130 MODEL AVIATION
THIS COLUMN WILL review an oversight in the July column,
detail some experiences with a Sig Rascal ARF, and describe an
unlikely and confusing potential source of glitching.
Late News: The 2nd Annual Best Electrics in South Texas meet is
scheduled for October 8-10 in New Waverly, Texas. Check out
www.tri-countybarnstormers.com, E-mail [email protected],
or call Scott Mrosko at (936) 539-5123 or New Creations R/C at (936)
856-4630.
The July column included a photo and a brief description of Eric
Einarsson’s version of the Universal Slow Charger (USC). A reader
favorite in the last couple of years, the USC was published as a feature
article in the September 2000 MA.
As often happens, this July revisit reminded some of—and
introduced others to—that article. This resulted in fresh reader mail on
the subject—something I welcome. Unfortunately, however, this topic
was also an unintentional “disservice by omission,” as follows.
First, I failed to mention that you can get copies of the original
article from AMA Librarian Rich LaGrange at (765) 287-1256,
extension 506. Ask for a copy of “Universal Slow Charger” on pages
37-46 of the September 2000 issue. You also need to get copies of
correction information from the October 2000 issue (page 60) and the
November 2000 issue (page 7). I am unable to supply these copies.
Second, the original article included a detailed parts list describing
all of the components and the suppliers for them. Another part of the
July disservice was failing to mention that one of the key suppliers had
discontinued doing business approximately two years ago. But not to
worry!
In October 2002 I developed a multipage “USC Update,”
addressing the latter problem. It remains available, and you can get one
by sending me an SASE. To the best of my knowledge, this update
covers all necessary information, in conjunction with the preceding
references, to allow you to build a USC, as many others have done.
Do remember my offer of assistance for anyone who experiences
problems with this or any of my other published projects. You can
undertake any of them with the confidence that I won’t let you fail,
provided you give me the opportunity to help.
So dig out your old issues of MA or purchase article copies from
AMA, send me an SASE for the USC Update, and get going!
My friend Paul, a full-scale pilot of many decades, frequently hangs
with some local E-aeromodelers and has enjoyed some occasional
stick time throughout the years—always doing rather well. He seemed
to enjoy the experience.
Earlier this season I ventured that he might like his own RC
Electric. He liked the idea but did not want to build and was otherwise
“cold” in the general area of outfitting an E-RC. I offered to assist.
I set about seeking an appropriate ARF for the ability I’d seen him
demonstrate, and after conversing with two others in the area who own
them, I selected the Sig Rascal as a candidate. I showed Paul a picture
and he went for it. Then I pegged the all-up material cost at roughly
$500 with free labor, and that was okay too. I started working on
getting all the stuff to get Paul up in the electric air.
The Rascal ARF went together nicely and quickly, with excellent
parts fit everywhere. All assembly tasks were well described in the
accompanying booklet except for some omissions; they were
apparently the result of recent improvements in the ARF kit makeup
without the manual being updated accordingly.
These issues—such as a change in the nature of the pushrods and
horns—would be no problem for an experienced aeromodeler, but they
Bob Kopski, 25 West End Dr., Lansdale PA 19446
RADIO CONTROL ELECTRICS
A happy Paul with his new Rascal and friends Carole and Spike.
Backdrop is private, limited E-power flying site.
Split pushrods and clamping wheel collars permit secure
adjustment. Plastic horns shown are change to Rascal kit.
Shown is M5 receiver/servo installation. Notice inner holes in
servo arms to permit “beginner” surface movements.
10sig5.QXD 7/23/04 9:19 am Page 130
October 2004 131
might be “showstoppers” for a first-timer. Sig
would do well to include a supplemental or
update sheet along with the Rascal’s manual.
Photos show some modifications I
incorporated, one of which was simply
substituting two flat plastic landing-gear clamp
straps for the sheet-metal screws that hold the
bottom fuselage battery hatch.
These “catches” swing out of the way to
allow easy access to the battery; screws would
surely get dropped and lost along the way. The
clamps are easy to install. Glue a piece of 1⁄8
balsa inside the fuselage bottom for the pivot
screws to bite into. Use the original #2 SM
screws for this.
I also modified the kit change in the
pushrods. The newly supplied 40-mil-diameter
solid wires seemed a bit sluggish in the already
installed guide tubes. The surface of these
wires was ripply to the touch, which might
have been the reason for the apparent drag. I
substituted some K&S .032-inch pieces, which
felt much better sliding in the guide tubes.
In addition, I employed my own form of
pushrod adjustment, which is shown in a
photo. I connected both rods via Z bends to the
servo arms and short “stub rods” to both horns
with Z bends. Dual 1⁄16-inch wheel collars
clamp the overlapping ends of the rod sets,
permitting postinstallation adjustability with a
secure clamping thereafter. Also note the extra
holes in the servo arms, to get the controlsurface
movements more in-line with the
manual’s recommendations.
