114 MODEL AVIATION
AS THE BUILDING season starts to creep up on most of the
country, it’s time to start thinking about that next project.
Generally, the state of the art for Scale Aerobatics (SA) aircraft
hasn’t changed much in the last year or so, but some new trends
are starting to emerge and new equipment is becoming available
all the time.
I thought you might like to see my most recent build and some
of the detail I used in this Unlimited-class aerobat. You may know
that I’m a dyed-in-the-wool Extra fan. I’ve owned many of Carden
Aircraft’s designs through the years, so it was a no-brainer that I
would build the company’s newest 40%er: the Extra 330S.
I started building with the intention of using JR DS8411 servos. I
would use four for the rudder, two for each aileron, and two for
each elevator half. But during the building process, JR announced
the release of its new digital DS8611 servo. It has the same fast
transit speed as the DS8411—of .18 second/60° at 4.8 volts—but
is ultra high torque at 220 inch-ounce at 4.8 volts or 260 at 6 volts,
all in a standard-size case. (Well, it is slightly bigger, but it fits
with only a slight amount of shoehorning.)
Besides the 8611’s high torque, it features numerous upgrades
compared with other servos, making it more precise, stronger, and
more reliable than ever before. The new 8611s meant that I could
use three fewer servos in my airplane, saving cost, weight, and
complexity in the whole setup. Switching to these was a must.
Now I have three servos for the rudder and one for each
elevator half. I stayed with two for the ailerons. Because of the
span of the aileron, I felt that it was better supported at two points
than one. So it was not a question of servo power, but for the sake
of spreading the load.
To set the 8611s up, I used a program mix for the rudder servos
to match them in a ganged configuration, mixing the other two
servos directly to the rudder channel. A multipoint mix could be
used to get the servos matched exactly, but it wasn’t needed;
Mike Hurley, 11542 Decatur Ct., Westminster CO 80234; E-mail: [email protected]
RADIO CONTROL SCALE AEROBATICS
The author’s Carden Extra 330S weighs 40 pounds, 2 ounces,
with full-length tuned pipes and has new JR 8611 servos.
The Extra uses one receiver and 10 servos. Custom-molded CF
pipe tunnel is just below ganged rudder-servo tray. Forward pipe
tunnel is CF false floor supporting fuel tank.
Mike’s wife Candie prepares to fuel the Extra. Tuned pipes add
extra 500 rpm and smooth transition considerably while keeping
model exceptionally quiet.
09sig4.QXD 6/23/04 1:05 pm Page 114
standard mixes did the trick. For the
ailerons I used a matchbox buried in the
root of each wing to match the servos.
Hangar 9 has come out with an in-line
volt/amp meter for measuring current draw
of the servos. This neat little digitalreadout
device proved to be invaluable in
matching the servos exactly. You just plug
the meter in-line while setting up any servo
and adjust the mix down to the lowest
amperage draw. It made servo setup easy,
and you know you have it right when
you’re done.
Another new trend in the big models is to
use just one receiver. For the last several
years, most pilots who build 40% or larger
SA aircraft used two receivers; we’ve
talked about many of the reasons why.
Most say it’s either for redundancy or for
power distribution needed for so many
servos. The practice has needlessly started
to creep down into the smaller 35% and
33% airplanes, and I’ve even seen two
receivers used in a 27% model. I don’t
think most people even understand why
they do it. They just see other airplanes
with two receivers, so they do it too!
The fact is that a receiver is one of the
least likely components in your aircraft to
fail. Tape the crystal in and mount it so
that vibration doesn’t reach the unit, and
you’ve taken all the precaution you need.
So the argument of redundancy is usually a
case of ignorance of the facts.
We’re also starting to see that dividing
the power distribution because of load
demands was more of a perceived problem
than a real one. JR has started researching
and testing receiver current loads, servo
loads, and the demands made on the whole
system to see if a single receiver power bus
can handle the demands made by all the
servos in a large SA airplane. They’ve
found that the bus will handle up to 60
amps. A fully stalled 8411 is roughly 1.5
amps, although I could only get one to
September 2004 115
Inside pipe tunnel, air enters forward engine-box area and exits
three slots forward of engine-box former. You can see pipebracket
former inside tunnel.
