July 2004 85
THIS IS THE third monthly column in which I try to give you the
best answers to questions you have written or E-mailed to me. I
give each question a sequential number for identification purposes.
Because publication space is limited, part of this column will
appear in print and spillover material will appear only on the AMA
Web site. Stated another way, all questions and answers will be
posted on the AMA Web site. Let’s start!
Q25: “I just acquired a Global Hobbies ProMax Activator peak
digital charger. I am just getting into electric power, but would like
to use this charger on my regular RC transmitter and receiver
batteries. It states in the instructions that you should set the charge
current to two or three times the rated capacity of the battery pack.
Is that okay?
“You also said in your ‘Battery Basics’ article (October 2003
Model Aviation) that a battery pack is bad when it is depleted to
20% of its rated capacity. How do I know when I get there? Can
you straighten me out?”
A25: Several answers are necessary, and this is an important
subject. The ProMax charger the reader referenced works well, and
I have no problem with it. The basic charging circuit was designed
with the electric-power enthusiast in mind.
You can charge one to eight (Ni-Cd or NiMH) cells at selectable
charge currents ranging from 0.5 to 6.0 amps. It is essentially a fast
charger with peak-detect cutoff. There is also a “Slow Peak Mode”
that applies a fixed 0.2-amp (200 mA) charge current to the smaller
battery packs. There are no discharge testing capabilities in this
unit.
I do not recommend that you fast-charge your RC transmitter
battery. Most of these cells are rated at 500-600 mAh. If you apply
a 3C charge current (600 x 3 = 1,800, or 1.8 amps), you might blow
out the internal charging circuit wiring inside your transmitter.
I recommend that you charge your RC transmitter battery pack
with the system charger that the manufacturer supplied. That will
always be at the overnight rate (or for at least 10-12 hours). You
can do this every other day and never overcharge the battery at that
rate.
For the most part I also favor charging the RC airborne
receiver/servo battery pack with the system manufacturer’s charger
at the same overnight rate. Unless you want to fly for more than
two hours at a particular flying session, there is no need to fastcharge
these batteries. Most RC-system batteries were never
intended for fast charging in the first place. So I recommend that
you save your ProMax charger for your electric-power battery
packs. It will do a fine job.
In the next part of his question, the reader indicated that my
article stated that a battery needs replacing when it falls to 20% of
its originally rated capacity. He then wondered if he could interpret
data from the ProMax charger that would allow him to derive
battery capacity.
Here we go again with the fine print! In that article I wrote that I
discard battery packs when they drop 20% from their original
capacity rating. As an example I wrote that a 600 mAh pack should
be discarded when the capacity reaches 480 mAh (600 less 20%). I
referred to when it goes down 20%—not when it goes down to
20%.
The peak voltage and time showing up on the ProMax display
will not directly tell you anything about the battery’s capacity. To
find that out, you need a simple battery discharge tester. This
device applies a load to the battery, usually taking the voltage down
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]
The new Sirius Electronics SuperTest PRO precision battery
tester will sell for $99.95 plus shipping and handling.
To dispense cyanoacrylate, squeeze on the CA SUCK-ER body. It
is much easier than trying to pour glue from the bottle.
This is how to suck cyaonacrylate from bottle into Syrette.
07sig3.QXD 4/23/04 1:05 pm Page 85
86 MODEL AVIATION
Close up of elevator dual rate (on/off) switch on Hitec Eclipse 7
transmitter. Bob points to elevator switch. Rudder dual rate
(on/off) switch is at right.
CH 2 or elevator dual rate has been selected and elevator
control-surface throw has been reduced to 80% of normal.
Expo rate function called up on Eclipse LCD screen. CH 2 or
elevator function and 30% nonlinearity have been selected. This
is moderate expo rate control.
Chart copied from Eclipse instruction manual explains the
difference between linear- and nonlinear-type control.
to 1 volt per cell. The amount of the load and the time it took to get
to the 1 volt per cell is integrated into a single capacity reading in
mAh.
I’ve included a photo of the new Sirius Electronics (a division of
Peak Electronics, Inc.) SuperTest PRO precision battery tester,
which can handle as many as 14 battery cells. You can set the
voltage cutoff point in 1-volt increments up to 14 volts. This
enables you to test Ni-Cd, NiMH, and even Li-Poly batteries. To
learn more about this battery tester, go to www.siriuselectronics.
com/supr_tst.htm.