Another photo shows some personalization
in the motor area. I installed a 10-amp ATM
(automotive) fuse in one ESC-to-motor wire in
reaction to a normal safety hang-up I have. I
used Mouser ([800] 346-6873 or www.mou
ser.com) fuse connectors (catalog number 534-
3544), and then I used heat-shrink tubing to
complete the job. (See the April 2003 column
for detailed instructions with photos.)
Last, I covered the otherwise exposed
motor gear set with 3⁄4-inch-wide plastic tape
to pre-empt dust and dirt from finding a
home in the machinery. First I put a bit of
White Lithium Grease (available from any
auto-parts store) on the gears—standard
practice in my geared systems.
Plastic landing-gear clamps swing out of the way for battery
access; swapping packs is now extraordinarily easy.
Easy-to-incorporate 10-amp ATM fuse and plastic-tape gearbox
covering make Rascal installation safer and less trouble.
I used Hitec HS-55 servos per the
manual’s suggestion, an FMA Direct M5
receiver, a GWS Dream Starter II transmitter,
a programmable Castle Creations Pixie-20P
(my Speed 400-application favorite) that I
substituted for the kit ESC, two seven-cell
500AR Ni-Cd packs, Deans four-pin
connectors, a GWS MC-2002DC charger
with the necessary matching connector, and
an APC 9 X 6E propeller following some
current-drain measurements. Knowing the
local terrain, I omitted the otherwise
attractive wheel pants. The Rascal was ready
to go!
The model flew well right off, and Paul
now has numerous assisted flights to his
credit. The Rascal flies nicely with
moderate power, and, as such, is easy for
fliers with limited experience, including in
low-wind conditions. In fact, a slight
headwind is a big assist in rising off ground
from a smooth surface.
The only trim tweak I made was to add
roughly 2° of downthrust (a 1⁄32-inch shim
under the front motor clamp screw locations),
which eliminated some power-on porpoising
tendency.
In retrospect, a personal wish for the
Rascal design is that the wing be rubberbanded
in place for beginning pilots.
Although it’s not as attractive as the bolt-on
method, rubbered wing attachment is far
more forgiving at the time of greatest need:
while learning to fly!
The overall materials tally—for all new
stuff from scratch—came to $498.49. I’m a
firm believer in not minimizing the cost to an
inquiring newbie, but to tell it like it is.
This Rascal project brought with it an eyeopening
experience on the bench. Even
though the final installation includes BEC
power for the receiver/servos, I often use a
separate “bench” four-Ni-Cd pack to power
10sig5.QXD 7/23/04 9:20 am Page 131
132 MODEL AVIATION
OVER A DOZEN MODELS OF WWI, WWII, AND CLASSIC CIVILIAN
AIRCRAFT AVAILABLE WITH MORE VERSIONS TO FOLLOW!
• Electric motor(s) with prop and gear reduction included.
• Highly prefabricated for very short building times.
• 3-4 functions: rudder, aileron & elevator (rudder & ailerons on
one servo, or on separate servos.)
• Laser-cut wood parts for an accurate fit.
• Propeller and spinner included.
• Landing gear and wheels included.
(some kits have removable gear for grass field flying.)
• Contact your local hobby shop, or order direct at: www.djaerotech.com
Ryan ST / PT-16
Wingspan: 28.1 in. • Length: 20.2 in.
Weight: 4.5-5.5 oz. (ready to fly)
Wing Loading: 5.5-6.7 oz/sq. ft.
We
carry
E-tec Li-Poly
batteries &
chargers
Single motor WWII kits ....$48.95
Lockheed P-38...............$56.95
Curtiss Jenny .................$64.95
Sopwith Camel...............$72.95
Fokker Triplane ..............$73.95
DC-3 ............................$66.95
Lockheed Electra............$68.95
Piper J-3 Cub.................$51.95
Curtiss-Wright Junior.......$51.95
Ryan ST / PT-16.............$59.95
B-17F .........................$124.95
(Shipping & Handling extra)
Prices subject to
change without notice.
the receiver/servos during installation setup.
Thus I can check out receiver, servo, and
pushrod operation without having the ESC
and motor battery in place. I did so during
this project, and in the process I experienced
something new.
Before the on-order M5 arrived, I
temporarily used my own Hitec 555
receiver to preliminarily set up the servos
and rods. I did shut off the transmitter in the
process, and to my amazement, the servos
went nuts with intense, nonstop glitching!
How could this be? There was no noisy
ESC/motor in place and no other
transmitters around. There was nothing else
that I could identify. Yet the servos were
banging their mechanical limits—nonstop—
in the absence of a transmitter signal. I tried
it repeatedly and got the same thing. It was
actually painful to watch. What could this
be?
I tried another 555 receiver and got the
same results. Then I tried an older FMA
Direct Extreme—no problem at all. I tried
other servos, including other Hitecs,
Futabas, and GWSs, and had no problem
with the Extreme or the two 555s. Then I
added receiver types to the mix, including a
Quantum 6 and a Futaba FP-R148DF. Only
the 555/HS-55 combination went totally
crazy upon loss of a transmitter signal, and I
remain at a loss to explain this one.
