THE EDWARDS Rhomboidal biplane
was built in Great Britain in 1911. In the
1920s Norman Hall-Warren designed a
rhomboidal wing for his home-built
airplane. He found that the joined wing
was resistant to stalling in flight.
My Rhom-Bus test flights did
display a stall-resistant characteristic.
Especially when flying into a light
headwind, with nearly full up-elevator
and low throttle, the model comes down
like a parasail. Another of the wing
design’s positive characteristics is the
nonexistence of wing warping because
18 MODEL AVIATION
BY FERRELL PAPIC
of the joined wingtips.
Owing to the design’s strut-bracing
feature, wings can take a much greater
“G” load before wing failure occurs. I
have built and flown several gaspowered
FF joined-wing models with
varying degrees of incidence angle
between the front and rear wing. The
models with less incidence flew fast and
straight, and the models with more
incidence exhibited the parasail
characteristics.
Having done that I often thought an
interesting experiment would be to
install a servo-controlled incidence
angle to achieve the desired flight
characteristics when flying crosscountry
or landing.
Another experiment I would like to
try someday is to install an electric
speed control with a motor reverse.
Since the CG is near the center of the
model, a forward and reverse turn might
be possible by manipulating the elevator
and rudder.
CONSTRUCTION
Stabilizers, Rudder, Elevator: Patterns
The Rhom-Bus’s distinctive joined-wing planform contributes to its stall-resistant
characteristics. It looks neat too!
Photos by the author
11of the stabilizer parts are provided on
the drawing plans.
Assemble the 1/16 balsa horizontal
stabilizer on the vertical stabilizer with a
square and corner braces. Install the 1/32
balsa wing guides on the underside of
the horizontal stabilizer.
Install the 1/32 plywood control horns
on the rudder and elevator. Attach the
rudder and elevator to the stabilizers
with figure-8 thread hinges.
Fuselage: Patterns of the fuselage parts
are provided on the drawing plans.
Assemble the 1/16 balsa bulkheads.
Cut the 1/8 balsa fuselage base. Mount
the 3/32 balsa base brace. Match-drill the
holes in the fuselage sides for the 1/16-
inch aluminum wing-mounting tubes.
Since the Rhom-Bus’s CG is near the
middle of the airplane, a GWS 40 or 50
electric ducted fan can be installed in
place of the propeller drive. The
recommended ducted-fan motor batteries
can range from 550 mAh to 1200 mAh
7.4-volt Li-Polys.
Install and drill doublers inside the
fuselage at the tube mounting holes.
Assemble the fuselage, 1/16 balsa
windshield, stabilizer assembly, motormount
base, and motor mount. Shape the
motor-mount doublers with sandpaper
glued to a wood dowel.
Rough out the foam nose block and
glue it in place with yellow carpenter’s
glue. After the glue dries, final-shape
the nose block with a sanding block.
Install the 1/16-inch-diameter wingmounting
aluminum tubes after painting
and installing decorations.
November 2007 19
Power-option 1 consists of a Roadkill N20 6-volt geared motor with a 5.2 Gunther
propeller.
The elevator is small in area, but it is plenty for proper control response because of
the CG placement.
The second choice for power is to install a GWS 40 ducted-fan unit. The wide CG
range allows this option.
A unique
biplane
with power
options for
the FF or
RC modeler
11sig1.QXD 9/24/07 9:09 AM Page 19sig1.QXD 9/21/07 1:45 PM Page 18
20 MODEL AVIATION
Wing: The wing-rib pattern is shown with spars and LEs and
TEs for reference.
The front wings are joined with 1.2 inches of dihedral on
each wingtip. The rear wings are joined with 2.16 inches of
dihedral on each wingtip. Those amounts are required when
flying in an enclosed gymnasium space.
The rear wing joiner requires 1/32 balsa guides attached to
the center top and bottom so it aligns properly in the verticalstabilizer
slot.
Cover the front wing center-section with heavy paper
adhered with a light application of yellow carpenter’s glue. I
covered my wings with red Reynolds Plastic Wrap using waterthinned
RC/56 canopy cement on the wing edges and centers.
This material will heat shrink but can be damaged by excessive
heat.
It is best to join the front and rear wings after the fuselage is
complete. Slide the rear wing into the vertical-stabilizer slot
and then install the front wing with wing-mounting rubber
bands.
Cut some 90° 2.99-inch high-gauge blocks and align the
wingtips so they are parallel to each other. Then it is safe to
join the front wingtips to the rear wingtips. To give the wings a
finishing touch, add the 1/32 balsa wingtip plates to the
wingtips.
Finishing: I sprayed a light coat of white latex model paint on
the fuselage and stabilizers.
I decorated the fuselage sides and vertical stabilizer with
computer ink-jet art on bond paper, which I adhered with a
light application of yellow carpenter’s glue. Contact me by Email
if you would like a copy of the digital Windows Metafile
artwork.
