Dave builds an enlarged and modified version of Ralph Bradley’s Sky Bug
July 2006 85
Also included in this column:
• MIFF meet in Kansas City
Micro-Flying Dave Robelen | [email protected]
The Sky Bug (L) inspired the author’s Sky Bird: a larger model that can handle light
breezes, turn tightly, and has good slow-flight characteristics.
The size of the author’s Sky Bird is shown with a pen for reference.
The close-up of the Sky Bird’s nose shows
the Plantraco GB04 drive.
HELLO MICRO MODELERS!
Another couple of months have passed
and this fast-paced field keeps
developing.
I am going to break with my usual
pattern and provide some detailed
information about how to build a model I
have been enjoying. As space permits, I
will provide some coverage of the Mid-
America Indoor Fun Fly (MIFF) meet
that I attended in Kansas City, Missouri.
Last season I acquired some of the
Plantraco 900 MHz equipment: a Deluxe
Starter Package with the GB04 drive and
0.9-gram receiver, and a receiver and a 30
mAh Li-Poly cell meant for the Butterfly
model. This equipment has served me
well, flying in a variety of quickly built
foam prototype models and a scale
ultralight aircraft.
Recently I saw a picture of Ralph
Bradley’s charming little Sky Bug in his
brother Paul’s column in MA, and I
resolved to build one. With a few
modifications, my version has served me
well—so well that it inspired a larger
version for more utility.
One of this month’s photos shows the
two models together. It is this larger
version that I am going to detail.
Basic plans are shown with this
86 MODEL AVIATION
Among the Plantraco equipment acquired
by the author is this GB04 drive shown
with a pen tip for reference.
The BSD Micro table featured a line of simple foam-sheet models that flew well during
open flying periods at the MIFF meet in Kansas City, Missouri.
This Mr. Bones delta, one of the author’s published designs from several years ago, has
a brushless motor in the fan unit and offers smooth handling.
column but will need enlarging. Take them
to an office copier with that function, and
enlarge the drawing until the scale bar on
the bottom matches the 4-inch dimension.
The wing panel is 6 inches long. With
apologies to Ralph, I named this one Sky
Bird, to keep the series going. One photo
shows the Sky Bird and another is a closeup
of the nose and drive.
When I first built my Sky Bird, it had
the standard Plantraco GB04 drive, along
with the 90 mAh Li-Poly cell attached
with the Bahoma magnet system. The total
weight was 15.5 grams, and the
performance was quite reasonable with a
flying time of roughly 10 minutes on a
charge.
The Sky Bird could handle light
breezes and turn extremely tightly, and it
had excellent slow flight characteristics.
Still, I was having my share of issues with
the battery-magnet system. Keeping the
magnets clean for good contact was a
chore and any load in flight was capable
of breaking the connection momentarily,
which would cause the system to stop
functioning and begin a reset. This was
especially a nuisance on touch-and-go
landing attempts.
My solution was to remove the
magnets from the receiver with a
soldering iron and install a pair of wires
with a polarized connector. Meanwhile,
the magnets on the battery seemed to be
welded in place, so I soldered the wires to
the exposed straps next to the magnets.
Problem solved!
This did mean that a different battery
charging system was in order, and I found
a neat little adjustable Li-Poly charger on
Bob Selman’s site at www.bsd
microrc.com. I had met Bob and his
associate Gary Jones at the MIFF meet
and they showed me a neat little drive
with a 4:1 ratio, ball bearings, and using
a 7mm motor. After some negotiations,
Gary removed one of these drives from a
model he had been flying and sent me
home with it. Thanks, Gary.
It took little time to alter the Sky Bird
for this more powerful drive and fit a
GWS 4 x 4 propeller to the nifty
propeller-saver unit. The increase in
performance was dramatic, but it was
clear that the 90 mAh cell was not the
best match for this high-current drive. I
switched to a 170 mAh cell that came
from Bob Selman, and this is the package
I am currently flying.