Thus I can’t tell if there is something
peculiar with the two new HS-55s I
purchased for the Rascal. If so, is this
something about all HS-55s or just these?
Surely the 555 receivers are okay; I’ve been
using ’em for years.
I suppose that if I still had the Rascal on
the bench, I might be able to further pursue
this quandary, but I don’t. All I can do is
share this strange experience with you for
your information. But why should you have
concern? After all, it’s highly unlikely that
you’d shut the transmitter off in flight—
right?
This brings me back to the same kind of
discussions as in the April and May 2004
columns. As therein, at one time or another
you will fly through regions of no signal; i.e.,
signal nulls caused by “multipath”
propagation—otherwise called signal
“dropouts.” These are (usually repeatable)
locations in the air where the signal at your
airplane becomes weak to nonexistent—and
this can happen even close-in. (It need not be
a “range” issue.)
These experiences are normally of short
duration/distance and are more pronounced
the slower a model flies. It’s the in-flight
equivalent of momentarily shutting your
transmitter off. Such a no-signal condition is
exactly the time for any electrical noise (or
other misbehavior as herein) to easily though
momentarily clobber your control system,
and your model will likely glitch.
In the past I’ve discussed this situation
with regard to power-system-generated
electrical noise, knowing that that was a
likely potential culprit. I must add to this the
particular 555/HS-55 peculiarity I’ve
experienced. There may even be comparably
offensive receiver/servo combos out there of
which I’m unaware. What to do?
I need to “upgrade” my earlier procedural
recommendations to include a bench
checkout of your guidance installation with a
temporary receiver battery; i.e., don’t use a
BEC initially. Verify operation, including
what happens to your controls when you
shut off the transmitter to simulate
momentary in-flight signal loss. At least you
will be prepared if the results are disturbing.
But let’s get back to the Rascal installation.
Fortunately I had chosen the M5 for this
model, which is an excellent receiver. It
basically shrugs off most in-flight signal
disturbances, and now the servos don’t even
twitch when I shut off the transmitter as a
test.
At the same time I’m still using my
(four) 555s in other applications with other
servos, with no problems at all. I must admit
that this is “one for the books” for me! Now
I know to check out systems/installations
even more carefully than my prior five
decades of RC experience taught me to.
Amazing, no?
That’s all for now. Please enclose an SASE
with any correspondence for which you’d
like a reply. Everyone so doing does get
one. And please continue to enjoy many
happy E-landings—as Paul is doing with his
new E-flying Rascal! MA
SG Model Engines
P.O. Box 280303
Northridge, CA 91328
Tel. (818) 472-8460
Engines, Accessories & Parts
Dealers
Welcome
Web Site: Shop.vendio.com/RossiEnginesUSA
SCALE FLIGHT MODEL CO.
Repro Rubber Power Kits, Comet, Megow, Burd,
Scientific, Jasco, also available - Campbell,
Diels, Dumas, Florio Flyer, Guillow’s,
Golden Age Repro, Herr, Micro-X, Peck, Sig.
Send $2.00 for Model Airplane Catalog
Penn Valley Hobby Center
837-A W. Main St., Lansdale, PA 19446
www.pennvalleyhobbycenter.com
Our Full-Size Plans List has
hundreds of models to
choose from.
See page 191 for details.
10sig5.QXD 7/23/04 9:21 am Page 132
Edition: Model Aviation - 2004/10
Page Numbers: 130,131,132
Edition: Model Aviation - 2004/10
Page Numbers: 130,131,132
130 MODEL AVIATION
THIS COLUMN WILL review an oversight in the July column,
detail some experiences with a Sig Rascal ARF, and describe an
unlikely and confusing potential source of glitching.
Late News: The 2nd Annual Best Electrics in South Texas meet is
scheduled for October 8-10 in New Waverly, Texas. Check out
www.tri-countybarnstormers.com, E-mail [email protected],
or call Scott Mrosko at (936) 539-5123 or New Creations R/C at (936)
856-4630.
The July column included a photo and a brief description of Eric
Einarsson’s version of the Universal Slow Charger (USC). A reader
favorite in the last couple of years, the USC was published as a feature
article in the September 2000 MA.
As often happens, this July revisit reminded some of—and
introduced others to—that article. This resulted in fresh reader mail on
the subject—something I welcome. Unfortunately, however, this topic
was also an unintentional “disservice by omission,” as follows.
First, I failed to mention that you can get copies of the original
article from AMA Librarian Rich LaGrange at (765) 287-1256,
extension 506. Ask for a copy of “Universal Slow Charger” on pages
37-46 of the September 2000 issue. You also need to get copies of
correction information from the October 2000 issue (page 60) and the
November 2000 issue (page 7). I am unable to supply these copies.
Second, the original article included a detailed parts list describing
all of the components and the suppliers for them. Another part of the
July disservice was failing to mention that one of the key suppliers had
discontinued doing business approximately two years ago. But not to
worry!
In October 2002 I developed a multipage “USC Update,”
addressing the latter problem. It remains available, and you can get one
by sending me an SASE. To the best of my knowledge, this update
covers all necessary information, in conjunction with the preceding
references, to allow you to build a USC, as many others have done.
