plywood front mount firewall. For
rear-mounted outrunner types, use the rear 3/16
plywood firewall. Pylon racers who use glow
engines taught me that a solid firewall is
essential for reducing rpm-robbing vibration.
Cut N1 and N2 from 1/8 plywood. Make
the opening on the rear of N2 the required size
to clear the retracts. The plans fit the Robart
600 series.
Epoxy N1 to N2 and add N3, made from
1/8 balsa. These are right-angle pieces. Add the
maple or spruce hardwood retract bearing
rails. Glue on the 1/4 stringers and the nose
firewall. The 1/4 square stringers can be used
as datum.
If you’re using the rear firewall, cut it from
3/16 plywood. Depending on your motors, you
can move it forward or rearward and it is still
on the datum thrustline. Neat, huh?
You might need to trim or add slightly to
the firewall bottom to fit it in place. Mark and
drill for the motor mounts and epoxy in place.
Fit the retract servo, or retract unit if using
electric units. Bend the legs to match the plans
or to fit your application. Test operation,
because things are better to fix now rather
than later. I used mini ball links with metalgear
servos to operate the retracts.
The inner and outer referred to on the
nacelle sides relates to wing orientation; inner
is toward the root and outer is toward the tip.
Cut an “inner” and an “outer” side from 1/16
balsa and glue one on each side. Be positive
that these are on straight.
Cut a second side of each, and glue to the
nacelles back to N3, but no farther than that.
You should now have 1/8-inch-thick nacelle
sides. Glue the 1/8 top and bottom fillers in
place.
Wet the rear sides of the nacelles, and pin
or clamp together along the rear edge. Let dry
and then remove pins and glue together.
That’s how you make 1/8-inch wood bend that
tight; do it in layers.
Add the lower front and rear blocks, and
make the gear doors or center filler block with
retract gear hole. I initially made clamshell
gear doors, but after much fuss I decided that
holes to clear the gear were much more
simple and lighter.
Denny made removable pieces, with
dowels and magnets to hold them on. This
way he can still remove them for
maintenance. Add the 1/4-inch-diameter
dowels that go up into the wing cores.
Build the hatches directly on the nacelles
by gluing NH1, NH2, and NH3 on top of two
strips of 1/8 x 1/4 balsa and planking with 1/8 x
1/4 balsa strips. I used clothing snaps in the
front and a magnet on the rear to hold them in
place. You might find that the hatches are
easier to assemble after the nacelles are glued
to the wing.
Repeat construction for the second nacelle,
being sure not to build two left or right ones!
Final Assembly/Covering: If you stand the
wing on its TE, you can mark 9 inches from
the centerline of the wing to each nacelle
centerline, and mark them with a triangle on
the wing bottom sheeting.
Mark the holes and drill for the 1/4-inchdiameter
dowels in the nacelles. Fit all wiring
through the nacelle opening, and trial-fit the
nacelles. Use an incidence meter and/or
06sig1x.QXD_00MSTRPG.QXD 4/20/11 11:21 AM Page 26
levels and draw sand for perfect fitment.
Epoxy the nacelles to the wing bottom.
Since there are many hidden right angles in
this design, they come in handy. If you have a
long triangle, use it to ensure that the nacelles
are glued on aligned. They can also easily be
measured as 18 inches from center to center at
the front and at the rear.
A good-performing model must be
assembled straight. Trimming in the air can
correct for only so much, and a straight
airplane flies much better than one with
something that is off and corrected for with
trim.
Trial-fit the fin/rudder and double-check to
make sure that the stabilizer has -1/2°.
I cover the SST at this point. I used white
and Metallic Wine MonoKote on mine, and
Denny used red UltraCote. I strongly suggest
employing a vibrant color scheme with large
panels of bright colors; it makes this aircraft
much easier to see in the air.
After covering, hinge the surfaces using
pieces cut from floppy disk material. I use thin
CA to adhere them in place and have yet to
have one break. Stock up if you see floppy
disks in a store; they are becoming rare.
Glue on the stabilizer, making sure that it’s
aligned, and then glue on the fin with the
dorsal.
