110 MODEL AVIATION
THIS IS THE sixth monthly column in which I try to give you
the best possible answers to the questions you write in or E-mail. I
expect to make this introduction in a few more columns, until you
get comfortable with the routine.
Each question has a sequential number for identification
purposes. Because publication space is limited, spillover material
will be posted on the AMA Web site at http://modelaircraft.org/
mag/FAQ/index.asp. Actually, all questions and answers will be
posted on the AMA Web site.
Let’s start!
Q45: “I want to replace an 8-cell NiMH battery pack (nominal 9.6
volts) with a 2-cell Li-Poly battery pack (nominal 7.4 volts). I
realize that the voltage will be lower, so I want to know if it is
okay to add 2 NiMH from my surplus supply and place them in
series with the 2 Li-Poly cells. That ought to get me close to the
desired 9.6 volts. Since I’ll be using part NiMH cells in this pack,
is it okay for me to use my peak detect charger?”
A45: With all of the current controversy regarding the safety
aspects of Li-Poly battery cells in general, this nontypical
question is timely. Basically, the answer is No!
I was so upset when I read this that I immediately E-mailed the
reader with my concerns and told him to please never try such a
mixture of cells. You should never mix battery types, brands, or
capacities in any single pack or grouping of cells.
In this instance the reader knew his voltage would be lower
and thought he could add a couple of NiMH cells he had lying
around his shop to increase the voltage to what it was originally.
The problem with Li-Poly cells, as we are quickly learning, is
that they have a nominal voltage of roughly 3.7 volts. Two cells at
7.4 volts might not be enough, but three cells at 11.1 volts might
be too much.
The solution to this problem is generally to go to the higher
voltage, and then select a propeller that draws less current or, if
Bob Aberle
F r e q u e n t l y A s k e d Q u e s t i o n s
E-mail: [email protected]
A reader asked if it is okay to add two NiMH battery cells (L) to a
Li-Poly battery pack of two cells (R). No! Never!
The larger servo—a Hitec 422—operates the rudder and nosegear
steering control on a Hobby Lobby Bonnie 20 ARF.
Bonnie firewall, showing nose-gear strut and two mounting
brackets. Steering arm is located between the two brackets.
Rear of Bonnie fuselage. Rudder control rod coming from rudder
servo attaches to rudder control horn with plastic clevis.
10sig4.QXD 7/23/04 10:44 am Page 110
using a gear drive, change the reduction
ratio to reduce the current. But never add
in other types of battery cells in an effort
to increase the voltage.
In the same regard, if you attempted to
charge this “combination” of Li-Poly and
NiMH cells on a peak-detect charger, you
would quickly exceed the 4.2 volts
maximum per Li-Poly cell, and with that
the cell(s) would quickly be destroyed.
You won’t get an explosion with Li-Poly
batteries, but the pack will swell up, and in
some worst cases catch fire.
Again, never add other types of cells to
Li-Poly types, and never attempt to charge
Li-Poly cells with anything except a
dedicated Li-Poly charger.
Q46: “I just bought my first model aircraft
with a steerable nose gear. I’m not sure
how I should hook this up so that I can
steer the model while on the ground.”
A46: I recently reviewed the Hobby Lobby
Bonnie 20 electric-powered ARF advanced
trainer in AMA’s new online magazine,
Sport Aviator. I’ll steal a couple photos
from that article, but you might want to
look it up to obtain other ideas.
Basically, the nose-gear wire strut is
held in place (usually to the firewall) with
a pair of nylon brackets. The brackets are
actually bearing points that allow the strut
to rotate, which causes a steering action. A
tiller arm is installed on the strut. A wire
control rod is run from that tiller arm (or
steering arm) back to the output arm of
your rudder servo.
I like to use an adjustable servo output
arm for this type of installation. The wire
coming from the nose-gear tiller arm is
placed in the inside hole of the servo
output arm; i.e., the hole closer to the
center hub of your servo output arm.
