PLEASE WRITE IN with your questions, since that is the only way
we can keep this column format going. When referring to published
Qs and As (for follow-ups), provide the number as a reference.
References to addresses and Web sites are now placed in a group,
separate from the text, at the end of this column under “Sources.”
Q418: “I happen to like the popular Deans Ultra connectors but have
a hard time separating the two mating halves because the fit is so
tight. I’ve seen a suggestion that employs nylon-fishing line that helps
you pull the two halves apart. I’ve also seen your March 2009 FAQ
column (page 83) where you referenced the Duralite Flight Systems
Ultra connectors with added grips.
“However, that requires that you connect the pigtail leads into
your aircraft wiring. So I’m still looking for something simple, yet
effective. Do you have any more suggestions?”
A418: A reader, Cal Malinka, mentioned an idea he saw awhile back
in one of the hobby magazines. I’m sorry I don’t have a specific
reference.
Cal sent me
photos of the idea,
but they were of low
resolution. So I
decided to make
mating halves of
Deans Ultra
connectors and
follow the idea as he
described to me.
The first part of
the idea involves
squaring the end of
an ordinary
clothespin. Then
make two holes with
a No. 55 drill on
both sides of the
clothespin, as shown
in a photo.
Insert a length of
.047-inch-diameter wire into each of the holes so that roughly 3/16 inch
of each wire is left exposed. Put a bit of CA cement on the pins, but
be careful not to cement the clothespin halves together.
Plug the connectors together. Mark where two holes are drilled.
One hole will go into each connector half. Mark the hole spacing so
that it matches the space of the two wires on the clothespin.
Make sure you drill the two holes so that it passes between the two
connector pins but does not touch either pin. Make the connector
holes with a No. 53 drill, which will accept the .047-inch-diameter
wire pins.
To separate the Ultra connector halves, insert the two wires of the
clothespin into the two holes drilled into the connector. Squeeze the
clothespin end, which will spread the wire pins and force the
connector halves apart. The photos should provide all the details you
need.
The nice part of this idea is that you don’t need to get both hands
into your fuselage to pull the connectors apart. Just one hand on the
clothespin does the full job.
For drill bits, I used a set purchased from X-Acto (catalog item
6410) that includes an assortment of 12 bits ranging from No. 45 to
No. 60. I find more uses for these twist drills than you could imagine.
I like this idea and think it will catch on quickly. Many Li-Poly
battery packs are now being supplied with this type of connector. The
Separating Deans Ultra connectors
? Frequently Asked Questions Bob Aberle | [email protected]
October 2009 81
The pins at the end of the clothespin
have been inserted into the two
holes drilled into the Deans Ultra
connector halves.
Squeezing the end of the clothespin opens the other end,
resulting in the connector halves being easily separated.
Also included in this column:
• Harbor Freight drill press
• Swiffer Dusters
• Food-wrap box ends
• RC receivers’ low-voltage
problem
The ends of a clothespin have
been squared and No. 55
holes drilled for the .047 wire
pins. No. 53 holes are
drilled into both
connector halves.
10sig3.QXD 8/21/09 12:16 PM Page 81
Since I’m on the
topic of household
products that can
help our hobby, I’ll
mention something I
saw on a recent local
TV program. We
modelers use several
types of “wrap”
material to aid us in
our hobby, such as
waxed and
parchment paper to
prevent wood
structures from
sticking to plans. We
also use plastic wrap
in clear and colors to
cover micro and indoor models.
All of this paper and plastic is contained on
rolls that rest inside boxes. You open the box,
pull out the amount of material you need, and
tear it off using a cutting edge on the end of the
box.
Have you ever had the entire roll of material
fall out of the box while you were trying to pull
out a short length? It’s annoying, right? Look at
the end of the box. Many manufacturers now
place tabs at each end that you press in. By
doing that, the roll inside is “captured.” As a
result, it will not pull out with the material.
