Eric Henderson, 303 Shady Ln., Marlton NJ 08053; E-mail: [email protected]
RADIO CONTROL AEROBATICS
Jason Shulman won the 2004 AMA F3A Nats with an Impact. This
is what the model looks like fresh out of the box.
As you peel off the metallic-looking “skin,” you find a molded
fuselage that has already been painted in the mold.
The Impact’s stabilizer arrives basically complete. It’s prehinged
and only needs the horn to be fitted.
SINCE JASON SHULMAN won the 2004 AMA Nats and FAI
F3A Team Trials with an electric-powered model, there has been
a flurry of information about the pros and cons of electric power.
This month I will instead take a close look at the Impact that
Jason flew.
This type of airplane is exotic in its construction. It is
manufactured as a completely painted-in-the-mold model. The
skins are supported by thin layers of cyanoacrylate-compatible
polyurethane foam.
The structure is a contradiction, in that it is immensely
strong/stiff, yet vulnerable to puncture from items such as
modeling pins. It requires a relatively new set of building skills
and employs liberal use of carbon fiber and epoxy resins.
To obtain an Impact, I contacted Composite-ARF
(www.composite-arf.com). I was greeted by the voice of a
familiar Pattern acquaintance: Bobby Shapiro, who is based in
Naples, Florida.
Bobby is really an “escapee” from National Society of Radio
Controlled Aerobatics District 1 and used to live in New York
City. After I explained that I had many incriminating District 1
photographs in my possession, he was kind enough to get me on
“the list” for one of the first batch. (Only joking about the
photographs.)
To illustrate the nature of a composite Pattern model, I’ll
“walk through” the information that comes with the airplane.
Composite-ARF conveyed the following about its model.
“The Impact is not really a ready to fly (RTF) airplane. With
the Impact we have tried an approach that will appeal to the
‘professional’ or advanced-builder type of Pattern flier. Typically
this would be one who wants to enter this exciting class of
competition flying for the first time. [I think that means FAI.]
“We want to give the modeler as many choices for individual
completion as possible, so we include some hardware but do not
insist on your using it all. We know that Pattern fliers have
developed their own techniques based on long-term experience.
“For the pilot/builder with less experience in building and flying
these kinds of contest airplanes, we included the hardware that we
would use. Hardware that will definitely be a workable solution for
anyone.
“This is not a beginner’s model, and not a trainer. We expect
experience in building and flying aerobatic airplanes. We do not
expect experience in composites building. Although it might be your
first all-composite airplane, you will find, when finished building,
that this was not complicated at all. Just acknowledge some very
important advice in building and handling this piece of technology.
“If you follow the instruction book, you will learn a lot about
composites and their handling and maintenance and you will
understand that there are no secrets. Everything is hands-on
technology, and it has huge advantages and benefits against the
common wood construction.”
A turned-aluminum insert uses a sliding 3⁄16-inch-piano-wire rod
to find the center of the engine on the firewall.
Thin plywood skinned with carbon-fiber sheeting makes up the
aircraft’s firewall and other components.
This carbon-fiber “cradle” is a work of art that is designed to
hold carbon-fiber gear legs firmly in place.
Special horns that are made from circuit board are epoxied into
the composite control surfaces.
The author fabricated an alignment tool to help position engine
mounts in removable cowl installations.
Composite-ARF is clear about the fact that you need to be
experienced to build the Impact. This is because it comes with the
outside finished and the inside unfinished. You build all of the
insides to make it into a Pattern model.
The airplane arrives by freight in a huge, tough cardboard box.
(You can save yourself a bunch of money if you pick it up from
the nearest distribution center. It also saves you from having to
guide a rather large 18-wheeler down and back out of your side
street.) Getting the box open is hard work—akin to breaking into
an Egyptian crypt.
The airplane comes with a shiny, metallic-looking set of soft
covers. Removing these skins reveals a model that looks as
though it is almost ready to fly. All major parts—such as the
fuselage, wings, etc.—are protected this way. The custom silver
protection bags are also intended for storage and transport after
the Impact is finished.
