RADIO CONTROL ELECTRICS - 2003/06

100 MODEL AVIATION
THIS COLUMN includes four meet
announcements, references an E-powered
video airplane article, adds another note
about chokes, discusses a pack discharger,
and continues the discussion of multimotor
installations.
Joe Beshar (198 Merritt Dr., Oradell NJ
07649; Tel.: [201] 261-1281; Fax: [201]
261-0223) wrote to tell me about the 7th
Eagles Electric Fly In, scheduled for
Saturday, May 17, 2003, with a rain date
of Sunday, May 18. The location is Hope,
New Jersey, and you can get detailed
driving directions and other printed info
from Joe.
This year’s meet, again sponsored by
Flying Models magazine, is being held in
memory of Chuck Gill—proprietor of The
Aeroplane Works—for his dedication to
model aviation. Electrics of all types are
invited, including Free Flight, and one
event is planned: Elexaco.
Elexaco is Joe’s brainchild from several
years ago. It is a timed event with simple
rules. The latest rules allow any aircraft
design with an aspect ratio of eight or less
and powered with a ferrite Speed 400
motor on a seven-cell 250-350 mAh pack.
Those are the basics; there are some other
details, and, again, you can request more
information from Joe. Be sure to tell him
Bob sent ya!
The National Indoor Remote-controlled
Aircraft Council (NIRAC) has announced
the inaugural indoor Radio Control (RC)
championship, to be held Saturday, May
31 and Sunday, June 1. The location is the
Oakland Yard Dome in Waterford,
Michigan, approximately 100 miles north
of Toledo, Ohio, and northwest of Detroit,
Michigan. This facility measures roughly
240 x 300 feet, with a ceiling of
approximately 82 feet. There are six events
planned, with trophies to third place.
You can find all of the rules and a
registration form at www.nirac.org. John
Worth ([email protected]) can tell you
about local lodging and a Saturday-night
banquet. NIRAC President Bob Wilder
([email protected]) and Vice President
Bob Aberle ([email protected]) can
supply general info. Preregistration is
recommended.
Brian Allen (47036 Berwick Ct.,
Sterling VA 20165; Tel.: [703] 430-5849;
E-mail: [email protected]) sent info
about the Loudoun County Aeromodelers
Association 4th Annual Electric Fly In
scheduled for July 26, 2003. The meet will
be held at the Loudoun County
Aeromodelers Association (LCAA) flying
field at Banshee Reeks Park in Leesburg,
Virginia.
Check out the club Web site at
www.lcaa.org. An alternate contact person
is Ron Anderson (115 Sue Ann Ct.,
Sterling VA 20164; Tel.: [703] 444-3215;
E-mail: [email protected]). A
detailed mailer is available.
September 12-14 are the dates for the
2003 Northeast Electric Aircraft
Technology (NEAT) Fair, which, as in
recent years, is expected to be the largest
E-meet in the country. The Silent Electric
Flyers of Long Island (SEFLI) manages
the meet, and everyone is welcome. Last
year more than 290 pilots and many more
spectators attended. If you want to see
every possible kind of Electric there is, this
is the place to go!
You can get more info and even
Bob Kopski, 25 West End Dr., Lansdale PA 19446
RADIO CONTROL ELECTRICS
Joanne Levy holds husband Joe’s geared
Astro 40-powered Hangar 9 Cub. It has 18
cells and 14 x 8 Master Airscrew propeller.
Mark Murdock built this Elipstik 460 in
pseudo Air Force scheme to honor son
Chase, who is in training at Lackland AFB.
DUMP’R is a pack discharger for nearly all four- to 18-cell packs. Half-amp discharge
stops automatically at 0.9 volts/cell-equivalent pack voltage.
102 MODEL AVIATION
preregister at the NEAT Web site:
www.neatfair.org. You can also get info
about the gorgeous meet site—Peaceful
Valley Campsite in Shinhopple, New
York—at www.peaceful-valley.com. This
is an extensive campground setting with
the flying field right in the middle; you
have to see it to fully appreciate it. If you
can only make one meet this year, this
should be the one. If you’re new to EWilliam
Torbert sent inside, outside look at his rendering of Small-Pack Slow
Charger (June 2002 MA). Larger box holds six individual slow-charging circuits.
Outside view
Inside view
power, plan to be overwhelmed!
Nuts & Volts is a monthly magazine for
the electronics hobbyist. Many of this
column’s readers also enjoy electronics as
a hobby, so perhaps some are familiar with
this publication. The February 2003 issue
includes an article by Phil Blake, who
describes his airborne live video system
installed in, of all things, a park flyer!
The model is the Great Planes
Escapade ARF (Almost Ready to Fly). The
onboard video camera and transmitter
operate on 900 MHz and do require an
amateur radio license to operate, according
to Phil. (I do not know if there are
alternatives to this system/requirement or
not.) Considering the nature of the
airplane, this is impressive!
If you are interested but do not get this
magazine, go to www.nutsvolts.com, or
you may be able to find it at your local
library. The story is well worth the look.
I have written about chokes several times
in recent issues, and reader reaction keeps
coming in. So far all reports are good, with
absolutely no disappointments reported.
One letter came from Bob Pearsall, author
for Radio Control Boat Modeler, who
described solving glitch problems with
chokes in Elmira: his Astro 25-powered,
45-pound RC electric tug. Control was
tenuous, but not anymore.