Q26: “I’m having a tough time using my thin CA cement because
the nozzle on the top of the dispenser bottle keeps continuously
clogging. This slows down my building process. Is there any
possible solution to this problem?”
A26: Many of us have experienced the frustrations of clogged
cyanoacrylate-glue bottles. Several years ago an item was
introduced that I believe came from the surgical-supply industry. It
is a plastic Syrette that looks like a squeeze bottle reservoir with a
plastic spout or tip. The accompanying photos help explain.
You insert the tip or spout into an opened cyanoacrylate glue
bottle. You squeeze the Syrette bottle and then let go. When you do
this, a certain amount of the cyanoacrylate is sucked up into the
Syrette.
You can pull on the spout with pliers and stretch the spout tube
into a thinner diameter. When you do this, you can dispense the
cyanoacrylate onto the model structure at an extraordinarily
controlled rate.
Try to keep the Syrette supported in a vertical position when it’s
not in use. Every once in awhile the spout will get clogged. When
that happens, cut a short length off of the spout until the clogged
portion is discarded. Stretch out the spout again by pulling on it,
and you are back in business.
These Syrettes don’t last that long, so keep a dozen or so on
hand. I have been buying mine from Balsa Products
(www.balsapr.com). They call this product the “CA SUCK-ER”—
naturally!
Q27: “I hear the expressions ‘dual rate control’ and ‘expo rate
control.’ Are they the same thing? Is one form of control better than
another?”
A27: This is an excellent, often-asked question. Dual rate control
and expo rate control work differently, yet they do tend to achieve
close to the same results. With dual rate control, you have a switch
for the function; it’s usually one switch for rudder or aileron and the
other for elevator.
With the switch in the off position, you will obtain full control
throw on that particular channel. When you turn the dual rate switch
to the on position, you can reduce the amount of servo control
throw or travel to at least 50% of the full control.
Let’s say you have a fast, heavily loaded airplane. When it flies
at slower speeds for takeoffs and landings, it requires a great deal of
07sig3.QXD 4/23/04 1:05 pm Page 86
control travel. But when it gets up to a fast
flying speed, it needs far less control
throw. At the faster speeds you want less
control to maintain a smooth flight. This is
where the dual rate functions come into
play.
You make your takeoffs and landings
with the dual rate turned off. Then during
high-speed flying, you turn on the dual rate
switch, which reduces the maximum
amount of servo travel (control). The key is
that you must physically throw that switch
while in flight to obtain the reduced
control. Keep in mind that while the dual
rate switch is on, you cannot obtain full
control throw. So if you need more control
in a hurry, you must first turn off the dual
rate switch.
Exponential rate control (which is
referred to as “expo”) does not have to be
operated by a switch. (It can be, but it
doesn’t have to be!) Nor does it cut back or
reduce your maximum servo control throw.
Expo rate basically provides for a
nonlinear-type control around the neutral
transmitter control-stick position.
In normal linear control, if you move
the transmitter control stick 50% of its
normal travel, the servo it operates moves
50% of its travel; the control response is
linear.
With expo rate, as you begin to move
the transmitter control stick, the servo will
respond slowly. By the time you move the
control stick 25%, the servo it operates
may have only moved 10%. The control
response is nonlinear. As you get up to
50% stick movement, the servo may be up
to 40%. When you get to full control-stick
movement, you get full servo control.
The degree of nonlinearity can be
adjusted. You can set the expo rate for a
little nonlinearity, which may be hardly
noticeable. Or you can set the expo rate for
maximum nonlinearity, which means that
when you move the control stick, the
responding control surface hardly moves at
all initially.
Expo rate control works best on highspeed,
highly maneuverable models. An
airplane that looks “jumpy” in high-speed
flight will become smooth when a good
amount of expo rate control is added.
The two best features of expo rate
compared to dual rate control are that you
get full control throw when you need it and
you don’t have to remember to keep
throwing a switch in flight.
The relatively inexpensive computer
transmitters I wrote about in the February
2004 installment of the “From the Ground
Up” series describe these functions in
detail. Even beginners or relatively new
RC pilots can benefit from dual and expo
rate control. However, keep in mind that
you must pay slightly more for an RC
system that provides such features.