Because the outside of the whole model is already painted in
the mold, you need to protect the “skin” from the outset.
Composite-ARF advises covering your workbench with bubble
pack or several layers of soft cloth. It is important to keep the
working surface clean of any dust or other particles; they are
responsible for the most damages on these parts.
The company also suggests that you wrap the whole airplane
in bubble pack and/or leave it in the protection covers as long as
you can.
There are many glues that will work
with composite aircraft parts and all of the
other hardware. You should use thick and
thin cyanoacrylate and 30-minute epoxy.
For certain purposes, a thin laminating
resin (12- to 24-hour-cure type) would be
useful.
Thin cyanoacrylate glue requires
extreme caution. The sandwich of the foam
will soak up any excess cyanoacrylate,
which will then start to cure and create
heat. This heat can be so high that it will
deform the outside skin of the fiberglass
part.
Use cyanoacrylate for “tacking” things
in place, and use epoxy to permanently
glue them on. If you want to use
cyanoacrylate extensively, you are better
off using the thick kind; it cannot soak into
the materials as quickly and cures slower.
The landing-gear support plate is
designed to spread the load of the
undercarriage through the shell of the
fuselage. It consists of a carbon-fiber-andplywood
composite cradle that you glue
into the fuselage using an epoxy-resin-andchopped-
fiberglass potion. The result is
lightweight and extremely strong.
The wing and stabilizer tubes have to
be fitted. This is a relatively high-skill task
and is crucial to the finished model’s
performance. The positions of the tubes
and adjusters are premarked on the
fuselage, but they still need to be finetuned
for the best alignment.
Composite-ARF recommends a Hyde
mount without a nose ring. This would be
the “A” type of mount. You have to fit the
firewall and then the Hyde mount to the
firewall. You do this by trial-fitting the
firewall into the fuselage with the correct
distance from the nose ring. A good
starting point is suggested as 2° of side
thrust and 0° of downthrust.
After confirming distance and angles,
mark the holes showing where to drill to
attach the Hyde mount to the firewall. Use
a small amount of cyanoacrylate glue to
tack the mount into position. Tack the
firewall in position, and permanently glue
it in place with resin and chopped fibers.
There are many steps just to mount the
engine, and none are easy tasks. Building
this airplane is much more like a kit than
an ARF in terms of time and effort needed.
The fuselage is completely hollow, or
an empty shell. This means that you have
to fit a “floor” to separate your tuned pipe
or four-stroke muffler from the fuel tank
and the electronics. The floor is supplied
with the kit and needs to be fitted and
sealed.
Composite-ARF does point out that
there can be high pressure in the fuselage
during flight, which can damage the
structure, pop the canopy off, and similar
things, so sealing the airflow from the rest
of the fuselage is a requirement not to be
ignored.
In addition, you need sufficient cooling
air exits in the bottom of the fuselage and
at the end of the pipe compartment. “Mill”
out the slots in the side scoops, which will
increase the airflow around your engine’s
crankcase, providing more engine power
and longer life span of the crankshaft
bearings.
It is unusual, at least in my experience,
but the company actually recommends a
specific servo brand and designation: JR
DS8411 on the ailerons and DS3821 on the
elevators. (I think the latter would be
DS4231 in the US.) The cutouts in the
stabilizer and wing ribs are made for these
servos.
You will have to decide whether you
want to go with the supplied hardware or
not. The horns are specially designed to be
epoxied into the slots in the control
surfaces, instead of the more common
practice of bolting a horn through the
control surface. The composite structures
do not handle compression very well, so
gluing the supplied horns is a better
option.
An interesting tip was to make sure fuel
lines cannot rub where they pass through
the carbon-sheeted plywood formers. The
edges of the carbon component are sharp
and can cut the fuel tubes during a single
flight. Always use bigger holes and
appropriate rubber grommets.
All wiring must be secured in the
fuselage and the wings. Attach at least
every 7-8 inches with a drop of soft heat
glue or silicone to the fuselage walls or
other appropriate spots. Vibration and
carbon edges will strip the insulation of a
wire or wires in one flight!