Radio Installation: I use the reliable GWS 5-gram, fourchannel
GWR-4P FM receiver; 5-gram GWS Pico servos; and a
GWS 2-amp speed control in my Rhom-Bus. For control cables
I use .043-inch-diameter plastic tube and #6 .015-inch-diameter
single-strand, stainless-steel fishing leader wire with Z-bend
connections to servos and control horns.
I like to use two-pin Deans gold-plated connectors on my
battery-pack and radio-gear connections. I charge my
conventional 8.4-volt, 150 mAh NiMH batteries with a Hobby
People Watt-Age pulse battery charger.
To prevent battery damage I must charge my 7.2-volt, 250
mAh Li-Poly batteries with a dedicated voltage-cutoff battery
charger, such as a Poteski unit from my local hobby dealer or
Hobby Club.
Adjust the battery and radio-gear location in the fuselage so
that the correct CG indicated on the construction plans is
achieved. Visually check the underside of the wing center at
arm length for correct left and right symmetry. Then check all
the servos for reversed controls.
Flying: Launch the model with your left hand so your right
thumb is on the transmitter control stick from the beginning of
the flight. Make transmitter-stick trim adjustments until the
model flies straight and level with hands-off control.
Outdoor flying is best done in no wind or moderate wind
conditions. Indoor flying is great anytime. MA
Ferrell Papic
[email protected]
The wing and fuselage separate for transportation. This design
uses ample FF technology!
Type: RC park flyer
Wingspan: 28 inches
Wing area: 127 square inches
Wing loading: .55 ounce/square foot
Length: 25 inches
Power option 1: Roadkill N20 6-volt geared motor
with 5.2 Gunther propeller
Power option 2: GWS 40 ducted fan
Motor current: 850 mA for N20; 3 amps for fan
Motor voltage: 8
Motor power: 1-3 ounces of thrust
rpm: 4,200 for N20; 22,000 for fan
Watts/ounce: 6.8 for N20; 24 for fan
Battery: Seven-cell, 150 mAh NiMH or two-cell Li-
Poly for fan
Radio system: Three channels minimum with
GWS 5-gram receiver and 5-gram servos
Flying weight: 7 ounces
Flight duration: Five minutes
Construction: Sheet and strip balsa
Covering/finish: Plastic wrap, RC/56, ink-jet
artwork
11sig1.QXD 9/21/07 1:47 PM Page 20
The wing construction utilizes geodetic bracing for torsional rigidity. It builds into an
extraordinarily light and strong unit.
Notice the shear webbing between the ribs in the center-section. This adds
considerable strength with a small weight penalty.
The fuselage is built in the same manner as that of a competition FF model, with
sheet sides and cross-grain sheeting on the top and bottom. The nose block is
made from foam.
Edition: Model Aviation - 2007/11
Page Numbers: 18,19,20,21,22
Edition: Model Aviation - 2007/11
Page Numbers: 18,19,20,21,22
THE EDWARDS Rhomboidal biplane
was built in Great Britain in 1911. In the
1920s Norman Hall-Warren designed a
rhomboidal wing for his home-built
airplane. He found that the joined wing
was resistant to stalling in flight.
My Rhom-Bus test flights did
display a stall-resistant characteristic.
Especially when flying into a light
headwind, with nearly full up-elevator
and low throttle, the model comes down
like a parasail. Another of the wing
design’s positive characteristics is the
nonexistence of wing warping because
18 MODEL AVIATION
BY FERRELL PAPIC
of the joined wingtips.
Owing to the design’s strut-bracing
feature, wings can take a much greater
“G” load before wing failure occurs. I
have built and flown several gaspowered
FF joined-wing models with
varying degrees of incidence angle
between the front and rear wing. The
models with less incidence flew fast and
straight, and the models with more
incidence exhibited the parasail
characteristics.
Having done that I often thought an
interesting experiment would be to
install a servo-controlled incidence
angle to achieve the desired flight
characteristics when flying crosscountry
or landing.
Another experiment I would like to
try someday is to install an electric
speed control with a motor reverse.
Since the CG is near the center of the
model, a forward and reverse turn might
be possible by manipulating the elevator
and rudder.
CONSTRUCTION
Stabilizers, Rudder, Elevator: Patterns
The Rhom-Bus’s distinctive joined-wing planform contributes to its stall-resistant
characteristics. It looks neat too!
Photos by the author
11of the stabilizer parts are provided on
the drawing plans.
Assemble the 1/16 balsa horizontal
stabilizer on the vertical stabilizer with a
square and corner braces. Install the 1/32
balsa wing guides on the underside of
the horizontal stabilizer.
Install the 1/32 plywood control horns
on the rudder and elevator. Attach the
rudder and elevator to the stabilizers
with figure-8 thread hinges.