Glue on the canopy. I used a Great Planes
Spirit glider unit, trimmed to fit. I’m sure that
others will fit as well, so don’t be afraid to
look around.
Equipment Installation: I am using a Hitec
Eclipse 7 radio system with a 2.4 GHz
module, also from Hitec. This combo has
worked flawlessly, with no interference from
any of the wiring or motors.
The radio install is rather straightforward,
having one aileron servo (HS-65MG) with
torque rods, one elevator servo (HS-82MG),
one rudder servo (HS-82MG), and retract
servos in the nacelles.
I mounted the rudder and elevator servos
directly behind the wing, on hardwood rails.
The receiver is mounted on the fuselage side
with double-stick tape.
Make pushrods using 1/4 spruce and
threaded ends. For the best in precision, you
can use ball links on the pushrods.
My SST has 750 watts of power on tap
from two incredibly reliable E-flite Power 10
1100 Kv motors. I also equipped it with 9 x 9
APC propellers and E-flite aluminum
spinners.
These motors have big, sturdy shafts and
bearings, and they really put out the power
while staying cool. Mount your motors to the
firewall, and hook up the ESCs.
I’m using the E-flite 40-Amp Pro heatsinked
speed controller and one BEC, by
disconnecting the red wire on one of the
ESCs. These are capable of handling up to
seven servos each and have performed well as
set up. You can use a separate BEC if you
prefer, but I see no need.
I’ve been flying with two 2600 mAh, 11.1-
volt 30C Li-Poly packs—one for each
individual ESC. You can set yours up this way
or as Denny has done, with one 5000 mAh,
11.1-volt pack powering both ESCs. Whatever
June 2011 27
you choose, make sure that the battery and the
connector(s) can handle the amperage draw.
Use a hook-and-loop fastener to hold your
battery in place, and make sure that it has
adequate cooling air going over it.
Balance at the forward point shown on the
plans for the model’s first flights, and then
move it rearward. Don’t go past 33%, or it
gets a bit “twitchy.”
Initial control throws are:
Low:
Aileron: 3/16 up/down
Elevator: 1/4 up/down
Rudder: 1/2 left/right (at bottom)
High:
Aileron: 1/4 up/down
Elevator: 3/8 up/down
Rudder: 1 left/right (at bottom)
Flying: As you always should, double- and
triple-check the throws on low and high rates
and for the proper direction of surface travel.
You might prefer to add exponential.
Have a buddy hold the model at least a
foot off of the ground and do a motor-running
range check. Never skip this step! Just
because you have 2.4 GHz capability does not
mean there might not be issues.
If everything seems good to go, install
fully charged batteries and get a feeling for the
SST’s ground handling. I’ve learned that a
few degrees of toe-in on the main gear helps
greatly. I tend to get a good feel for a model
before just jumping it off the ground.
Line up the airplane into the wind and
smoothly apply power. You’ll find that it likes
heavy right rudder until the tail lifts, and then
you can let off slightly. I use high-rate rudder
until flying and then switch to low.
Once the aircraft is up on the mains, apply
more power and it will smoothly lift off. Gain
some altitude and trim it out.
Test the stall and glide ratio. You’ll see
that the SST is fast and glides well. Line up
for landing with a great deal of ground in front
of it, to allow for that flat, fast glide.
Once back on the ground, give it a
thorough examination. Make sure that there
are no loose parts or equipment.
Now you can take this model up and wring
it out! Put a fresh pack or packs in and go up
again. You can do all of the RC Aerobatics
(Pattern) moves with it and outrun some glow
racers. The SST tracks like a Pattern model
with the speed of a racer.
Huge loops and vertical moves are easy,
and this airplane will do well inverted with
some practice. It also does good four-point
rolls and slow rolls.
I hope you enjoy your Super Sportwin as
much as I do! I’ll bet you’ll turn a few heads
at the flying field and swell with pride when
flying it. MA
Mark Rittinger
[email protected]
Sources:
Bob Hunt
(610) 746-0106
[email protected]
E-flite
(800) 338-4639
www.e-fliterc.com
Hitec RCD
(858) 748-6948
www.hitecrcd.com
APC
(530) 661-0399
www.apcprop.com
Robart
(630) 584-7616
www.robart.com
Why Pay a Dollar
for just 4 Screws?