There is much more to finishing this
type of airplane. Building it will definitely
make for a fun winter for me. One can
derive a great deal of pure pleasure from
trying these new technologies and
techniques.
This walk-through was intended to take
you inside the technology of one of these
newer composite airplanes. Next month I
will take a look at another new, high-end,
more conventional airplane that is arriving
on the Pattern scene.
Building Tip: Lining up an engine mount
with the spinner ring of a removable cowl
or finding the right spot on an ARF’s
firewall is a difficult task. If the cowl is
removable, it is not too hard to line it up
with the rest of the fuselage so that it looks
right. The next challenge is to find out
where the centerline of the engine
crankshaft should be.
The device shown was turned from
aluminum so that it would be a snug fit in
the backplate of the spinner that will be
used. A hole drilled in the center allows a
pointed 3⁄16-inch-diameter piano-wire rod
to be inserted. The spinner backplate can
then be held in place with one hand.
A light tap with a hammer will mark
the firewall exactly where the center of the
engine should be. It is then relatively easy
to align the engine mount using the mark
as a reference point. As always, it is a
good idea to drill a pilot hole or two to
make sure that the firewall angles are
consistent with the engine’s position
before permanently fixing the mount.
Have a good building season! MA
Edition: Model Aviation - 2005/03
Page Numbers: 77,78,80
Edition: Model Aviation - 2005/03
Page Numbers: 77,78,80
Eric Henderson, 303 Shady Ln., Marlton NJ 08053; E-mail: [email protected]
RADIO CONTROL AEROBATICS
Jason Shulman won the 2004 AMA F3A Nats with an Impact. This
is what the model looks like fresh out of the box.
As you peel off the metallic-looking “skin,” you find a molded
fuselage that has already been painted in the mold.
The Impact’s stabilizer arrives basically complete. It’s prehinged
and only needs the horn to be fitted.
SINCE JASON SHULMAN won the 2004 AMA Nats and FAI
F3A Team Trials with an electric-powered model, there has been
a flurry of information about the pros and cons of electric power.
This month I will instead take a close look at the Impact that
Jason flew.
This type of airplane is exotic in its construction. It is
manufactured as a completely painted-in-the-mold model. The
skins are supported by thin layers of cyanoacrylate-compatible
polyurethane foam.
The structure is a contradiction, in that it is immensely
strong/stiff, yet vulnerable to puncture from items such as
modeling pins. It requires a relatively new set of building skills
and employs liberal use of carbon fiber and epoxy resins.
To obtain an Impact, I contacted Composite-ARF
(www.composite-arf.com). I was greeted by the voice of a
familiar Pattern acquaintance: Bobby Shapiro, who is based in
Naples, Florida.
Bobby is really an “escapee” from National Society of Radio
Controlled Aerobatics District 1 and used to live in New York
City. After I explained that I had many incriminating District 1
photographs in my possession, he was kind enough to get me on
“the list” for one of the first batch. (Only joking about the
photographs.)
To illustrate the nature of a composite Pattern model, I’ll
“walk through” the information that comes with the airplane.
Composite-ARF conveyed the following about its model.
“The Impact is not really a ready to fly (RTF) airplane. With
the Impact we have tried an approach that will appeal to the
‘professional’ or advanced-builder type of Pattern flier. Typically
this would be one who wants to enter this exciting class of
competition flying for the first time. [I think that means FAI.]
“We want to give the modeler as many choices for individual
completion as possible, so we include some hardware but do not
insist on your using it all. We know that Pattern fliers have
developed their own techniques based on long-term experience.
“For the pilot/builder with less experience in building and flying
these kinds of contest airplanes, we included the hardware that we
would use. Hardware that will definitely be a workable solution for
anyone.
“This is not a beginner’s model, and not a trainer. We expect
experience in building and flying aerobatic airplanes. We do not
expect experience in composites building. Although it might be your
first all-composite airplane, you will find, when finished building,
that this was not complicated at all. Just acknowledge some very
important advice in building and handling this piece of technology.