Fuselage: Patterns of the fuselage parts
are provided on the drawing plans.
Assemble the 1/16 balsa bulkheads.
Cut the 1/8 balsa fuselage base. Mount
the 3/32 balsa base brace. Match-drill the
holes in the fuselage sides for the 1/16-
inch aluminum wing-mounting tubes.
Since the Rhom-Bus’s CG is near the
middle of the airplane, a GWS 40 or 50
electric ducted fan can be installed in
place of the propeller drive. The
recommended ducted-fan motor batteries
can range from 550 mAh to 1200 mAh
7.4-volt Li-Polys.
Install and drill doublers inside the
fuselage at the tube mounting holes.
Assemble the fuselage, 1/16 balsa
windshield, stabilizer assembly, motormount
base, and motor mount. Shape the
motor-mount doublers with sandpaper
glued to a wood dowel.
Rough out the foam nose block and
glue it in place with yellow carpenter’s
glue. After the glue dries, final-shape
the nose block with a sanding block.
Install the 1/16-inch-diameter wingmounting
aluminum tubes after painting
and installing decorations.
November 2007 19
Power-option 1 consists of a Roadkill N20 6-volt geared motor with a 5.2 Gunther
propeller.
The elevator is small in area, but it is plenty for proper control response because of
the CG placement.
The second choice for power is to install a GWS 40 ducted-fan unit. The wide CG
range allows this option.
A unique
biplane
with power
options for
the FF or
RC modeler
11sig1.QXD 9/24/07 9:09 AM Page 19sig1.QXD 9/21/07 1:45 PM Page 18
20 MODEL AVIATION
Wing: The wing-rib pattern is shown with spars and LEs and
TEs for reference.
The front wings are joined with 1.2 inches of dihedral on
each wingtip. The rear wings are joined with 2.16 inches of
dihedral on each wingtip. Those amounts are required when
flying in an enclosed gymnasium space.
The rear wing joiner requires 1/32 balsa guides attached to
the center top and bottom so it aligns properly in the verticalstabilizer
slot.
Cover the front wing center-section with heavy paper
adhered with a light application of yellow carpenter’s glue. I
covered my wings with red Reynolds Plastic Wrap using waterthinned
RC/56 canopy cement on the wing edges and centers.
This material will heat shrink but can be damaged by excessive
heat.
It is best to join the front and rear wings after the fuselage is
complete. Slide the rear wing into the vertical-stabilizer slot
and then install the front wing with wing-mounting rubber
bands.
Cut some 90° 2.99-inch high-gauge blocks and align the
wingtips so they are parallel to each other. Then it is safe to
join the front wingtips to the rear wingtips. To give the wings a
finishing touch, add the 1/32 balsa wingtip plates to the
wingtips.
Finishing: I sprayed a light coat of white latex model paint on
the fuselage and stabilizers.
I decorated the fuselage sides and vertical stabilizer with
computer ink-jet art on bond paper, which I adhered with a
light application of yellow carpenter’s glue. Contact me by Email
if you would like a copy of the digital Windows Metafile
artwork.
Radio Installation: I use the reliable GWS 5-gram, fourchannel
GWR-4P FM receiver; 5-gram GWS Pico servos; and a
GWS 2-amp speed control in my Rhom-Bus. For control cables
I use .043-inch-diameter plastic tube and #6 .015-inch-diameter
single-strand, stainless-steel fishing leader wire with Z-bend
connections to servos and control horns.
I like to use two-pin Deans gold-plated connectors on my
battery-pack and radio-gear connections. I charge my
conventional 8.4-volt, 150 mAh NiMH batteries with a Hobby
People Watt-Age pulse battery charger.
To prevent battery damage I must charge my 7.2-volt, 250
mAh Li-Poly batteries with a dedicated voltage-cutoff battery
charger, such as a Poteski unit from my local hobby dealer or
Hobby Club.
Adjust the battery and radio-gear location in the fuselage so
that the correct CG indicated on the construction plans is
achieved. Visually check the underside of the wing center at
arm length for correct left and right symmetry. Then check all
the servos for reversed controls.
Flying: Launch the model with your left hand so your right
thumb is on the transmitter control stick from the beginning of
the flight. Make transmitter-stick trim adjustments until the
model flies straight and level with hands-off control.
Outdoor flying is best done in no wind or moderate wind
conditions. Indoor flying is great anytime. MA
Ferrell Papic
[email protected]
The wing and fuselage separate for transportation. This design
uses ample FF technology!