You can see how installed pipes fit in custom-molded tunnel.
Exhaust exits just aft of the wing. CF hatch with molded NACA
air inlet covers pipes in flight.
st.net
OVER A DOZEN MODELS OF WWI, WWII, AND CLASSIC CIVILIAN
AIRCRAFT AVAILABLE WITH MORE VERSIONS TO FOLLOW!
• Electric motor(s) with prop and gear reduction included.
• Highly prefabricated for very short building times.
• 3-4 functions: rudder, aileron & elevator (rudder & ailerons on
one servo, or on separate servos.)
• Laser-cut wood parts for an accurate fit.
• Propeller and spinner included.
• Landing gear and wheels included.
(some kits have removable gear for grass field flying.)
• Contact your local hobby shop, or order direct at: www.djaerotech.com
Ryan ST / PT-16
Wingspan: 28.1 in. • Length: 20.2 in.
Weight: 4.5-5.5 oz. (ready to fly)
Wing Loading: 5.5-6.7 oz/sq. ft.
We
carry
E-tec Li-Poly
batteries &
chargers
Single motor WWII kits ....$48.95
Lockheed P-38...............$56.95
Curtiss Jenny .................$64.95
Sopwith Camel...............$72.95
Fokker Triplane ..............$73.95
DC-3 ............................$66.95
Lockheed Electra............$68.95
Piper J-3 Cub.................$51.95
Curtiss-Wright Junior.......$51.95
Ryan ST / PT-16.............$59.95
B-17F .........................$124.95
(Shipping & Handling extra)
Prices subject to
change without notice.
draw approximately 800 mA. They tell us
that an 8611 will draw 2.7 amps; multiply
that by 10 servos and it’s still only 27
amps, leaving more than adequate fudge
room.
Other factors go into this whole
equation, such as voltage drop past
connectors, battery current capacity, and so
on, but I am only discussing the receiver
bus here. From the tests that have been
made, I’d say that a single receiver is more
than up to the job of handling 10 highcurrent-
draw servos. Another finding is
that a second receiver can reduce your
reception range. Receivers and their
antennas do give off radio frequency and
can affect each other. Some of the testers
at JR have confirmed that they have better
range tests when switching to a single
receiver. Quique Somenzini and Peter
Goldsmith are now using a single receiver
in their giant SA airplanes, and many pilots
out in the field are beginning to do so too.
I’m back to the old adage that simple is
better. My giant 40% SA aerobat has one
receiver, two NiMH battery packs, two
switches, two matchboxes, 10 servos, and
that’s it; no regulators, power-distribution
09sig4.QXD 6/23/04 1:05 pm Page 115
116 MODEL AVIATION
systems, bells, or whistles.
A significant change for me in this build
was adding tuned pipes. That’s right;
long, baseball bat-sized, tuned pipes—not
canister mufflers. Because this model is
slightly bigger than most other 40%
airplanes, it is also a couple pounds
heavier than others I have. My problem
was that at my altitude flying in Denver,
the engine couldn’t handle the extra
weight.
The decision to go with tuned pipes
was tough. Very few have been installed
across the country, and the results were
not a sure thing. In addition to that, the
pipes would add another 2-3 pounds to
the model, so I was taking a risk. They
not only needed to perform well, but they
needed to add enough power to
compensate for an already topped-out
power-to-weight ratio and added weight
of the pipes themselves. The potential of
a quieter model with more power was
enough for me to give it a go.
Installing the pipes wasn’t too hard,
but it did require a bit of planning. I
wanted them to be isolated from the rest
of the inside of the fuselage. The engine
box on the Carden Extra is exactly the
right size for two canisters, but roughly
14 inches too short for these pipes, so I
had to modify the rear engine-box former
to allow the pipes to pass through it.