The Sky Bird will do large loops from
level flight, smooth rudder rolls, pretty
stall turns, and neat touch-and-gos. As a
bonus the model can handle stronger
breezes. The slow flight is still quite
reasonable, and the airplane is able to fly
in confined quarters.
Are you interested in building a Sky
Bird? I chose to build mine using nearly
all balsa with a carbon-fiber rod for a
tailboom. The stock for the wing and tail
should be from a nice, flat, light sheet,
while the 3/32-inch fuselage can be
slightly more firm.
I get the best results with these singlesurface
wings if I preform the approximate
airfoil before assembly. I dampen the
upper surface with window-cleaner spray
and tape the limp sheets to a larger wing
that has nearly the desired airfoil curve.
When it is dry, I use Elmer’s Carpenter
Glue to attach the ribs, using pins to clamp
the panels to a flat surface while drying.
Remember to tilt the center ribs in to
account for the dihedral. A few swipes
with a sanding block in the center, and the
wing panels can be joined.
The tail surfaces are cut from the same
sheet of 1/32-inch wood. Do not cut the
hinge lines yet.
I found a nice, light, clear sealer spray
at the local Wal-Mart called Color Place
Clear Gloss. Misted on and sanded smooth
with 400-grit sandpaper, a couple coats
will do a fine job. The color trim on mine
is carefully misted on straight from the
spray can.
The fuselage front can be cut to shape
and the boom added now. I covered mine
with black tissue to resemble carbon fiber.
The notch for the drive and the actuator
mounting holes can be cut now. The .020-
inch wire landing gear is installed with a
3/32-inch balsa filler for a brace. Mount the
actuators and the drive, and we are getting
there.
The hinge lines should be cut in the tail
now, and the surfaces hinged with 3/16-
inch-wide strips of frosted Magic Mending
tape. I used some neat little fiberglass
control horns sold by Plantraco on my Sky
Bird, and the wheels came from the same
source.
Mount the surfaces to the boom and
make up a couple of pushrods. I used .015-
inch steel wire for the main part, with a 2-
inch length of .020-inch brass wire spliced
on at the actuator end. Be sure that the
controls center with the actuators at the
center.
Mount the wing and install the drive
with the propeller on the nose. The battery
and receiver should be located on the sides
in a position that will achieve the correct
balance. If you choose to use all Plantraco
gear including the GB04 drive, make the
88 MODEL AVIATION
nose 3/4 inch longer for proper balance.
The Sky Bird will take off from a
variety of surfaces. Making the first
flights from a surface takeoff can reveal
any trim issues before they become
dangerous. If you build one of these
models, please send me a picture and your
comments. It will be fun to see how others
make out.
I mentioned the MIFF meet in Kansas
City. This took place the weekend of
March 18-19, 2006. Based on the
promotional material, I chose to drive the
1,200 miles to attend, and I am glad I did.
The site was the indoor practice facility
for the Kansas City Chiefs, and it was
huge. The club that organized the meet—
the Kansas City Flying Circuits—did an
excellent job handling the operation, and
the Saturday-night banquet was delicious.
There was ample open flying divided
into periods for the different classes of
models, as well as several categories of
competition. The classes included IPS
Racing, RC Scale, and Extreme
Aerobatics. There was also a flight period
for demonstrating replicas of early-period
FF models. I counted 104 pilots registered
and a large number of aircraft.
There was a good turnout of vendor
displays, with a wide variety of indoorrelated
goodies. One that caught my
“micro eye” was the BSD Micro table that
featured a line of simple foam-sheet
models that flew well during the open
flying periods.
There were many fine projects
displayed throughout the building, but one
in particular caught my eye for personal
reasons. A photo shows a Mr. Bones delta
model—a design that I had published
several years ago in Backyard Flyer. This
one had a brushless motor in the fan unit,
and when it was opened up it tore around,
yet the low speed was fine with smooth
handling. I suppose I need to get mine
back down and fit it with one of those
brushless motors. That looked like fun.
I will continue with more coverage of
this fine meet in the next column.