You probably think I’m crazy, but look at a
few of these boxes and see if they have these
tabs. The photos should help identify what I’m
talking about.
Q420: “I noted in a recent review of a spread
spectrum RC system (Model Aviation March
2009, page 66) that the photo caption at the
bottom right corner of the page said the
following: Use 6-volt batteries for any 2.4 GHz
system.
82 MODEL AVIATION
Above: Casey Brandsema holds the Swiffer Duster that cleans his models
with no solvents. It works well for electric aircraft and sailplanes, on which
fuel residue is absent.
Left: Bob bought this 8-inch drill press from Harbor Freight at a sale price of
roughly $50. It features a keyless chuck and a light that illuminates the work area.
Many paper and plastic-wrap boxes have
push tabs on each end that lock the roll
inside. When the paper or foil is pulled
out, the roll won’t pop out.
other nice part about using the Ultra is that it
can easily be soldered, and no special
crimping tool is necessary.
I recently visited the large Harbor Freight
warehouse, which is right off of I-95 in the
town of Dillon, South Carolina. I had wanted
a drill press for a long time and found one in
the store for slightly more than $50. It is
shown in the included photo.
Is it a heavy-duty machine? Probably not,
but it will last a long time for our modeling
needs. I mention this drill press because I
used it to manufacture the holes in my Ultra
connectors. It made the job easy.
I also saw some inexpensive modelertype
rotary tools and accessory kits at Harbor
Freight. I recommend that you get a catalog
or go to the company’s Web site.
Q419: “I’ve heard of many suggestions for
getting fuel residue off my model aircraft.
Usually it involves a solvent, like Windex
and paper towels. But my electric powered
aircraft and my sailplanes just get dirty; they
don’t really need a solvent. Can you
recommend something like a household
duster?”
A419: I think I have what you need. I
watched a fellow SEFLI (Silent Electric
Flyers of Long Island) club member, Casey
Brandsema, use a popular household product
known as Swiffer Dusters. They are made
from disposable fibers that attach to a handle.
The soft material attracts dust and dirt
quickly and easily.
Because Swiffer Dusters are so soft, there
is little chance of scratching your aircraft.
They also let you get into many tight places.
You can use these same dusters to help keep
your RC transmitters and even keyboards on
your PC and laptop clean.
A closer look at the Swiffer
Duster and the supporting handle.
Refill boxes are available. The
Duster also works well
on RC transmitters.
10sig3.QXD 8/21/09 12:19 PM Page 82
I’ve seen this kicked around recently on some
of the model nets and forums and I truly
believe the problem, if there is one, is
possibly being misunderstood.”
A420: I’ve seen the references to this 2.4
GHz spread spectrum “battery problem” on
several forums and agree with you that it
might be more of a misunderstanding. As you
will read in the following, there might still be
a problem—but for other reasons, not related
to only 2.4 GHz spread spectrum radio
systems.
The 6-volt battery refers to the receiver
power source. It has nothing to do with the
transmitter. The problem noted is that a 2.4
GHz spread spectrum receiver might quit
unexpectedly in flight because of a low-
84 MODEL AVIATION
voltage situation. As stated, this situation
supposedly affects all 2.4 GHz receivers on
the market.
If you are flying with electric power,
most modern ESCs have built-in circuitry
that will cut off the motor when a preset
low-voltage level is reached. This feature is
important when using Li-Poly batteries,
since they should not be discharged below
3.0 volts per cell.
At that cutoff point, there is still plenty
of power remaining to supply 5.0 volts
(through a regulator) to operate your RC
system and safely land your aircraft. This is
true when your ESC has a BEC.
If you fall into this popular model-power
category, you should have no receiverpower
problem, regardless of whether you
operate on 72 MHz, 6 meters, or 2.4 GHz
spread spectrum. It makes no difference.
However, many who fly with fueled
power and even some who use electric
power with higher-powered systems might
use a separate receiver battery pack. It is
these situations that might prompt a
problem, but it might not be your receiver.