That former turned out to be a perfect
place to put a simple but effective pipe
bracket that MTW makes and Desert
Aircraft sells. The bracket is nothing
more than a former designed to hold four
pieces of silicone tubing that fit snugly
around the pipe and hold it in place.
To isolate the pipes inside the engine
box, I used a piece of carbon-fiber (CF)
laminate to make a false floor. The CF
also added a great deal of strength and
rigidity to the engine-box assembly. Aft
of the engine-box former, I had to make a
pipe tunnel of some sort. Erik Richard
molded a single-layer CF tunnel that was
epoxied inside the fuselage. The tunnel
weighed a scant 2 ounces, and the false
floor came in at 4 ounces! Not only is the
structure as minimal as possible, but it
also looks great.
Where these KS tuned pipes really
shine is in their operation. When most
people think of tuned pipes, they
automatically think of peaky performance,
higher rpm nonlinear power, or even dead
or flat spots in the throttle response.
Nothing could be further from the truth in
this case. Overall, the power is improved
from the bottom to the top, linearity is
improved, and transition is much
smoother with no flat spots or burble.
The power is incredible, with an
average increase of 500 rpm at the top
end. (That is a huge power and thrust
increase for this type of airplane.) The
best part is the sound. Noise was
decreased dramatically on the ground and
in the air with a much more sophisticated
note. Propeller noise is still present at the
high rpm the engine is able to produce,
but that could be reduced with the
addition of a correct-size three-blade
propeller. I’m so pleased with the results
with the tuned pipes that it will be
standard equipment on all my future
projects.
I hope you’ve enjoyed seeing my latest
project. The airplane turned out beautiful.
Carden makes a fantastic model that top
fliers choose again and again, and I’ll
always have a couple of them in my
stable. This is my seventh Carden model.
The Extra is equipped with a Desert
Aircraft DA-150 engine, KS #1090 tuned
pipes, JR radio equipment, SWB servo
arms and engine mount, Nelson hardware,
and a Tru-Turn spinner. MA
Turn your HELI into a CAMERASHIP!
www.RotorKraft.com
518-686-0483
High-Quality
Aerial Imaging
Products:
Camera Gimbals
Retractable
Gear Units
Sport 3D Video
Video Downlinks
Video Glasses
Expert Advice
Gasoline Heli
Specialists
and more!
G7
GimbalMount TM
Pan & tilt capabilities in
an ultra-lightweight unit.
AVAILABLE IN KIT FORM!
Premium R/C Helicopters and Accessories
09sig4.QXD 6/23/04 1:06 pm Page 116
Edition: Model Aviation - 2004/09
Page Numbers: 114,115,116
Edition: Model Aviation - 2004/09
Page Numbers: 114,115,116
114 MODEL AVIATION
AS THE BUILDING season starts to creep up on most of the
country, it’s time to start thinking about that next project.
Generally, the state of the art for Scale Aerobatics (SA) aircraft
hasn’t changed much in the last year or so, but some new trends
are starting to emerge and new equipment is becoming available
all the time.
I thought you might like to see my most recent build and some
of the detail I used in this Unlimited-class aerobat. You may know
that I’m a dyed-in-the-wool Extra fan. I’ve owned many of Carden
Aircraft’s designs through the years, so it was a no-brainer that I
would build the company’s newest 40%er: the Extra 330S.
I started building with the intention of using JR DS8411 servos. I
would use four for the rudder, two for each aileron, and two for
each elevator half. But during the building process, JR announced
the release of its new digital DS8611 servo. It has the same fast
transit speed as the DS8411—of .18 second/60° at 4.8 volts—but
is ultra high torque at 220 inch-ounce at 4.8 volts or 260 at 6 volts,
all in a standard-size case. (Well, it is slightly bigger, but it fits
with only a slight amount of shoehorning.)
Besides the 8611’s high torque, it features numerous upgrades
compared with other servos, making it more precise, stronger, and
more reliable than ever before. The new 8611s meant that I could
use three fewer servos in my airplane, saving cost, weight, and
complexity in the whole setup. Switching to these was a must.