Meanwhile, thanks
Edition: Model Aviation - 2006/07
Page Numbers: 85,86,87,88
Edition: Model Aviation - 2006/07
Page Numbers: 85,86,87,88
Dave builds an enlarged and modified version of Ralph Bradley’s Sky Bug
July 2006 85
Also included in this column:
• MIFF meet in Kansas City
Micro-Flying Dave Robelen | [email protected]
The Sky Bug (L) inspired the author’s Sky Bird: a larger model that can handle light
breezes, turn tightly, and has good slow-flight characteristics.
The size of the author’s Sky Bird is shown with a pen for reference.
The close-up of the Sky Bird’s nose shows
the Plantraco GB04 drive.
HELLO MICRO MODELERS!
Another couple of months have passed
and this fast-paced field keeps
developing.
I am going to break with my usual
pattern and provide some detailed
information about how to build a model I
have been enjoying. As space permits, I
will provide some coverage of the Mid-
America Indoor Fun Fly (MIFF) meet
that I attended in Kansas City, Missouri.
Last season I acquired some of the
Plantraco 900 MHz equipment: a Deluxe
Starter Package with the GB04 drive and
0.9-gram receiver, and a receiver and a 30
mAh Li-Poly cell meant for the Butterfly
model. This equipment has served me
well, flying in a variety of quickly built
foam prototype models and a scale
ultralight aircraft.
Recently I saw a picture of Ralph
Bradley’s charming little Sky Bug in his
brother Paul’s column in MA, and I
resolved to build one. With a few
modifications, my version has served me
well—so well that it inspired a larger
version for more utility.
One of this month’s photos shows the
two models together. It is this larger
version that I am going to detail.
Basic plans are shown with this
86 MODEL AVIATION
Among the Plantraco equipment acquired
by the author is this GB04 drive shown
with a pen tip for reference.
The BSD Micro table featured a line of simple foam-sheet models that flew well during
open flying periods at the MIFF meet in Kansas City, Missouri.
This Mr. Bones delta, one of the author’s published designs from several years ago, has
a brushless motor in the fan unit and offers smooth handling.
column but will need enlarging. Take them
to an office copier with that function, and
enlarge the drawing until the scale bar on
the bottom matches the 4-inch dimension.
The wing panel is 6 inches long. With
apologies to Ralph, I named this one Sky
Bird, to keep the series going. One photo
shows the Sky Bird and another is a closeup
of the nose and drive.
When I first built my Sky Bird, it had
the standard Plantraco GB04 drive, along
with the 90 mAh Li-Poly cell attached
with the Bahoma magnet system. The total
weight was 15.5 grams, and the
performance was quite reasonable with a
flying time of roughly 10 minutes on a
charge.
The Sky Bird could handle light
breezes and turn extremely tightly, and it
had excellent slow flight characteristics.
Still, I was having my share of issues with
the battery-magnet system. Keeping the
magnets clean for good contact was a
chore and any load in flight was capable
of breaking the connection momentarily,
which would cause the system to stop
functioning and begin a reset. This was
especially a nuisance on touch-and-go
landing attempts.
My solution was to remove the
magnets from the receiver with a
soldering iron and install a pair of wires
with a polarized connector. Meanwhile,
the magnets on the battery seemed to be
welded in place, so I soldered the wires to
the exposed straps next to the magnets.
Problem solved!
This did mean that a different battery
charging system was in order, and I found
a neat little adjustable Li-Poly charger on
Bob Selman’s site at www.bsd
microrc.com. I had met Bob and his
associate Gary Jones at the MIFF meet
and they showed me a neat little drive
with a 4:1 ratio, ball bearings, and using
a 7mm motor. After some negotiations,
Gary removed one of these drives from a
model he had been flying and sent me
home with it. Thanks, Gary.
It took little time to alter the Sky Bird
for this more powerful drive and fit a
GWS 4 x 4 propeller to the nifty
propeller-saver unit. The increase in
performance was dramatic, but it was
clear that the 90 mAh cell was not the
best match for this high-current drive. I
switched to a 170 mAh cell that came
from Bob Selman, and this is the package
I am currently flying.