That’s it for now; please keep those letters
and E-mails coming. Receiving your input
is the only way we can continue this
column! MA
88 MODEL AVIATION
PO Box 564 • Hobart, IN 46342
(800) 348-3497
www. m i dwe s t p r oducts.com
Only $24.99 Stock #813
Three cradle positions to hold
your models
Convenient Parts Tray to hold
pieces you're removing / applying
Padded cradles to protect your
models
Adjustable upright supports
Introducing the most convenient
stand ever offered! The ONLY
stand with all these features:
PLANES
BOATS VEHICLES
ULTRA BRITE LITES
NEW
NEED
MORE
INFO?
See your hobby retailer or send a #10 S.A.S.E. to
229 E. Rollins Rd. Round Lake Beach, IL 60073
847-740-8726 Fax 847-740-8727
www.RamRCandRamTrack.com
• W h i t e L E D ’ s
•Br i g h t e r • Tougher
• 5 X B a t t e r y L i f e
Flashing Navigation, (3) Lites,
Adj. rate, to 96”, 9V.......................RAM 121 $44.95
“Strobe” Lite, Adj. rate, 9V...............RAM 122 29.95
Landing Lites, (2) w/switch, 9V.......RAM 123 29.95
Giant Scale Nav., (3) to 168”, 9V...RAM 124 39.95
Non Flash Nav., (3) to 96”, 9V.......RAM 125 34.95
Park Flyer Nav., (3) to 48”,
6 grams, 5-8 cells .........................RAM 132 24.95
Introduces NEW!
SUPER COOL Plug with
Hi Temp Insulator
In addition to . . .
● The FIREBALL R/C IDLE BAR plug
only $2.75
● Hot & Standard Non-Idle Bar plugs
still only $2.45
only $2.75
Swanson
Associates
P.O. Box 151
Wayne, NJ
07470
Since 1948
07sig3.QXD 4/23/04 1:06 pm Page 88
Edition: Model Aviation - 2004/07
Page Numbers: 85,86,88
Edition: Model Aviation - 2004/07
Page Numbers: 85,86,88
July 2004 85
THIS IS THE third monthly column in which I try to give you the
best answers to questions you have written or E-mailed to me. I
give each question a sequential number for identification purposes.
Because publication space is limited, part of this column will
appear in print and spillover material will appear only on the AMA
Web site. Stated another way, all questions and answers will be
posted on the AMA Web site. Let’s start!
Q25: “I just acquired a Global Hobbies ProMax Activator peak
digital charger. I am just getting into electric power, but would like
to use this charger on my regular RC transmitter and receiver
batteries. It states in the instructions that you should set the charge
current to two or three times the rated capacity of the battery pack.
Is that okay?
“You also said in your ‘Battery Basics’ article (October 2003
Model Aviation) that a battery pack is bad when it is depleted to
20% of its rated capacity. How do I know when I get there? Can
you straighten me out?”
A25: Several answers are necessary, and this is an important
subject. The ProMax charger the reader referenced works well, and
I have no problem with it. The basic charging circuit was designed
with the electric-power enthusiast in mind.
You can charge one to eight (Ni-Cd or NiMH) cells at selectable
charge currents ranging from 0.5 to 6.0 amps. It is essentially a fast
charger with peak-detect cutoff. There is also a “Slow Peak Mode”
that applies a fixed 0.2-amp (200 mA) charge current to the smaller
battery packs. There are no discharge testing capabilities in this
unit.
I do not recommend that you fast-charge your RC transmitter
battery. Most of these cells are rated at 500-600 mAh. If you apply
a 3C charge current (600 x 3 = 1,800, or 1.8 amps), you might blow
out the internal charging circuit wiring inside your transmitter.
I recommend that you charge your RC transmitter battery pack
with the system charger that the manufacturer supplied. That will
always be at the overnight rate (or for at least 10-12 hours). You
can do this every other day and never overcharge the battery at that
rate.
For the most part I also favor charging the RC airborne
receiver/servo battery pack with the system manufacturer’s charger
at the same overnight rate. Unless you want to fly for more than
two hours at a particular flying session, there is no need to fastcharge
these batteries. Most RC-system batteries were never
intended for fast charging in the first place. So I recommend that
you save your ProMax charger for your electric-power battery
packs. It will do a fine job.