At the outermost hole, in that same
servo arm, you place a second control wire
which is routed aft, inside the fuselage,
and eventually connects to the control horn
located on the movable aircraft rudder.
By having the rudder connection on the
outside hole of the arm, you will obtain a
considerable amount of rudder control
throw, and that is what you want. The
“inside” hole connection for the nose-gear
strut is to reduce the amount of nose-wheel
steering. If you have a great deal of nosewheel
steering, you will find it difficult to
track a straight course while maneuvering
your aircraft on the ground.
The other thing you must make sure of
is that the rudder and nose wheel steer in
the same direction. When you move the
rudder control stick on your RC transmitter
to the right, the rudder should move for a
right turn and the nose wheel should also
turn in the direction that causes a right
turn. If the directions are opposite, you
will have a big problem.
The nose-wheel strut absorbs many
“shock loads” while the model is taxiing
around before taking flight. Much of those
loads is transmitted back to the rudder
servo and its gear train. Because of this,
you are generally advised to use a higheroutput
(more rugged) servo for the
rudder/nose-wheel-steering application.
Q47: “When I transitioned from three
channel functions to four, I had
considerable difficulty steering the aircraft
with my left hand. Are there any tricks that
might help in this transition?”
A47: This question relates somewhat to
the previous inquiry concerning the
steerable-nose-gear function. If you started
with only three-channel control of the
rudder, elevator, and motor throttle, you
did your ground steering and flight
steering using the rudder and your right
hand. Even an aircraft with aileron control,
but no landing gear, would be flown just
with the right hand.
But then you moved up to the full four
flight-control functions, and you have the
aileron and elevator control using your
right hand while the rudder and throttle is
operated by your left hand.
Initially that takes a lot of getting used
to. It is one of the reasons I like to get my
students up to full four-channel control as
fast as possible. Once you learn to steer
with the left hand, usually you will have
no trouble going back to a three-channelcontrol
aircraft. It becomes intuitive with
some experience.
As I pointed out in the previous
question, you should try to reduce the
amount of nose-gear steering (rotation of
the nose wheel) to make turning less
sensitive while maneuvering on the
ground.
Another big help is to employ some
exponential (expo) rate control on the
rudder channel. This is available on the
more advanced RC transmitters and is
another reason why I recommend these RC
systems, even for the rank beginners.
Using expo rate control, the rudder
action is desensitized around the neutral
position. A large amount of rudder
command at the transmitter control stick
produces a relatively small amount of
nose-wheel (or tail-wheel) steering. The
effect is to soften the control response
around the neutral position, which tends to
smooth out your turning maneuvers. I use
expo rate in one form or another on almost
all of my models. I hope you will keep that
thought in mind.
Q48: “In the June issue of Model Aviation
in your article titled “Introduction to
Parking Lot Flying” is a photo of you and
your grandson (page 49, right side). In that
photo you are holding a ‘pro-type’ or
advanced RC transmitter. Don’t you
realize that you shouldn’t be using or even
suggesting the use of a ‘high-powered’ RC
transmitter for parking lot flying? Your
advanced RC transmitter might easily
interfere with other parking lot flyers
operating several blocks away. I can’t
believe you did this!
October 2004 111
Airtronics VG6000’s LCD screen has been selected for “EXP,” or
exponential rate control. You can choose 0% to 100% expo.
Polk’s Hobby Tracker II’s built-in scanning receiver determines if
anyone is operating on the channel you expect to use.
10sig4.QXD 7/23/04 10:45 am Page 111
A48: I had to sit back and think about this
for a few seconds. My reader friend was
sincere and concerned. The transmitter I
happened to be using when that photo was
taken was a Hitec Eclipse. It is one of my
most popular transmitters, and I generally
use all seven memory positions while
operating my “fleet” of parking lot and
indoor RC models. It is definitely an
“advanced” RC transmitter.
But you must understand that it is
advanced by virtue of having an internal
microchip, or essentially a computer
circuit. This chip provides many extra
control features and allows for the storage
of specific controls in a memory bank that
can handle as many as seven models.
