I HAVE MENTIONED this before, but this
sure is a great time to be a person who likes to
build model airplanes. The available
technology makes the process fun and helps
modelers achieve nice results. This technology
is enhancing all aspects of the hobby, but for
me it is especially true in the process of
designing and fabricating the parts of the
wonderful flying machines we enjoy at our
local flying sites.
Because I like to design models as well as
build those that others have designed, I tend to
study the details of the internal structure. It is
interesting to see how different designers
approach this all-important part of the model.
You often see vastly different approaches
to the structural design of two similar-size
scale models of the same aircraft. Allowing for
the same intended flying format, such as radio
control, you will see one design use a heavy,
robust structure while the other is based on a
light minimal structure. Both produce niceflying
models that represent the full-scale
aircraft. One works well in the small-field
venues, and the other is better suited to larger
flying sites.
Model-airplane structural design got a shot
in the arm when computer-driven lasers came
onto the scene. One of the first people I know
who applied this technology to models is
Thomas Herr. It has been awhile since he
started selling laser-cut kits, and today it is
hard to imagine building a kit that has not had
the parts generated via a laser cutter.
Laser-cutting the parts in itself is a major
enhancement to the fabrication of models, but
that is not the complete story. The big news is
what laser-cutting allows in the way parts are
laid out and the overall structural design of a
model.
The ability of a computer-driven laser
cutter to create precise components with
intricate designs is the key. Parts can be cut
from balsa or plywood that would be difficult
to duplicate using manual methods. The
pieces, in turn, can be configured to create
structures that are strong and light. Those two
characteristics are crucial for enjoyable smallfield
models.
Fortunately, the world of laser-cutting and
associated parts design does not have to be the
sole realm of the kit manufacturer. A number
of companies that handle laser-cutting for kit
makers also offer their services to the “oneoff”
modeler. Getting parts custom cut is
becoming more common and is surprisingly
affordable.
I have been considering several modeling
projects and have thought how great it would
be to have the parts laser cut. I finally took the
plunge.
I have been dabbling with 1/2-scale versions
of some of the early RC Aerobatics models
that helped define the world of AMA Pattern
flying. One such model is the Fred Dunndesigned
Astro-Hog, which first appeared in
the modeling press in the April 1958 Model
Airplane News magazine.
The 1958 version of the Astro-Hog differs
a bit from the one that Sig currently sells in kit
form. The early version used “barn door”
ailerons rather than the more modern strip
ailerons.
I’m by no means the first person to build a
reduced-size Astro-Hog. When I developed
my 1/2-scale version, I wanted to more closely
duplicate the features and structure of the
original. Since I planned on having the parts
laser cut, I made a few parts-layout changes to
take advantage of the available technology.
The results are shown in the picture of the
model bones.
Manzano Laser Works cut the parts. I have
provided contact information in the source
listing. Other laser cutters will also do custom
work. Look at the advertisements in the
magazines.
My reason for going on about laser-cutting
is to encourage you to consider that
technology when you are developing your
next design. I was pleasantly surprised by the
affordability and am thrilled with the resulting
parts. You can bet that the 1/2-scale Astro Hog
will not be my last custom laser-cut project.
On the subject of laser-cutting technology in
present-day designs, I have information about
Pat Tritle’s latest offering. He is an absolute
master at creating minimum-weight models
that have surprisingly strong structures. His
airplanes are designed for laser-cutting and
take nice advantage of the structural design
features that allow his light models to perform
well at smaller fields.
Pat has created a very nice rendition of the
Piper L-4. The full-scale World War II
airplane was based on the well-proven Cub
airframe and lends itself to the world of
model aviation.
The L-4 is a larger small-field model. At
1/8 scale, it sports a 53-inch wingspan. This is
a great size for building, and with a flying
weight of roughly 16 ounces, it is perfect for
relaxed flying in small venues.
The basic Piper Cub has been rendered as
a model more often than most full-scale
airplanes, but many models incorporate some
compromises relative to scale fidelity.
Recognizing this fact, Pat set out to develop a
much more accurate Piper L-4 than we
commonly see in the size range that is suitable
for small-field flying.