“If you follow the instruction book, you will learn a lot about
composites and their handling and maintenance and you will
understand that there are no secrets. Everything is hands-on
technology, and it has huge advantages and benefits against the
common wood construction.”
A turned-aluminum insert uses a sliding 3⁄16-inch-piano-wire rod
to find the center of the engine on the firewall.
Thin plywood skinned with carbon-fiber sheeting makes up the
aircraft’s firewall and other components.
This carbon-fiber “cradle” is a work of art that is designed to
hold carbon-fiber gear legs firmly in place.
Special horns that are made from circuit board are epoxied into
the composite control surfaces.
The author fabricated an alignment tool to help position engine
mounts in removable cowl installations.
Composite-ARF is clear about the fact that you need to be
experienced to build the Impact. This is because it comes with the
outside finished and the inside unfinished. You build all of the
insides to make it into a Pattern model.
The airplane arrives by freight in a huge, tough cardboard box.
(You can save yourself a bunch of money if you pick it up from
the nearest distribution center. It also saves you from having to
guide a rather large 18-wheeler down and back out of your side
street.) Getting the box open is hard work—akin to breaking into
an Egyptian crypt.
The airplane comes with a shiny, metallic-looking set of soft
covers. Removing these skins reveals a model that looks as
though it is almost ready to fly. All major parts—such as the
fuselage, wings, etc.—are protected this way. The custom silver
protection bags are also intended for storage and transport after
the Impact is finished.
Because the outside of the whole model is already painted in
the mold, you need to protect the “skin” from the outset.
Composite-ARF advises covering your workbench with bubble
pack or several layers of soft cloth. It is important to keep the
working surface clean of any dust or other particles; they are
responsible for the most damages on these parts.
The company also suggests that you wrap the whole airplane
in bubble pack and/or leave it in the protection covers as long as
you can.
There are many glues that will work
with composite aircraft parts and all of the
other hardware. You should use thick and
thin cyanoacrylate and 30-minute epoxy.
For certain purposes, a thin laminating
resin (12- to 24-hour-cure type) would be
useful.
Thin cyanoacrylate glue requires
extreme caution. The sandwich of the foam
will soak up any excess cyanoacrylate,
which will then start to cure and create
heat. This heat can be so high that it will
deform the outside skin of the fiberglass
part.
Use cyanoacrylate for “tacking” things
in place, and use epoxy to permanently
glue them on. If you want to use
cyanoacrylate extensively, you are better
off using the thick kind; it cannot soak into
the materials as quickly and cures slower.
The landing-gear support plate is
designed to spread the load of the
undercarriage through the shell of the
fuselage. It consists of a carbon-fiber-andplywood
composite cradle that you glue
into the fuselage using an epoxy-resin-andchopped-
fiberglass potion. The result is
lightweight and extremely strong.
The wing and stabilizer tubes have to
be fitted. This is a relatively high-skill task
and is crucial to the finished model’s
performance. The positions of the tubes
and adjusters are premarked on the
fuselage, but they still need to be finetuned
for the best alignment.
Composite-ARF recommends a Hyde
mount without a nose ring. This would be
the “A” type of mount. You have to fit the
firewall and then the Hyde mount to the
firewall. You do this by trial-fitting the
firewall into the fuselage with the correct
distance from the nose ring. A good
starting point is suggested as 2° of side
thrust and 0° of downthrust.
After confirming distance and angles,
mark the holes showing where to drill to
attach the Hyde mount to the firewall. Use
a small amount of cyanoacrylate glue to
tack the mount into position. Tack the
firewall in position, and permanently glue
it in place with resin and chopped fibers.
There are many steps just to mount the
engine, and none are easy tasks. Building
this airplane is much more like a kit than
an ARF in terms of time and effort needed.
The fuselage is completely hollow, or
an empty shell. This means that you have
to fit a “floor” to separate your tuned pipe
or four-stroke muffler from the fuel tank
and the electronics. The floor is supplied
with the kit and needs to be fitted and
sealed.