The problem is more likely battery
management.
When using a separate four- or five-cell
(4.8- to 6-volt) battery to power the receiver
and servos, many times there is no lowvoltage
warning.
(Editor’s note: When a battery can’t
deliver the minimum voltage requirement,
the modern 2.4 GHz receiver follows its
safety protocols and engages a
programmed hold position. [Read the
manual for more details and how to set this
condition to suit.]
Some spread spectrum systems recover
more quickly than others if the voltage
bounces back, but to the RC pilot it feels
like a loss of control, which it certainly is,
and it’s easy for us to blame the radio. The
recommendation to use a higher-voltage
battery pack is to reduce the chance that a
receiver might see a low-voltage level
cutoff—typically 3.7 volts.
This lesson goes back to why it’s so
important to not only select a quality
battery pack, but also to select the right
capacity. A four-cell pack will work
perfectly in a spread spectrum radio
system, as long as the correct size is
chosen to handle the load at hand. And to
play it safe, maybe it would be better to use
a 1000 mAh battery in that sport model
instead of the standard 600 mAh.)
Another thing is that it would be nice to
have a safety device onboard that sensed a
preset low voltage and then cycled the
throttle servo to the idle position. But I’m
not aware of any such piece of equipment.
A smart and enterprising manufacturer
might want to look into developing such a
device.
Many modelers neglect to check their
receiver-battery capacity before each flight.
They assume that they can make five, six,
eight, or more flights and that there will
always be enough voltage to get the job
done. Well, my friends, batteries don’t last
forever. They lose capacity with age. And
in some cases, a battery pack might be
charged improperly or not charged at all (if
you forgot).
The only way to preclude a receiver
low-voltage situation is to use a plug-in
voltmeter and, most important, that
voltmeter must have a load (such as 300-
500 mA). A good voltmeter with a load is
the Custom Electronics Loaded Digital
Voltmeter (item CEL-1530), which you can
purchase from Peak Electronics.
Other meters will do the same job. But
remember that the meter must place a load
on the battery to make a meaningful test. It
only takes five to 10 seconds before each
flight to determine that you will have a safe
one.
In this instance, I feel that the
manufacturers of 2.4 GHz receivers are
getting a “bad rap.” The low-voltage
problem could have happened with any RC
receiver. If you have doubts, contact your
RC receiver’s manufacturer and ask
specifically what the low-voltage cutoff
point specification is for its product. MA
Sources:
Harbor Freight
(800) 444-3353
www.harborfreight.com
Peak Electronics
(800) 532-0092
www.siriuselectronics.com
Edition: Model Aviation - 2009/10
Page Numbers: 81,82,84
Edition: Model Aviation - 2009/10
Page Numbers: 81,82,84
PLEASE WRITE IN with your questions, since that is the only way
we can keep this column format going. When referring to published
Qs and As (for follow-ups), provide the number as a reference.
References to addresses and Web sites are now placed in a group,
separate from the text, at the end of this column under “Sources.”
Q418: “I happen to like the popular Deans Ultra connectors but have
a hard time separating the two mating halves because the fit is so
tight. I’ve seen a suggestion that employs nylon-fishing line that helps
you pull the two halves apart. I’ve also seen your March 2009 FAQ
column (page 83) where you referenced the Duralite Flight Systems
Ultra connectors with added grips.
“However, that requires that you connect the pigtail leads into
your aircraft wiring. So I’m still looking for something simple, yet
effective. Do you have any more suggestions?”
A418: A reader, Cal Malinka, mentioned an idea he saw awhile back
in one of the hobby magazines. I’m sorry I don’t have a specific
reference.
Cal sent me
photos of the idea,
but they were of low
resolution. So I
decided to make
mating halves of
Deans Ultra
connectors and
follow the idea as he
described to me.
The first part of
the idea involves
squaring the end of
an ordinary
clothespin. Then
make two holes with
a No. 55 drill on
both sides of the
clothespin, as shown
in a photo.