He wrote:
“This one began with a good set of 3-
views, along with a bunch of photos of fullsize
airplanes. This time the outlines were
unaltered, and the rib spacing is accurate.
“The side door opens for battery access, so
there are no ‘non-scale’ hatches. Also, to keep
the cabin looking more scale the wings are
plugged in and are retained with rare earth
magnets so there’s no visible hardware.”
The L-4 uses a Himax 2808-980 motor
driving a 9 x 5 propeller and gets energy from
a two-cell, 1320 mAh Li-Poly battery pack.
All flight controls are functional, and Pat
reports that the model is extremely well
behaved—as you would expect from a Cubbased
airplane.
Short kits are available from Pat’s Custom
Models. Please see the source listing at the
end of this column for contact information.
The L-4 story doesn’t end yet. Look closely
at the photo of Pat’s model; the cowl sports a
112 MODEL AVIATION
nice-looking set of engine cylinders extending
out into the breeze.
This is not something you typically see on
a Cub-style scale model of this size. Most
Cubs we see in the smaller scales have limited
renditions of engine cylinders. The visible
engine cylinders are such a distinctive feature
of the L-4 that making realistic-looking
dummy cylinders was a key objective in Pat’s
project.
Not being afraid to reach out for help when
needed, he called on the talented Keith Sparks
to develop the tooling and vacuum-formed
parts that make up the L-4 cowl and simulated
engine. Keith does plastic work for many of
the companies that manufacture models
typically constructed by members of the
small-field community.
This limited space does not allow me to
cover Keith’s entire process for developing
parts such as the L-4 cowl and engine, but
some insight might be helpful to those of us
who struggle to make similar parts for our
models. Keith said:
“Making the cowl itself was easy. Pat sent
me a plug to fit the fuselage. Since I was given
the opportunity to help make this model stand
out from other Cubs I concentrated on what is
lacking on every Cub I’ve seen, the engine
detail.
“I started with two blocks of auto body
filler bonded with a drop of CA at the parting
line. The side, top and front view of a
Continental engine cylinder and head are
drawn on the block and as the sculptures say ‘I
trimmed away the parts that were not the
engine.’
“The tools are then separated and a test run
is made looking for problems in forming and
fit. This is the step I dislike because it usually
involves giving up detail. Also any
adjustments to the tooling must be made with
the tool halves together to maintain an exact
match at the parting line.
“When parts like the scoops on the L-4 are
needed to mate to the finished assembly, an
assembled cowl/engine is used to build the
tool form. Molding clay and Plaster of Paris
are used to take a cast directly off the
assembled parts for the best fit possible.”
I have provided a close-up photo of the
prototype cowl and engine for your reference.
Keith does nice work.
I have some great news regarding the L-4
cowl/engine assembly. In addition to
including the cowl and engine parts in the L-4
short kit, Pat is selling the parts package
separately. This is a perfect way for those of
you with 1/8-scale Cubs to make a low-cost
upgrade to the front end of your models.
Keith has written a great book about
building with foam. Check the source listing at
the end for contact information.
So you don’t think I believe everything has to
be laser cut, I’ll show you another innovative
micro flyer from John Krouse. He has shared
several of his neat models with us in the past.
This time he is exploring the use of
ducted-fan power for what we typically call a
“slow flyer” airframe. I have the feeling that
John’s models get plenty of attention when he
shows up at his local venue.
The aircraft in the photo has an 18-inch
wingspan. The wing was fabricated from two
4-inch-chord, preformed, blue-foam wing
panels.
All electronics are mounted inside a builtup
pylon. The ducted fan is a D.C. Enterprises
ED-30 10/3/20T brushless outrunner unit
from Bob Selman Designs. Contact
information is at the end of the column. The
impeller has a diameter of 30mm (1.2 inches).
With a single 170 mAh Li-Poly battery, the
model has a flying weight of 39 grams (1.4
ounces).
John reports a fairly aggressive climb with
a comfortable throttled-back cruise. He notes
that “it just sounds fast.”
Very nice, John. This is definitely a
departure from the typical relaxed micro flyer.
Another reader who has shared a project in
these pages is Lyn Coon; I featured his nice
profile Piper Cub in the December 2007
column. Lyn comes from a modeling family,
and his father, Leonard Coon, was so inspired
by the Cub that he decided to develop a
profile scale indoor flyer of his own.