The Sky Bird will do large loops from
level flight, smooth rudder rolls, pretty
stall turns, and neat touch-and-gos. As a
bonus the model can handle stronger
breezes. The slow flight is still quite
reasonable, and the airplane is able to fly
in confined quarters.
Are you interested in building a Sky
Bird? I chose to build mine using nearly
all balsa with a carbon-fiber rod for a
tailboom. The stock for the wing and tail
should be from a nice, flat, light sheet,
while the 3/32-inch fuselage can be
slightly more firm.
I get the best results with these singlesurface
wings if I preform the approximate
airfoil before assembly. I dampen the
upper surface with window-cleaner spray
and tape the limp sheets to a larger wing
that has nearly the desired airfoil curve.
When it is dry, I use Elmer’s Carpenter
Glue to attach the ribs, using pins to clamp
the panels to a flat surface while drying.
Remember to tilt the center ribs in to
account for the dihedral. A few swipes
with a sanding block in the center, and the
wing panels can be joined.
The tail surfaces are cut from the same
sheet of 1/32-inch wood. Do not cut the
hinge lines yet.
I found a nice, light, clear sealer spray
at the local Wal-Mart called Color Place
Clear Gloss. Misted on and sanded smooth
with 400-grit sandpaper, a couple coats
will do a fine job. The color trim on mine
is carefully misted on straight from the
spray can.
The fuselage front can be cut to shape
and the boom added now. I covered mine
with black tissue to resemble carbon fiber.
The notch for the drive and the actuator
mounting holes can be cut now. The .020-
inch wire landing gear is installed with a
3/32-inch balsa filler for a brace. Mount the
actuators and the drive, and we are getting
there.
The hinge lines should be cut in the tail
now, and the surfaces hinged with 3/16-
inch-wide strips of frosted Magic Mending
tape. I used some neat little fiberglass
control horns sold by Plantraco on my Sky
Bird, and the wheels came from the same
source.
Mount the surfaces to the boom and
make up a couple of pushrods. I used .015-
inch steel wire for the main part, with a 2-
inch length of .020-inch brass wire spliced
on at the actuator end. Be sure that the
controls center with the actuators at the
center.
Mount the wing and install the drive
with the propeller on the nose. The battery
and receiver should be located on the sides
in a position that will achieve the correct
balance. If you choose to use all Plantraco
gear including the GB04 drive, make the
88 MODEL AVIATION
nose 3/4 inch longer for proper balance.
The Sky Bird will take off from a
variety of surfaces. Making the first
flights from a surface takeoff can reveal
any trim issues before they become
dangerous. If you build one of these
models, please send me a picture and your
comments. It will be fun to see how others
make out.
I mentioned the MIFF meet in Kansas
City. This took place the weekend of
March 18-19, 2006. Based on the
promotional material, I chose to drive the
1,200 miles to attend, and I am glad I did.
The site was the indoor practice facility
for the Kansas City Chiefs, and it was
huge. The club that organized the meet—
the Kansas City Flying Circuits—did an
excellent job handling the operation, and
the Saturday-night banquet was delicious.
There was ample open flying divided
into periods for the different classes of
models, as well as several categories of
competition. The classes included IPS
Racing, RC Scale, and Extreme
Aerobatics. There was also a flight period
for demonstrating replicas of early-period
FF models. I counted 104 pilots registered
and a large number of aircraft.
There was a good turnout of vendor
displays, with a wide variety of indoorrelated
goodies. One that caught my
“micro eye” was the BSD Micro table that
featured a line of simple foam-sheet
models that flew well during the open
flying periods.
There were many fine projects
displayed throughout the building, but one
in particular caught my eye for personal
reasons. A photo shows a Mr. Bones delta
model—a design that I had published
several years ago in Backyard Flyer. This
one had a brushless motor in the fan unit,
and when it was opened up it tore around,
yet the low speed was fine with smooth
handling. I suppose I need to get mine
back down and fit it with one of those
brushless motors. That looked like fun.
I will continue with more coverage of
this fine meet in the next column.