Type: RC park flyer
Wingspan: 28 inches
Wing area: 127 square inches
Wing loading: .55 ounce/square foot
Length: 25 inches
Power option 1: Roadkill N20 6-volt geared motor
with 5.2 Gunther propeller
Power option 2: GWS 40 ducted fan
Motor current: 850 mA for N20; 3 amps for fan
Motor voltage: 8
Motor power: 1-3 ounces of thrust
rpm: 4,200 for N20; 22,000 for fan
Watts/ounce: 6.8 for N20; 24 for fan
Battery: Seven-cell, 150 mAh NiMH or two-cell Li-
Poly for fan
Radio system: Three channels minimum with
GWS 5-gram receiver and 5-gram servos
Flying weight: 7 ounces
Flight duration: Five minutes
Construction: Sheet and strip balsa
Covering/finish: Plastic wrap, RC/56, ink-jet
artwork
11sig1.QXD 9/21/07 1:47 PM Page 20
The wing construction utilizes geodetic bracing for torsional rigidity. It builds into an
extraordinarily light and strong unit.
Notice the shear webbing between the ribs in the center-section. This adds
considerable strength with a small weight penalty.
The fuselage is built in the same manner as that of a competition FF model, with
sheet sides and cross-grain sheeting on the top and bottom. The nose block is
made from foam.
Edition: Model Aviation - 2007/11
Page Numbers: 18,19,20,21,22
THE EDWARDS Rhomboidal biplane
was built in Great Britain in 1911. In the
1920s Norman Hall-Warren designed a
rhomboidal wing for his home-built
airplane. He found that the joined wing
was resistant to stalling in flight.
My Rhom-Bus test flights did
display a stall-resistant characteristic.
Especially when flying into a light
headwind, with nearly full up-elevator
and low throttle, the model comes down
like a parasail. Another of the wing
design’s positive characteristics is the
nonexistence of wing warping because
18 MODEL AVIATION
BY FERRELL PAPIC
of the joined wingtips.
Owing to the design’s strut-bracing
feature, wings can take a much greater
“G” load before wing failure occurs. I
have built and flown several gaspowered
FF joined-wing models with
varying degrees of incidence angle
between the front and rear wing. The
models with less incidence flew fast and
straight, and the models with more
incidence exhibited the parasail
characteristics.
Having done that I often thought an
interesting experiment would be to
install a servo-controlled incidence
angle to achieve the desired flight
characteristics when flying crosscountry
or landing.
Another experiment I would like to
try someday is to install an electric
speed control with a motor reverse.
Since the CG is near the center of the
model, a forward and reverse turn might
be possible by manipulating the elevator
and rudder.
CONSTRUCTION
Stabilizers, Rudder, Elevator: Patterns
The Rhom-Bus’s distinctive joined-wing planform contributes to its stall-resistant
characteristics. It looks neat too!
Photos by the author
11of the stabilizer parts are provided on
the drawing plans.
Assemble the 1/16 balsa horizontal
stabilizer on the vertical stabilizer with a
square and corner braces. Install the 1/32
balsa wing guides on the underside of
the horizontal stabilizer.
Install the 1/32 plywood control horns
on the rudder and elevator. Attach the
rudder and elevator to the stabilizers
with figure-8 thread hinges.
Fuselage: Patterns of the fuselage parts
are provided on the drawing plans.
Assemble the 1/16 balsa bulkheads.
Cut the 1/8 balsa fuselage base. Mount
the 3/32 balsa base brace. Match-drill the
holes in the fuselage sides for the 1/16-
inch aluminum wing-mounting tubes.
Since the Rhom-Bus’s CG is near the
middle of the airplane, a GWS 40 or 50
electric ducted fan can be installed in
place of the propeller drive. The
recommended ducted-fan motor batteries
can range from 550 mAh to 1200 mAh
7.4-volt Li-Polys.
Install and drill doublers inside the
fuselage at the tube mounting holes.
Assemble the fuselage, 1/16 balsa
windshield, stabilizer assembly, motormount
base, and motor mount. Shape the
motor-mount doublers with sandpaper
glued to a wood dowel.
Rough out the foam nose block and
glue it in place with yellow carpenter’s
glue. After the glue dries, final-shape
the nose block with a sanding block.
Install the 1/16-inch-diameter wingmounting
aluminum tubes after painting
and installing decorations.
November 2007 19
Power-option 1 consists of a Roadkill N20 6-volt geared motor with a 5.2 Gunther
propeller.
The elevator is small in area, but it is plenty for proper control response because of
the CG placement.
The second choice for power is to install a GWS 40 ducted-fan unit. The wide CG
range allows this option.
A unique
biplane
with power
options for
the FF or
RC modeler
11sig1.QXD 9/24/07 9:09 AM Page 19sig1.QXD 9/21/07 1:45 PM Page 18
20 MODEL AVIATION
Wing: The wing-rib pattern is shown with spars and LEs and
TEs for reference.
The front wings are joined with 1.2 inches of dihedral on
each wingtip. The rear wings are joined with 2.16 inches of
dihedral on each wingtip. Those amounts are required when
flying in an enclosed gymnasium space.