Keep in mind that the computer circuits
are what make this an advanced RC
transmitter.
Consider also that on the output side of
this transmitter, the radiated radiofrequency
(RF) power going to the
transmitter’s antenna is limited by FCC
regulation to 3⁄4-watt (750-milliwatt)
output. All RC transmitters conform to
this specification.
In fact, it is more than likely that most
of the output circuit semiconductors are
the same type or close to it. Considering
this, all RC transmitters, from an output
standpoint, are essentially created equal.
Yes, it is possible that two groups of
parking lot flyers, several blocks apart,
might interfere with one another. But if
such interference occurred, it would
simply be because of the closeness of the
groups—not because of the transmitter’s
power output.
I got back to the reader and explained
everything. He believed my explanation
and was actually slightly embarrassed that
he even brought up the subject. The fact is
that local parking lot flyers should be
aware of who is flying in the immediate
area. Local hobby shops and RC clubs can
help pinpoint parking lot-flying activity so
that one person doesn’t interfere with
another. The problem will always be
there; it’s just that the transmitter’s output
power is not the real problem.
An excellent way to avoid RC
interference from groups flying in close
proximity is by using an RC transmitter
that has a built-in scanning receiver.
Polk’s Hobby’s Tracker II and several of
the new Hitec/Multiplex transmitters have
this feature.
When you turn your transmitter power
switch on, only the scanning receiver is
turned on. In a few seconds this receiver
scans the channel on which you are set to
operate. If it is clear, the receiver will
indicate “OK” and turn on the signal. If it
senses someone else on the same channel,
it states “Wait—In Use” and will not
allow you to operate your RC system.
This takes the guesswork out of
frequency control. It is also perfect for
determining if another parking lot flyer is
attempting to fly nearby on your RC
channel. MA
112 MODEL AVIATION
Wireless Video Systems
Micro Cam 2 color video camera puts you in the pilot seat.
Camera features a built in 2.4ghz transmitter which sends real
time video and audio up to 2000ft*, no special license required.
www.MicroWireless.net
[email protected]
817-715-1989
Dealers inquire
Micro Cam 2 includes
Color camera w/audio
Four channel receiver
Camera mount
A/C adapters
9v battery cable
Audio/video cables
Micro Cam
Intro price
$114.95
*LOS using optional receiver antenna
Check out the new
Amateur video
camera systems
featuring CCD
cameras and high
power transmitters.
Starting at $249
Visa/MasterCard accepted
7865 Mill Road, Elkins Park, PA. 19027 USA
Tel. 215 635 6520 Orders ONLY 888 721 0128 Fax. 215 635 4951
Email [email protected] www.sonictronics.com
A Division of Sonic-Tronics Inc.
Performance Plus
NI-STARTER
“Still here and working”
When the others are
only a memory !
®
Watch our web site for new
products and special offers.
The “Electronic Ni-Starter”
is coming soon.
McDaniel R/C
10sig4.QXD 7/23/04 10:45 am Page 112
Edition: Model Aviation - 2004/10
Page Numbers: 110,111,112
Edition: Model Aviation - 2004/10
Page Numbers: 110,111,112
110 MODEL AVIATION
THIS IS THE sixth monthly column in which I try to give you
the best possible answers to the questions you write in or E-mail. I
expect to make this introduction in a few more columns, until you
get comfortable with the routine.
Each question has a sequential number for identification
purposes. Because publication space is limited, spillover material
will be posted on the AMA Web site at http://modelaircraft.org/
mag/FAQ/index.asp. Actually, all questions and answers will be
posted on the AMA Web site.
Let’s start!
Q45: “I want to replace an 8-cell NiMH battery pack (nominal 9.6
volts) with a 2-cell Li-Poly battery pack (nominal 7.4 volts). I
realize that the voltage will be lower, so I want to know if it is
okay to add 2 NiMH from my surplus supply and place them in
series with the 2 Li-Poly cells. That ought to get me close to the
desired 9.6 volts. Since I’ll be using part NiMH cells in this pack,
is it okay for me to use my peak detect charger?”