Do remember my offer of assistance for anyone who experiences
problems with this or any of my other published projects. You can
undertake any of them with the confidence that I won’t let you fail,
provided you give me the opportunity to help.
So dig out your old issues of MA or purchase article copies from
AMA, send me an SASE for the USC Update, and get going!
My friend Paul, a full-scale pilot of many decades, frequently hangs
with some local E-aeromodelers and has enjoyed some occasional
stick time throughout the years—always doing rather well. He seemed
to enjoy the experience.
Earlier this season I ventured that he might like his own RC
Electric. He liked the idea but did not want to build and was otherwise
“cold” in the general area of outfitting an E-RC. I offered to assist.
I set about seeking an appropriate ARF for the ability I’d seen him
demonstrate, and after conversing with two others in the area who own
them, I selected the Sig Rascal as a candidate. I showed Paul a picture
and he went for it. Then I pegged the all-up material cost at roughly
$500 with free labor, and that was okay too. I started working on
getting all the stuff to get Paul up in the electric air.
The Rascal ARF went together nicely and quickly, with excellent
parts fit everywhere. All assembly tasks were well described in the
accompanying booklet except for some omissions; they were
apparently the result of recent improvements in the ARF kit makeup
without the manual being updated accordingly.
These issues—such as a change in the nature of the pushrods and
horns—would be no problem for an experienced aeromodeler, but they
Bob Kopski, 25 West End Dr., Lansdale PA 19446
RADIO CONTROL ELECTRICS
A happy Paul with his new Rascal and friends Carole and Spike.
Backdrop is private, limited E-power flying site.
Split pushrods and clamping wheel collars permit secure
adjustment. Plastic horns shown are change to Rascal kit.
Shown is M5 receiver/servo installation. Notice inner holes in
servo arms to permit “beginner” surface movements.
10sig5.QXD 7/23/04 9:19 am Page 130
October 2004 131
might be “showstoppers” for a first-timer. Sig
would do well to include a supplemental or
update sheet along with the Rascal’s manual.
Photos show some modifications I
incorporated, one of which was simply
substituting two flat plastic landing-gear clamp
straps for the sheet-metal screws that hold the
bottom fuselage battery hatch.
These “catches” swing out of the way to
allow easy access to the battery; screws would
surely get dropped and lost along the way. The
clamps are easy to install. Glue a piece of 1⁄8
balsa inside the fuselage bottom for the pivot
screws to bite into. Use the original #2 SM
screws for this.
I also modified the kit change in the
pushrods. The newly supplied 40-mil-diameter
solid wires seemed a bit sluggish in the already
installed guide tubes. The surface of these
wires was ripply to the touch, which might
have been the reason for the apparent drag. I
substituted some K&S .032-inch pieces, which
felt much better sliding in the guide tubes.
In addition, I employed my own form of
pushrod adjustment, which is shown in a
photo. I connected both rods via Z bends to the
servo arms and short “stub rods” to both horns
with Z bends. Dual 1⁄16-inch wheel collars
clamp the overlapping ends of the rod sets,
permitting postinstallation adjustability with a
secure clamping thereafter. Also note the extra
holes in the servo arms, to get the controlsurface
movements more in-line with the
manual’s recommendations.
Another photo shows some personalization
in the motor area. I installed a 10-amp ATM
(automotive) fuse in one ESC-to-motor wire in
reaction to a normal safety hang-up I have. I
used Mouser ([800] 346-6873 or www.mou
ser.com) fuse connectors (catalog number 534-
3544), and then I used heat-shrink tubing to
complete the job. (See the April 2003 column
for detailed instructions with photos.)
Last, I covered the otherwise exposed
motor gear set with 3⁄4-inch-wide plastic tape
to pre-empt dust and dirt from finding a
home in the machinery. First I put a bit of
White Lithium Grease (available from any
auto-parts store) on the gears—standard
practice in my geared systems.
Plastic landing-gear clamps swing out of the way for battery
access; swapping packs is now extraordinarily easy.
Easy-to-incorporate 10-amp ATM fuse and plastic-tape gearbox
covering make Rascal installation safer and less trouble.
I used Hitec HS-55 servos per the
manual’s suggestion, an FMA Direct M5
receiver, a GWS Dream Starter II transmitter,
a programmable Castle Creations Pixie-20P
(my Speed 400-application favorite) that I
substituted for the kit ESC, two seven-cell
500AR Ni-Cd packs, Deans four-pin
connectors, a GWS MC-2002DC charger
with the necessary matching connector, and
an APC 9 X 6E propeller following some
current-drain measurements. Knowing the
local terrain, I omitted the otherwise
attractive wheel pants. The Rascal was ready
to go!
The model flew well right off, and Paul
now has numerous assisted flights to his
credit. The Rascal flies nicely with
moderate power, and, as such, is easy for
fliers with limited experience, including in
low-wind conditions. In fact, a slight
headwind is a big assist in rising off ground
from a smooth surface.