The rear wing joiner requires 1/32 balsa guides attached to
the center top and bottom so it aligns properly in the verticalstabilizer
slot.
Cover the front wing center-section with heavy paper
adhered with a light application of yellow carpenter’s glue. I
covered my wings with red Reynolds Plastic Wrap using waterthinned
RC/56 canopy cement on the wing edges and centers.
This material will heat shrink but can be damaged by excessive
heat.
It is best to join the front and rear wings after the fuselage is
complete. Slide the rear wing into the vertical-stabilizer slot
and then install the front wing with wing-mounting rubber
bands.
Cut some 90° 2.99-inch high-gauge blocks and align the
wingtips so they are parallel to each other. Then it is safe to
join the front wingtips to the rear wingtips. To give the wings a
finishing touch, add the 1/32 balsa wingtip plates to the
wingtips.
Finishing: I sprayed a light coat of white latex model paint on
the fuselage and stabilizers.
I decorated the fuselage sides and vertical stabilizer with
computer ink-jet art on bond paper, which I adhered with a
light application of yellow carpenter’s glue. Contact me by Email
if you would like a copy of the digital Windows Metafile
artwork.
Radio Installation: I use the reliable GWS 5-gram, fourchannel
GWR-4P FM receiver; 5-gram GWS Pico servos; and a
GWS 2-amp speed control in my Rhom-Bus. For control cables
I use .043-inch-diameter plastic tube and #6 .015-inch-diameter
single-strand, stainless-steel fishing leader wire with Z-bend
connections to servos and control horns.
I like to use two-pin Deans gold-plated connectors on my
battery-pack and radio-gear connections. I charge my
conventional 8.4-volt, 150 mAh NiMH batteries with a Hobby
People Watt-Age pulse battery charger.
To prevent battery damage I must charge my 7.2-volt, 250
mAh Li-Poly batteries with a dedicated voltage-cutoff battery
charger, such as a Poteski unit from my local hobby dealer or
Hobby Club.
Adjust the battery and radio-gear location in the fuselage so
that the correct CG indicated on the construction plans is
achieved. Visually check the underside of the wing center at
arm length for correct left and right symmetry. Then check all
the servos for reversed controls.
Flying: Launch the model with your left hand so your right
thumb is on the transmitter control stick from the beginning of
the flight. Make transmitter-stick trim adjustments until the
model flies straight and level with hands-off control.
Outdoor flying is best done in no wind or moderate wind
conditions. Indoor flying is great anytime. MA
Ferrell Papic
[email protected]
The wing and fuselage separate for transportation. This design
uses ample FF technology!
Type: RC park flyer
Wingspan: 28 inches
Wing area: 127 square inches
Wing loading: .55 ounce/square foot
Length: 25 inches
Power option 1: Roadkill N20 6-volt geared motor
with 5.2 Gunther propeller
Power option 2: GWS 40 ducted fan
Motor current: 850 mA for N20; 3 amps for fan
Motor voltage: 8
Motor power: 1-3 ounces of thrust
rpm: 4,200 for N20; 22,000 for fan
Watts/ounce: 6.8 for N20; 24 for fan
Battery: Seven-cell, 150 mAh NiMH or two-cell Li-
Poly for fan
Radio system: Three channels minimum with
GWS 5-gram receiver and 5-gram servos
Flying weight: 7 ounces
Flight duration: Five minutes
Construction: Sheet and strip balsa
Covering/finish: Plastic wrap, RC/56, ink-jet
artwork
11sig1.QXD 9/21/07 1:47 PM Page 20
The wing construction utilizes geodetic bracing for torsional rigidity. It builds into an
extraordinarily light and strong unit.
Notice the shear webbing between the ribs in the center-section. This adds
considerable strength with a small weight penalty.
The fuselage is built in the same manner as that of a competition FF model, with
sheet sides and cross-grain sheeting on the top and bottom. The nose block is
made from foam.
Edition: Model Aviation - 2007/11
Page Numbers: 18,19,20,21,22
THE EDWARDS Rhomboidal biplane
was built in Great Britain in 1911. In the
1920s Norman Hall-Warren designed a
rhomboidal wing for his home-built
airplane. He found that the joined wing
was resistant to stalling in flight.
My Rhom-Bus test flights did
display a stall-resistant characteristic.
Especially when flying into a light
headwind, with nearly full up-elevator
and low throttle, the model comes down
like a parasail. Another of the wing
design’s positive characteristics is the
nonexistence of wing warping because
18 MODEL AVIATION
BY FERRELL PAPIC
of the joined wingtips.
Owing to the design’s strut-bracing
feature, wings can take a much greater
“G” load before wing failure occurs. I
have built and flown several gaspowered
FF joined-wing models with
varying degrees of incidence angle
between the front and rear wing. The
models with less incidence flew fast and
straight, and the models with more
incidence exhibited the parasail
characteristics.