He built a nice Beech Staggerwing from
No-Cal plans from A.A. Lidberg Model Plan
Service. See the source listing.
Leonard’s model has a 16-inch wingspan.
Power is from a Gary Jones GWJ 7mm
gearbox/motor combination from Bob Selman
Designs. A Micro Invent 5 x 3 carbon
propeller is being used. With Plantraco
electronics onboard, the Staggerwing’s flying
weight is 24 grams.
Good work, Leonard. Keep them coming.
This wraps up another edition. You can tell
me about your latest project via regular mail
or E-mail. MA
Sources:
Manzano Laser Works
(505) 286-2640
www.manzanolaser.com
Pat’s Custom Models
(505) 296-4511
www.patscustom-models.com
Building With Foam by Keith Sparks
(817) 656-2295 (Please call between 9 a.m.
and noon.)
http://home.att.net/~parkflyerplastics
Bob Selman Designs
(417) 358-9521
www.bsdmicrorc.com
A.A. Lidberg Model Plan Service
(480) 839-8154 (6 p.m.-10 p.m. evenings and
weekends)
www.aalmps.com
Paul Bradley
10201 Scarlet Oak Dr.
Independence KY 41051
Edition: Model Aviation - 2008/08
Page Numbers: 110,111,112
Edition: Model Aviation - 2008/08
Page Numbers: 110,111,112
I HAVE MENTIONED this before, but this
sure is a great time to be a person who likes to
build model airplanes. The available
technology makes the process fun and helps
modelers achieve nice results. This technology
is enhancing all aspects of the hobby, but for
me it is especially true in the process of
designing and fabricating the parts of the
wonderful flying machines we enjoy at our
local flying sites.
Because I like to design models as well as
build those that others have designed, I tend to
study the details of the internal structure. It is
interesting to see how different designers
approach this all-important part of the model.
You often see vastly different approaches
to the structural design of two similar-size
scale models of the same aircraft. Allowing for
the same intended flying format, such as radio
control, you will see one design use a heavy,
robust structure while the other is based on a
light minimal structure. Both produce niceflying
models that represent the full-scale
aircraft. One works well in the small-field
venues, and the other is better suited to larger
flying sites.
Model-airplane structural design got a shot
in the arm when computer-driven lasers came
onto the scene. One of the first people I know
who applied this technology to models is
Thomas Herr. It has been awhile since he
started selling laser-cut kits, and today it is
hard to imagine building a kit that has not had
the parts generated via a laser cutter.
Laser-cutting the parts in itself is a major
enhancement to the fabrication of models, but
that is not the complete story. The big news is
what laser-cutting allows in the way parts are
laid out and the overall structural design of a
model.
The ability of a computer-driven laser
cutter to create precise components with
intricate designs is the key. Parts can be cut
from balsa or plywood that would be difficult
to duplicate using manual methods. The
pieces, in turn, can be configured to create
structures that are strong and light. Those two
characteristics are crucial for enjoyable smallfield
models.
Fortunately, the world of laser-cutting and
associated parts design does not have to be the
sole realm of the kit manufacturer. A number
of companies that handle laser-cutting for kit
makers also offer their services to the “oneoff”
modeler. Getting parts custom cut is
becoming more common and is surprisingly
affordable.
I have been considering several modeling
projects and have thought how great it would
be to have the parts laser cut. I finally took the
plunge.
I have been dabbling with 1/2-scale versions
of some of the early RC Aerobatics models
that helped define the world of AMA Pattern
flying. One such model is the Fred Dunndesigned
Astro-Hog, which first appeared in
the modeling press in the April 1958 Model
Airplane News magazine.
The 1958 version of the Astro-Hog differs
a bit from the one that Sig currently sells in kit
form. The early version used “barn door”
ailerons rather than the more modern strip
ailerons.
I’m by no means the first person to build a
reduced-size Astro-Hog. When I developed
my 1/2-scale version, I wanted to more closely
duplicate the features and structure of the
original. Since I planned on having the parts
laser cut, I made a few parts-layout changes to
take advantage of the available technology.