In the next part of his question, the reader indicated that my
article stated that a battery needs replacing when it falls to 20% of
its originally rated capacity. He then wondered if he could interpret
data from the ProMax charger that would allow him to derive
battery capacity.
Here we go again with the fine print! In that article I wrote that I
discard battery packs when they drop 20% from their original
capacity rating. As an example I wrote that a 600 mAh pack should
be discarded when the capacity reaches 480 mAh (600 less 20%). I
referred to when it goes down 20%—not when it goes down to
20%.
The peak voltage and time showing up on the ProMax display
will not directly tell you anything about the battery’s capacity. To
find that out, you need a simple battery discharge tester. This
device applies a load to the battery, usually taking the voltage down
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]
The new Sirius Electronics SuperTest PRO precision battery
tester will sell for $99.95 plus shipping and handling.
To dispense cyanoacrylate, squeeze on the CA SUCK-ER body. It
is much easier than trying to pour glue from the bottle.
This is how to suck cyaonacrylate from bottle into Syrette.
07sig3.QXD 4/23/04 1:05 pm Page 85
86 MODEL AVIATION
Close up of elevator dual rate (on/off) switch on Hitec Eclipse 7
transmitter. Bob points to elevator switch. Rudder dual rate
(on/off) switch is at right.
CH 2 or elevator dual rate has been selected and elevator
control-surface throw has been reduced to 80% of normal.
Expo rate function called up on Eclipse LCD screen. CH 2 or
elevator function and 30% nonlinearity have been selected. This
is moderate expo rate control.
Chart copied from Eclipse instruction manual explains the
difference between linear- and nonlinear-type control.
to 1 volt per cell. The amount of the load and the time it took to get
to the 1 volt per cell is integrated into a single capacity reading in
mAh.
I’ve included a photo of the new Sirius Electronics (a division of
Peak Electronics, Inc.) SuperTest PRO precision battery tester,
which can handle as many as 14 battery cells. You can set the
voltage cutoff point in 1-volt increments up to 14 volts. This
enables you to test Ni-Cd, NiMH, and even Li-Poly batteries. To
learn more about this battery tester, go to www.siriuselectronics.
com/supr_tst.htm.
Q26: “I’m having a tough time using my thin CA cement because
the nozzle on the top of the dispenser bottle keeps continuously
clogging. This slows down my building process. Is there any
possible solution to this problem?”
A26: Many of us have experienced the frustrations of clogged
cyanoacrylate-glue bottles. Several years ago an item was
introduced that I believe came from the surgical-supply industry. It
is a plastic Syrette that looks like a squeeze bottle reservoir with a
plastic spout or tip. The accompanying photos help explain.
You insert the tip or spout into an opened cyanoacrylate glue
bottle. You squeeze the Syrette bottle and then let go. When you do
this, a certain amount of the cyanoacrylate is sucked up into the
Syrette.
You can pull on the spout with pliers and stretch the spout tube
into a thinner diameter. When you do this, you can dispense the
cyanoacrylate onto the model structure at an extraordinarily
controlled rate.
Try to keep the Syrette supported in a vertical position when it’s
not in use. Every once in awhile the spout will get clogged. When
that happens, cut a short length off of the spout until the clogged
portion is discarded. Stretch out the spout again by pulling on it,
and you are back in business.
These Syrettes don’t last that long, so keep a dozen or so on
hand. I have been buying mine from Balsa Products
(www.balsapr.com). They call this product the “CA SUCK-ER”—
naturally!
Q27: “I hear the expressions ‘dual rate control’ and ‘expo rate
control.’ Are they the same thing? Is one form of control better than
another?”
A27: This is an excellent, often-asked question. Dual rate control
and expo rate control work differently, yet they do tend to achieve
close to the same results. With dual rate control, you have a switch
for the function; it’s usually one switch for rudder or aileron and the
other for elevator.
With the switch in the off position, you will obtain full control
throw on that particular channel. When you turn the dual rate switch
to the on position, you can reduce the amount of servo control
throw or travel to at least 50% of the full control.
Let’s say you have a fast, heavily loaded airplane. When it flies
at slower speeds for takeoffs and landings, it requires a great deal of
07sig3.QXD 4/23/04 1:05 pm Page 86
control travel. But when it gets up to a fast
flying speed, it needs far less control
throw. At the faster speeds you want less
control to maintain a smooth flight. This is
where the dual rate functions come into
play.
