FMA Direct Cellpro 4S Charger Adapters
? Frequently Asked Questions Bob Aberle | [email protected]
Also included in this column:
• Selecting balsa wood by weight
• Hook-and-fastener tape
convention
• 1/2A radial engine mounts
• Heat-shrink tubing
The My Weigh tiny digital scale is one of
many on the market. You need a scale
that reads down to a tenth of a gram.
This 1/16 balsa sheet weighs 7.7 grams; some
weigh more than 20. The proper-weight
balsa for a specific application is critical to
good model building.
At the bottom is FMA Direct’s Cellpro 4S charger. In the upper left are two of four FMA
Direct adapters. They allow you to plug various suppliers’ battery packs into the charger.
THIS IS THE 40th monthly column in which
I try to give you the best possible answers to
questions you have written or E-mailed to me.
Each new inquiry is given a sequential
number for future reference.
Many questions and answers have been
posted to the AMA Web site at www.model
aircraft.org/mag/faq/index.asp. Unfortunately
that posting stopped in August 2005 and will
not continue until this section of the AMA
Web site is revamped. In the meantime, if
you can’t find the subject matter you are
interested in, drop me an E-mail or letter
and I will try to assist you.
Q300: “I just finished building your reduced
size version of Joe Wagner’s Sioux, the
construction article for which appeared in
Quiet Flyer magazine several years ago. My
particular Sioux ended up heavier than your
own and was, in fact, tail-heavy.
“After finishing the construction and
recognizing I had a problem, I weighed a
typical piece of my 1/16 x 3 x 36-inch balsa
sheeting and found that it weighed about 20
grams. I have no criteria as to whether this is
too heavy or what.
“Can you shed some light on this? Can
you also tell me of sources of supply for good
graded balsa wood?”
A300: I always weigh my balsa using a small
digital scale. I use a My Weigh (model MX-
120). I tried looking up that scale to provide a
reference and found, by accident, a newer
version (model 200Z) that weighs as much as
200 grams in 0.1-gram increments and costs
only $22.99. You can find it at www.right
onscales.com/web/120z.htm.
I picked a medium to soft 1/16 x 3 x 36
balsa sheet from my wood stock. (I would
guess that is where I found the wood to
build my original Sioux.) It weighed only
7.7 grams, or 62% less than what the reader
found. I’m sure that extra balsa weight
caused the tail-heavy situation.
I checked my Sioux, which I still fly,
and without a battery pack it still balances
at 50% of the wing chord. With the battery
in place it balances exactly as shown on the
plans: approximately 25% back from the
wing LE. So please take more note of wood
weight.
If you are buying from a hobby shop or
craft store, bring the tiny digital scale with
you. Most mail-order houses that supply
balsa wood are wonderful at grading from
light to medium to heavy.
I buy my wood from Balsa USA
(www.balsausa.com), Lone Star Balsa
(www.lonestar-models.com), National
Balsa Co. (www.nationalbalsa.com), Sig
Manufacturing Co. (www.sigmfg.com),
Solarbo USA (www.solarbo.peachhost.
74 MODEL AVIATION
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July 2007 75
Using hook-and-fastener mounting tape, placing the “hook” side on a battery pack and
the “fuzzy” side on a model’s fuselage lets club members swap packs.
Typical fiberglass-filled engine mount by
Kraft-Hayes (the KM-09 for .09-size glow
engines). These are available for
.049/.051 engines.
Don’t attempt to shrink your heat-shrink
tubing with the heat from your soldering
iron; use a hot-air gun (shown).
Bob buys single-edge razor blades and XActo
No. 11 knife blades in 100-count
boxes and changes them often to make
sure they are always sharp.
com), and Superior Balsa (www.superior
balsa.com).
Q301: “I’m beginning to learn that every
Li-Poly battery supplier has its style of
balance or node connector. This is the
connector that allows you to balance all the
cells in a pack.
“I happen to like the FMA Cellpro 4S
balanced charger, but none of my packs will
plug into the balance connector on the
Cellpro. To make matters worse, FMA
Direct went out of the battery business. So
what am I to do with their charger?”
A301: If you look further into your Cellpro
4S instruction manual or at www.fma
direct.com/products.htm?cat=45&nid=4 you
will find that FMA Direct offers adapters
that allow you to plug Li-Poly battery packs
supplied by Apogee, E-flite, ParkZone,
ElectriFly, Poly-Quest, Thunder Power,
Hobby Lobby Twenty, and Tanic into the
charger. Any of the original FMA Direct
Cellpro packs will plug directly into the 4S.
FMA Direct also sells its own node
connector and cable so you can separately
wire cells in any of your packs that don’t have
that feature. The instructions supplied with
this cable are excellent, but please be careful
not to short out any cells in the process.
Q302: “Do RC clubs establish a convention
for the use of the popular hook and fastener
tape? I was thinking of suggesting this so that
I could easily share some of my battery packs
and radio equipment with my fellow club
members.”
A302: This popular mounting tape achieves
its adhesion by having one “hook” and one
“fuzzy” surface. When the two come in
contact they literally attract like magnets. It is
known by the brand name Velcro.