Bob went on to describe fixing a
friend’s Douglas 4 seaplane, which was
previously so glitch-plagued it was
considered unsafe to fly. Bob described
the same happy outcome with one of his
own airplanes with “ … radio glitches are
a thing of the past.” He was happy about
all of this, and he wrote to say so. Thanks,
Bob.
All of you who have been dubious or
otherwise putting it off, dig out the
September 2002 and February 2003
columns to get all of the info you need to
try this yourself. Cost is but a few dollars,
time needed is short, and good results can
make the difference between flying (or
sailing!) and not.
Discharging packs can be one of those
nuisance tasks that E-modelers face. It’s a
little like having to empty a wet-power
fuel tank, only not nearly as messy!
Sometimes one can have one or more
charged airplanes and/or packs ready to fly
but not have the opportunity to do so for a
variety of reasons. This happens to me; I
charge more than there is daylight left to
enjoy. What to do?
I briefly mentioned this circumstance
in the March 2003 column. I described
how some products, such as the new Astro
110 Deluxe charger, are capable of
discharging as well as charging. The
problem I faced was that my Deluxe was
installed in the minivan and I don’t like
taking it out. I needed a more portable way
to deal with this need, and the need was
growing primarily because I was
accumulating more and more packs for
park flyers.
After considering several approaches,
DUMP’R came about. This is a fairly
simple electronic discharger. It is selfcontained
and does not need any external
power input; it is powered by the pack it is
discharging. Further, it discharges at a
known, constant rate of approximately 500
mA.
DUMP’R is useful for cell counts of
four to 18; the number is rotary-switch
selected. Once started (with the push of a
button), it continues discharging until the
cell equivalent voltage of roughly 0.9
volts is reached—the reason for dialing in
the cell count—then it shuts off
automatically. This shutdown prevents
overdischarge, which can be very hard on,
if not destructive to, packs. I’ve had
DUMP’R in trouble-free use for one full
season, and I’m getting ready to make
additional units.
I know from years of experience that
many of you like electronics projects as
related to E-aeromodeling, so I’m sharing
this here as a “tease” of sorts. I’m sort of
probing to see what interest in this you
may have, and if there is enough positive
reaction to the idea I’ll see what I can do
to share the design and construction info
in the future. Meanwhile, I’m unable to
share preliminary details (no good
drawings and absolutely no text exist!), so
let me hear from you.
Last month’s column began a discussion
of multimotor installations and twins in
particular. But twins are not the limit, so
trimotors, quads, and even more are
possible and relatively easy to implement.
With electric there’s not much worry
about “losing” one side, getting all motors
running, or synchronism thereafter. And
the sound can be awesome—not loud, but
beautifully “engulfing”!
Despite the range of motor counts
possible, probably the next most popular
multimotor application after twins is the
four-motor installation. Now the familiar
questions and decisions come into play:
Series? Parallel? Or what?
A review of the last column will
provide a refresher of the considerations
associated with series- and parallel-wiring
two motors. It turns out that the same
options are feasible in the four-motor
setup, but there are more possibilities too.
A modeler could simply wire all four
motors in series, then use roughly four
times as many cells as with one motor. Or
one could wire all four in parallel and
nominally have four times the current
demand of one. Depending on the motors,
cell count, and cell size, this all in
combination can become a bit
discouraging. What to do? Consider a
compromise.
Many people with quad installations
use a combination of series and parallel
wiring. Thus twice the cell count with
cells of twice the capacity can be far less
scary a thought than the preceding. Here’s
how this works.
Consider one twin installation, such as
that discussed last month, where the
motors are wired in series. This would
require nominally two times the cell count
of one motor with cells of the same
nominal capacity as one might choose for
that one motor. Now think of installing
two such series motor sets to make a quad.
This is not two systems, but two sets of
series motors.
To complete this installation, one needs
nominally twice the cell count as might be
used with one motor, with cells of
nominally twice the capacity as might be
used with one motor. There is still just one
Electronic Speed Control (ESC), arming
switch, etc. needed.
As an example, consider a quad Speed
400 installation. As a single, one such
motor might use seven cells of 1.0 Ah
capacity. A series-wired twin system
might use 14 cells of 1.0 Ah capacity.
This quad example would use 14 cells of
2.0 or 2.4 Ah capacity. This is a
comfortable, workable compromise, but
that still leaves some wiring details to be
worked out.
Although it’s possible, and even
tempting, to connect the two left motors in
series and the two right motors in series,
bringing the wiring from each pair in to a
common ESC/supply point, it may not be
the best choice. An alternative scheme is
to wire the two inboard motors in series
and the two outboard motors in series.
This may be a bit more wiring/connector
complexity, but it offers some insurance.
Electrics are reliable, but given the
remote chance of having some problem
with one motor/propeller resulting in the
loss of one motor pair, there would still be
one motor on each wing operating.
Therefore, one would not lose either side
fully and would retain balanced power
with the associated ease of flight control.
So unless there is some pressing need to
make the series pairs of motors both lefts
and both rights, choose the inboards and
outboards combinations instead.
Thus ends one more column—and 2003
is halfway finished, columnwise. It’s also
the beginning of the summer flying
season: my favorite time of year!
Please include an SASE with any
correspondence for which you’d like a
reply. Everyone so doing does get one.
And once again, I do not use E-mail for
this purpose.
Many safe summertime E-landings,
everyone! MA
106 MODEL AVIATION