A45: With all of the current controversy regarding the safety
aspects of Li-Poly battery cells in general, this nontypical
question is timely. Basically, the answer is No!
I was so upset when I read this that I immediately E-mailed the
reader with my concerns and told him to please never try such a
mixture of cells. You should never mix battery types, brands, or
capacities in any single pack or grouping of cells.
In this instance the reader knew his voltage would be lower
and thought he could add a couple of NiMH cells he had lying
around his shop to increase the voltage to what it was originally.
The problem with Li-Poly cells, as we are quickly learning, is
that they have a nominal voltage of roughly 3.7 volts. Two cells at
7.4 volts might not be enough, but three cells at 11.1 volts might
be too much.
The solution to this problem is generally to go to the higher
voltage, and then select a propeller that draws less current or, if
Bob Aberle
F r e q u e n t l y A s k e d Q u e s t i o n s
E-mail: [email protected]
A reader asked if it is okay to add two NiMH battery cells (L) to a
Li-Poly battery pack of two cells (R). No! Never!
The larger servo—a Hitec 422—operates the rudder and nosegear
steering control on a Hobby Lobby Bonnie 20 ARF.
Bonnie firewall, showing nose-gear strut and two mounting
brackets. Steering arm is located between the two brackets.
Rear of Bonnie fuselage. Rudder control rod coming from rudder
servo attaches to rudder control horn with plastic clevis.
10sig4.QXD 7/23/04 10:44 am Page 110
using a gear drive, change the reduction
ratio to reduce the current. But never add
in other types of battery cells in an effort
to increase the voltage.
In the same regard, if you attempted to
charge this “combination” of Li-Poly and
NiMH cells on a peak-detect charger, you
would quickly exceed the 4.2 volts
maximum per Li-Poly cell, and with that
the cell(s) would quickly be destroyed.
You won’t get an explosion with Li-Poly
batteries, but the pack will swell up, and in
some worst cases catch fire.
Again, never add other types of cells to
Li-Poly types, and never attempt to charge
Li-Poly cells with anything except a
dedicated Li-Poly charger.
Q46: “I just bought my first model aircraft
with a steerable nose gear. I’m not sure
how I should hook this up so that I can
steer the model while on the ground.”
A46: I recently reviewed the Hobby Lobby
Bonnie 20 electric-powered ARF advanced
trainer in AMA’s new online magazine,
Sport Aviator. I’ll steal a couple photos
from that article, but you might want to
look it up to obtain other ideas.
Basically, the nose-gear wire strut is
held in place (usually to the firewall) with
a pair of nylon brackets. The brackets are
actually bearing points that allow the strut
to rotate, which causes a steering action. A
tiller arm is installed on the strut. A wire
control rod is run from that tiller arm (or
steering arm) back to the output arm of
your rudder servo.
I like to use an adjustable servo output
arm for this type of installation. The wire
coming from the nose-gear tiller arm is
placed in the inside hole of the servo
output arm; i.e., the hole closer to the
center hub of your servo output arm.
At the outermost hole, in that same
servo arm, you place a second control wire
which is routed aft, inside the fuselage,
and eventually connects to the control horn
located on the movable aircraft rudder.
By having the rudder connection on the
outside hole of the arm, you will obtain a
considerable amount of rudder control
throw, and that is what you want. The
“inside” hole connection for the nose-gear
strut is to reduce the amount of nose-wheel
steering. If you have a great deal of nosewheel
steering, you will find it difficult to
track a straight course while maneuvering
your aircraft on the ground.
The other thing you must make sure of
is that the rudder and nose wheel steer in
the same direction. When you move the
rudder control stick on your RC transmitter
to the right, the rudder should move for a
right turn and the nose wheel should also
turn in the direction that causes a right
turn. If the directions are opposite, you
will have a big problem.
The nose-wheel strut absorbs many
“shock loads” while the model is taxiing
around before taking flight. Much of those
loads is transmitted back to the rudder
servo and its gear train. Because of this,
you are generally advised to use a higheroutput
(more rugged) servo for the
rudder/nose-wheel-steering application.