Now I have three servos for the rudder and one for each
elevator half. I stayed with two for the ailerons. Because of the
span of the aileron, I felt that it was better supported at two points
than one. So it was not a question of servo power, but for the sake
of spreading the load.
To set the 8611s up, I used a program mix for the rudder servos
to match them in a ganged configuration, mixing the other two
servos directly to the rudder channel. A multipoint mix could be
used to get the servos matched exactly, but it wasn’t needed;
Mike Hurley, 11542 Decatur Ct., Westminster CO 80234; E-mail: [email protected]
RADIO CONTROL SCALE AEROBATICS
The author’s Carden Extra 330S weighs 40 pounds, 2 ounces,
with full-length tuned pipes and has new JR 8611 servos.
The Extra uses one receiver and 10 servos. Custom-molded CF
pipe tunnel is just below ganged rudder-servo tray. Forward pipe
tunnel is CF false floor supporting fuel tank.
Mike’s wife Candie prepares to fuel the Extra. Tuned pipes add
extra 500 rpm and smooth transition considerably while keeping
model exceptionally quiet.
09sig4.QXD 6/23/04 1:05 pm Page 114
standard mixes did the trick. For the
ailerons I used a matchbox buried in the
root of each wing to match the servos.
Hangar 9 has come out with an in-line
volt/amp meter for measuring current draw
of the servos. This neat little digitalreadout
device proved to be invaluable in
matching the servos exactly. You just plug
the meter in-line while setting up any servo
and adjust the mix down to the lowest
amperage draw. It made servo setup easy,
and you know you have it right when
you’re done.
Another new trend in the big models is to
use just one receiver. For the last several
years, most pilots who build 40% or larger
SA aircraft used two receivers; we’ve
talked about many of the reasons why.
Most say it’s either for redundancy or for
power distribution needed for so many
servos. The practice has needlessly started
to creep down into the smaller 35% and
33% airplanes, and I’ve even seen two
receivers used in a 27% model. I don’t
think most people even understand why
they do it. They just see other airplanes
with two receivers, so they do it too!
The fact is that a receiver is one of the
least likely components in your aircraft to
fail. Tape the crystal in and mount it so
that vibration doesn’t reach the unit, and
you’ve taken all the precaution you need.
So the argument of redundancy is usually a
case of ignorance of the facts.
We’re also starting to see that dividing
the power distribution because of load
demands was more of a perceived problem
than a real one. JR has started researching
and testing receiver current loads, servo
loads, and the demands made on the whole
system to see if a single receiver power bus
can handle the demands made by all the
servos in a large SA airplane. They’ve
found that the bus will handle up to 60
amps. A fully stalled 8411 is roughly 1.5
amps, although I could only get one to
September 2004 115
Inside pipe tunnel, air enters forward engine-box area and exits
three slots forward of engine-box former. You can see pipebracket
former inside tunnel.
You can see how installed pipes fit in custom-molded tunnel.
Exhaust exits just aft of the wing. CF hatch with molded NACA
air inlet covers pipes in flight.
st.net
OVER A DOZEN MODELS OF WWI, WWII, AND CLASSIC CIVILIAN
AIRCRAFT AVAILABLE WITH MORE VERSIONS TO FOLLOW!
• Electric motor(s) with prop and gear reduction included.
• Highly prefabricated for very short building times.
• 3-4 functions: rudder, aileron & elevator (rudder & ailerons on
one servo, or on separate servos.)
• Laser-cut wood parts for an accurate fit.
• Propeller and spinner included.
• Landing gear and wheels included.
(some kits have removable gear for grass field flying.)
• Contact your local hobby shop, or order direct at: www.djaerotech.com
Ryan ST / PT-16
Wingspan: 28.1 in. • Length: 20.2 in.
Weight: 4.5-5.5 oz. (ready to fly)
Wing Loading: 5.5-6.7 oz/sq. ft.