Meanwhile, thanks
Edition: Model Aviation - 2006/07
Page Numbers: 85,86,87,88
Dave builds an enlarged and modified version of Ralph Bradley’s Sky Bug
July 2006 85
Also included in this column:
• MIFF meet in Kansas City
Micro-Flying Dave Robelen | [email protected]
The Sky Bug (L) inspired the author’s Sky Bird: a larger model that can handle light
breezes, turn tightly, and has good slow-flight characteristics.
The size of the author’s Sky Bird is shown with a pen for reference.
The close-up of the Sky Bird’s nose shows
the Plantraco GB04 drive.
HELLO MICRO MODELERS!
Another couple of months have passed
and this fast-paced field keeps
developing.
I am going to break with my usual
pattern and provide some detailed
information about how to build a model I
have been enjoying. As space permits, I
will provide some coverage of the Mid-
America Indoor Fun Fly (MIFF) meet
that I attended in Kansas City, Missouri.
Last season I acquired some of the
Plantraco 900 MHz equipment: a Deluxe
Starter Package with the GB04 drive and
0.9-gram receiver, and a receiver and a 30
mAh Li-Poly cell meant for the Butterfly
model. This equipment has served me
well, flying in a variety of quickly built
foam prototype models and a scale
ultralight aircraft.
Recently I saw a picture of Ralph
Bradley’s charming little Sky Bug in his
brother Paul’s column in MA, and I
resolved to build one. With a few
modifications, my version has served me
well—so well that it inspired a larger
version for more utility.
One of this month’s photos shows the
two models together. It is this larger
version that I am going to detail.
Basic plans are shown with this
86 MODEL AVIATION
Among the Plantraco equipment acquired
by the author is this GB04 drive shown
with a pen tip for reference.
The BSD Micro table featured a line of simple foam-sheet models that flew well during
open flying periods at the MIFF meet in Kansas City, Missouri.
This Mr. Bones delta, one of the author’s published designs from several years ago, has
a brushless motor in the fan unit and offers smooth handling.
column but will need enlarging. Take them
to an office copier with that function, and
enlarge the drawing until the scale bar on
the bottom matches the 4-inch dimension.
The wing panel is 6 inches long. With
apologies to Ralph, I named this one Sky
Bird, to keep the series going. One photo
shows the Sky Bird and another is a closeup
of the nose and drive.
When I first built my Sky Bird, it had
the standard Plantraco GB04 drive, along
with the 90 mAh Li-Poly cell attached
with the Bahoma magnet system. The total
weight was 15.5 grams, and the
performance was quite reasonable with a
flying time of roughly 10 minutes on a
charge.
The Sky Bird could handle light
breezes and turn extremely tightly, and it
had excellent slow flight characteristics.
Still, I was having my share of issues with
the battery-magnet system. Keeping the
magnets clean for good contact was a
chore and any load in flight was capable
of breaking the connection momentarily,
which would cause the system to stop
functioning and begin a reset. This was
especially a nuisance on touch-and-go
landing attempts.
My solution was to remove the
magnets from the receiver with a
soldering iron and install a pair of wires
with a polarized connector. Meanwhile,
the magnets on the battery seemed to be
welded in place, so I soldered the wires to
the exposed straps next to the magnets.
Problem solved!
This did mean that a different battery
charging system was in order, and I found
a neat little adjustable Li-Poly charger on
Bob Selman’s site at www.bsd
microrc.com. I had met Bob and his
associate Gary Jones at the MIFF meet
and they showed me a neat little drive
with a 4:1 ratio, ball bearings, and using
a 7mm motor. After some negotiations,
Gary removed one of these drives from a
model he had been flying and sent me
home with it. Thanks, Gary.
It took little time to alter the Sky Bird
for this more powerful drive and fit a
GWS 4 x 4 propeller to the nifty
propeller-saver unit. The increase in
performance was dramatic, but it was
clear that the 90 mAh cell was not the
best match for this high-current drive. I
switched to a 170 mAh cell that came
from Bob Selman, and this is the package
I am currently flying.