W e h a v e t h e h a r d w a r e y o u n e e d
at a fraction of retail!
Order today at:
www.rtlfasteners.com
or call 800-239-6010
708 Battlefield Blvd South #107
Chesapeake, VA 23322
06sig1x.QXD_00MSTRPG.QXD 4/20/11 11:21 AM Page 27

20 MODEL AVIATION
cTaphteio nbasic fuselage components are laid out. This model uses caption
basic box-type construction with a turtledeck to keep it simple.
This airplane needs to be built straight. Use clamps to ensure
that nothing moves while the glue dries.
IN 2001, at the height of the “Speed 400” craze, I designed
my original Sportwin. Spanning 38 inches with simple,
all-balsa construction, it was an instant hit.
Many Sportwins were built around the world, and it gained quite a
following as a fun, fast, quick-building, slick little electric twin. This model
shocked (no pun intended!) many people with its great handling and good
performance on the meager power that was available at the time.
Brushless motors came into vogue shortly after, and they were soon followed
by Li-Poly batteries. Both of those developments were major leaps forward in
power plant design for electric models.
No longer was it necessary to watch every gram; an abundance of power was
at your service. Numerous Sportwins were built with brushless and Li-Poly
power, and some were extremely quick.
A sleek twin-motor
electric that is
built for speed
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:26 AM Page 20
June 2011 21
Half of the rear deck is glued and held in place with T-pins. The
other half is wet and ready to be glued in the same fashion.
The empennage uses simple sheet vertical and horizontal
stabilizers. The small filler pieces that are shown were added
to finish it off.
by Mark Rittinger Sportwin
Super
The Super Sportwin is elegant and
exciting in the air and on the ground.
06sig1x.QXD_00MSTA carved, drooped wingtip is worth the work. It helps with both
stability and efficiency.
The basic nacelle structure shows retracts, servo, and motor
installed.
Dowel pegs help align the nacelle on the wing and spread the load.
Use epoxy to adhere the nacelle to the wing.
Sand nacelles, if necessary, and confirm that both fit at 0°.
Above: Each nacelle has a hatch for easy access to
the motor and ESC. The author used E-flite
aluminum spinners for their clean look.
Left: Once all of the structures have been built, it’s
time to cover and then assemble the SST. MonoKote
and UltraCote covering were used on the prototypes.
Photos by the author
22 MODEL AVIATION
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:29 AM Page 22
RPG.QXD 4/21/11 9:25 AM Page 21
CLOSE
caption
June 2011 23
Super Sportwin
The completed and
temporarily assembled
model shows its Sportwin
heritage and clean lines.
The finished model is sexy and fast.
The 750 watts of power makes it move!
Type: RC sport
Skill level: Intermediate builder;
intermediate pilot
Wingspan: 50 inches
Wing area: 450 square inches
Length: 431/4 inches
Weight: 4 pounds, 7 ounces
Power: Two E-flite Power 10
outrunner motors; two E-flite 40-
Amp Pro ESCs; two 2600 mAh,
three-cell Li-Poly or one 5000
mAh, three-cell Li-Poly battery
Propeller: APC 9 x 9
Construction: Balsa-sheeted foam wing; balsa-andplywood
fuselage, empennage, nacelles
Finish: Iron-on covering
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:31 AM Page 23
24 MODEL AVIATION
Full-Size Plans Available—See Page 171
Super Sportwin
06sig1x.QXD_00MSTRPG.QXD 4/21/11 9:32 AM Page 24
June 2011 25
I Not long after the design hit, I was asked
to design a larger model with a landing gear
or possibly retractable undercarriage. I was
busy designing Scale aircraft, so I kept
pushing the request back, waiting for the right
time.
During the summer of 2009 I saw Denny
Sumner flying a Sportwin at the Mid-America
Electric Flies meet, and that reminded me
what a great little design it was. The bug bit
me again—and hard. I sat down and drew the
Super Sportwin a few days later.
