Letters to the Editor - 2004/04

Depron Blues
Editor’s note: In his February “Flying for
Fun” column, D.B. Mathews wrote about the
increasingly popular SPAD (Simple Plastic
Airplane Designs)-type models and the use of
Depron and fan-fold foam in fabricating them.
D.B. innocently received erroneous
information about the Depron material’s
properties and usage from his sources, and
we have received two letters, which follow,
from authorities on this material that set the
record straight.
The first letter is from Scott McKie, who
was a former partner in DepronUSA: a
company that imports Depron foam products.
The second letter is from Tim Hart
(incorrectly identified in the column as Tim
Holt), who designs the models for the Foamy
Factory and hosts its Web site
(www.foamyfactory.com/airplanes.htm).
I am writing to you about the February
column “Flying for Fun” by D.B. Mathews.
What I am writing about is the totally
incorrect comparison Mr. Mathews makes
between the product Depron and fan-fold
foam. Depron is not a blue polyurethane foam
core material that is covered with a thin layer
of semitransparent plastic. This statement is
totally incorrect and has no basis in fact.
Depron, as used in the modeling field here
in the US, is a closed cell polystyrene foam
product that gets its surfacing qualities only
after it is drawn through a compression/heat
process at the factory. It isn’t “sheeted” with
anything.
I know of which I speak because I, after
collecting all of the relevant information about
Depron, formed a company named
DepronUSA with Mr. Carl Crabb, my then
next door neighbor, to import Depron in
quantity to be retailed over the Internet
predominately for the RC modeling hobby
field.
We were the first in the US, and I
understand that Mr. Crabb still successfully
operates DepronUSA, as I have gone on to
form another company that will be kitting a
number of RC kit airplanes—specifically
including Tim Hart’s (Foamy Factory)
Ultimate biplane as shown in the column. We
are also negotiating to kit the 3DX for Tim,
along with his future designs.
I am writing to ask that a correction as to
the properties of Depron be made in your
magazine so that your readers are not given
incorrect information. Other than the fact that
they both are “foam,” there are no
comparisons that can honestly be made
between the two foams mentioned together.
Depron is only available in either
processed sheets of varying millimeter
thickness or elsewhere in the world in the
form of unprocessed rolls, whereas “blue
foam” has to be hot-wire cut from larger
thickness blocks to get pieces as thin as
Depron.
Also, there is absolutely no comparison in
structural sheet strength between a sheet of
standard processed Depron and a piece of
comparable thickness “blue foam.” Try it and
you will see what I mean.
Scott McKie
Chairman, Gamma Star International
(GSI)
[email protected]
I’ll try to clear up some of the “foam
issues” that have been brought up. We (Scott
and I) are in the negotiating process of his
kitting some of my designs.
In Scott’s letter, he mentions that blue
foam needs to be hot wired to get the correct
thicknesses. This is true; however, BlueCor,
or fan-fold foam, comes in 3⁄16-inch-thick
sheets and has the clear plastic coating on
both sides and does not need to be hot wired.
Depron and BlueCor are, in fact, two different
types of foam.
With that said, here we go on the foam
explanation. Blue foam is an expanded bead
polystyrene foam (similar to white “wing
core” foam), typically used in hot-wire-cut
foam core wings, which are then sheeted with
balsa and fiberglassed.
Depron is a brand name, and is only
widely available in Europe. (Something about
not meeting fire code here in the US, not that
it matters for airplanes.) All of the Depron that
is used in modeling here in the US is imported
from Europe.
We have no source here in the US that
manufactures Depron. Depron is superior to
fan fold in many ways. It is more rigid,
stronger, and lighter. Depron comes in 2mm,
4mm, and 6mm thicknesses for modeling use.
BlueCor is also a brand name. It is
manufactured by Dow and Georgia-Pacific,
and is primarily used as insulation under vinyl
or aluminum siding. This is the stuff that is
referred to as fan-fold, BlueCor, FFF, etc. and
has the clear plastic coating on both sides of
the sheet.
Fan fold is a generic term. The Dow
product (which is blue), one made by Owens
Corning (which is pink), Amocor (green), and
a few others fall under this category. The
foam is sold in 3⁄16-inch (or 3⁄8-inch)-thick
sheets that are 4 feet tall and 50 feet long. It is
then “fan-folded” back and forth into 25 4-
foot x 2-foot sheets.
A bundle that size usually sells for
about $25 and will build 10-20 airplanes,
depending on how much foam you waste
and how big your airplanes are. The foam
sandwiched between the poster board,
which goes by the names Fome-Cor and
Sturdy Board, can be used as a substitute,
but you have to peel off the paper and it
gets pricey. Still, it has its uses.
Both types of foam work well and have
their advantages and disadvantages. Depron is
superior, in my opinion. However, because it
is imported, it is much more expensive.
Hope this clears some things up for you.
By the way, I thought the article was great as
is (other than that my name was misspelled!).
Tim Hart
Arm Soar
I enjoy your magazine and look forward
each month to receiving it! Jean Pailet’s
article on the Arm Soar Hand-Launched
Glider inspired me to get some 6-pound balsa
out and build it. Since the article included a
full-sized plan, I got started.
When measuring the 1⁄4-inch wood for the
wing, I realized the plan was not full size, but
90% of full size. The 5-inch dimension for the
inner wing sections is really 4.5 inches. It
looks like a great glider, just be aware and
take the plan to Kinko’s and make the
appropriate adjustment!
Bob Peterson
Youngstown, New York
History Class
I have a problem with the cover of MA for
February 2004. The Corsairs are painted in
July ’44 colors, and the USS Yorktown has a
“Hurricane Bow” that they put on it in about
’54-’55.
I was born in ’49 and walked under the
Yorktown in Bremerton [Washington]
when they had it in dry-dock to put the
new bow on it.
Rich Border
Middletown, New Jersey
Editor’s note: We have received a few
comments from readers who have found
several historical inaccuracies in the
February 2004 cover description. To be quite
honest, we never even gave a thought to
checking that piece for historical correctness;
we just thought it was a clever use of a real
model airplane in a piece of composite art.
We are sorry if the scene depicted offends
anyone who is a student of history, and we are
especially sorry if it offends those who served
our country in the time frame captured by that
cover art. We believe that this cover does
indeed capture the spirit and flavor of the
time. We’ll be more careful in the future to
have this type of art checked for historical
accuracy.
Me 109 or Bf 109?
In the February 2004 issue of Model
Aviation, a letter to the editor stated that there
Model Aviation, 5161 E. Memorial Dr., Muncie IN 47302
Letters to the Editor
April 2004 9
Continued on page 168