Having done that I often thought an
interesting experiment would be to
install a servo-controlled incidence
angle to achieve the desired flight
characteristics when flying crosscountry
or landing.
Another experiment I would like to
try someday is to install an electric
speed control with a motor reverse.
Since the CG is near the center of the
model, a forward and reverse turn might
be possible by manipulating the elevator
and rudder.
CONSTRUCTION
Stabilizers, Rudder, Elevator: Patterns
The Rhom-Bus’s distinctive joined-wing planform contributes to its stall-resistant
characteristics. It looks neat too!
Photos by the author
11of the stabilizer parts are provided on
the drawing plans.
Assemble the 1/16 balsa horizontal
stabilizer on the vertical stabilizer with a
square and corner braces. Install the 1/32
balsa wing guides on the underside of
the horizontal stabilizer.
Install the 1/32 plywood control horns
on the rudder and elevator. Attach the
rudder and elevator to the stabilizers
with figure-8 thread hinges.
Fuselage: Patterns of the fuselage parts
are provided on the drawing plans.
Assemble the 1/16 balsa bulkheads.
Cut the 1/8 balsa fuselage base. Mount
the 3/32 balsa base brace. Match-drill the
holes in the fuselage sides for the 1/16-
inch aluminum wing-mounting tubes.
Since the Rhom-Bus’s CG is near the
middle of the airplane, a GWS 40 or 50
electric ducted fan can be installed in
place of the propeller drive. The
recommended ducted-fan motor batteries
can range from 550 mAh to 1200 mAh
7.4-volt Li-Polys.
Install and drill doublers inside the
fuselage at the tube mounting holes.
Assemble the fuselage, 1/16 balsa
windshield, stabilizer assembly, motormount
base, and motor mount. Shape the
motor-mount doublers with sandpaper
glued to a wood dowel.
Rough out the foam nose block and
glue it in place with yellow carpenter’s
glue. After the glue dries, final-shape
the nose block with a sanding block.
Install the 1/16-inch-diameter wingmounting
aluminum tubes after painting
and installing decorations.
November 2007 19
Power-option 1 consists of a Roadkill N20 6-volt geared motor with a 5.2 Gunther
propeller.
The elevator is small in area, but it is plenty for proper control response because of
the CG placement.
The second choice for power is to install a GWS 40 ducted-fan unit. The wide CG
range allows this option.
A unique
biplane
with power
options for
the FF or
RC modeler
11sig1.QXD 9/24/07 9:09 AM Page 19sig1.QXD 9/21/07 1:45 PM Page 18
20 MODEL AVIATION
Wing: The wing-rib pattern is shown with spars and LEs and
TEs for reference.
The front wings are joined with 1.2 inches of dihedral on
each wingtip. The rear wings are joined with 2.16 inches of
dihedral on each wingtip. Those amounts are required when
flying in an enclosed gymnasium space.
The rear wing joiner requires 1/32 balsa guides attached to
the center top and bottom so it aligns properly in the verticalstabilizer
slot.
Cover the front wing center-section with heavy paper
adhered with a light application of yellow carpenter’s glue. I
covered my wings with red Reynolds Plastic Wrap using waterthinned
RC/56 canopy cement on the wing edges and centers.
This material will heat shrink but can be damaged by excessive
heat.
It is best to join the front and rear wings after the fuselage is
complete. Slide the rear wing into the vertical-stabilizer slot
and then install the front wing with wing-mounting rubber
bands.
Cut some 90° 2.99-inch high-gauge blocks and align the
wingtips so they are parallel to each other. Then it is safe to
join the front wingtips to the rear wingtips. To give the wings a
finishing touch, add the 1/32 balsa wingtip plates to the
wingtips.
Finishing: I sprayed a light coat of white latex model paint on
the fuselage and stabilizers.
I decorated the fuselage sides and vertical stabilizer with
computer ink-jet art on bond paper, which I adhered with a
light application of yellow carpenter’s glue. Contact me by Email
if you would like a copy of the digital Windows Metafile
artwork.
Radio Installation: I use the reliable GWS 5-gram, fourchannel
GWR-4P FM receiver; 5-gram GWS Pico servos; and a
GWS 2-amp speed control in my Rhom-Bus. For control cables
I use .043-inch-diameter plastic tube and #6 .015-inch-diameter
single-strand, stainless-steel fishing leader wire with Z-bend
connections to servos and control horns.
I like to use two-pin Deans gold-plated connectors on my
battery-pack and radio-gear connections. I charge my
conventional 8.4-volt, 150 mAh NiMH batteries with a Hobby
People Watt-Age pulse battery charger.
To prevent battery damage I must charge my 7.2-volt, 250
mAh Li-Poly batteries with a dedicated voltage-cutoff battery
charger, such as a Poteski unit from my local hobby dealer or
Hobby Club.