I competed at thae 2010 Toledo Weak
Signals R/C Show with the new “SST.” It
placed second in Sport Plane category 30
years after my dad won the now-defunct 1/2A
category.
This is not merely a scaled-up rendering of
the Sportwin. It’s an entirely new model,
designed from the ground up, using the
general shapes of the Speed 400 version.
There are many differences.
The SST wing is made from foam and
removable, the airfoil is semisymmetrical, the
tail is longer, the stabilizer is larger, it has
retracts, rudder, and 1 horsepower (750 watts)
hauls it around the big blue!
Although this is not a beginner’s model in
the sense of construction or flying, anyone
who has scratch-built an airplane should have
no problems with it. My designs feature
hidden right angles or straight lines that might
not be readily apparent.
I have arranged for Bob Hunt, of CL
Aerobatics fame, to make wing cores
available, and they are perfect. Robart and Eflite
retracts fit in the nacelles with minor
trimming.
So if you are still interested, let’s get
building!
CONSTRUCTION
Fuselage: This part of the SST is fairly
straightforward; it’s a basic box type with a
turtledeck. All wood dimensions are inches.
Cut matching sides from medium 3/32
balsa. Cut the top turtledeck section oversize,
to allow for the curvature.
Add the 1/8 square spruce stringer, 3/32
balsa doubler from wing TE to nose, and 1/2
triangle stock along the bottom front and rear
of the fuselage. Glue in the stabilizer mount
doubler and small 3/16 sheet tripler in the nose.
Slice F2 from 1/8 plywood, and glue on the
1/8 square spruce and F2 doubler, also from 1/8
plywood. Glue to left side as shown on the
plans.
Cut F3 and F3B from two layers of crossgrain
1/16 balsa. Pay attention to the 45° angle
of the notches. Glue to the left fuselage side
against the doubler.
Carefully line up the left and right sides,
and adhere them at F2 and F3. Using the top
view, glue the tail together.
Cut F1 from layered 1/16 balsa and glue in
place in the nose. The fuselage side doubler
should stop 1/8 inch from the nose, to allow
for fitment of F1. Slide F4 and F5 into place
and glue. Install the three 1/4 square rear deck
stringers.
Wet one fuselage side on the turtledeck
with hot water on the outside only, and it will
begin to bend toward the center stringer. Mark
the center and cut to size. Glue to the top and
side stringer and repeat for the other side.
Sheet the bottom rear section with 1/16
balsa. Cut to rough shape and glue on the top
nose block and nose. Do not sheet the lower
nose at this time.
Add the hardwood wing hold-down blocks
and 1/8 plywood plates. By now the structure
looks like a submarine!
Build the hatch directly on top of the
fuselage. Using 1/16 with grain running side to
side, lay the hatch floor. Sand to match the
sides of the fuselage.
Glue on the 1/8 square, H1 through H5,
triangle braces, and stringers. Plank or sheet
the hatch with 3/32 balsa. On the underside of
the hatch, you can add hatch-alignment aids
from scrap balsa, magnet hold-downs, or
rubber band hooks.
Sand everything to be ultraslick, and set
aside to work on the wing.
Wing: This is a simple foam affair, sheeted
with 1/16 balsa, using a single aileron servo.
I’ve grown tired of seeing ugly servos
sticking out all over pretty models, so take a
few extra minutes to make a clean aileronservo
installation.
Using the templates on the plans, cut the
cores with 3/16 inch of washout per tip or order
them from Bob Hunt.
Lightly sand the cores to remove the
cutting fuzz. Assemble the core sheeting from
48-inch-long sheets of matched 1/16 balsa. I
used six pieces of 3 x 48 x 1/16.
Cut the core sheeting slightly oversized
using the core as a template. Spray the
sheeting with a light coat of plain hair spray,
to aid in adhesion.
To sheet the foam, I used finishing resin
and made a “wing press” from two 24-inchsquare
pieces of 11/2-inch-thick hardwood. I
drilled six holes through and inserted threaded
rods.