The results are shown in the picture of the
model bones.
Manzano Laser Works cut the parts. I have
provided contact information in the source
listing. Other laser cutters will also do custom
work. Look at the advertisements in the
magazines.
My reason for going on about laser-cutting
is to encourage you to consider that
technology when you are developing your
next design. I was pleasantly surprised by the
affordability and am thrilled with the resulting
parts. You can bet that the 1/2-scale Astro Hog
will not be my last custom laser-cut project.
On the subject of laser-cutting technology in
present-day designs, I have information about
Pat Tritle’s latest offering. He is an absolute
master at creating minimum-weight models
that have surprisingly strong structures. His
airplanes are designed for laser-cutting and
take nice advantage of the structural design
features that allow his light models to perform
well at smaller fields.
Pat has created a very nice rendition of the
Piper L-4. The full-scale World War II
airplane was based on the well-proven Cub
airframe and lends itself to the world of
model aviation.
The L-4 is a larger small-field model. At
1/8 scale, it sports a 53-inch wingspan. This is
a great size for building, and with a flying
weight of roughly 16 ounces, it is perfect for
relaxed flying in small venues.
The basic Piper Cub has been rendered as
a model more often than most full-scale
airplanes, but many models incorporate some
compromises relative to scale fidelity.
Recognizing this fact, Pat set out to develop a
much more accurate Piper L-4 than we
commonly see in the size range that is suitable
for small-field flying.
He wrote:
“This one began with a good set of 3-
views, along with a bunch of photos of fullsize
airplanes. This time the outlines were
unaltered, and the rib spacing is accurate.
“The side door opens for battery access, so
there are no ‘non-scale’ hatches. Also, to keep
the cabin looking more scale the wings are
plugged in and are retained with rare earth
magnets so there’s no visible hardware.”
The L-4 uses a Himax 2808-980 motor
driving a 9 x 5 propeller and gets energy from
a two-cell, 1320 mAh Li-Poly battery pack.
All flight controls are functional, and Pat
reports that the model is extremely well
behaved—as you would expect from a Cubbased
airplane.
Short kits are available from Pat’s Custom
Models. Please see the source listing at the
end of this column for contact information.
The L-4 story doesn’t end yet. Look closely
at the photo of Pat’s model; the cowl sports a
112 MODEL AVIATION
nice-looking set of engine cylinders extending
out into the breeze.
This is not something you typically see on
a Cub-style scale model of this size. Most
Cubs we see in the smaller scales have limited
renditions of engine cylinders. The visible
engine cylinders are such a distinctive feature
of the L-4 that making realistic-looking
dummy cylinders was a key objective in Pat’s
project.
Not being afraid to reach out for help when
needed, he called on the talented Keith Sparks
to develop the tooling and vacuum-formed
parts that make up the L-4 cowl and simulated
engine. Keith does plastic work for many of
the companies that manufacture models
typically constructed by members of the
small-field community.
This limited space does not allow me to
cover Keith’s entire process for developing
parts such as the L-4 cowl and engine, but
some insight might be helpful to those of us
who struggle to make similar parts for our
models. Keith said:
“Making the cowl itself was easy. Pat sent
me a plug to fit the fuselage. Since I was given
the opportunity to help make this model stand
out from other Cubs I concentrated on what is
lacking on every Cub I’ve seen, the engine
detail.
“I started with two blocks of auto body
filler bonded with a drop of CA at the parting
line. The side, top and front view of a
Continental engine cylinder and head are
drawn on the block and as the sculptures say ‘I
trimmed away the parts that were not the
engine.’
“The tools are then separated and a test run
is made looking for problems in forming and
fit. This is the step I dislike because it usually
involves giving up detail. Also any
adjustments to the tooling must be made with
the tool halves together to maintain an exact
match at the parting line.
“When parts like the scoops on the L-4 are
needed to mate to the finished assembly, an
assembled cowl/engine is used to build the
tool form. Molding clay and Plaster of Paris
are used to take a cast directly off the
assembled parts for the best fit possible.”
I have provided a close-up photo of the
prototype cowl and engine for your reference.
Keith does nice work.