The only trim tweak I made was to add
roughly 2° of downthrust (a 1⁄32-inch shim
under the front motor clamp screw locations),
which eliminated some power-on porpoising
tendency.
In retrospect, a personal wish for the
Rascal design is that the wing be rubberbanded
in place for beginning pilots.
Although it’s not as attractive as the bolt-on
method, rubbered wing attachment is far
more forgiving at the time of greatest need:
while learning to fly!
The overall materials tally—for all new
stuff from scratch—came to $498.49. I’m a
firm believer in not minimizing the cost to an
inquiring newbie, but to tell it like it is.
This Rascal project brought with it an eyeopening
experience on the bench. Even
though the final installation includes BEC
power for the receiver/servos, I often use a
separate “bench” four-Ni-Cd pack to power
10sig5.QXD 7/23/04 9:20 am Page 131
132 MODEL AVIATION
OVER A DOZEN MODELS OF WWI, WWII, AND CLASSIC CIVILIAN
AIRCRAFT AVAILABLE WITH MORE VERSIONS TO FOLLOW!
• Electric motor(s) with prop and gear reduction included.
• Highly prefabricated for very short building times.
• 3-4 functions: rudder, aileron & elevator (rudder & ailerons on
one servo, or on separate servos.)
• Laser-cut wood parts for an accurate fit.
• Propeller and spinner included.
• Landing gear and wheels included.
(some kits have removable gear for grass field flying.)
• Contact your local hobby shop, or order direct at: www.djaerotech.com
Ryan ST / PT-16
Wingspan: 28.1 in. • Length: 20.2 in.
Weight: 4.5-5.5 oz. (ready to fly)
Wing Loading: 5.5-6.7 oz/sq. ft.
We
carry
E-tec Li-Poly
batteries &
chargers
Single motor WWII kits ....$48.95
Lockheed P-38...............$56.95
Curtiss Jenny .................$64.95
Sopwith Camel...............$72.95
Fokker Triplane ..............$73.95
DC-3 ............................$66.95
Lockheed Electra............$68.95
Piper J-3 Cub.................$51.95
Curtiss-Wright Junior.......$51.95
Ryan ST / PT-16.............$59.95
B-17F .........................$124.95
(Shipping & Handling extra)
Prices subject to
change without notice.
the receiver/servos during installation setup.
Thus I can check out receiver, servo, and
pushrod operation without having the ESC
and motor battery in place. I did so during
this project, and in the process I experienced
something new.
Before the on-order M5 arrived, I
temporarily used my own Hitec 555
receiver to preliminarily set up the servos
and rods. I did shut off the transmitter in the
process, and to my amazement, the servos
went nuts with intense, nonstop glitching!
How could this be? There was no noisy
ESC/motor in place and no other
transmitters around. There was nothing else
that I could identify. Yet the servos were
banging their mechanical limits—nonstop—
in the absence of a transmitter signal. I tried
it repeatedly and got the same thing. It was
actually painful to watch. What could this
be?
I tried another 555 receiver and got the
same results. Then I tried an older FMA
Direct Extreme—no problem at all. I tried
other servos, including other Hitecs,
Futabas, and GWSs, and had no problem
with the Extreme or the two 555s. Then I
added receiver types to the mix, including a
Quantum 6 and a Futaba FP-R148DF. Only
the 555/HS-55 combination went totally
crazy upon loss of a transmitter signal, and I
remain at a loss to explain this one.
Thus I can’t tell if there is something
peculiar with the two new HS-55s I
purchased for the Rascal. If so, is this
something about all HS-55s or just these?
Surely the 555 receivers are okay; I’ve been
using ’em for years.
I suppose that if I still had the Rascal on
the bench, I might be able to further pursue
this quandary, but I don’t. All I can do is
share this strange experience with you for
your information. But why should you have
concern? After all, it’s highly unlikely that
you’d shut the transmitter off in flight—
right?
This brings me back to the same kind of
discussions as in the April and May 2004
columns. As therein, at one time or another
you will fly through regions of no signal; i.e.,
signal nulls caused by “multipath”
propagation—otherwise called signal
“dropouts.” These are (usually repeatable)
locations in the air where the signal at your
airplane becomes weak to nonexistent—and
this can happen even close-in. (It need not be
a “range” issue.)
These experiences are normally of short
duration/distance and are more pronounced
the slower a model flies. It’s the in-flight
equivalent of momentarily shutting your
transmitter off. Such a no-signal condition is
exactly the time for any electrical noise (or
other misbehavior as herein) to easily though
momentarily clobber your control system,
and your model will likely glitch.
In the past I’ve discussed this situation
with regard to power-system-generated
electrical noise, knowing that that was a
likely potential culprit. I must add to this the
particular 555/HS-55 peculiarity I’ve
experienced. There may even be comparably
offensive receiver/servo combos out there of
which I’m unaware. What to do?
I need to “upgrade” my earlier procedural
recommendations to include a bench
checkout of your guidance installation with a
temporary receiver battery; i.e., don’t use a
BEC initially. Verify operation, including
what happens to your controls when you
shut off the transmitter to simulate
momentary in-flight signal loss. At least you
will be prepared if the results are disturbing.