I spread a thin coat of resin on the cores,
placed them in their beds with the sheeting,
and put them in the press. Tightening the nuts
put even, firm pressure on the cores until they
were dry, which was approximately six hours.
If you have a flat workbench and heavy
weights, that will work just as well. Other
glues such as wood glue, contact cements, and
epoxy will also work to sheet the wings. The
key is a true surface. Uneven, warped wings
perform poorly.
After the wings are sheeted, add the 1/4
hard balsa LE and the 1/8 balsa rear cap. Sand
to shape. Sand the root to match 4° (13/4
inches) per panel dihedral, and epoxy them
together, ensuring that they are aligned.
Decide on the wingtip shape you will use,
and add them to the tips. Add the center TE
section, plywood wing mount, and torque
rods.
Cut the hole for the aileron servo. Sand the
LE flat to match the opening in the fuselage,
and sand the wing to perfectly fit the fuselage
opening.
Cut ailerons to fit, and drill holes for the
torque rods. I used floppy disk material for
hinges, after covering.
Mark locations for the ESC, retract (if
used), and power wires to run through the
06sig1x.QXD_00MSTRPG.QXD 4/20/11 11:21 AM Page 25
26 MODEL AVIATION
wing from the center fuselage area to the
nacelles.
Use an X-Acto knife to slice a “V” in the
sheeting where the wires will run. I run the
motor power wires approximately 1 inch or
more from the ESC signal wires, and I twist
the positive and negative power wires to
reduce radio frequency interference issues.
Remove the foam from the V piece cut
from the wing, install the wires, and glue the
piece back on. Wrap the center-section with
two layers of fiberglass or nylon cloth and 30-
minute epoxy.
Carefully align the wing in the fuselage,
and clamp in place. Use a long 1/4-inch drill to
make a hole through F2 and its doubler into
the wing for two wing-alignment dowels.
Screw an old nylon wing screw, ground to
a point, through from inside the fuselage to
mark the wing hold-down-screw locations.
Remove the clamps, and install two 1/4-
inch dowels in the wing with epoxy. Drill
holes through the wing for the nylon screws.
Attach the wing to the fuselage and
double-check alignment. It should be straight
and fit tight to the fuselage. If it isn’t find out
what is off and adjust it.
Now you can build, from scrap balsa, the
lower center-section under the wing, and sand
it to fit. You can also sheet the lower fuselage
nose and sand it to a nice contour—something
similar to a cross between a P-38 and a de
Havilland Comet.
Empennage: The SST uses simple sheet
vertical and horizontal stabilizers. Cut the
horizontal stabilizer from 3/8 light balsa, add
the tips, and sand to an airfoil shape as shown.
Cut the elevators from 1/4 balsa, and taper
to match the stabilizer. Make a joiner from 3/32
music or piano wire, and fit to the elevator
halves.
Using an incidence meter, set the wing to
0°, make it immobile with weights or
sandbags, and sand the fuselage to get -1/2° in
the stabilizer.
Cut the fin, rudder, dorsal, and skeg from
3/16 balsa, and sand to fit the fuselage. The fin
is glued to the top of the fuselage and the top
of the stabilizer, and small filler pieces are
added to finish it.
I do not install the fin and stabilizer until
after covering. I find it much easier to cover
this way.
The tail wheel wire runs through a tube
and into the fin. Denny built the second
prototype, and he elected to make the rudder
run all the way to the bottom of the model;
you can do that too.
Nacelles: The nacelles are built around a
frame of plywood and balsa. Use aircraftgrade
plywood in this area; light plywood
won’t hold up.
At this point you must decide what motors
you will use and what type of retracts, if any.
This model can be simplified significantly by
making it hand-launchable or with fixed gear.
Firewall location and servo/retract location are
much easier to adjust now than later.
If you plan on employing inrunner motors,
use a 3/16 plywood front mount firewall. For
rear-mounted outrunner types, use the rear 3/16
plywood firewall. Pylon racers who use glow
engines taught me that a solid firewall is
essential for reducing rpm-robbing vibration.