Insert a length of
.047-inch-diameter wire into each of the holes so that roughly 3/16 inch
of each wire is left exposed. Put a bit of CA cement on the pins, but
be careful not to cement the clothespin halves together.
Plug the connectors together. Mark where two holes are drilled.
One hole will go into each connector half. Mark the hole spacing so
that it matches the space of the two wires on the clothespin.
Make sure you drill the two holes so that it passes between the two
connector pins but does not touch either pin. Make the connector
holes with a No. 53 drill, which will accept the .047-inch-diameter
wire pins.
To separate the Ultra connector halves, insert the two wires of the
clothespin into the two holes drilled into the connector. Squeeze the
clothespin end, which will spread the wire pins and force the
connector halves apart. The photos should provide all the details you
need.
The nice part of this idea is that you don’t need to get both hands
into your fuselage to pull the connectors apart. Just one hand on the
clothespin does the full job.
For drill bits, I used a set purchased from X-Acto (catalog item
6410) that includes an assortment of 12 bits ranging from No. 45 to
No. 60. I find more uses for these twist drills than you could imagine.
I like this idea and think it will catch on quickly. Many Li-Poly
battery packs are now being supplied with this type of connector. The
Separating Deans Ultra connectors
? Frequently Asked Questions Bob Aberle | [email protected]
October 2009 81
The pins at the end of the clothespin
have been inserted into the two
holes drilled into the Deans Ultra
connector halves.
Squeezing the end of the clothespin opens the other end,
resulting in the connector halves being easily separated.
Also included in this column:
• Harbor Freight drill press
• Swiffer Dusters
• Food-wrap box ends
• RC receivers’ low-voltage
problem
The ends of a clothespin have
been squared and No. 55
holes drilled for the .047 wire
pins. No. 53 holes are
drilled into both
connector halves.
10sig3.QXD 8/21/09 12:16 PM Page 81
Since I’m on the
topic of household
products that can
help our hobby, I’ll
mention something I
saw on a recent local
TV program. We
modelers use several
types of “wrap”
material to aid us in
our hobby, such as
waxed and
parchment paper to
prevent wood
structures from
sticking to plans. We
also use plastic wrap
in clear and colors to
cover micro and indoor models.
All of this paper and plastic is contained on
rolls that rest inside boxes. You open the box,
pull out the amount of material you need, and
tear it off using a cutting edge on the end of the
box.
Have you ever had the entire roll of material
fall out of the box while you were trying to pull
out a short length? It’s annoying, right? Look at
the end of the box. Many manufacturers now
place tabs at each end that you press in. By
doing that, the roll inside is “captured.” As a
result, it will not pull out with the material.
You probably think I’m crazy, but look at a
few of these boxes and see if they have these
tabs. The photos should help identify what I’m
talking about.
Q420: “I noted in a recent review of a spread
spectrum RC system (Model Aviation March
2009, page 66) that the photo caption at the
bottom right corner of the page said the
following: Use 6-volt batteries for any 2.4 GHz
system.
82 MODEL AVIATION
Above: Casey Brandsema holds the Swiffer Duster that cleans his models
with no solvents. It works well for electric aircraft and sailplanes, on which
fuel residue is absent.
Left: Bob bought this 8-inch drill press from Harbor Freight at a sale price of
roughly $50. It features a keyless chuck and a light that illuminates the work area.
Many paper and plastic-wrap boxes have
push tabs on each end that lock the roll
inside. When the paper or foil is pulled
out, the roll won’t pop out.
other nice part about using the Ultra is that it
can easily be soldered, and no special
crimping tool is necessary.
I recently visited the large Harbor Freight
warehouse, which is right off of I-95 in the
town of Dillon, South Carolina. I had wanted
a drill press for a long time and found one in
the store for slightly more than $50. It is
shown in the included photo.
Is it a heavy-duty machine? Probably not,
but it will last a long time for our modeling
needs. I mention this drill press because I
used it to manufacture the holes in my Ultra
connectors. It made the job easy.