Composite-ARF does point out that
there can be high pressure in the fuselage
during flight, which can damage the
structure, pop the canopy off, and similar
things, so sealing the airflow from the rest
of the fuselage is a requirement not to be
ignored.
In addition, you need sufficient cooling
air exits in the bottom of the fuselage and
at the end of the pipe compartment. “Mill”
out the slots in the side scoops, which will
increase the airflow around your engine’s
crankcase, providing more engine power
and longer life span of the crankshaft
bearings.
It is unusual, at least in my experience,
but the company actually recommends a
specific servo brand and designation: JR
DS8411 on the ailerons and DS3821 on the
elevators. (I think the latter would be
DS4231 in the US.) The cutouts in the
stabilizer and wing ribs are made for these
servos.
You will have to decide whether you
want to go with the supplied hardware or
not. The horns are specially designed to be
epoxied into the slots in the control
surfaces, instead of the more common
practice of bolting a horn through the
control surface. The composite structures
do not handle compression very well, so
gluing the supplied horns is a better
option.
An interesting tip was to make sure fuel
lines cannot rub where they pass through
the carbon-sheeted plywood formers. The
edges of the carbon component are sharp
and can cut the fuel tubes during a single
flight. Always use bigger holes and
appropriate rubber grommets.
All wiring must be secured in the
fuselage and the wings. Attach at least
every 7-8 inches with a drop of soft heat
glue or silicone to the fuselage walls or
other appropriate spots. Vibration and
carbon edges will strip the insulation of a
wire or wires in one flight!
There is much more to finishing this
type of airplane. Building it will definitely
make for a fun winter for me. One can
derive a great deal of pure pleasure from
trying these new technologies and
techniques.
This walk-through was intended to take
you inside the technology of one of these
newer composite airplanes. Next month I
will take a look at another new, high-end,
more conventional airplane that is arriving
on the Pattern scene.
Building Tip: Lining up an engine mount
with the spinner ring of a removable cowl
or finding the right spot on an ARF’s
firewall is a difficult task. If the cowl is
removable, it is not too hard to line it up
with the rest of the fuselage so that it looks
right. The next challenge is to find out
where the centerline of the engine
crankshaft should be.
The device shown was turned from
aluminum so that it would be a snug fit in
the backplate of the spinner that will be
used. A hole drilled in the center allows a
pointed 3⁄16-inch-diameter piano-wire rod
to be inserted. The spinner backplate can
then be held in place with one hand.
A light tap with a hammer will mark
the firewall exactly where the center of the
engine should be. It is then relatively easy
to align the engine mount using the mark
as a reference point. As always, it is a
good idea to drill a pilot hole or two to
make sure that the firewall angles are
consistent with the engine’s position
before permanently fixing the mount.
Have a good building season! MA
Edition: Model Aviation - 2005/03
Page Numbers: 77,78,80
Eric Henderson, 303 Shady Ln., Marlton NJ 08053; E-mail: [email protected]
RADIO CONTROL AEROBATICS
Jason Shulman won the 2004 AMA F3A Nats with an Impact. This
is what the model looks like fresh out of the box.
As you peel off the metallic-looking “skin,” you find a molded
fuselage that has already been painted in the mold.
The Impact’s stabilizer arrives basically complete. It’s prehinged
and only needs the horn to be fitted.
SINCE JASON SHULMAN won the 2004 AMA Nats and FAI
F3A Team Trials with an electric-powered model, there has been
a flurry of information about the pros and cons of electric power.
This month I will instead take a close look at the Impact that
Jason flew.
This type of airplane is exotic in its construction. It is
manufactured as a completely painted-in-the-mold model. The
skins are supported by thin layers of cyanoacrylate-compatible
polyurethane foam.
The structure is a contradiction, in that it is immensely
strong/stiff, yet vulnerable to puncture from items such as
modeling pins. It requires a relatively new set of building skills
and employs liberal use of carbon fiber and epoxy resins.
To obtain an Impact, I contacted Composite-ARF
(www.composite-arf.com). I was greeted by the voice of a
familiar Pattern acquaintance: Bobby Shapiro, who is based in
Naples, Florida.