Cut N1 and N2 from 1/8 plywood. Make
the opening on the rear of N2 the required size
to clear the retracts. The plans fit the Robart
600 series.
Epoxy N1 to N2 and add N3, made from
1/8 balsa. These are right-angle pieces. Add the
maple or spruce hardwood retract bearing
rails. Glue on the 1/4 stringers and the nose
firewall. The 1/4 square stringers can be used
as datum.
If you’re using the rear firewall, cut it from
3/16 plywood. Depending on your motors, you
can move it forward or rearward and it is still
on the datum thrustline. Neat, huh?
You might need to trim or add slightly to
the firewall bottom to fit it in place. Mark and
drill for the motor mounts and epoxy in place.
Fit the retract servo, or retract unit if using
electric units. Bend the legs to match the plans
or to fit your application. Test operation,
because things are better to fix now rather
than later. I used mini ball links with metalgear
servos to operate the retracts.
The inner and outer referred to on the
nacelle sides relates to wing orientation; inner
is toward the root and outer is toward the tip.
Cut an “inner” and an “outer” side from 1/16
balsa and glue one on each side. Be positive
that these are on straight.
Cut a second side of each, and glue to the
nacelles back to N3, but no farther than that.
You should now have 1/8-inch-thick nacelle
sides. Glue the 1/8 top and bottom fillers in
place.
Wet the rear sides of the nacelles, and pin
or clamp together along the rear edge. Let dry
and then remove pins and glue together.
That’s how you make 1/8-inch wood bend that
tight; do it in layers.
Add the lower front and rear blocks, and
make the gear doors or center filler block with
retract gear hole. I initially made clamshell
gear doors, but after much fuss I decided that
holes to clear the gear were much more
simple and lighter.
Denny made removable pieces, with
dowels and magnets to hold them on. This
way he can still remove them for
maintenance. Add the 1/4-inch-diameter
dowels that go up into the wing cores.
Build the hatches directly on the nacelles
by gluing NH1, NH2, and NH3 on top of two
strips of 1/8 x 1/4 balsa and planking with 1/8 x
1/4 balsa strips. I used clothing snaps in the
front and a magnet on the rear to hold them in
place. You might find that the hatches are
easier to assemble after the nacelles are glued
to the wing.
Repeat construction for the second nacelle,
being sure not to build two left or right ones!
Final Assembly/Covering: If you stand the
wing on its TE, you can mark 9 inches from
the centerline of the wing to each nacelle
centerline, and mark them with a triangle on
the wing bottom sheeting.
Mark the holes and drill for the 1/4-inchdiameter
dowels in the nacelles. Fit all wiring
through the nacelle opening, and trial-fit the
nacelles. Use an incidence meter and/or
06sig1x.QXD_00MSTRPG.QXD 4/20/11 11:21 AM Page 26
levels and draw sand for perfect fitment.
Epoxy the nacelles to the wing bottom.
Since there are many hidden right angles in
this design, they come in handy. If you have a
long triangle, use it to ensure that the nacelles
are glued on aligned. They can also easily be
measured as 18 inches from center to center at
the front and at the rear.
A good-performing model must be
assembled straight. Trimming in the air can
correct for only so much, and a straight
airplane flies much better than one with
something that is off and corrected for with
trim.
Trial-fit the fin/rudder and double-check to
make sure that the stabilizer has -1/2°.
I cover the SST at this point. I used white
and Metallic Wine MonoKote on mine, and
Denny used red UltraCote. I strongly suggest
employing a vibrant color scheme with large
panels of bright colors; it makes this aircraft
much easier to see in the air.
After covering, hinge the surfaces using
pieces cut from floppy disk material. I use thin
CA to adhere them in place and have yet to
have one break. Stock up if you see floppy
disks in a store; they are becoming rare.
Glue on the stabilizer, making sure that it’s
aligned, and then glue on the fin with the
dorsal.
Glue on the canopy. I used a Great Planes
Spirit glider unit, trimmed to fit. I’m sure that
others will fit as well, so don’t be afraid to
look around.