Adjust the battery and radio-gear location in the fuselage so
that the correct CG indicated on the construction plans is
achieved. Visually check the underside of the wing center at
arm length for correct left and right symmetry. Then check all
the servos for reversed controls.
Flying: Launch the model with your left hand so your right
thumb is on the transmitter control stick from the beginning of
the flight. Make transmitter-stick trim adjustments until the
model flies straight and level with hands-off control.
Outdoor flying is best done in no wind or moderate wind
conditions. Indoor flying is great anytime. MA
Ferrell Papic
[email protected]
The wing and fuselage separate for transportation. This design
uses ample FF technology!
Type: RC park flyer
Wingspan: 28 inches
Wing area: 127 square inches
Wing loading: .55 ounce/square foot
Length: 25 inches
Power option 1: Roadkill N20 6-volt geared motor
with 5.2 Gunther propeller
Power option 2: GWS 40 ducted fan
Motor current: 850 mA for N20; 3 amps for fan
Motor voltage: 8
Motor power: 1-3 ounces of thrust
rpm: 4,200 for N20; 22,000 for fan
Watts/ounce: 6.8 for N20; 24 for fan
Battery: Seven-cell, 150 mAh NiMH or two-cell Li-
Poly for fan
Radio system: Three channels minimum with
GWS 5-gram receiver and 5-gram servos
Flying weight: 7 ounces
Flight duration: Five minutes
Construction: Sheet and strip balsa
Covering/finish: Plastic wrap, RC/56, ink-jet
artwork
11sig1.QXD 9/21/07 1:47 PM Page 20
The wing construction utilizes geodetic bracing for torsional rigidity. It builds into an
extraordinarily light and strong unit.
Notice the shear webbing between the ribs in the center-section. This adds
considerable strength with a small weight penalty.
The fuselage is built in the same manner as that of a competition FF model, with
sheet sides and cross-grain sheeting on the top and bottom. The nose block is
made from foam.
Edition: Model Aviation - 2007/11
Page Numbers: 18,19,20,21,22
THE EDWARDS Rhomboidal biplane
was built in Great Britain in 1911. In the
1920s Norman Hall-Warren designed a
rhomboidal wing for his home-built
airplane. He found that the joined wing
was resistant to stalling in flight.
My Rhom-Bus test flights did
display a stall-resistant characteristic.
Especially when flying into a light
headwind, with nearly full up-elevator
and low throttle, the model comes down
like a parasail. Another of the wing
design’s positive characteristics is the
nonexistence of wing warping because
18 MODEL AVIATION
BY FERRELL PAPIC
of the joined wingtips.
Owing to the design’s strut-bracing
feature, wings can take a much greater
“G” load before wing failure occurs. I
have built and flown several gaspowered
FF joined-wing models with
varying degrees of incidence angle
between the front and rear wing. The
models with less incidence flew fast and
straight, and the models with more
incidence exhibited the parasail
characteristics.
Having done that I often thought an
interesting experiment would be to
install a servo-controlled incidence
angle to achieve the desired flight
characteristics when flying crosscountry
or landing.
Another experiment I would like to
try someday is to install an electric
speed control with a motor reverse.
Since the CG is near the center of the
model, a forward and reverse turn might
be possible by manipulating the elevator
and rudder.
CONSTRUCTION
Stabilizers, Rudder, Elevator: Patterns
The Rhom-Bus’s distinctive joined-wing planform contributes to its stall-resistant
characteristics. It looks neat too!
Photos by the author
11of the stabilizer parts are provided on
the drawing plans.
Assemble the 1/16 balsa horizontal
stabilizer on the vertical stabilizer with a
square and corner braces. Install the 1/32
balsa wing guides on the underside of
the horizontal stabilizer.
Install the 1/32 plywood control horns
on the rudder and elevator. Attach the
rudder and elevator to the stabilizers
with figure-8 thread hinges.
Fuselage: Patterns of the fuselage parts
are provided on the drawing plans.
Assemble the 1/16 balsa bulkheads.
Cut the 1/8 balsa fuselage base. Mount
the 3/32 balsa base brace. Match-drill the
holes in the fuselage sides for the 1/16-
inch aluminum wing-mounting tubes.
Since the Rhom-Bus’s CG is near the
middle of the airplane, a GWS 40 or 50
electric ducted fan can be installed in
place of the propeller drive. The
recommended ducted-fan motor batteries
can range from 550 mAh to 1200 mAh
7.4-volt Li-Polys.
Install and drill doublers inside the
fuselage at the tube mounting holes.
Assemble the fuselage, 1/16 balsa
windshield, stabilizer assembly, motormount
base, and motor mount. Shape the
motor-mount doublers with sandpaper
glued to a wood dowel.
Rough out the foam nose block and
glue it in place with yellow carpenter’s
glue. After the glue dries, final-shape
the nose block with a sanding block.
