Letters to the Editor - 2003/10

Digital Photography
Mark Lanterman’s story “Capturing
Models Digitally” [in the August issue] hit
my spot. I’ve been looking for information
about digital photography for some time.
Everytime I try to get information, the
person I’m talking to assumes that I already
know all about it. I don’t know diddly!
I’ve tried to read articles in photo
magazines with no results. This article is
the best anywhere! I’m on my way to
buying a camera!
Jim Pate
Oakland, California
Thank you for a very clear and useful
article on digital cameras. I’ve not yet
bought one, but am thinking along those
lines, and your article gives me the info I
need to make an informed decision.
I’d like to see you do a similar article on
photo software and color printers.
Frank Korman
Dallas, Texas
The middle picture caption on page 69
stating that using a longer focal-length lens
will minimize depth of field is a bit
misleading. Using a longer lens changes the
perspective. You can see how much shorter
the Mustang in the middle picture looks
than the one on the top.
Albeit that longer lenses have a shorter
depth of field, the depth of field is a
function of f-stop. By using a lowernumber
f-stop (larger opening), the
background will be blurred without
changing the perspective.
John J. Seaton
Las Vegas, New Mexico
Many digital cameras do not allow you
to manually adjust the aperture (f-stop) of
the lens. By backing away from the subject
and zooming in, you trick the camera into
automatically opening the f-stop, thus
achieving the depth-of-field effect.
Mark Lanterman
Fairfield, Ohio
Thanks to MA
I just wanted to drop a line to everyone
who helps to put articles in the magazine
and say how much I love to read Model
Aviation. To me, it is the best magazine
that I have ever bought/received.
I like the new section about “From the
Ground Up.” Even though I have been
flying for about two years now, there is
always something for everyone to learn—
even for the veterans who have been flying
for many decades.
I have learned things about RC airplanes
and transmitters that I have never known. It
shows me how an airplane controlling
system is set up. Also, what controller has
the best fit for different kinds of airplanes.
I especially love the section “Focal
Point.” This shows me many, many
different color schemes that I can and
might use for later airplanes that I might
build. I just like to see what people can
really make when they aren’t thinking
about how much money they have spent on
the model, but of how much fun and how
many memories they will have when they
fly and are done building. The pictures are
great!
I really like the section (among the other
many sections) about “Worth a Closer
Look.” I like this because it shows me and
other fellow RC model enthusiasts what
new products have come out. The best
thing is that it also has a picture of the
product and a brief description about it.
Last, but certainly not least, is the hardworking
district reporters who usually,
regardless of what they do, go out of their
way to go around the country and show
pictures and reports of the literally
hundreds of fly-in and clubs that they go to.
I love to look at these pictures and reports
to see what other RC people are doing at
their clubs.
Thanks very much to the Model
Aviation staff who puts together this
incredible, magnificent, and excellent
magazine.
Michael Carr
Charlotte, North Carolina
Best Covers
The AMA magazine Model Aviation has
undoubtedly the best covers of any
magazine published. I appreciate the lack
of article names, etc. on the cover.
Gene Midyette
Jefferson, North Carolina
This note is simply to thank Mark
Lanterman (and you) for the strikingly
beautiful cover on the August issue. It is an
“eye magnet” for me that in one photo
captures the thrill of RC flight and the
beauty of a fine subject.
In more than 15 years of reading RC
magazines, this one is my pick for the best
ever. And Mark’s article on capturing
digital images is timely and well done. That
guy knows his stuff. Thanks!
Chuck Kunce
Leesburg, Virginia
Electric-Power Quandary
The author/writer explains [in the July
2003 “From the Ground Up” installment
“Introduction to Electric Power”] the use
of electric power versus the glow-plug
fuel/energy for model airplanes.
His details are very well explained as
to all the components and how they are to
perform. Also, other important
maintenance for and the advantage
comparisons over glow-fuel-operated
models.
However, I am at a loss to understand
the use of equipment with mismatched or
unlike voltages. He describes the motor as
a Speed 400, 6-volt winding direct-drive
system with the APP connectors. Later on
in the script he identified the initials APP
as Anderson Power Pole.
Yet all the other power items, battery
pack, and charger are stated as 12-volt
operation. If I am missing something in
this setup or hookup, will a 12-volt source
not harm 6-volt motor operation and cause
failure?
Donald Kreis
Largo, Florida
You bring up an excellent point. In
writing this series I realized at the start
that the options and variations can go on
forever. It was important for me to select
all the components so that a beginner
would not have to search for anything at
the start. I also hoped that the beginner
would get quickly out to a local flying
field, where questions, such as yours,
could be answered quickly and in real
time.
My references to voltages or voltage
levels were strictly for identification
purposes. I didn’t want to imply, for
example, that everything operated at 12
volts. Let me explain further. The
specified motor is a Speed 400. It is very
common and inexpensive. It is generally
available in three different windings,
classified as 4.8-volt, 6.0-volt, and 7.2-
volt.
Each of these three windings has a
specific purpose. My choice for the
beginner was the 6-volt winding which
works well with direct drive (the propeller
mounted directly on the motor shaft).
Even though this motor is designated
as “6-volt,” by experience we have found
that it works best with battery packs of
seven cells (for Ni-Cd batteries) and eight
cells for NiMH batteries (as I chose for
my example). At 1.2 volts per cell
nominal, eight cells would equate to
approximately 9.6 volts. That is the
voltage going into the Speed 400 (6-volt
winding) motor.
There isn’t any real rationale for this;
it is strictly a point of identification. As
you progress in electric power these motor
Model Aviation, 5161 E. Memorial Dr., Muncie IN 47302
Letters to the Editor
October 2003 9
Continued on page 191
Letters
identifications will become as easy to use
as engine displacement is for glow
engines.
So now we have a Speed 400 6-volt
winding motor being operated at 9.6 volts
from an eight-cell 1100 mAh NiMH
battery pack. My reference to a 12-volt
charger strictly meant that it was capable
of operating (inputwise) from a 12-volt car
or storage battery while at the flying field.
The particular charger I recommended
(Watt-Age PF-12 Park Flyer AC/DC Peak
Charger) can also be powered from
115VAC house current for charging your
batteries in your home or shop—an added
convenience.
When you power up your charger, the
first thing you do is set the charge current.
You should be concerned with charge
current—not voltage. In this case the 1100
mAh battery, as explained in the article,
requires a charge current of close to 2.2
amps. At full output, this charger can get
to 2.0 amps which is close enough for our
purposes. The key point to answering your
question is that the charger operates from
12 volts but is putting something different
into the battery pack. However, that
should not be your concern.
This may still be confusing to you. The
best suggestion is to follow my
recommendations for all of the products:
the motor, propeller, battery, battery
charger, and speed controllers. Assemble
the entire power system and then install it
in the recommended Pogo ARF model
(covered in the August Model Aviation)
and go out and learn to fly.
You will be pleasantly surprised at how
fast the detailed pieces fall together. But
again, a visit to a local flying field,
especially where electric power is
employed, is worth a lot more than
correspondence or Internet forums. Fly
first and then learn all the subtleties later
on. Good luck as you proceed! MA
Bob Aberle