Equipment Installation: I am using a Hitec
Eclipse 7 radio system with a 2.4 GHz
module, also from Hitec. This combo has
worked flawlessly, with no interference from
any of the wiring or motors.
The radio install is rather straightforward,
having one aileron servo (HS-65MG) with
torque rods, one elevator servo (HS-82MG),
one rudder servo (HS-82MG), and retract
servos in the nacelles.
I mounted the rudder and elevator servos
directly behind the wing, on hardwood rails.
The receiver is mounted on the fuselage side
with double-stick tape.
Make pushrods using 1/4 spruce and
threaded ends. For the best in precision, you
can use ball links on the pushrods.
My SST has 750 watts of power on tap
from two incredibly reliable E-flite Power 10
1100 Kv motors. I also equipped it with 9 x 9
APC propellers and E-flite aluminum
spinners.
These motors have big, sturdy shafts and
bearings, and they really put out the power
while staying cool. Mount your motors to the
firewall, and hook up the ESCs.
I’m using the E-flite 40-Amp Pro heatsinked
speed controller and one BEC, by
disconnecting the red wire on one of the
ESCs. These are capable of handling up to
seven servos each and have performed well as
set up. You can use a separate BEC if you
prefer, but I see no need.
I’ve been flying with two 2600 mAh, 11.1-
volt 30C Li-Poly packs—one for each
individual ESC. You can set yours up this way
or as Denny has done, with one 5000 mAh,
11.1-volt pack powering both ESCs. Whatever
June 2011 27
you choose, make sure that the battery and the
connector(s) can handle the amperage draw.
Use a hook-and-loop fastener to hold your
battery in place, and make sure that it has
adequate cooling air going over it.
Balance at the forward point shown on the
plans for the model’s first flights, and then
move it rearward. Don’t go past 33%, or it
gets a bit “twitchy.”
Initial control throws are:
Low:
Aileron: 3/16 up/down
Elevator: 1/4 up/down
Rudder: 1/2 left/right (at bottom)
High:
Aileron: 1/4 up/down
Elevator: 3/8 up/down
Rudder: 1 left/right (at bottom)
Flying: As you always should, double- and
triple-check the throws on low and high rates
and for the proper direction of surface travel.
You might prefer to add exponential.
Have a buddy hold the model at least a
foot off of the ground and do a motor-running
range check. Never skip this step! Just
because you have 2.4 GHz capability does not
mean there might not be issues.
If everything seems good to go, install
fully charged batteries and get a feeling for the
SST’s ground handling. I’ve learned that a
few degrees of toe-in on the main gear helps
greatly. I tend to get a good feel for a model
before just jumping it off the ground.
Line up the airplane into the wind and
smoothly apply power. You’ll find that it likes
heavy right rudder until the tail lifts, and then
you can let off slightly. I use high-rate rudder
until flying and then switch to low.
Once the aircraft is up on the mains, apply
more power and it will smoothly lift off. Gain
some altitude and trim it out.
Test the stall and glide ratio. You’ll see
that the SST is fast and glides well. Line up
for landing with a great deal of ground in front
of it, to allow for that flat, fast glide.
Once back on the ground, give it a
thorough examination. Make sure that there
are no loose parts or equipment.
Now you can take this model up and wring
it out! Put a fresh pack or packs in and go up
again. You can do all of the RC Aerobatics
(Pattern) moves with it and outrun some glow
racers. The SST tracks like a Pattern model
with the speed of a racer.
Huge loops and vertical moves are easy,
and this airplane will do well inverted with
some practice. It also does good four-point
rolls and slow rolls.
I hope you enjoy your Super Sportwin as
much as I do! I’ll bet you’ll turn a few heads
at the flying field and swell with pride when
flying it. MA
Mark Rittinger
[email protected]
Sources:
Bob Hunt
(610) 746-0106
[email protected]
E-flite
(800) 338-4639
www.e-fliterc.com
Hitec RCD
(858) 748-6948
www.hitecrcd.com
APC
(530) 661-0399
www.apcprop.com
Robart
(630) 584-7616
www.robart.com
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