The Sky Bird will do large loops from
level flight, smooth rudder rolls, pretty
stall turns, and neat touch-and-gos. As a
bonus the model can handle stronger
breezes. The slow flight is still quite
reasonable, and the airplane is able to fly
in confined quarters.
Are you interested in building a Sky
Bird? I chose to build mine using nearly
all balsa with a carbon-fiber rod for a
tailboom. The stock for the wing and tail
should be from a nice, flat, light sheet,
while the 3/32-inch fuselage can be
slightly more firm.
I get the best results with these singlesurface
wings if I preform the approximate
airfoil before assembly. I dampen the
upper surface with window-cleaner spray
and tape the limp sheets to a larger wing
that has nearly the desired airfoil curve.
When it is dry, I use Elmer’s Carpenter
Glue to attach the ribs, using pins to clamp
the panels to a flat surface while drying.
Remember to tilt the center ribs in to
account for the dihedral. A few swipes
with a sanding block in the center, and the
wing panels can be joined.
The tail surfaces are cut from the same
sheet of 1/32-inch wood. Do not cut the
hinge lines yet.
I found a nice, light, clear sealer spray
at the local Wal-Mart called Color Place
Clear Gloss. Misted on and sanded smooth
with 400-grit sandpaper, a couple coats
will do a fine job. The color trim on mine
is carefully misted on straight from the
spray can.
The fuselage front can be cut to shape
and the boom added now. I covered mine
with black tissue to resemble carbon fiber.
The notch for the drive and the actuator
mounting holes can be cut now. The .020-
inch wire landing gear is installed with a
3/32-inch balsa filler for a brace. Mount the
actuators and the drive, and we are getting
there.
The hinge lines should be cut in the tail
now, and the surfaces hinged with 3/16-
inch-wide strips of frosted Magic Mending
tape. I used some neat little fiberglass
control horns sold by Plantraco on my Sky
Bird, and the wheels came from the same
source.
Mount the surfaces to the boom and
make up a couple of pushrods. I used .015-
inch steel wire for the main part, with a 2-
inch length of .020-inch brass wire spliced
on at the actuator end. Be sure that the
controls center with the actuators at the
center.
Mount the wing and install the drive
with the propeller on the nose. The battery
and receiver should be located on the sides
in a position that will achieve the correct
balance. If you choose to use all Plantraco
gear including the GB04 drive, make the
88 MODEL AVIATION
nose 3/4 inch longer for proper balance.
The Sky Bird will take off from a
variety of surfaces. Making the first
flights from a surface takeoff can reveal
any trim issues before they become
dangerous. If you build one of these
models, please send me a picture and your
comments. It will be fun to see how others
make out.
I mentioned the MIFF meet in Kansas
City. This took place the weekend of
March 18-19, 2006. Based on the
promotional material, I chose to drive the
1,200 miles to attend, and I am glad I did.
The site was the indoor practice facility
for the Kansas City Chiefs, and it was
huge. The club that organized the meet—
the Kansas City Flying Circuits—did an
excellent job handling the operation, and
the Saturday-night banquet was delicious.
There was ample open flying divided
into periods for the different classes of
models, as well as several categories of
competition. The classes included IPS
Racing, RC Scale, and Extreme
Aerobatics. There was also a flight period
for demonstrating replicas of early-period
FF models. I counted 104 pilots registered
and a large number of aircraft.
There was a good turnout of vendor
displays, with a wide variety of indoorrelated
goodies. One that caught my
“micro eye” was the BSD Micro table that
featured a line of simple foam-sheet
models that flew well during the open
flying periods.
There were many fine projects
displayed throughout the building, but one
in particular caught my eye for personal
reasons. A photo shows a Mr. Bones delta
model—a design that I had published
several years ago in Backyard Flyer. This
one had a brushless motor in the fan unit,
and when it was opened up it tore around,
yet the low speed was fine with smooth
handling. I suppose I need to get mine
back down and fit it with one of those
brushless motors. That looked like fun.
I will continue with more coverage of
this fine meet in the next column.