Q47: “When I transitioned from three
channel functions to four, I had
considerable difficulty steering the aircraft
with my left hand. Are there any tricks that
might help in this transition?”
A47: This question relates somewhat to
the previous inquiry concerning the
steerable-nose-gear function. If you started
with only three-channel control of the
rudder, elevator, and motor throttle, you
did your ground steering and flight
steering using the rudder and your right
hand. Even an aircraft with aileron control,
but no landing gear, would be flown just
with the right hand.
But then you moved up to the full four
flight-control functions, and you have the
aileron and elevator control using your
right hand while the rudder and throttle is
operated by your left hand.
Initially that takes a lot of getting used
to. It is one of the reasons I like to get my
students up to full four-channel control as
fast as possible. Once you learn to steer
with the left hand, usually you will have
no trouble going back to a three-channelcontrol
aircraft. It becomes intuitive with
some experience.
As I pointed out in the previous
question, you should try to reduce the
amount of nose-gear steering (rotation of
the nose wheel) to make turning less
sensitive while maneuvering on the
ground.
Another big help is to employ some
exponential (expo) rate control on the
rudder channel. This is available on the
more advanced RC transmitters and is
another reason why I recommend these RC
systems, even for the rank beginners.
Using expo rate control, the rudder
action is desensitized around the neutral
position. A large amount of rudder
command at the transmitter control stick
produces a relatively small amount of
nose-wheel (or tail-wheel) steering. The
effect is to soften the control response
around the neutral position, which tends to
smooth out your turning maneuvers. I use
expo rate in one form or another on almost
all of my models. I hope you will keep that
thought in mind.
Q48: “In the June issue of Model Aviation
in your article titled “Introduction to
Parking Lot Flying” is a photo of you and
your grandson (page 49, right side). In that
photo you are holding a ‘pro-type’ or
advanced RC transmitter. Don’t you
realize that you shouldn’t be using or even
suggesting the use of a ‘high-powered’ RC
transmitter for parking lot flying? Your
advanced RC transmitter might easily
interfere with other parking lot flyers
operating several blocks away. I can’t
believe you did this!
October 2004 111
Airtronics VG6000’s LCD screen has been selected for “EXP,” or
exponential rate control. You can choose 0% to 100% expo.
Polk’s Hobby Tracker II’s built-in scanning receiver determines if
anyone is operating on the channel you expect to use.
10sig4.QXD 7/23/04 10:45 am Page 111
A48: I had to sit back and think about this
for a few seconds. My reader friend was
sincere and concerned. The transmitter I
happened to be using when that photo was
taken was a Hitec Eclipse. It is one of my
most popular transmitters, and I generally
use all seven memory positions while
operating my “fleet” of parking lot and
indoor RC models. It is definitely an
“advanced” RC transmitter.
But you must understand that it is
advanced by virtue of having an internal
microchip, or essentially a computer
circuit. This chip provides many extra
control features and allows for the storage
of specific controls in a memory bank that
can handle as many as seven models.
Keep in mind that the computer circuits
are what make this an advanced RC
transmitter.
Consider also that on the output side of
this transmitter, the radiated radiofrequency
(RF) power going to the
transmitter’s antenna is limited by FCC
regulation to 3⁄4-watt (750-milliwatt)
output. All RC transmitters conform to
this specification.
In fact, it is more than likely that most
of the output circuit semiconductors are
the same type or close to it. Considering
this, all RC transmitters, from an output
standpoint, are essentially created equal.
Yes, it is possible that two groups of
parking lot flyers, several blocks apart,
might interfere with one another. But if
such interference occurred, it would
simply be because of the closeness of the
groups—not because of the transmitter’s
power output.
I got back to the reader and explained
everything. He believed my explanation
and was actually slightly embarrassed that
he even brought up the subject. The fact is
that local parking lot flyers should be
aware of who is flying in the immediate
area. Local hobby shops and RC clubs can
help pinpoint parking lot-flying activity so
that one person doesn’t interfere with
another. The problem will always be
there; it’s just that the transmitter’s output
power is not the real problem.