Install the 1/16-inch-diameter wingmounting
aluminum tubes after painting
and installing decorations.
November 2007 19
Power-option 1 consists of a Roadkill N20 6-volt geared motor with a 5.2 Gunther
propeller.
The elevator is small in area, but it is plenty for proper control response because of
the CG placement.
The second choice for power is to install a GWS 40 ducted-fan unit. The wide CG
range allows this option.
A unique
biplane
with power
options for
the FF or
RC modeler
11sig1.QXD 9/24/07 9:09 AM Page 19sig1.QXD 9/21/07 1:45 PM Page 18
20 MODEL AVIATION
Wing: The wing-rib pattern is shown with spars and LEs and
TEs for reference.
The front wings are joined with 1.2 inches of dihedral on
each wingtip. The rear wings are joined with 2.16 inches of
dihedral on each wingtip. Those amounts are required when
flying in an enclosed gymnasium space.
The rear wing joiner requires 1/32 balsa guides attached to
the center top and bottom so it aligns properly in the verticalstabilizer
slot.
Cover the front wing center-section with heavy paper
adhered with a light application of yellow carpenter’s glue. I
covered my wings with red Reynolds Plastic Wrap using waterthinned
RC/56 canopy cement on the wing edges and centers.
This material will heat shrink but can be damaged by excessive
heat.
It is best to join the front and rear wings after the fuselage is
complete. Slide the rear wing into the vertical-stabilizer slot
and then install the front wing with wing-mounting rubber
bands.
Cut some 90° 2.99-inch high-gauge blocks and align the
wingtips so they are parallel to each other. Then it is safe to
join the front wingtips to the rear wingtips. To give the wings a
finishing touch, add the 1/32 balsa wingtip plates to the
wingtips.
Finishing: I sprayed a light coat of white latex model paint on
the fuselage and stabilizers.
I decorated the fuselage sides and vertical stabilizer with
computer ink-jet art on bond paper, which I adhered with a
light application of yellow carpenter’s glue. Contact me by Email
if you would like a copy of the digital Windows Metafile
artwork.
Radio Installation: I use the reliable GWS 5-gram, fourchannel
GWR-4P FM receiver; 5-gram GWS Pico servos; and a
GWS 2-amp speed control in my Rhom-Bus. For control cables
I use .043-inch-diameter plastic tube and #6 .015-inch-diameter
single-strand, stainless-steel fishing leader wire with Z-bend
connections to servos and control horns.
I like to use two-pin Deans gold-plated connectors on my
battery-pack and radio-gear connections. I charge my
conventional 8.4-volt, 150 mAh NiMH batteries with a Hobby
People Watt-Age pulse battery charger.
To prevent battery damage I must charge my 7.2-volt, 250
mAh Li-Poly batteries with a dedicated voltage-cutoff battery
charger, such as a Poteski unit from my local hobby dealer or
Hobby Club.
Adjust the battery and radio-gear location in the fuselage so
that the correct CG indicated on the construction plans is
achieved. Visually check the underside of the wing center at
arm length for correct left and right symmetry. Then check all
the servos for reversed controls.
Flying: Launch the model with your left hand so your right
thumb is on the transmitter control stick from the beginning of
the flight. Make transmitter-stick trim adjustments until the
model flies straight and level with hands-off control.
Outdoor flying is best done in no wind or moderate wind
conditions. Indoor flying is great anytime. MA
Ferrell Papic
[email protected]
The wing and fuselage separate for transportation. This design
uses ample FF technology!
Type: RC park flyer
Wingspan: 28 inches
Wing area: 127 square inches
Wing loading: .55 ounce/square foot
Length: 25 inches
Power option 1: Roadkill N20 6-volt geared motor
with 5.2 Gunther propeller
Power option 2: GWS 40 ducted fan
Motor current: 850 mA for N20; 3 amps for fan
Motor voltage: 8
Motor power: 1-3 ounces of thrust
rpm: 4,200 for N20; 22,000 for fan
Watts/ounce: 6.8 for N20; 24 for fan
Battery: Seven-cell, 150 mAh NiMH or two-cell Li-
Poly for fan
Radio system: Three channels minimum with
GWS 5-gram receiver and 5-gram servos
Flying weight: 7 ounces
Flight duration: Five minutes
Construction: Sheet and strip balsa
Covering/finish: Plastic wrap, RC/56, ink-jet
artwork
11sig1.QXD 9/21/07 1:47 PM Page 20
The wing construction utilizes geodetic bracing for torsional rigidity. It builds into an
extraordinarily light and strong unit.
Notice the shear webbing between the ribs in the center-section. This adds
considerable strength with a small weight penalty.
The fuselage is built in the same manner as that of a competition FF model, with
sheet sides and cross-grain sheeting on the top and bottom. The nose block is
made from foam.