I have some great news regarding the L-4
cowl/engine assembly. In addition to
including the cowl and engine parts in the L-4
short kit, Pat is selling the parts package
separately. This is a perfect way for those of
you with 1/8-scale Cubs to make a low-cost
upgrade to the front end of your models.
Keith has written a great book about
building with foam. Check the source listing at
the end for contact information.
So you don’t think I believe everything has to
be laser cut, I’ll show you another innovative
micro flyer from John Krouse. He has shared
several of his neat models with us in the past.
This time he is exploring the use of
ducted-fan power for what we typically call a
“slow flyer” airframe. I have the feeling that
John’s models get plenty of attention when he
shows up at his local venue.
The aircraft in the photo has an 18-inch
wingspan. The wing was fabricated from two
4-inch-chord, preformed, blue-foam wing
panels.
All electronics are mounted inside a builtup
pylon. The ducted fan is a D.C. Enterprises
ED-30 10/3/20T brushless outrunner unit
from Bob Selman Designs. Contact
information is at the end of the column. The
impeller has a diameter of 30mm (1.2 inches).
With a single 170 mAh Li-Poly battery, the
model has a flying weight of 39 grams (1.4
ounces).
John reports a fairly aggressive climb with
a comfortable throttled-back cruise. He notes
that “it just sounds fast.”
Very nice, John. This is definitely a
departure from the typical relaxed micro flyer.
Another reader who has shared a project in
these pages is Lyn Coon; I featured his nice
profile Piper Cub in the December 2007
column. Lyn comes from a modeling family,
and his father, Leonard Coon, was so inspired
by the Cub that he decided to develop a
profile scale indoor flyer of his own.
He built a nice Beech Staggerwing from
No-Cal plans from A.A. Lidberg Model Plan
Service. See the source listing.
Leonard’s model has a 16-inch wingspan.
Power is from a Gary Jones GWJ 7mm
gearbox/motor combination from Bob Selman
Designs. A Micro Invent 5 x 3 carbon
propeller is being used. With Plantraco
electronics onboard, the Staggerwing’s flying
weight is 24 grams.
Good work, Leonard. Keep them coming.
This wraps up another edition. You can tell
me about your latest project via regular mail
or E-mail. MA
Sources:
Manzano Laser Works
(505) 286-2640
www.manzanolaser.com
Pat’s Custom Models
(505) 296-4511
www.patscustom-models.com
Building With Foam by Keith Sparks
(817) 656-2295 (Please call between 9 a.m.
and noon.)
http://home.att.net/~parkflyerplastics
Bob Selman Designs
(417) 358-9521
www.bsdmicrorc.com
A.A. Lidberg Model Plan Service
(480) 839-8154 (6 p.m.-10 p.m. evenings and
weekends)
www.aalmps.com
Paul Bradley
10201 Scarlet Oak Dr.
Independence KY 41051
Edition: Model Aviation - 2008/08
Page Numbers: 110,111,112
I HAVE MENTIONED this before, but this
sure is a great time to be a person who likes to
build model airplanes. The available
technology makes the process fun and helps
modelers achieve nice results. This technology
is enhancing all aspects of the hobby, but for
me it is especially true in the process of
designing and fabricating the parts of the
wonderful flying machines we enjoy at our
local flying sites.
Because I like to design models as well as
build those that others have designed, I tend to
study the details of the internal structure. It is
interesting to see how different designers
approach this all-important part of the model.
You often see vastly different approaches
to the structural design of two similar-size
scale models of the same aircraft. Allowing for
the same intended flying format, such as radio
control, you will see one design use a heavy,
robust structure while the other is based on a
light minimal structure. Both produce niceflying
models that represent the full-scale
aircraft. One works well in the small-field
venues, and the other is better suited to larger
flying sites.
Model-airplane structural design got a shot
in the arm when computer-driven lasers came
onto the scene. One of the first people I know
who applied this technology to models is
Thomas Herr. It has been awhile since he
started selling laser-cut kits, and today it is
hard to imagine building a kit that has not had
the parts generated via a laser cutter.
Laser-cutting the parts in itself is a major
enhancement to the fabrication of models, but
that is not the complete story. The big news is
what laser-cutting allows in the way parts are
laid out and the overall structural design of a
model.