We
carry
E-tec Li-Poly
batteries &
chargers
Single motor WWII kits ....$48.95
Lockheed P-38...............$56.95
Curtiss Jenny .................$64.95
Sopwith Camel...............$72.95
Fokker Triplane ..............$73.95
DC-3 ............................$66.95
Lockheed Electra............$68.95
Piper J-3 Cub.................$51.95
Curtiss-Wright Junior.......$51.95
Ryan ST / PT-16.............$59.95
B-17F .........................$124.95
(Shipping & Handling extra)
Prices subject to
change without notice.
draw approximately 800 mA. They tell us
that an 8611 will draw 2.7 amps; multiply
that by 10 servos and it’s still only 27
amps, leaving more than adequate fudge
room.
Other factors go into this whole
equation, such as voltage drop past
connectors, battery current capacity, and so
on, but I am only discussing the receiver
bus here. From the tests that have been
made, I’d say that a single receiver is more
than up to the job of handling 10 highcurrent-
draw servos. Another finding is
that a second receiver can reduce your
reception range. Receivers and their
antennas do give off radio frequency and
can affect each other. Some of the testers
at JR have confirmed that they have better
range tests when switching to a single
receiver. Quique Somenzini and Peter
Goldsmith are now using a single receiver
in their giant SA airplanes, and many pilots
out in the field are beginning to do so too.
I’m back to the old adage that simple is
better. My giant 40% SA aerobat has one
receiver, two NiMH battery packs, two
switches, two matchboxes, 10 servos, and
that’s it; no regulators, power-distribution
09sig4.QXD 6/23/04 1:05 pm Page 115
116 MODEL AVIATION
systems, bells, or whistles.
A significant change for me in this build
was adding tuned pipes. That’s right;
long, baseball bat-sized, tuned pipes—not
canister mufflers. Because this model is
slightly bigger than most other 40%
airplanes, it is also a couple pounds
heavier than others I have. My problem
was that at my altitude flying in Denver,
the engine couldn’t handle the extra
weight.
The decision to go with tuned pipes
was tough. Very few have been installed
across the country, and the results were
not a sure thing. In addition to that, the
pipes would add another 2-3 pounds to
the model, so I was taking a risk. They
not only needed to perform well, but they
needed to add enough power to
compensate for an already topped-out
power-to-weight ratio and added weight
of the pipes themselves. The potential of
a quieter model with more power was
enough for me to give it a go.
Installing the pipes wasn’t too hard,
but it did require a bit of planning. I
wanted them to be isolated from the rest
of the inside of the fuselage. The engine
box on the Carden Extra is exactly the
right size for two canisters, but roughly
14 inches too short for these pipes, so I
had to modify the rear engine-box former
to allow the pipes to pass through it.
That former turned out to be a perfect
place to put a simple but effective pipe
bracket that MTW makes and Desert
Aircraft sells. The bracket is nothing
more than a former designed to hold four
pieces of silicone tubing that fit snugly
around the pipe and hold it in place.
To isolate the pipes inside the engine
box, I used a piece of carbon-fiber (CF)
laminate to make a false floor. The CF
also added a great deal of strength and
rigidity to the engine-box assembly. Aft
of the engine-box former, I had to make a
pipe tunnel of some sort. Erik Richard
molded a single-layer CF tunnel that was
epoxied inside the fuselage. The tunnel
weighed a scant 2 ounces, and the false
floor came in at 4 ounces! Not only is the
structure as minimal as possible, but it
also looks great.
Where these KS tuned pipes really
shine is in their operation. When most
people think of tuned pipes, they
automatically think of peaky performance,
higher rpm nonlinear power, or even dead
or flat spots in the throttle response.
Nothing could be further from the truth in
this case. Overall, the power is improved
from the bottom to the top, linearity is
improved, and transition is much
smoother with no flat spots or burble.