Bobby is really an “escapee” from National Society of Radio
Controlled Aerobatics District 1 and used to live in New York
City. After I explained that I had many incriminating District 1
photographs in my possession, he was kind enough to get me on
“the list” for one of the first batch. (Only joking about the
photographs.)
To illustrate the nature of a composite Pattern model, I’ll
“walk through” the information that comes with the airplane.
Composite-ARF conveyed the following about its model.
“The Impact is not really a ready to fly (RTF) airplane. With
the Impact we have tried an approach that will appeal to the
‘professional’ or advanced-builder type of Pattern flier. Typically
this would be one who wants to enter this exciting class of
competition flying for the first time. [I think that means FAI.]
“We want to give the modeler as many choices for individual
completion as possible, so we include some hardware but do not
insist on your using it all. We know that Pattern fliers have
developed their own techniques based on long-term experience.
“For the pilot/builder with less experience in building and flying
these kinds of contest airplanes, we included the hardware that we
would use. Hardware that will definitely be a workable solution for
anyone.
“This is not a beginner’s model, and not a trainer. We expect
experience in building and flying aerobatic airplanes. We do not
expect experience in composites building. Although it might be your
first all-composite airplane, you will find, when finished building,
that this was not complicated at all. Just acknowledge some very
important advice in building and handling this piece of technology.
“If you follow the instruction book, you will learn a lot about
composites and their handling and maintenance and you will
understand that there are no secrets. Everything is hands-on
technology, and it has huge advantages and benefits against the
common wood construction.”
A turned-aluminum insert uses a sliding 3⁄16-inch-piano-wire rod
to find the center of the engine on the firewall.
Thin plywood skinned with carbon-fiber sheeting makes up the
aircraft’s firewall and other components.
This carbon-fiber “cradle” is a work of art that is designed to
hold carbon-fiber gear legs firmly in place.
Special horns that are made from circuit board are epoxied into
the composite control surfaces.
The author fabricated an alignment tool to help position engine
mounts in removable cowl installations.
Composite-ARF is clear about the fact that you need to be
experienced to build the Impact. This is because it comes with the
outside finished and the inside unfinished. You build all of the
insides to make it into a Pattern model.
The airplane arrives by freight in a huge, tough cardboard box.
(You can save yourself a bunch of money if you pick it up from
the nearest distribution center. It also saves you from having to
guide a rather large 18-wheeler down and back out of your side
street.) Getting the box open is hard work—akin to breaking into
an Egyptian crypt.
The airplane comes with a shiny, metallic-looking set of soft
covers. Removing these skins reveals a model that looks as
though it is almost ready to fly. All major parts—such as the
fuselage, wings, etc.—are protected this way. The custom silver
protection bags are also intended for storage and transport after
the Impact is finished.
Because the outside of the whole model is already painted in
the mold, you need to protect the “skin” from the outset.
Composite-ARF advises covering your workbench with bubble
pack or several layers of soft cloth. It is important to keep the
working surface clean of any dust or other particles; they are
responsible for the most damages on these parts.
The company also suggests that you wrap the whole airplane
in bubble pack and/or leave it in the protection covers as long as
you can.
There are many glues that will work
with composite aircraft parts and all of the
other hardware. You should use thick and
thin cyanoacrylate and 30-minute epoxy.
For certain purposes, a thin laminating
resin (12- to 24-hour-cure type) would be
useful.
Thin cyanoacrylate glue requires
extreme caution. The sandwich of the foam
will soak up any excess cyanoacrylate,
which will then start to cure and create
heat. This heat can be so high that it will
deform the outside skin of the fiberglass
part.
Use cyanoacrylate for “tacking” things
in place, and use epoxy to permanently
glue them on. If you want to use
cyanoacrylate extensively, you are better
off using the thick kind; it cannot soak into
the materials as quickly and cures slower.
The landing-gear support plate is
designed to spread the load of the
undercarriage through the shell of the
fuselage. It consists of a carbon-fiber-andplywood
composite cradle that you glue
into the fuselage using an epoxy-resin-andchopped-
fiberglass potion. The result is
lightweight and extremely strong.