I also saw some inexpensive modelertype
rotary tools and accessory kits at Harbor
Freight. I recommend that you get a catalog
or go to the company’s Web site.
Q419: “I’ve heard of many suggestions for
getting fuel residue off my model aircraft.
Usually it involves a solvent, like Windex
and paper towels. But my electric powered
aircraft and my sailplanes just get dirty; they
don’t really need a solvent. Can you
recommend something like a household
duster?”
A419: I think I have what you need. I
watched a fellow SEFLI (Silent Electric
Flyers of Long Island) club member, Casey
Brandsema, use a popular household product
known as Swiffer Dusters. They are made
from disposable fibers that attach to a handle.
The soft material attracts dust and dirt
quickly and easily.
Because Swiffer Dusters are so soft, there
is little chance of scratching your aircraft.
They also let you get into many tight places.
You can use these same dusters to help keep
your RC transmitters and even keyboards on
your PC and laptop clean.
A closer look at the Swiffer
Duster and the supporting handle.
Refill boxes are available. The
Duster also works well
on RC transmitters.
10sig3.QXD 8/21/09 12:19 PM Page 82
I’ve seen this kicked around recently on some
of the model nets and forums and I truly
believe the problem, if there is one, is
possibly being misunderstood.”
A420: I’ve seen the references to this 2.4
GHz spread spectrum “battery problem” on
several forums and agree with you that it
might be more of a misunderstanding. As you
will read in the following, there might still be
a problem—but for other reasons, not related
to only 2.4 GHz spread spectrum radio
systems.
The 6-volt battery refers to the receiver
power source. It has nothing to do with the
transmitter. The problem noted is that a 2.4
GHz spread spectrum receiver might quit
unexpectedly in flight because of a low-
84 MODEL AVIATION
voltage situation. As stated, this situation
supposedly affects all 2.4 GHz receivers on
the market.
If you are flying with electric power,
most modern ESCs have built-in circuitry
that will cut off the motor when a preset
low-voltage level is reached. This feature is
important when using Li-Poly batteries,
since they should not be discharged below
3.0 volts per cell.
At that cutoff point, there is still plenty
of power remaining to supply 5.0 volts
(through a regulator) to operate your RC
system and safely land your aircraft. This is
true when your ESC has a BEC.
If you fall into this popular model-power
category, you should have no receiverpower
problem, regardless of whether you
operate on 72 MHz, 6 meters, or 2.4 GHz
spread spectrum. It makes no difference.
However, many who fly with fueled
power and even some who use electric
power with higher-powered systems might
use a separate receiver battery pack. It is
these situations that might prompt a
problem, but it might not be your receiver.
The problem is more likely battery
management.
When using a separate four- or five-cell
(4.8- to 6-volt) battery to power the receiver
and servos, many times there is no lowvoltage
warning.
(Editor’s note: When a battery can’t
deliver the minimum voltage requirement,
the modern 2.4 GHz receiver follows its
safety protocols and engages a
programmed hold position. [Read the
manual for more details and how to set this
condition to suit.]
Some spread spectrum systems recover
more quickly than others if the voltage
bounces back, but to the RC pilot it feels
like a loss of control, which it certainly is,
and it’s easy for us to blame the radio. The
recommendation to use a higher-voltage
battery pack is to reduce the chance that a
receiver might see a low-voltage level
cutoff—typically 3.7 volts.
This lesson goes back to why it’s so
important to not only select a quality
battery pack, but also to select the right
capacity. A four-cell pack will work
perfectly in a spread spectrum radio
system, as long as the correct size is
chosen to handle the load at hand. And to
play it safe, maybe it would be better to use
a 1000 mAh battery in that sport model
instead of the standard 600 mAh.)
Another thing is that it would be nice to
have a safety device onboard that sensed a
preset low voltage and then cycled the
throttle servo to the idle position. But I’m
not aware of any such piece of equipment.