But let’s get back to the Rascal installation.
Fortunately I had chosen the M5 for this
model, which is an excellent receiver. It
basically shrugs off most in-flight signal
disturbances, and now the servos don’t even
twitch when I shut off the transmitter as a
test.
At the same time I’m still using my
(four) 555s in other applications with other
servos, with no problems at all. I must admit
that this is “one for the books” for me! Now
I know to check out systems/installations
even more carefully than my prior five
decades of RC experience taught me to.
Amazing, no?
That’s all for now. Please enclose an SASE
with any correspondence for which you’d
like a reply. Everyone so doing does get
one. And please continue to enjoy many
happy E-landings—as Paul is doing with his
new E-flying Rascal! MA
SG Model Engines
P.O. Box 280303
Northridge, CA 91328
Tel. (818) 472-8460
Engines, Accessories & Parts
Dealers
Welcome
Web Site: Shop.vendio.com/RossiEnginesUSA
SCALE FLIGHT MODEL CO.
Repro Rubber Power Kits, Comet, Megow, Burd,
Scientific, Jasco, also available - Campbell,
Diels, Dumas, Florio Flyer, Guillow’s,
Golden Age Repro, Herr, Micro-X, Peck, Sig.
Send $2.00 for Model Airplane Catalog
Penn Valley Hobby Center
837-A W. Main St., Lansdale, PA 19446
www.pennvalleyhobbycenter.com
Our Full-Size Plans List has
hundreds of models to
choose from.
See page 191 for details.
10sig5.QXD 7/23/04 9:21 am Page 132
Edition: Model Aviation - 2004/10
Page Numbers: 130,131,132
130 MODEL AVIATION
THIS COLUMN WILL review an oversight in the July column,
detail some experiences with a Sig Rascal ARF, and describe an
unlikely and confusing potential source of glitching.
Late News: The 2nd Annual Best Electrics in South Texas meet is
scheduled for October 8-10 in New Waverly, Texas. Check out
www.tri-countybarnstormers.com, E-mail [email protected],
or call Scott Mrosko at (936) 539-5123 or New Creations R/C at (936)
856-4630.
The July column included a photo and a brief description of Eric
Einarsson’s version of the Universal Slow Charger (USC). A reader
favorite in the last couple of years, the USC was published as a feature
article in the September 2000 MA.
As often happens, this July revisit reminded some of—and
introduced others to—that article. This resulted in fresh reader mail on
the subject—something I welcome. Unfortunately, however, this topic
was also an unintentional “disservice by omission,” as follows.
First, I failed to mention that you can get copies of the original
article from AMA Librarian Rich LaGrange at (765) 287-1256,
extension 506. Ask for a copy of “Universal Slow Charger” on pages
37-46 of the September 2000 issue. You also need to get copies of
correction information from the October 2000 issue (page 60) and the
November 2000 issue (page 7). I am unable to supply these copies.
Second, the original article included a detailed parts list describing
all of the components and the suppliers for them. Another part of the
July disservice was failing to mention that one of the key suppliers had
discontinued doing business approximately two years ago. But not to
worry!
In October 2002 I developed a multipage “USC Update,”
addressing the latter problem. It remains available, and you can get one
by sending me an SASE. To the best of my knowledge, this update
covers all necessary information, in conjunction with the preceding
references, to allow you to build a USC, as many others have done.
Do remember my offer of assistance for anyone who experiences
problems with this or any of my other published projects. You can
undertake any of them with the confidence that I won’t let you fail,
provided you give me the opportunity to help.
So dig out your old issues of MA or purchase article copies from
AMA, send me an SASE for the USC Update, and get going!
My friend Paul, a full-scale pilot of many decades, frequently hangs
with some local E-aeromodelers and has enjoyed some occasional
stick time throughout the years—always doing rather well. He seemed
to enjoy the experience.
Earlier this season I ventured that he might like his own RC
Electric. He liked the idea but did not want to build and was otherwise
“cold” in the general area of outfitting an E-RC. I offered to assist.
I set about seeking an appropriate ARF for the ability I’d seen him
demonstrate, and after conversing with two others in the area who own
them, I selected the Sig Rascal as a candidate. I showed Paul a picture
and he went for it. Then I pegged the all-up material cost at roughly
$500 with free labor, and that was okay too. I started working on
getting all the stuff to get Paul up in the electric air.
The Rascal ARF went together nicely and quickly, with excellent
parts fit everywhere. All assembly tasks were well described in the
accompanying booklet except for some omissions; they were
apparently the result of recent improvements in the ARF kit makeup
without the manual being updated accordingly.
These issues—such as a change in the nature of the pushrods and
horns—would be no problem for an experienced aeromodeler, but they
Bob Kopski, 25 West End Dr., Lansdale PA 19446
RADIO CONTROL ELECTRICS
A happy Paul with his new Rascal and friends Carole and Spike.
Backdrop is private, limited E-power flying site.