Meanwhile, thanks
Edition: Model Aviation - 2006/07
Page Numbers: 85,86,87,88
Dave builds an enlarged and modified version of Ralph Bradley’s Sky Bug
July 2006 85
Also included in this column:
• MIFF meet in Kansas City
Micro-Flying Dave Robelen | [email protected]
The Sky Bug (L) inspired the author’s Sky Bird: a larger model that can handle light
breezes, turn tightly, and has good slow-flight characteristics.
The size of the author’s Sky Bird is shown with a pen for reference.
The close-up of the Sky Bird’s nose shows
the Plantraco GB04 drive.
HELLO MICRO MODELERS!
Another couple of months have passed
and this fast-paced field keeps
developing.
I am going to break with my usual
pattern and provide some detailed
information about how to build a model I
have been enjoying. As space permits, I
will provide some coverage of the Mid-
America Indoor Fun Fly (MIFF) meet
that I attended in Kansas City, Missouri.
Last season I acquired some of the
Plantraco 900 MHz equipment: a Deluxe
Starter Package with the GB04 drive and
0.9-gram receiver, and a receiver and a 30
mAh Li-Poly cell meant for the Butterfly
model. This equipment has served me
well, flying in a variety of quickly built
foam prototype models and a scale
ultralight aircraft.
Recently I saw a picture of Ralph
Bradley’s charming little Sky Bug in his
brother Paul’s column in MA, and I
resolved to build one. With a few
modifications, my version has served me
well—so well that it inspired a larger
version for more utility.
One of this month’s photos shows the
two models together. It is this larger
version that I am going to detail.
Basic plans are shown with this
86 MODEL AVIATION
Among the Plantraco equipment acquired
by the author is this GB04 drive shown
with a pen tip for reference.
The BSD Micro table featured a line of simple foam-sheet models that flew well during
open flying periods at the MIFF meet in Kansas City, Missouri.
This Mr. Bones delta, one of the author’s published designs from several years ago, has
a brushless motor in the fan unit and offers smooth handling.
column but will need enlarging. Take them
to an office copier with that function, and
enlarge the drawing until the scale bar on
the bottom matches the 4-inch dimension.
The wing panel is 6 inches long. With
apologies to Ralph, I named this one Sky
Bird, to keep the series going. One photo
shows the Sky Bird and another is a closeup
of the nose and drive.
When I first built my Sky Bird, it had
the standard Plantraco GB04 drive, along
with the 90 mAh Li-Poly cell attached
with the Bahoma magnet system. The total
weight was 15.5 grams, and the
performance was quite reasonable with a
flying time of roughly 10 minutes on a
charge.
The Sky Bird could handle light
breezes and turn extremely tightly, and it
had excellent slow flight characteristics.
Still, I was having my share of issues with
the battery-magnet system. Keeping the
magnets clean for good contact was a
chore and any load in flight was capable
of breaking the connection momentarily,
which would cause the system to stop
functioning and begin a reset. This was
especially a nuisance on touch-and-go
landing attempts.
My solution was to remove the
magnets from the receiver with a
soldering iron and install a pair of wires
with a polarized connector. Meanwhile,
the magnets on the battery seemed to be
welded in place, so I soldered the wires to
the exposed straps next to the magnets.
Problem solved!
This did mean that a different battery
charging system was in order, and I found
a neat little adjustable Li-Poly charger on
Bob Selman’s site at www.bsd
microrc.com. I had met Bob and his
associate Gary Jones at the MIFF meet
and they showed me a neat little drive
with a 4:1 ratio, ball bearings, and using
a 7mm motor. After some negotiations,
Gary removed one of these drives from a
model he had been flying and sent me
home with it. Thanks, Gary.
It took little time to alter the Sky Bird
for this more powerful drive and fit a
GWS 4 x 4 propeller to the nifty
propeller-saver unit. The increase in
performance was dramatic, but it was
clear that the 90 mAh cell was not the
best match for this high-current drive. I
switched to a 170 mAh cell that came
from Bob Selman, and this is the package
I am currently flying.