An excellent way to avoid RC
interference from groups flying in close
proximity is by using an RC transmitter
that has a built-in scanning receiver.
Polk’s Hobby’s Tracker II and several of
the new Hitec/Multiplex transmitters have
this feature.
When you turn your transmitter power
switch on, only the scanning receiver is
turned on. In a few seconds this receiver
scans the channel on which you are set to
operate. If it is clear, the receiver will
indicate “OK” and turn on the signal. If it
senses someone else on the same channel,
it states “Wait—In Use” and will not
allow you to operate your RC system.
This takes the guesswork out of
frequency control. It is also perfect for
determining if another parking lot flyer is
attempting to fly nearby on your RC
channel. MA
112 MODEL AVIATION
Wireless Video Systems
Micro Cam 2 color video camera puts you in the pilot seat.
Camera features a built in 2.4ghz transmitter which sends real
time video and audio up to 2000ft*, no special license required.
www.MicroWireless.net
[email protected]
817-715-1989
Dealers inquire
Micro Cam 2 includes
Color camera w/audio
Four channel receiver
Camera mount
A/C adapters
9v battery cable
Audio/video cables
Micro Cam
Intro price
$114.95
*LOS using optional receiver antenna
Check out the new
Amateur video
camera systems
featuring CCD
cameras and high
power transmitters.
Starting at $249
Visa/MasterCard accepted
7865 Mill Road, Elkins Park, PA. 19027 USA
Tel. 215 635 6520 Orders ONLY 888 721 0128 Fax. 215 635 4951
Email [email protected] www.sonictronics.com
A Division of Sonic-Tronics Inc.
Performance Plus
NI-STARTER
“Still here and working”
When the others are
only a memory !
®
Watch our web site for new
products and special offers.
The “Electronic Ni-Starter”
is coming soon.
McDaniel R/C
10sig4.QXD 7/23/04 10:45 am Page 112
Edition: Model Aviation - 2004/10
Page Numbers: 110,111,112
110 MODEL AVIATION
THIS IS THE sixth monthly column in which I try to give you
the best possible answers to the questions you write in or E-mail. I
expect to make this introduction in a few more columns, until you
get comfortable with the routine.
Each question has a sequential number for identification
purposes. Because publication space is limited, spillover material
will be posted on the AMA Web site at http://modelaircraft.org/
mag/FAQ/index.asp. Actually, all questions and answers will be
posted on the AMA Web site.
Let’s start!
Q45: “I want to replace an 8-cell NiMH battery pack (nominal 9.6
volts) with a 2-cell Li-Poly battery pack (nominal 7.4 volts). I
realize that the voltage will be lower, so I want to know if it is
okay to add 2 NiMH from my surplus supply and place them in
series with the 2 Li-Poly cells. That ought to get me close to the
desired 9.6 volts. Since I’ll be using part NiMH cells in this pack,
is it okay for me to use my peak detect charger?”
A45: With all of the current controversy regarding the safety
aspects of Li-Poly battery cells in general, this nontypical
question is timely. Basically, the answer is No!
I was so upset when I read this that I immediately E-mailed the
reader with my concerns and told him to please never try such a
mixture of cells. You should never mix battery types, brands, or
capacities in any single pack or grouping of cells.
In this instance the reader knew his voltage would be lower
and thought he could add a couple of NiMH cells he had lying
around his shop to increase the voltage to what it was originally.
The problem with Li-Poly cells, as we are quickly learning, is
that they have a nominal voltage of roughly 3.7 volts. Two cells at
7.4 volts might not be enough, but three cells at 11.1 volts might
be too much.
The solution to this problem is generally to go to the higher
voltage, and then select a propeller that draws less current or, if
Bob Aberle
F r e q u e n t l y A s k e d Q u e s t i o n s
E-mail: [email protected]
A reader asked if it is okay to add two NiMH battery cells (L) to a
Li-Poly battery pack of two cells (R). No! Never!