Split pushrods and clamping wheel collars permit secure
adjustment. Plastic horns shown are change to Rascal kit.
Shown is M5 receiver/servo installation. Notice inner holes in
servo arms to permit “beginner” surface movements.
10sig5.QXD 7/23/04 9:19 am Page 130
October 2004 131
might be “showstoppers” for a first-timer. Sig
would do well to include a supplemental or
update sheet along with the Rascal’s manual.
Photos show some modifications I
incorporated, one of which was simply
substituting two flat plastic landing-gear clamp
straps for the sheet-metal screws that hold the
bottom fuselage battery hatch.
These “catches” swing out of the way to
allow easy access to the battery; screws would
surely get dropped and lost along the way. The
clamps are easy to install. Glue a piece of 1⁄8
balsa inside the fuselage bottom for the pivot
screws to bite into. Use the original #2 SM
screws for this.
I also modified the kit change in the
pushrods. The newly supplied 40-mil-diameter
solid wires seemed a bit sluggish in the already
installed guide tubes. The surface of these
wires was ripply to the touch, which might
have been the reason for the apparent drag. I
substituted some K&S .032-inch pieces, which
felt much better sliding in the guide tubes.
In addition, I employed my own form of
pushrod adjustment, which is shown in a
photo. I connected both rods via Z bends to the
servo arms and short “stub rods” to both horns
with Z bends. Dual 1⁄16-inch wheel collars
clamp the overlapping ends of the rod sets,
permitting postinstallation adjustability with a
secure clamping thereafter. Also note the extra
holes in the servo arms, to get the controlsurface
movements more in-line with the
manual’s recommendations.
Another photo shows some personalization
in the motor area. I installed a 10-amp ATM
(automotive) fuse in one ESC-to-motor wire in
reaction to a normal safety hang-up I have. I
used Mouser ([800] 346-6873 or www.mou
ser.com) fuse connectors (catalog number 534-
3544), and then I used heat-shrink tubing to
complete the job. (See the April 2003 column
for detailed instructions with photos.)
Last, I covered the otherwise exposed
motor gear set with 3⁄4-inch-wide plastic tape
to pre-empt dust and dirt from finding a
home in the machinery. First I put a bit of
White Lithium Grease (available from any
auto-parts store) on the gears—standard
practice in my geared systems.
Plastic landing-gear clamps swing out of the way for battery
access; swapping packs is now extraordinarily easy.
Easy-to-incorporate 10-amp ATM fuse and plastic-tape gearbox
covering make Rascal installation safer and less trouble.
I used Hitec HS-55 servos per the
manual’s suggestion, an FMA Direct M5
receiver, a GWS Dream Starter II transmitter,
a programmable Castle Creations Pixie-20P
(my Speed 400-application favorite) that I
substituted for the kit ESC, two seven-cell
500AR Ni-Cd packs, Deans four-pin
connectors, a GWS MC-2002DC charger
with the necessary matching connector, and
an APC 9 X 6E propeller following some
current-drain measurements. Knowing the
local terrain, I omitted the otherwise
attractive wheel pants. The Rascal was ready
to go!
The model flew well right off, and Paul
now has numerous assisted flights to his
credit. The Rascal flies nicely with
moderate power, and, as such, is easy for
fliers with limited experience, including in
low-wind conditions. In fact, a slight
headwind is a big assist in rising off ground
from a smooth surface.
The only trim tweak I made was to add
roughly 2° of downthrust (a 1⁄32-inch shim
under the front motor clamp screw locations),
which eliminated some power-on porpoising
tendency.
In retrospect, a personal wish for the
Rascal design is that the wing be rubberbanded
in place for beginning pilots.
Although it’s not as attractive as the bolt-on
method, rubbered wing attachment is far
more forgiving at the time of greatest need:
while learning to fly!
The overall materials tally—for all new
stuff from scratch—came to $498.49. I’m a
firm believer in not minimizing the cost to an
inquiring newbie, but to tell it like it is.
This Rascal project brought with it an eyeopening
experience on the bench. Even
though the final installation includes BEC
power for the receiver/servos, I often use a
separate “bench” four-Ni-Cd pack to power
10sig5.QXD 7/23/04 9:20 am Page 131
132 MODEL AVIATION
OVER A DOZEN MODELS OF WWI, WWII, AND CLASSIC CIVILIAN
AIRCRAFT AVAILABLE WITH MORE VERSIONS TO FOLLOW!
• Electric motor(s) with prop and gear reduction included.
• Highly prefabricated for very short building times.
• 3-4 functions: rudder, aileron & elevator (rudder & ailerons on
one servo, or on separate servos.)
• Laser-cut wood parts for an accurate fit.
• Propeller and spinner included.
• Landing gear and wheels included.
(some kits have removable gear for grass field flying.)
• Contact your local hobby shop, or order direct at: www.djaerotech.com
Ryan ST / PT-16
Wingspan: 28.1 in. • Length: 20.2 in.
Weight: 4.5-5.5 oz. (ready to fly)
Wing Loading: 5.5-6.7 oz/sq. ft.