The power is incredible, with an
average increase of 500 rpm at the top
end. (That is a huge power and thrust
increase for this type of airplane.) The
best part is the sound. Noise was
decreased dramatically on the ground and
in the air with a much more sophisticated
note. Propeller noise is still present at the
high rpm the engine is able to produce,
but that could be reduced with the
addition of a correct-size three-blade
propeller. I’m so pleased with the results
with the tuned pipes that it will be
standard equipment on all my future
projects.
I hope you’ve enjoyed seeing my latest
project. The airplane turned out beautiful.
Carden makes a fantastic model that top
fliers choose again and again, and I’ll
always have a couple of them in my
stable. This is my seventh Carden model.
The Extra is equipped with a Desert
Aircraft DA-150 engine, KS #1090 tuned
pipes, JR radio equipment, SWB servo
arms and engine mount, Nelson hardware,
and a Tru-Turn spinner. MA
Turn your HELI into a CAMERASHIP!
www.RotorKraft.com
518-686-0483
High-Quality
Aerial Imaging
Products:
Camera Gimbals
Retractable
Gear Units
Sport 3D Video
Video Downlinks
Video Glasses
Expert Advice
Gasoline Heli
Specialists
and more!
G7
GimbalMount TM
Pan & tilt capabilities in
an ultra-lightweight unit.
AVAILABLE IN KIT FORM!
Premium R/C Helicopters and Accessories
09sig4.QXD 6/23/04 1:06 pm Page 116
Edition: Model Aviation - 2004/09
Page Numbers: 114,115,116
114 MODEL AVIATION
AS THE BUILDING season starts to creep up on most of the
country, it’s time to start thinking about that next project.
Generally, the state of the art for Scale Aerobatics (SA) aircraft
hasn’t changed much in the last year or so, but some new trends
are starting to emerge and new equipment is becoming available
all the time.
I thought you might like to see my most recent build and some
of the detail I used in this Unlimited-class aerobat. You may know
that I’m a dyed-in-the-wool Extra fan. I’ve owned many of Carden
Aircraft’s designs through the years, so it was a no-brainer that I
would build the company’s newest 40%er: the Extra 330S.
I started building with the intention of using JR DS8411 servos. I
would use four for the rudder, two for each aileron, and two for
each elevator half. But during the building process, JR announced
the release of its new digital DS8611 servo. It has the same fast
transit speed as the DS8411—of .18 second/60° at 4.8 volts—but
is ultra high torque at 220 inch-ounce at 4.8 volts or 260 at 6 volts,
all in a standard-size case. (Well, it is slightly bigger, but it fits
with only a slight amount of shoehorning.)
Besides the 8611’s high torque, it features numerous upgrades
compared with other servos, making it more precise, stronger, and
more reliable than ever before. The new 8611s meant that I could
use three fewer servos in my airplane, saving cost, weight, and
complexity in the whole setup. Switching to these was a must.
Now I have three servos for the rudder and one for each
elevator half. I stayed with two for the ailerons. Because of the
span of the aileron, I felt that it was better supported at two points
than one. So it was not a question of servo power, but for the sake
of spreading the load.
To set the 8611s up, I used a program mix for the rudder servos
to match them in a ganged configuration, mixing the other two
servos directly to the rudder channel. A multipoint mix could be
used to get the servos matched exactly, but it wasn’t needed;
Mike Hurley, 11542 Decatur Ct., Westminster CO 80234; E-mail: [email protected]
RADIO CONTROL SCALE AEROBATICS
The author’s Carden Extra 330S weighs 40 pounds, 2 ounces,
with full-length tuned pipes and has new JR 8611 servos.
The Extra uses one receiver and 10 servos. Custom-molded CF
pipe tunnel is just below ganged rudder-servo tray. Forward pipe
tunnel is CF false floor supporting fuel tank.
Mike’s wife Candie prepares to fuel the Extra. Tuned pipes add
extra 500 rpm and smooth transition considerably while keeping
model exceptionally quiet.
09sig4.QXD 6/23/04 1:05 pm Page 114
standard mixes did the trick. For the
ailerons I used a matchbox buried in the
root of each wing to match the servos.