The larger servo—a Hitec 422—operates the rudder and nosegear
steering control on a Hobby Lobby Bonnie 20 ARF.
Bonnie firewall, showing nose-gear strut and two mounting
brackets. Steering arm is located between the two brackets.
Rear of Bonnie fuselage. Rudder control rod coming from rudder
servo attaches to rudder control horn with plastic clevis.
10sig4.QXD 7/23/04 10:44 am Page 110
using a gear drive, change the reduction
ratio to reduce the current. But never add
in other types of battery cells in an effort
to increase the voltage.
In the same regard, if you attempted to
charge this “combination” of Li-Poly and
NiMH cells on a peak-detect charger, you
would quickly exceed the 4.2 volts
maximum per Li-Poly cell, and with that
the cell(s) would quickly be destroyed.
You won’t get an explosion with Li-Poly
batteries, but the pack will swell up, and in
some worst cases catch fire.
Again, never add other types of cells to
Li-Poly types, and never attempt to charge
Li-Poly cells with anything except a
dedicated Li-Poly charger.
Q46: “I just bought my first model aircraft
with a steerable nose gear. I’m not sure
how I should hook this up so that I can
steer the model while on the ground.”
A46: I recently reviewed the Hobby Lobby
Bonnie 20 electric-powered ARF advanced
trainer in AMA’s new online magazine,
Sport Aviator. I’ll steal a couple photos
from that article, but you might want to
look it up to obtain other ideas.
Basically, the nose-gear wire strut is
held in place (usually to the firewall) with
a pair of nylon brackets. The brackets are
actually bearing points that allow the strut
to rotate, which causes a steering action. A
tiller arm is installed on the strut. A wire
control rod is run from that tiller arm (or
steering arm) back to the output arm of
your rudder servo.
I like to use an adjustable servo output
arm for this type of installation. The wire
coming from the nose-gear tiller arm is
placed in the inside hole of the servo
output arm; i.e., the hole closer to the
center hub of your servo output arm.
At the outermost hole, in that same
servo arm, you place a second control wire
which is routed aft, inside the fuselage,
and eventually connects to the control horn
located on the movable aircraft rudder.
By having the rudder connection on the
outside hole of the arm, you will obtain a
considerable amount of rudder control
throw, and that is what you want. The
“inside” hole connection for the nose-gear
strut is to reduce the amount of nose-wheel
steering. If you have a great deal of nosewheel
steering, you will find it difficult to
track a straight course while maneuvering
your aircraft on the ground.
The other thing you must make sure of
is that the rudder and nose wheel steer in
the same direction. When you move the
rudder control stick on your RC transmitter
to the right, the rudder should move for a
right turn and the nose wheel should also
turn in the direction that causes a right
turn. If the directions are opposite, you
will have a big problem.
The nose-wheel strut absorbs many
“shock loads” while the model is taxiing
around before taking flight. Much of those
loads is transmitted back to the rudder
servo and its gear train. Because of this,
you are generally advised to use a higheroutput
(more rugged) servo for the
rudder/nose-wheel-steering application.
Q47: “When I transitioned from three
channel functions to four, I had
considerable difficulty steering the aircraft
with my left hand. Are there any tricks that
might help in this transition?”
A47: This question relates somewhat to
the previous inquiry concerning the
steerable-nose-gear function. If you started
with only three-channel control of the
rudder, elevator, and motor throttle, you
did your ground steering and flight
steering using the rudder and your right
hand. Even an aircraft with aileron control,
but no landing gear, would be flown just
with the right hand.
But then you moved up to the full four
flight-control functions, and you have the
aileron and elevator control using your
right hand while the rudder and throttle is
operated by your left hand.
Initially that takes a lot of getting used
to. It is one of the reasons I like to get my
students up to full four-channel control as
fast as possible. Once you learn to steer
with the left hand, usually you will have
no trouble going back to a three-channelcontrol
aircraft. It becomes intuitive with
some experience.