The reader is suggesting that clubs set up a
convention so that each member places the
hook portion of the tape on the battery pack
and fuzzy, or mating, surface on the model.
This way, if you are at the flying field you
can swap with a club member because every
pack will have the hook surface.
We didn’t make a thing out of this at
my local SEFLI (Silent Electric Flyers of
Long Island) club, but everyone seems to
have adopted the same convention. My
flying partner Tom Hunt and I have done
this since back in the days when we
competed in the AMA Electrics Nats in
Muncie, Indiana.
When flying in competition, it is
important that last-minute substitutions be
made easily. We even use the same
convention when attaching RC receivers
and ESCs to aircraft fuselages. You never
know when you might have a failure and
need some quick help. It is a good point!
Q303: “I’m having trouble trying to locate
a radial engine mount for a Cox Tee Dee
.049 glow-fueled engine. I know there
were many brands of such mounts years
ago. Has the market ‘dried up’ or can
some mounts still be purchased?”
A303: I still have several such radial
mounts in my collection. The one in the
photograph is a Kraft-Hayes type KM-09
(the next size larger) because I don’t have
a KM-05 (.049 engine size) in my
inventory. These mounts were generally
made from a molded filled nylon material.
Thanks to the Google search engine I was
able to locate these mounts for sale at RC
Hobby Center Inc., 2047 Harschman Rd.,
07sig3.QXD 5/23/07 10:27 AM Page 75
Dayton OH 45424; Tel: (937) 236-2455. The
catalog item code is HAY059—a Kraft-
Hayes Engine Mount KM-05—listing for
only $2.25.
I also found fiberglass-filled nylon engine
mounts on the Dave Brown Products Web
site. Catalog number 0405 is intended for
Cox .049 and .051 engines. You can obtain
these from Dave Brown Products Inc. at
4560 Layhigh Rd., Hamilton OH 45013;
Tel.: (513) 738-1576.
Another popular engine mount in its day
was the Fourmost Racing Products Airflo. It
was also a beam to radial mount, but the
bottom was streamlined much like a forwardfuselage
cowl. These were intended for use
on 1/2A RC Pylon Racing models at the time.
I have no way of knowing if these mounts
are still available. The address for Fourmost
Products is 4040 24th Ave., Forest Grove OR
97116; Tel.: (503) 357-2732; E-mail:
[email protected]. It might be
worth a try!
Q304: “I keep hearing that you should add
heat-shrink tubing to wire splices and where
the wire goes into a connector block or pin. I
picked up some of this tubing at my local
RadioShack store, but I have to admit that
every time I get the heat from my soldering
in close proximity to the tubing it tends to
melt before it shrinks.
“Did I buy the wrong tubing or am I
applying the wrong kind of heat?”
A304: I’m a firm believer in using heatshrink
tubing for almost all my electric
wiring jobs. What you bought from
RadioShack is fine, but I have found some
that is quite firm, or rigid. Alternative
suppliers include Batteries America
(www.batteriesamerica.com), Radical RC
(www.radicalrc.com), and Air Dynamics
(www.airdyn.com).
The real problem is that you should never
use heat from an iron. As hot as the element
gets, you still have to practically touch the
tubing to get it to shrink. Invariably you will
be close enough to melt the tubing before it
gets a chance to shrink.
The best way to shrink the tubing is with
a heat gun. These are the same tools we use
to shrink iron-on covering and reshrink the
same covering when it goes limp on us. You
will be surprised to see how well that gun
shrinks the tubing.
I pick up loads of this tubing at any of the
regional hobby trade shows where they cut it
off a reel. It comes in a variety of diameters
(sizes), so make sure you always get a good
selection. The suppliers I mentioned sell
tubing in large diameters, such as 2, 3, and 4
inches.
This kind of tubing can be slipped over a
battery pack you assembled. With an
application of heat from the gun, you end up
with a pack that looks like a pro assembled it.
Q305: “I read your article titled ‘The Case
for Building Model Aircraft’ (November
2005 MA). In it you show a lot of the tools
you use for building your own models. I’d
like to see more info presented in future
articles or in your column.”
A305: When you get down to it, I don’t
use much in the way of tools. All the ones
I use are referred to in that article. I still
use a 20-year-old Dremel rotary device. It
isn’t modern by a long shot, but it does
work well.
However, your request has merit. I’ll
try to work in more of the “tool”-type
items in the future.
I build many airplanes using practically
nothing in the form of implements. I
balance my models with my fingertips
under the wing. My most important “tool”
is a trusty balsa-block building board.
I wrote a portion of MA’s “From the
Ground Up” series in 2004 that amounted to
10 articles. All of them are posted on the MA
Web site at www.modelaircraft.org/mag/
FTGU/titlespageftgu.htm. Parts 6, 9A, and 9B
include details about building, assembly, and
tools. They should be interesting to you.
I do have one item to share. It will
probably sound like trivia, but I buy XActo
No. 11 blades and single-edge razor
blades in boxes of 100. I have definite
applications for both. I change these
blades as often as a dozen times while I
am building just one aircraft. A sharp
blade builds the best aircraft!
Thanks for E-mailing me. I will pursue
some of your ideas. MA