Hangar 9 has come out with an in-line
volt/amp meter for measuring current draw
of the servos. This neat little digitalreadout
device proved to be invaluable in
matching the servos exactly. You just plug
the meter in-line while setting up any servo
and adjust the mix down to the lowest
amperage draw. It made servo setup easy,
and you know you have it right when
you’re done.
Another new trend in the big models is to
use just one receiver. For the last several
years, most pilots who build 40% or larger
SA aircraft used two receivers; we’ve
talked about many of the reasons why.
Most say it’s either for redundancy or for
power distribution needed for so many
servos. The practice has needlessly started
to creep down into the smaller 35% and
33% airplanes, and I’ve even seen two
receivers used in a 27% model. I don’t
think most people even understand why
they do it. They just see other airplanes
with two receivers, so they do it too!
The fact is that a receiver is one of the
least likely components in your aircraft to
fail. Tape the crystal in and mount it so
that vibration doesn’t reach the unit, and
you’ve taken all the precaution you need.
So the argument of redundancy is usually a
case of ignorance of the facts.
We’re also starting to see that dividing
the power distribution because of load
demands was more of a perceived problem
than a real one. JR has started researching
and testing receiver current loads, servo
loads, and the demands made on the whole
system to see if a single receiver power bus
can handle the demands made by all the
servos in a large SA airplane. They’ve
found that the bus will handle up to 60
amps. A fully stalled 8411 is roughly 1.5
amps, although I could only get one to
September 2004 115
Inside pipe tunnel, air enters forward engine-box area and exits
three slots forward of engine-box former. You can see pipebracket
former inside tunnel.
You can see how installed pipes fit in custom-molded tunnel.
Exhaust exits just aft of the wing. CF hatch with molded NACA
air inlet covers pipes in flight.
st.net
OVER A DOZEN MODELS OF WWI, WWII, AND CLASSIC CIVILIAN
AIRCRAFT AVAILABLE WITH MORE VERSIONS TO FOLLOW!
• Electric motor(s) with prop and gear reduction included.
• Highly prefabricated for very short building times.
• 3-4 functions: rudder, aileron & elevator (rudder & ailerons on
one servo, or on separate servos.)
• Laser-cut wood parts for an accurate fit.
• Propeller and spinner included.
• Landing gear and wheels included.
(some kits have removable gear for grass field flying.)
• Contact your local hobby shop, or order direct at: www.djaerotech.com
Ryan ST / PT-16
Wingspan: 28.1 in. • Length: 20.2 in.
Weight: 4.5-5.5 oz. (ready to fly)
Wing Loading: 5.5-6.7 oz/sq. ft.
We
carry
E-tec Li-Poly
batteries &
chargers
Single motor WWII kits ....$48.95
Lockheed P-38...............$56.95
Curtiss Jenny .................$64.95
Sopwith Camel...............$72.95
Fokker Triplane ..............$73.95
DC-3 ............................$66.95
Lockheed Electra............$68.95
Piper J-3 Cub.................$51.95
Curtiss-Wright Junior.......$51.95
Ryan ST / PT-16.............$59.95
B-17F .........................$124.95
(Shipping & Handling extra)
Prices subject to
change without notice.
draw approximately 800 mA. They tell us
that an 8611 will draw 2.7 amps; multiply
that by 10 servos and it’s still only 27
amps, leaving more than adequate fudge
room.
Other factors go into this whole
equation, such as voltage drop past
connectors, battery current capacity, and so
on, but I am only discussing the receiver
bus here. From the tests that have been
made, I’d say that a single receiver is more
than up to the job of handling 10 highcurrent-
draw servos. Another finding is
that a second receiver can reduce your
reception range. Receivers and their
antennas do give off radio frequency and
can affect each other. Some of the testers
at JR have confirmed that they have better
range tests when switching to a single
receiver. Quique Somenzini and Peter
Goldsmith are now using a single receiver
in their giant SA airplanes, and many pilots
out in the field are beginning to do so too.