You make your takeoffs and landings
with the dual rate turned off. Then during
high-speed flying, you turn on the dual rate
switch, which reduces the maximum
amount of servo travel (control). The key is
that you must physically throw that switch
while in flight to obtain the reduced
control. Keep in mind that while the dual
rate switch is on, you cannot obtain full
control throw. So if you need more control
in a hurry, you must first turn off the dual
rate switch.
Exponential rate control (which is
referred to as “expo”) does not have to be
operated by a switch. (It can be, but it
doesn’t have to be!) Nor does it cut back or
reduce your maximum servo control throw.
Expo rate basically provides for a
nonlinear-type control around the neutral
transmitter control-stick position.
In normal linear control, if you move
the transmitter control stick 50% of its
normal travel, the servo it operates moves
50% of its travel; the control response is
linear.
With expo rate, as you begin to move
the transmitter control stick, the servo will
respond slowly. By the time you move the
control stick 25%, the servo it operates
may have only moved 10%. The control
response is nonlinear. As you get up to
50% stick movement, the servo may be up
to 40%. When you get to full control-stick
movement, you get full servo control.
The degree of nonlinearity can be
adjusted. You can set the expo rate for a
little nonlinearity, which may be hardly
noticeable. Or you can set the expo rate for
maximum nonlinearity, which means that
when you move the control stick, the
responding control surface hardly moves at
all initially.
Expo rate control works best on highspeed,
highly maneuverable models. An
airplane that looks “jumpy” in high-speed
flight will become smooth when a good
amount of expo rate control is added.
The two best features of expo rate
compared to dual rate control are that you
get full control throw when you need it and
you don’t have to remember to keep
throwing a switch in flight.
The relatively inexpensive computer
transmitters I wrote about in the February
2004 installment of the “From the Ground
Up” series describe these functions in
detail. Even beginners or relatively new
RC pilots can benefit from dual and expo
rate control. However, keep in mind that
you must pay slightly more for an RC
system that provides such features.
That’s it for now; please keep those letters
and E-mails coming. Receiving your input
is the only way we can continue this
column! MA
88 MODEL AVIATION
PO Box 564 • Hobart, IN 46342
(800) 348-3497
www. m i dwe s t p r oducts.com
Only $24.99 Stock #813
Three cradle positions to hold
your models
Convenient Parts Tray to hold
pieces you're removing / applying
Padded cradles to protect your
models
Adjustable upright supports
Introducing the most convenient
stand ever offered! The ONLY
stand with all these features:
PLANES
BOATS VEHICLES
ULTRA BRITE LITES
NEW
NEED
MORE
INFO?
See your hobby retailer or send a #10 S.A.S.E. to
229 E. Rollins Rd. Round Lake Beach, IL 60073
847-740-8726 Fax 847-740-8727
www.RamRCandRamTrack.com
• W h i t e L E D ’ s
•Br i g h t e r • Tougher
• 5 X B a t t e r y L i f e
Flashing Navigation, (3) Lites,
Adj. rate, to 96”, 9V.......................RAM 121 $44.95
“Strobe” Lite, Adj. rate, 9V...............RAM 122 29.95
Landing Lites, (2) w/switch, 9V.......RAM 123 29.95
Giant Scale Nav., (3) to 168”, 9V...RAM 124 39.95
Non Flash Nav., (3) to 96”, 9V.......RAM 125 34.95
Park Flyer Nav., (3) to 48”,
6 grams, 5-8 cells .........................RAM 132 24.95
Introduces NEW!
SUPER COOL Plug with
Hi Temp Insulator
In addition to . . .
● The FIREBALL R/C IDLE BAR plug
only $2.75
● Hot & Standard Non-Idle Bar plugs
still only $2.45
only $2.75
Swanson
Associates
P.O. Box 151
Wayne, NJ
07470
Since 1948
07sig3.QXD 4/23/04 1:06 pm Page 88
Edition: Model Aviation - 2004/07
Page Numbers: 85,86,88
July 2004 85
THIS IS THE third monthly column in which I try to give you the
best answers to questions you have written or E-mailed to me. I
give each question a sequential number for identification purposes.