The Sky Bird will do large loops from
level flight, smooth rudder rolls, pretty
stall turns, and neat touch-and-gos. As a
bonus the model can handle stronger
breezes. The slow flight is still quite
reasonable, and the airplane is able to fly
in confined quarters.
Are you interested in building a Sky
Bird? I chose to build mine using nearly
all balsa with a carbon-fiber rod for a
tailboom. The stock for the wing and tail
should be from a nice, flat, light sheet,
while the 3/32-inch fuselage can be
slightly more firm.
I get the best results with these singlesurface
wings if I preform the approximate
airfoil before assembly. I dampen the
upper surface with window-cleaner spray
and tape the limp sheets to a larger wing
that has nearly the desired airfoil curve.
When it is dry, I use Elmer’s Carpenter
Glue to attach the ribs, using pins to clamp
the panels to a flat surface while drying.
Remember to tilt the center ribs in to
account for the dihedral. A few swipes
with a sanding block in the center, and the
wing panels can be joined.
The tail surfaces are cut from the same
sheet of 1/32-inch wood. Do not cut the
hinge lines yet.
I found a nice, light, clear sealer spray
at the local Wal-Mart called Color Place
Clear Gloss. Misted on and sanded smooth
with 400-grit sandpaper, a couple coats
will do a fine job. The color trim on mine
is carefully misted on straight from the
spray can.
The fuselage front can be cut to shape
and the boom added now. I covered mine
with black tissue to resemble carbon fiber.
The notch for the drive and the actuator
mounting holes can be cut now. The .020-
inch wire landing gear is installed with a
3/32-inch balsa filler for a brace. Mount the
actuators and the drive, and we are getting
there.
The hinge lines should be cut in the tail
now, and the surfaces hinged with 3/16-
inch-wide strips of frosted Magic Mending
tape. I used some neat little fiberglass
control horns sold by Plantraco on my Sky
Bird, and the wheels came from the same
source.
Mount the surfaces to the boom and
make up a couple of pushrods. I used .015-
inch steel wire for the main part, with a 2-
inch length of .020-inch brass wire spliced
on at the actuator end. Be sure that the
controls center with the actuators at the
center.
Mount the wing and install the drive
with the propeller on the nose. The battery
and receiver should be located on the sides
in a position that will achieve the correct
balance. If you choose to use all Plantraco
gear including the GB04 drive, make the
88 MODEL AVIATION
nose 3/4 inch longer for proper balance.
The Sky Bird will take off from a
variety of surfaces. Making the first
flights from a surface takeoff can reveal
any trim issues before they become
dangerous. If you build one of these
models, please send me a picture and your
comments. It will be fun to see how others
make out.
I mentioned the MIFF meet in Kansas
City. This took place the weekend of
March 18-19, 2006. Based on the
promotional material, I chose to drive the
1,200 miles to attend, and I am glad I did.
The site was the indoor practice facility
for the Kansas City Chiefs, and it was
huge. The club that organized the meet—
the Kansas City Flying Circuits—did an
excellent job handling the operation, and
the Saturday-night banquet was delicious.
There was ample open flying divided
into periods for the different classes of
models, as well as several categories of
competition. The classes included IPS
Racing, RC Scale, and Extreme
Aerobatics. There was also a flight period
for demonstrating replicas of early-period
FF models. I counted 104 pilots registered
and a large number of aircraft.
There was a good turnout of vendor
displays, with a wide variety of indoorrelated
goodies. One that caught my
“micro eye” was the BSD Micro table that
featured a line of simple foam-sheet
models that flew well during the open
flying periods.
There were many fine projects
displayed throughout the building, but one
in particular caught my eye for personal
reasons. A photo shows a Mr. Bones delta
model—a design that I had published
several years ago in Backyard Flyer. This
one had a brushless motor in the fan unit,
and when it was opened up it tore around,
yet the low speed was fine with smooth
handling. I suppose I need to get mine
back down and fit it with one of those
brushless motors. That looked like fun.
I will continue with more coverage of
this fine meet in the next column.
Meanwhile, thanks