A smart and enterprising manufacturer
might want to look into developing such a
device.
Many modelers neglect to check their
receiver-battery capacity before each flight.
They assume that they can make five, six,
eight, or more flights and that there will
always be enough voltage to get the job
done. Well, my friends, batteries don’t last
forever. They lose capacity with age. And
in some cases, a battery pack might be
charged improperly or not charged at all (if
you forgot).
The only way to preclude a receiver
low-voltage situation is to use a plug-in
voltmeter and, most important, that
voltmeter must have a load (such as 300-
500 mA). A good voltmeter with a load is
the Custom Electronics Loaded Digital
Voltmeter (item CEL-1530), which you can
purchase from Peak Electronics.
Other meters will do the same job. But
remember that the meter must place a load
on the battery to make a meaningful test. It
only takes five to 10 seconds before each
flight to determine that you will have a safe
one.
In this instance, I feel that the
manufacturers of 2.4 GHz receivers are
getting a “bad rap.” The low-voltage
problem could have happened with any RC
receiver. If you have doubts, contact your
RC receiver’s manufacturer and ask
specifically what the low-voltage cutoff
point specification is for its product. MA
Sources:
Harbor Freight
(800) 444-3353
www.harborfreight.com
Peak Electronics
(800) 532-0092
www.siriuselectronics.com
Edition: Model Aviation - 2009/10
Page Numbers: 81,82,84
PLEASE WRITE IN with your questions, since that is the only way
we can keep this column format going. When referring to published
Qs and As (for follow-ups), provide the number as a reference.
References to addresses and Web sites are now placed in a group,
separate from the text, at the end of this column under “Sources.”
Q418: “I happen to like the popular Deans Ultra connectors but have
a hard time separating the two mating halves because the fit is so
tight. I’ve seen a suggestion that employs nylon-fishing line that helps
you pull the two halves apart. I’ve also seen your March 2009 FAQ
column (page 83) where you referenced the Duralite Flight Systems
Ultra connectors with added grips.
“However, that requires that you connect the pigtail leads into
your aircraft wiring. So I’m still looking for something simple, yet
effective. Do you have any more suggestions?”
A418: A reader, Cal Malinka, mentioned an idea he saw awhile back
in one of the hobby magazines. I’m sorry I don’t have a specific
reference.
Cal sent me
photos of the idea,
but they were of low
resolution. So I
decided to make
mating halves of
Deans Ultra
connectors and
follow the idea as he
described to me.
The first part of
the idea involves
squaring the end of
an ordinary
clothespin. Then
make two holes with
a No. 55 drill on
both sides of the
clothespin, as shown
in a photo.
Insert a length of
.047-inch-diameter wire into each of the holes so that roughly 3/16 inch
of each wire is left exposed. Put a bit of CA cement on the pins, but
be careful not to cement the clothespin halves together.
Plug the connectors together. Mark where two holes are drilled.
One hole will go into each connector half. Mark the hole spacing so
that it matches the space of the two wires on the clothespin.
Make sure you drill the two holes so that it passes between the two
connector pins but does not touch either pin. Make the connector
holes with a No. 53 drill, which will accept the .047-inch-diameter
wire pins.
To separate the Ultra connector halves, insert the two wires of the
clothespin into the two holes drilled into the connector. Squeeze the
clothespin end, which will spread the wire pins and force the
connector halves apart. The photos should provide all the details you
need.
The nice part of this idea is that you don’t need to get both hands
into your fuselage to pull the connectors apart. Just one hand on the
clothespin does the full job.
For drill bits, I used a set purchased from X-Acto (catalog item
6410) that includes an assortment of 12 bits ranging from No. 45 to
No. 60. I find more uses for these twist drills than you could imagine.
I like this idea and think it will catch on quickly. Many Li-Poly
battery packs are now being supplied with this type of connector. The
Separating Deans Ultra connectors
? Frequently Asked Questions Bob Aberle | [email protected]
October 2009 81
The pins at the end of the clothespin
have been inserted into the two
holes drilled into the Deans Ultra
connector halves.