Because publication space is limited, part of this column will
appear in print and spillover material will appear only on the AMA
Web site. Stated another way, all questions and answers will be
posted on the AMA Web site. Let’s start!
Q25: “I just acquired a Global Hobbies ProMax Activator peak
digital charger. I am just getting into electric power, but would like
to use this charger on my regular RC transmitter and receiver
batteries. It states in the instructions that you should set the charge
current to two or three times the rated capacity of the battery pack.
Is that okay?
“You also said in your ‘Battery Basics’ article (October 2003
Model Aviation) that a battery pack is bad when it is depleted to
20% of its rated capacity. How do I know when I get there? Can
you straighten me out?”
A25: Several answers are necessary, and this is an important
subject. The ProMax charger the reader referenced works well, and
I have no problem with it. The basic charging circuit was designed
with the electric-power enthusiast in mind.
You can charge one to eight (Ni-Cd or NiMH) cells at selectable
charge currents ranging from 0.5 to 6.0 amps. It is essentially a fast
charger with peak-detect cutoff. There is also a “Slow Peak Mode”
that applies a fixed 0.2-amp (200 mA) charge current to the smaller
battery packs. There are no discharge testing capabilities in this
unit.
I do not recommend that you fast-charge your RC transmitter
battery. Most of these cells are rated at 500-600 mAh. If you apply
a 3C charge current (600 x 3 = 1,800, or 1.8 amps), you might blow
out the internal charging circuit wiring inside your transmitter.
I recommend that you charge your RC transmitter battery pack
with the system charger that the manufacturer supplied. That will
always be at the overnight rate (or for at least 10-12 hours). You
can do this every other day and never overcharge the battery at that
rate.
For the most part I also favor charging the RC airborne
receiver/servo battery pack with the system manufacturer’s charger
at the same overnight rate. Unless you want to fly for more than
two hours at a particular flying session, there is no need to fastcharge
these batteries. Most RC-system batteries were never
intended for fast charging in the first place. So I recommend that
you save your ProMax charger for your electric-power battery
packs. It will do a fine job.
In the next part of his question, the reader indicated that my
article stated that a battery needs replacing when it falls to 20% of
its originally rated capacity. He then wondered if he could interpret
data from the ProMax charger that would allow him to derive
battery capacity.
Here we go again with the fine print! In that article I wrote that I
discard battery packs when they drop 20% from their original
capacity rating. As an example I wrote that a 600 mAh pack should
be discarded when the capacity reaches 480 mAh (600 less 20%). I
referred to when it goes down 20%—not when it goes down to
20%.
The peak voltage and time showing up on the ProMax display
will not directly tell you anything about the battery’s capacity. To
find that out, you need a simple battery discharge tester. This
device applies a load to the battery, usually taking the voltage down
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]
The new Sirius Electronics SuperTest PRO precision battery
tester will sell for $99.95 plus shipping and handling.
To dispense cyanoacrylate, squeeze on the CA SUCK-ER body. It
is much easier than trying to pour glue from the bottle.
This is how to suck cyaonacrylate from bottle into Syrette.
07sig3.QXD 4/23/04 1:05 pm Page 85
86 MODEL AVIATION
Close up of elevator dual rate (on/off) switch on Hitec Eclipse 7
transmitter. Bob points to elevator switch. Rudder dual rate
(on/off) switch is at right.
CH 2 or elevator dual rate has been selected and elevator
control-surface throw has been reduced to 80% of normal.
Expo rate function called up on Eclipse LCD screen. CH 2 or
elevator function and 30% nonlinearity have been selected. This
is moderate expo rate control.
Chart copied from Eclipse instruction manual explains the
difference between linear- and nonlinear-type control.
to 1 volt per cell. The amount of the load and the time it took to get
to the 1 volt per cell is integrated into a single capacity reading in
mAh.
I’ve included a photo of the new Sirius Electronics (a division of
Peak Electronics, Inc.) SuperTest PRO precision battery tester,
which can handle as many as 14 battery cells. You can set the
voltage cutoff point in 1-volt increments up to 14 volts. This
enables you to test Ni-Cd, NiMH, and even Li-Poly batteries. To
learn more about this battery tester, go to www.siriuselectronics.
com/supr_tst.htm.