As I pointed out in the previous
question, you should try to reduce the
amount of nose-gear steering (rotation of
the nose wheel) to make turning less
sensitive while maneuvering on the
ground.
Another big help is to employ some
exponential (expo) rate control on the
rudder channel. This is available on the
more advanced RC transmitters and is
another reason why I recommend these RC
systems, even for the rank beginners.
Using expo rate control, the rudder
action is desensitized around the neutral
position. A large amount of rudder
command at the transmitter control stick
produces a relatively small amount of
nose-wheel (or tail-wheel) steering. The
effect is to soften the control response
around the neutral position, which tends to
smooth out your turning maneuvers. I use
expo rate in one form or another on almost
all of my models. I hope you will keep that
thought in mind.
Q48: “In the June issue of Model Aviation
in your article titled “Introduction to
Parking Lot Flying” is a photo of you and
your grandson (page 49, right side). In that
photo you are holding a ‘pro-type’ or
advanced RC transmitter. Don’t you
realize that you shouldn’t be using or even
suggesting the use of a ‘high-powered’ RC
transmitter for parking lot flying? Your
advanced RC transmitter might easily
interfere with other parking lot flyers
operating several blocks away. I can’t
believe you did this!
October 2004 111
Airtronics VG6000’s LCD screen has been selected for “EXP,” or
exponential rate control. You can choose 0% to 100% expo.
Polk’s Hobby Tracker II’s built-in scanning receiver determines if
anyone is operating on the channel you expect to use.
10sig4.QXD 7/23/04 10:45 am Page 111
A48: I had to sit back and think about this
for a few seconds. My reader friend was
sincere and concerned. The transmitter I
happened to be using when that photo was
taken was a Hitec Eclipse. It is one of my
most popular transmitters, and I generally
use all seven memory positions while
operating my “fleet” of parking lot and
indoor RC models. It is definitely an
“advanced” RC transmitter.
But you must understand that it is
advanced by virtue of having an internal
microchip, or essentially a computer
circuit. This chip provides many extra
control features and allows for the storage
of specific controls in a memory bank that
can handle as many as seven models.
Keep in mind that the computer circuits
are what make this an advanced RC
transmitter.
Consider also that on the output side of
this transmitter, the radiated radiofrequency
(RF) power going to the
transmitter’s antenna is limited by FCC
regulation to 3⁄4-watt (750-milliwatt)
output. All RC transmitters conform to
this specification.
In fact, it is more than likely that most
of the output circuit semiconductors are
the same type or close to it. Considering
this, all RC transmitters, from an output
standpoint, are essentially created equal.
Yes, it is possible that two groups of
parking lot flyers, several blocks apart,
might interfere with one another. But if
such interference occurred, it would
simply be because of the closeness of the
groups—not because of the transmitter’s
power output.
I got back to the reader and explained
everything. He believed my explanation
and was actually slightly embarrassed that
he even brought up the subject. The fact is
that local parking lot flyers should be
aware of who is flying in the immediate
area. Local hobby shops and RC clubs can
help pinpoint parking lot-flying activity so
that one person doesn’t interfere with
another. The problem will always be
there; it’s just that the transmitter’s output
power is not the real problem.
An excellent way to avoid RC
interference from groups flying in close
proximity is by using an RC transmitter
that has a built-in scanning receiver.
Polk’s Hobby’s Tracker II and several of
the new Hitec/Multiplex transmitters have
this feature.
When you turn your transmitter power
switch on, only the scanning receiver is
turned on. In a few seconds this receiver
scans the channel on which you are set to
operate. If it is clear, the receiver will
indicate “OK” and turn on the signal. If it
senses someone else on the same channel,
it states “Wait—In Use” and will not
allow you to operate your RC system.
This takes the guesswork out of
frequency control. It is also perfect for
determining if another parking lot flyer is
attempting to fly nearby on your RC
channel. MA
112 MODEL AVIATION
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10sig4.QXD 7/23/04 10:45 am Page 112