Squeezing the end of the clothespin opens the other end,
resulting in the connector halves being easily separated.
Also included in this column:
• Harbor Freight drill press
• Swiffer Dusters
• Food-wrap box ends
• RC receivers’ low-voltage
problem
The ends of a clothespin have
been squared and No. 55
holes drilled for the .047 wire
pins. No. 53 holes are
drilled into both
connector halves.
10sig3.QXD 8/21/09 12:16 PM Page 81
Since I’m on the
topic of household
products that can
help our hobby, I’ll
mention something I
saw on a recent local
TV program. We
modelers use several
types of “wrap”
material to aid us in
our hobby, such as
waxed and
parchment paper to
prevent wood
structures from
sticking to plans. We
also use plastic wrap
in clear and colors to
cover micro and indoor models.
All of this paper and plastic is contained on
rolls that rest inside boxes. You open the box,
pull out the amount of material you need, and
tear it off using a cutting edge on the end of the
box.
Have you ever had the entire roll of material
fall out of the box while you were trying to pull
out a short length? It’s annoying, right? Look at
the end of the box. Many manufacturers now
place tabs at each end that you press in. By
doing that, the roll inside is “captured.” As a
result, it will not pull out with the material.
You probably think I’m crazy, but look at a
few of these boxes and see if they have these
tabs. The photos should help identify what I’m
talking about.
Q420: “I noted in a recent review of a spread
spectrum RC system (Model Aviation March
2009, page 66) that the photo caption at the
bottom right corner of the page said the
following: Use 6-volt batteries for any 2.4 GHz
system.
82 MODEL AVIATION
Above: Casey Brandsema holds the Swiffer Duster that cleans his models
with no solvents. It works well for electric aircraft and sailplanes, on which
fuel residue is absent.
Left: Bob bought this 8-inch drill press from Harbor Freight at a sale price of
roughly $50. It features a keyless chuck and a light that illuminates the work area.
Many paper and plastic-wrap boxes have
push tabs on each end that lock the roll
inside. When the paper or foil is pulled
out, the roll won’t pop out.
other nice part about using the Ultra is that it
can easily be soldered, and no special
crimping tool is necessary.
I recently visited the large Harbor Freight
warehouse, which is right off of I-95 in the
town of Dillon, South Carolina. I had wanted
a drill press for a long time and found one in
the store for slightly more than $50. It is
shown in the included photo.
Is it a heavy-duty machine? Probably not,
but it will last a long time for our modeling
needs. I mention this drill press because I
used it to manufacture the holes in my Ultra
connectors. It made the job easy.
I also saw some inexpensive modelertype
rotary tools and accessory kits at Harbor
Freight. I recommend that you get a catalog
or go to the company’s Web site.
Q419: “I’ve heard of many suggestions for
getting fuel residue off my model aircraft.
Usually it involves a solvent, like Windex
and paper towels. But my electric powered
aircraft and my sailplanes just get dirty; they
don’t really need a solvent. Can you
recommend something like a household
duster?”
A419: I think I have what you need. I
watched a fellow SEFLI (Silent Electric
Flyers of Long Island) club member, Casey
Brandsema, use a popular household product
known as Swiffer Dusters. They are made
from disposable fibers that attach to a handle.
The soft material attracts dust and dirt
quickly and easily.
Because Swiffer Dusters are so soft, there
is little chance of scratching your aircraft.
They also let you get into many tight places.
You can use these same dusters to help keep
your RC transmitters and even keyboards on
your PC and laptop clean.
A closer look at the Swiffer
Duster and the supporting handle.
Refill boxes are available. The
Duster also works well
on RC transmitters.
10sig3.QXD 8/21/09 12:19 PM Page 82
I’ve seen this kicked around recently on some
of the model nets and forums and I truly
believe the problem, if there is one, is
possibly being misunderstood.”