The ability of a computer-driven laser
cutter to create precise components with
intricate designs is the key. Parts can be cut
from balsa or plywood that would be difficult
to duplicate using manual methods. The
pieces, in turn, can be configured to create
structures that are strong and light. Those two
characteristics are crucial for enjoyable smallfield
models.
Fortunately, the world of laser-cutting and
associated parts design does not have to be the
sole realm of the kit manufacturer. A number
of companies that handle laser-cutting for kit
makers also offer their services to the “oneoff”
modeler. Getting parts custom cut is
becoming more common and is surprisingly
affordable.
I have been considering several modeling
projects and have thought how great it would
be to have the parts laser cut. I finally took the
plunge.
I have been dabbling with 1/2-scale versions
of some of the early RC Aerobatics models
that helped define the world of AMA Pattern
flying. One such model is the Fred Dunndesigned
Astro-Hog, which first appeared in
the modeling press in the April 1958 Model
Airplane News magazine.
The 1958 version of the Astro-Hog differs
a bit from the one that Sig currently sells in kit
form. The early version used “barn door”
ailerons rather than the more modern strip
ailerons.
I’m by no means the first person to build a
reduced-size Astro-Hog. When I developed
my 1/2-scale version, I wanted to more closely
duplicate the features and structure of the
original. Since I planned on having the parts
laser cut, I made a few parts-layout changes to
take advantage of the available technology.
The results are shown in the picture of the
model bones.
Manzano Laser Works cut the parts. I have
provided contact information in the source
listing. Other laser cutters will also do custom
work. Look at the advertisements in the
magazines.
My reason for going on about laser-cutting
is to encourage you to consider that
technology when you are developing your
next design. I was pleasantly surprised by the
affordability and am thrilled with the resulting
parts. You can bet that the 1/2-scale Astro Hog
will not be my last custom laser-cut project.
On the subject of laser-cutting technology in
present-day designs, I have information about
Pat Tritle’s latest offering. He is an absolute
master at creating minimum-weight models
that have surprisingly strong structures. His
airplanes are designed for laser-cutting and
take nice advantage of the structural design
features that allow his light models to perform
well at smaller fields.
Pat has created a very nice rendition of the
Piper L-4. The full-scale World War II
airplane was based on the well-proven Cub
airframe and lends itself to the world of
model aviation.
The L-4 is a larger small-field model. At
1/8 scale, it sports a 53-inch wingspan. This is
a great size for building, and with a flying
weight of roughly 16 ounces, it is perfect for
relaxed flying in small venues.
The basic Piper Cub has been rendered as
a model more often than most full-scale
airplanes, but many models incorporate some
compromises relative to scale fidelity.
Recognizing this fact, Pat set out to develop a
much more accurate Piper L-4 than we
commonly see in the size range that is suitable
for small-field flying.
He wrote:
“This one began with a good set of 3-
views, along with a bunch of photos of fullsize
airplanes. This time the outlines were
unaltered, and the rib spacing is accurate.
“The side door opens for battery access, so
there are no ‘non-scale’ hatches. Also, to keep
the cabin looking more scale the wings are
plugged in and are retained with rare earth
magnets so there’s no visible hardware.”
The L-4 uses a Himax 2808-980 motor
driving a 9 x 5 propeller and gets energy from
a two-cell, 1320 mAh Li-Poly battery pack.
All flight controls are functional, and Pat
reports that the model is extremely well
behaved—as you would expect from a Cubbased
airplane.
Short kits are available from Pat’s Custom
Models. Please see the source listing at the
end of this column for contact information.
The L-4 story doesn’t end yet. Look closely
at the photo of Pat’s model; the cowl sports a
112 MODEL AVIATION
nice-looking set of engine cylinders extending
out into the breeze.
This is not something you typically see on
a Cub-style scale model of this size. Most
Cubs we see in the smaller scales have limited
renditions of engine cylinders. The visible
engine cylinders are such a distinctive feature
of the L-4 that making realistic-looking
dummy cylinders was a key objective in Pat’s
project.
Not being afraid to reach out for help when
needed, he called on the talented Keith Sparks
to develop the tooling and vacuum-formed
parts that make up the L-4 cowl and simulated
engine. Keith does plastic work for many of
the companies that manufacture models
typically constructed by members of the
small-field community.