I’m back to the old adage that simple is
better. My giant 40% SA aerobat has one
receiver, two NiMH battery packs, two
switches, two matchboxes, 10 servos, and
that’s it; no regulators, power-distribution
09sig4.QXD 6/23/04 1:05 pm Page 115
116 MODEL AVIATION
systems, bells, or whistles.
A significant change for me in this build
was adding tuned pipes. That’s right;
long, baseball bat-sized, tuned pipes—not
canister mufflers. Because this model is
slightly bigger than most other 40%
airplanes, it is also a couple pounds
heavier than others I have. My problem
was that at my altitude flying in Denver,
the engine couldn’t handle the extra
weight.
The decision to go with tuned pipes
was tough. Very few have been installed
across the country, and the results were
not a sure thing. In addition to that, the
pipes would add another 2-3 pounds to
the model, so I was taking a risk. They
not only needed to perform well, but they
needed to add enough power to
compensate for an already topped-out
power-to-weight ratio and added weight
of the pipes themselves. The potential of
a quieter model with more power was
enough for me to give it a go.
Installing the pipes wasn’t too hard,
but it did require a bit of planning. I
wanted them to be isolated from the rest
of the inside of the fuselage. The engine
box on the Carden Extra is exactly the
right size for two canisters, but roughly
14 inches too short for these pipes, so I
had to modify the rear engine-box former
to allow the pipes to pass through it.
That former turned out to be a perfect
place to put a simple but effective pipe
bracket that MTW makes and Desert
Aircraft sells. The bracket is nothing
more than a former designed to hold four
pieces of silicone tubing that fit snugly
around the pipe and hold it in place.
To isolate the pipes inside the engine
box, I used a piece of carbon-fiber (CF)
laminate to make a false floor. The CF
also added a great deal of strength and
rigidity to the engine-box assembly. Aft
of the engine-box former, I had to make a
pipe tunnel of some sort. Erik Richard
molded a single-layer CF tunnel that was
epoxied inside the fuselage. The tunnel
weighed a scant 2 ounces, and the false
floor came in at 4 ounces! Not only is the
structure as minimal as possible, but it
also looks great.
Where these KS tuned pipes really
shine is in their operation. When most
people think of tuned pipes, they
automatically think of peaky performance,
higher rpm nonlinear power, or even dead
or flat spots in the throttle response.
Nothing could be further from the truth in
this case. Overall, the power is improved
from the bottom to the top, linearity is
improved, and transition is much
smoother with no flat spots or burble.
The power is incredible, with an
average increase of 500 rpm at the top
end. (That is a huge power and thrust
increase for this type of airplane.) The
best part is the sound. Noise was
decreased dramatically on the ground and
in the air with a much more sophisticated
note. Propeller noise is still present at the
high rpm the engine is able to produce,
but that could be reduced with the
addition of a correct-size three-blade
propeller. I’m so pleased with the results
with the tuned pipes that it will be
standard equipment on all my future
projects.
I hope you’ve enjoyed seeing my latest
project. The airplane turned out beautiful.
Carden makes a fantastic model that top
fliers choose again and again, and I’ll
always have a couple of them in my
stable. This is my seventh Carden model.
The Extra is equipped with a Desert
Aircraft DA-150 engine, KS #1090 tuned
pipes, JR radio equipment, SWB servo
arms and engine mount, Nelson hardware,
and a Tru-Turn spinner. MA
Turn your HELI into a CAMERASHIP!
www.RotorKraft.com
518-686-0483
High-Quality
Aerial Imaging
Products:
Camera Gimbals
Retractable
Gear Units
Sport 3D Video
Video Downlinks
Video Glasses
Expert Advice
Gasoline Heli
Specialists
and more!
G7
GimbalMount TM
Pan & tilt capabilities in
an ultra-lightweight unit.
AVAILABLE IN KIT FORM!
Premium R/C Helicopters and Accessories
09sig4.QXD 6/23/04 1:06 pm Page 116