The wing and stabilizer tubes have to
be fitted. This is a relatively high-skill task
and is crucial to the finished model’s
performance. The positions of the tubes
and adjusters are premarked on the
fuselage, but they still need to be finetuned
for the best alignment.
Composite-ARF recommends a Hyde
mount without a nose ring. This would be
the “A” type of mount. You have to fit the
firewall and then the Hyde mount to the
firewall. You do this by trial-fitting the
firewall into the fuselage with the correct
distance from the nose ring. A good
starting point is suggested as 2° of side
thrust and 0° of downthrust.
After confirming distance and angles,
mark the holes showing where to drill to
attach the Hyde mount to the firewall. Use
a small amount of cyanoacrylate glue to
tack the mount into position. Tack the
firewall in position, and permanently glue
it in place with resin and chopped fibers.
There are many steps just to mount the
engine, and none are easy tasks. Building
this airplane is much more like a kit than
an ARF in terms of time and effort needed.
The fuselage is completely hollow, or
an empty shell. This means that you have
to fit a “floor” to separate your tuned pipe
or four-stroke muffler from the fuel tank
and the electronics. The floor is supplied
with the kit and needs to be fitted and
sealed.
Composite-ARF does point out that
there can be high pressure in the fuselage
during flight, which can damage the
structure, pop the canopy off, and similar
things, so sealing the airflow from the rest
of the fuselage is a requirement not to be
ignored.
In addition, you need sufficient cooling
air exits in the bottom of the fuselage and
at the end of the pipe compartment. “Mill”
out the slots in the side scoops, which will
increase the airflow around your engine’s
crankcase, providing more engine power
and longer life span of the crankshaft
bearings.
It is unusual, at least in my experience,
but the company actually recommends a
specific servo brand and designation: JR
DS8411 on the ailerons and DS3821 on the
elevators. (I think the latter would be
DS4231 in the US.) The cutouts in the
stabilizer and wing ribs are made for these
servos.
You will have to decide whether you
want to go with the supplied hardware or
not. The horns are specially designed to be
epoxied into the slots in the control
surfaces, instead of the more common
practice of bolting a horn through the
control surface. The composite structures
do not handle compression very well, so
gluing the supplied horns is a better
option.
An interesting tip was to make sure fuel
lines cannot rub where they pass through
the carbon-sheeted plywood formers. The
edges of the carbon component are sharp
and can cut the fuel tubes during a single
flight. Always use bigger holes and
appropriate rubber grommets.
All wiring must be secured in the
fuselage and the wings. Attach at least
every 7-8 inches with a drop of soft heat
glue or silicone to the fuselage walls or
other appropriate spots. Vibration and
carbon edges will strip the insulation of a
wire or wires in one flight!
There is much more to finishing this
type of airplane. Building it will definitely
make for a fun winter for me. One can
derive a great deal of pure pleasure from
trying these new technologies and
techniques.
This walk-through was intended to take
you inside the technology of one of these
newer composite airplanes. Next month I
will take a look at another new, high-end,
more conventional airplane that is arriving
on the Pattern scene.
Building Tip: Lining up an engine mount
with the spinner ring of a removable cowl
or finding the right spot on an ARF’s
firewall is a difficult task. If the cowl is
removable, it is not too hard to line it up
with the rest of the fuselage so that it looks
right. The next challenge is to find out
where the centerline of the engine
crankshaft should be.
The device shown was turned from
aluminum so that it would be a snug fit in
the backplate of the spinner that will be
used. A hole drilled in the center allows a
pointed 3⁄16-inch-diameter piano-wire rod
to be inserted. The spinner backplate can
then be held in place with one hand.
A light tap with a hammer will mark
the firewall exactly where the center of the
engine should be. It is then relatively easy
to align the engine mount using the mark
as a reference point. As always, it is a
good idea to drill a pilot hole or two to
make sure that the firewall angles are
consistent with the engine’s position
before permanently fixing the mount.
Have a good building season! MA