This limited space does not allow me to
cover Keith’s entire process for developing
parts such as the L-4 cowl and engine, but
some insight might be helpful to those of us
who struggle to make similar parts for our
models. Keith said:
“Making the cowl itself was easy. Pat sent
me a plug to fit the fuselage. Since I was given
the opportunity to help make this model stand
out from other Cubs I concentrated on what is
lacking on every Cub I’ve seen, the engine
detail.
“I started with two blocks of auto body
filler bonded with a drop of CA at the parting
line. The side, top and front view of a
Continental engine cylinder and head are
drawn on the block and as the sculptures say ‘I
trimmed away the parts that were not the
engine.’
“The tools are then separated and a test run
is made looking for problems in forming and
fit. This is the step I dislike because it usually
involves giving up detail. Also any
adjustments to the tooling must be made with
the tool halves together to maintain an exact
match at the parting line.
“When parts like the scoops on the L-4 are
needed to mate to the finished assembly, an
assembled cowl/engine is used to build the
tool form. Molding clay and Plaster of Paris
are used to take a cast directly off the
assembled parts for the best fit possible.”
I have provided a close-up photo of the
prototype cowl and engine for your reference.
Keith does nice work.
I have some great news regarding the L-4
cowl/engine assembly. In addition to
including the cowl and engine parts in the L-4
short kit, Pat is selling the parts package
separately. This is a perfect way for those of
you with 1/8-scale Cubs to make a low-cost
upgrade to the front end of your models.
Keith has written a great book about
building with foam. Check the source listing at
the end for contact information.
So you don’t think I believe everything has to
be laser cut, I’ll show you another innovative
micro flyer from John Krouse. He has shared
several of his neat models with us in the past.
This time he is exploring the use of
ducted-fan power for what we typically call a
“slow flyer” airframe. I have the feeling that
John’s models get plenty of attention when he
shows up at his local venue.
The aircraft in the photo has an 18-inch
wingspan. The wing was fabricated from two
4-inch-chord, preformed, blue-foam wing
panels.
All electronics are mounted inside a builtup
pylon. The ducted fan is a D.C. Enterprises
ED-30 10/3/20T brushless outrunner unit
from Bob Selman Designs. Contact
information is at the end of the column. The
impeller has a diameter of 30mm (1.2 inches).
With a single 170 mAh Li-Poly battery, the
model has a flying weight of 39 grams (1.4
ounces).
John reports a fairly aggressive climb with
a comfortable throttled-back cruise. He notes
that “it just sounds fast.”
Very nice, John. This is definitely a
departure from the typical relaxed micro flyer.
Another reader who has shared a project in
these pages is Lyn Coon; I featured his nice
profile Piper Cub in the December 2007
column. Lyn comes from a modeling family,
and his father, Leonard Coon, was so inspired
by the Cub that he decided to develop a
profile scale indoor flyer of his own.
He built a nice Beech Staggerwing from
No-Cal plans from A.A. Lidberg Model Plan
Service. See the source listing.
Leonard’s model has a 16-inch wingspan.
Power is from a Gary Jones GWJ 7mm
gearbox/motor combination from Bob Selman
Designs. A Micro Invent 5 x 3 carbon
propeller is being used. With Plantraco
electronics onboard, the Staggerwing’s flying
weight is 24 grams.
Good work, Leonard. Keep them coming.
This wraps up another edition. You can tell
me about your latest project via regular mail
or E-mail. MA
Sources:
Manzano Laser Works
(505) 286-2640
www.manzanolaser.com
Pat’s Custom Models
(505) 296-4511
www.patscustom-models.com
Building With Foam by Keith Sparks
(817) 656-2295 (Please call between 9 a.m.
and noon.)
http://home.att.net/~parkflyerplastics
Bob Selman Designs
(417) 358-9521
www.bsdmicrorc.com
A.A. Lidberg Model Plan Service
(480) 839-8154 (6 p.m.-10 p.m. evenings and
weekends)
www.aalmps.com
Paul Bradley
10201 Scarlet Oak Dr.
Independence KY 41051