Q26: “I’m having a tough time using my thin CA cement because
the nozzle on the top of the dispenser bottle keeps continuously
clogging. This slows down my building process. Is there any
possible solution to this problem?”
A26: Many of us have experienced the frustrations of clogged
cyanoacrylate-glue bottles. Several years ago an item was
introduced that I believe came from the surgical-supply industry. It
is a plastic Syrette that looks like a squeeze bottle reservoir with a
plastic spout or tip. The accompanying photos help explain.
You insert the tip or spout into an opened cyanoacrylate glue
bottle. You squeeze the Syrette bottle and then let go. When you do
this, a certain amount of the cyanoacrylate is sucked up into the
Syrette.
You can pull on the spout with pliers and stretch the spout tube
into a thinner diameter. When you do this, you can dispense the
cyanoacrylate onto the model structure at an extraordinarily
controlled rate.
Try to keep the Syrette supported in a vertical position when it’s
not in use. Every once in awhile the spout will get clogged. When
that happens, cut a short length off of the spout until the clogged
portion is discarded. Stretch out the spout again by pulling on it,
and you are back in business.
These Syrettes don’t last that long, so keep a dozen or so on
hand. I have been buying mine from Balsa Products
(www.balsapr.com). They call this product the “CA SUCK-ER”—
naturally!
Q27: “I hear the expressions ‘dual rate control’ and ‘expo rate
control.’ Are they the same thing? Is one form of control better than
another?”
A27: This is an excellent, often-asked question. Dual rate control
and expo rate control work differently, yet they do tend to achieve
close to the same results. With dual rate control, you have a switch
for the function; it’s usually one switch for rudder or aileron and the
other for elevator.
With the switch in the off position, you will obtain full control
throw on that particular channel. When you turn the dual rate switch
to the on position, you can reduce the amount of servo control
throw or travel to at least 50% of the full control.
Let’s say you have a fast, heavily loaded airplane. When it flies
at slower speeds for takeoffs and landings, it requires a great deal of
07sig3.QXD 4/23/04 1:05 pm Page 86
control travel. But when it gets up to a fast
flying speed, it needs far less control
throw. At the faster speeds you want less
control to maintain a smooth flight. This is
where the dual rate functions come into
play.
You make your takeoffs and landings
with the dual rate turned off. Then during
high-speed flying, you turn on the dual rate
switch, which reduces the maximum
amount of servo travel (control). The key is
that you must physically throw that switch
while in flight to obtain the reduced
control. Keep in mind that while the dual
rate switch is on, you cannot obtain full
control throw. So if you need more control
in a hurry, you must first turn off the dual
rate switch.
Exponential rate control (which is
referred to as “expo”) does not have to be
operated by a switch. (It can be, but it
doesn’t have to be!) Nor does it cut back or
reduce your maximum servo control throw.
Expo rate basically provides for a
nonlinear-type control around the neutral
transmitter control-stick position.
In normal linear control, if you move
the transmitter control stick 50% of its
normal travel, the servo it operates moves
50% of its travel; the control response is
linear.
With expo rate, as you begin to move
the transmitter control stick, the servo will
respond slowly. By the time you move the
control stick 25%, the servo it operates
may have only moved 10%. The control
response is nonlinear. As you get up to
50% stick movement, the servo may be up
to 40%. When you get to full control-stick
movement, you get full servo control.
The degree of nonlinearity can be
adjusted. You can set the expo rate for a
little nonlinearity, which may be hardly
noticeable. Or you can set the expo rate for
maximum nonlinearity, which means that
when you move the control stick, the
responding control surface hardly moves at
all initially.
Expo rate control works best on highspeed,
highly maneuverable models. An
airplane that looks “jumpy” in high-speed
flight will become smooth when a good
amount of expo rate control is added.
The two best features of expo rate
compared to dual rate control are that you
get full control throw when you need it and
you don’t have to remember to keep
throwing a switch in flight.
The relatively inexpensive computer
transmitters I wrote about in the February
2004 installment of the “From the Ground
Up” series describe these functions in
detail. Even beginners or relatively new
RC pilots can benefit from dual and expo
rate control. However, keep in mind that
you must pay slightly more for an RC
system that provides such features.
That’s it for now; please keep those letters
and E-mails coming. Receiving your input
is the only way we can continue this
column! MA
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07sig3.QXD 4/23/04 1:06 pm Page 88