A420: I’ve seen the references to this 2.4
GHz spread spectrum “battery problem” on
several forums and agree with you that it
might be more of a misunderstanding. As you
will read in the following, there might still be
a problem—but for other reasons, not related
to only 2.4 GHz spread spectrum radio
systems.
The 6-volt battery refers to the receiver
power source. It has nothing to do with the
transmitter. The problem noted is that a 2.4
GHz spread spectrum receiver might quit
unexpectedly in flight because of a low-
84 MODEL AVIATION
voltage situation. As stated, this situation
supposedly affects all 2.4 GHz receivers on
the market.
If you are flying with electric power,
most modern ESCs have built-in circuitry
that will cut off the motor when a preset
low-voltage level is reached. This feature is
important when using Li-Poly batteries,
since they should not be discharged below
3.0 volts per cell.
At that cutoff point, there is still plenty
of power remaining to supply 5.0 volts
(through a regulator) to operate your RC
system and safely land your aircraft. This is
true when your ESC has a BEC.
If you fall into this popular model-power
category, you should have no receiverpower
problem, regardless of whether you
operate on 72 MHz, 6 meters, or 2.4 GHz
spread spectrum. It makes no difference.
However, many who fly with fueled
power and even some who use electric
power with higher-powered systems might
use a separate receiver battery pack. It is
these situations that might prompt a
problem, but it might not be your receiver.
The problem is more likely battery
management.
When using a separate four- or five-cell
(4.8- to 6-volt) battery to power the receiver
and servos, many times there is no lowvoltage
warning.
(Editor’s note: When a battery can’t
deliver the minimum voltage requirement,
the modern 2.4 GHz receiver follows its
safety protocols and engages a
programmed hold position. [Read the
manual for more details and how to set this
condition to suit.]
Some spread spectrum systems recover
more quickly than others if the voltage
bounces back, but to the RC pilot it feels
like a loss of control, which it certainly is,
and it’s easy for us to blame the radio. The
recommendation to use a higher-voltage
battery pack is to reduce the chance that a
receiver might see a low-voltage level
cutoff—typically 3.7 volts.
This lesson goes back to why it’s so
important to not only select a quality
battery pack, but also to select the right
capacity. A four-cell pack will work
perfectly in a spread spectrum radio
system, as long as the correct size is
chosen to handle the load at hand. And to
play it safe, maybe it would be better to use
a 1000 mAh battery in that sport model
instead of the standard 600 mAh.)
Another thing is that it would be nice to
have a safety device onboard that sensed a
preset low voltage and then cycled the
throttle servo to the idle position. But I’m
not aware of any such piece of equipment.
A smart and enterprising manufacturer
might want to look into developing such a
device.
Many modelers neglect to check their
receiver-battery capacity before each flight.
They assume that they can make five, six,
eight, or more flights and that there will
always be enough voltage to get the job
done. Well, my friends, batteries don’t last
forever. They lose capacity with age. And
in some cases, a battery pack might be
charged improperly or not charged at all (if
you forgot).
The only way to preclude a receiver
low-voltage situation is to use a plug-in
voltmeter and, most important, that
voltmeter must have a load (such as 300-
500 mA). A good voltmeter with a load is
the Custom Electronics Loaded Digital
Voltmeter (item CEL-1530), which you can
purchase from Peak Electronics.
Other meters will do the same job. But
remember that the meter must place a load
on the battery to make a meaningful test. It
only takes five to 10 seconds before each
flight to determine that you will have a safe
one.
In this instance, I feel that the
manufacturers of 2.4 GHz receivers are
getting a “bad rap.” The low-voltage
problem could have happened with any RC
receiver. If you have doubts, contact your
RC receiver’s manufacturer and ask
specifically what the low-voltage cutoff
point specification is for its product. MA
Sources:
Harbor Freight
(800) 444-3353
www.harborfreight.com
Peak Electronics
(800) 532-0092
www.siriuselectronics.com