We
carry
E-tec Li-Poly
batteries &
chargers
Single motor WWII kits ....$48.95
Lockheed P-38...............$56.95
Curtiss Jenny .................$64.95
Sopwith Camel...............$72.95
Fokker Triplane ..............$73.95
DC-3 ............................$66.95
Lockheed Electra............$68.95
Piper J-3 Cub.................$51.95
Curtiss-Wright Junior.......$51.95
Ryan ST / PT-16.............$59.95
B-17F .........................$124.95
(Shipping & Handling extra)
Prices subject to
change without notice.
the receiver/servos during installation setup.
Thus I can check out receiver, servo, and
pushrod operation without having the ESC
and motor battery in place. I did so during
this project, and in the process I experienced
something new.
Before the on-order M5 arrived, I
temporarily used my own Hitec 555
receiver to preliminarily set up the servos
and rods. I did shut off the transmitter in the
process, and to my amazement, the servos
went nuts with intense, nonstop glitching!
How could this be? There was no noisy
ESC/motor in place and no other
transmitters around. There was nothing else
that I could identify. Yet the servos were
banging their mechanical limits—nonstop—
in the absence of a transmitter signal. I tried
it repeatedly and got the same thing. It was
actually painful to watch. What could this
be?
I tried another 555 receiver and got the
same results. Then I tried an older FMA
Direct Extreme—no problem at all. I tried
other servos, including other Hitecs,
Futabas, and GWSs, and had no problem
with the Extreme or the two 555s. Then I
added receiver types to the mix, including a
Quantum 6 and a Futaba FP-R148DF. Only
the 555/HS-55 combination went totally
crazy upon loss of a transmitter signal, and I
remain at a loss to explain this one.
Thus I can’t tell if there is something
peculiar with the two new HS-55s I
purchased for the Rascal. If so, is this
something about all HS-55s or just these?
Surely the 555 receivers are okay; I’ve been
using ’em for years.
I suppose that if I still had the Rascal on
the bench, I might be able to further pursue
this quandary, but I don’t. All I can do is
share this strange experience with you for
your information. But why should you have
concern? After all, it’s highly unlikely that
you’d shut the transmitter off in flight—
right?
This brings me back to the same kind of
discussions as in the April and May 2004
columns. As therein, at one time or another
you will fly through regions of no signal; i.e.,
signal nulls caused by “multipath”
propagation—otherwise called signal
“dropouts.” These are (usually repeatable)
locations in the air where the signal at your
airplane becomes weak to nonexistent—and
this can happen even close-in. (It need not be
a “range” issue.)
These experiences are normally of short
duration/distance and are more pronounced
the slower a model flies. It’s the in-flight
equivalent of momentarily shutting your
transmitter off. Such a no-signal condition is
exactly the time for any electrical noise (or
other misbehavior as herein) to easily though
momentarily clobber your control system,
and your model will likely glitch.
In the past I’ve discussed this situation
with regard to power-system-generated
electrical noise, knowing that that was a
likely potential culprit. I must add to this the
particular 555/HS-55 peculiarity I’ve
experienced. There may even be comparably
offensive receiver/servo combos out there of
which I’m unaware. What to do?
I need to “upgrade” my earlier procedural
recommendations to include a bench
checkout of your guidance installation with a
temporary receiver battery; i.e., don’t use a
BEC initially. Verify operation, including
what happens to your controls when you
shut off the transmitter to simulate
momentary in-flight signal loss. At least you
will be prepared if the results are disturbing.
But let’s get back to the Rascal installation.
Fortunately I had chosen the M5 for this
model, which is an excellent receiver. It
basically shrugs off most in-flight signal
disturbances, and now the servos don’t even
twitch when I shut off the transmitter as a
test.
At the same time I’m still using my
(four) 555s in other applications with other
servos, with no problems at all. I must admit
that this is “one for the books” for me! Now
I know to check out systems/installations
even more carefully than my prior five
decades of RC experience taught me to.
Amazing, no?
That’s all for now. Please enclose an SASE
with any correspondence for which you’d
like a reply. Everyone so doing does get
one. And please continue to enjoy many
happy E-landings—as Paul is doing with his
new E-flying Rascal! MA
SG Model Engines
P.O. Box 280303
Northridge, CA 91328
Tel. (818) 472-8460
Engines, Accessories & Parts
Dealers
Welcome
Web Site: Shop.vendio.com/RossiEnginesUSA
SCALE FLIGHT MODEL CO.
Repro Rubber Power Kits, Comet, Megow, Burd,
Scientific, Jasco, also available - Campbell,
Diels, Dumas, Florio Flyer, Guillow’s,
Golden Age Repro, Herr, Micro-X, Peck, Sig.
Send $2.00 for Model Airplane Catalog
Penn Valley Hobby Center
837-A W. Main St., Lansdale, PA 19446
www.pennvalleyhobbycenter.com
Our Full-Size Plans List has
hundreds of models to
choose from.
See page 191 for details.
10sig5.QXD 7/23/04 9:21 am Page 132