BLUE FOAM—not the fan-fold variety—
has been used as a model-airplane building
material since it was first introduced to the
home-building industry.
This material has several properties that
distinguish it from other types of foam
used in modeling. It has a fine texture that
makes attaining a smooth finish much
easier. It can also be shaped with tools
commonly used on balsa. There have been
some nice models built from blue foam
throughout the years in all areas of model
aviation.
One drawback to using blue foam for
some applications has been the form factor.
It comes in blocks rather than in thin
sheets. We do have BlueCor fan-fold
sheets, but they are thicker than needed for
many projects.
Thoughts about blue foam for smaller projects
Small-Field Flying Paul Bradley | [email protected]
Also included in this column:
Dumas Brewster Buffalo
Steve Lawrie cuts thin sheets of blue foam from blocks to develop
lightweight curved structures. Steve’s homemade blue-foam-sheet V-1 Buzz Bomb.
Plastic containers make the cowls on Marc Stermer’s profile FFits flying weight is 5.7-5.9 ounces, depending on the battery used.
Steve reports that the V-1 is slightly underpowered with two
1200 mAh Li-Poly cells but comes alive on three 1100 mAh cells.
The only issue with three cells is possibly shortening the motor
life, but heck, this is a Buzz Bomb. It does not need a long life.
The airplane is definitely an eye-catcher at the flying field.
Steve has a B-17 in the works that uses his thin blue-foam
sheets. I hope he will share a picture of that project when it is
finished.
Take a look at the photo of the profile Grumman F7F Tigercat by
Marc Stermer. It was built from 1/4-inch Dow BlueCor foam. This
is becoming a common practice when building electric-powered
profile models. It is also interesting to see the Grumman Tigercat
showing up more often these days as a small-field modeling
subject.
Marc’s project has several features that set it apart. He has
adopted some of the structural-design features commonly seen in
today’s profile 3-D aerobatic models—specifically the use of a
horizontal stiffener on the fuselage and nacelles. This improves
the structural rigidity of the fuselage and adds a sense of depth in
Marc’s Tigercat.
He has departed from the more common profile models by
incorporating three-dimensional cowls. These are simply plastic
containers that have the bottoms cut out. They definitely add eye
appeal to the model and hide the motors well.
The Tigercat sports a 40-inch wingspan. This is an excellent
size that allows the model to fly well and still be comfortable in
the spaces typically used for small-field flying. The controls are
aileron, elevator, and throttle. The flight controls use a pull-pull
setup.
Power comes from two Gen-II brushless motors from Model
Aviation Engineering (MAE). Both motors are driven by a single
brushless ESC. This is slightly different from the typical
brushless electric-motor setup, but it works fine according to
Marc and the people at MAE.
The weight of the model without a battery pack is 12.5 ounces.
February 2006 87
Okay, one more flight! Little Red, an original design by Mark
Miller, is a profile model built from balsa sheet.
Thomas Blakeney attended the 2005 BEST event with his
beautiful 1/72-scale rendition of the Republic X-12 Rainbow.
Carl Hock displayed his Dumas Brewster Buffalo electric RC
conversion at the BEST event in Texas.
Marc uses a two-cell, 1320 mAh Li-Poly pack for casual flying
and a three-cell, 1320 mAh pack for more spirited adventures in
the air. The finish is Tamiya foam-safe spray paint.
One more structural note about the Tigercat: Marc used some
carbon fiber in the wings to add bending strength across the span.
He noted:
“In building the wings, I used two 1/4-inch strips of carbon
fiber epoxied vertically in the wings. The vertical strips help the
wing resist sagging. I also used some strips of carbon fiber flat
against the wings across the center joint (on the bottom). I did not
use any braces.
“The carbon-fiber spars seem to work well. I have not had any
problems with wing flexing up and down, but it does exhibit some
twisting (warping) since the motors are mounted below the wing.
02sig3.QXD 12/22/05 11:46 AM Page 87
Tigercat. They hide the motors nicely.
A nice rendition of the 1942 Modelcraft Commando. Mark Miller
updated it for RC and electric power.
Modeler Steve Lawrie has bridged the
gap between blue-foam blocks and thin
sheets. He planned several new projects
that were to be smaller in size. He decided
that he wanted to use fairly thin sheets of
blue foam as the building material, which
would let him develop curved structures
and take advantage of the foam’s
properties.
Steve has developed a process for
cutting thinner sheets from blue-foam
blocks. Typically his sheets are 3/32 and 1/8
inch thick. To give you an idea of what
projects he is up to, take a look at the
photos. You will find a neat V-1 Buzz
Bomb.
The V-1 has a 25-inch wingspan and
uses a Grand Wing Servo EDF40 fan unit.
The model’s overall length is 29 inches and
86 MODEL AVIATION
Although the wing will twist when you
run the motors up to maximum speed
statically, it doesn’t seem to affect flying.”
Thanks for sharing your nice profile
Tigercat with us, Marc.
More offerings from Mark Miller: In my
October 2005 column I recounted a nice
scratch-built model from Mark Miller. As an
accomplished scratch builder, he has a few
more models in his hangar and has shared
some with us for this month.
One is his Commando, built from 1942
Modelcraft plans. He wrote:
“The Commando was updated for RC
and electric power but otherwise I stuck
pretty close to the plan configuration. I
originally had a GWS EPS 350C (shown in
the picture), but because the airplane was
tail heavy, I swapped it out for a 400. It was
still tail heavy and it’s taken a few iterations
to get that airplane dialed in.
“With a 52-inch span and wing loading
of less than 6 ounces per square foot, it’s
much happier in very calm conditions. My
preferred way to fly it is to get it up to
altitude, trim it for a wide circle, cut to
roughly one-third throttle, put the
transmitter down, and just let it free flight
for a while.”
A nice model, Mark!
In addition to his vintage Commando,
Mark sent a picture of a model of his own
design. Called the Little Red, it is a neatlooking
profile airplane built from balsa
sheet. He wrote:
“I’ve been having a blast with this little
airplane. It’s my own design: all balsa with a
formed-sheet wing. With the struts, it’s
turned out to be very robust—okay, there
have been a few ‘incidents.’ I spent more
time painting it than building it.
“At 7 ounces and approximately one
square foot of wing, a little Feigao brushless
motor, and a three-cell 340 mAh Li-Poly
pack, it’s nicely overpowered and quite
responsive. It’s my ‘okay, one more flight’
airplane.”
Again, nicely done, Mark. I sure see why
Little Red is your one-more-flight airplane.
For those who like to build from kits, I
want to pass along word that Dave Diels has
added several new models to his excellent
line of kits. If you are unfamiliar with Dave
Diels kits, they are for high-quality balsa
models intended for the rubber-powered FF
community. That type of kit is also perfect
for conversion to small-field RC flying.
The new kits from Dave include the
Curtiss P-40B/C Warhawk and Nakajima
Ki-84 Frank. Both feature 18.5-inch
wingspans. That makes them ideal for the
more compact venues or indoor flying.
The neat gear you have been seeing in
Dave Robelen’s column is perfect for use in
models such as those offered by Dave
Diels. For contact information regarding
Dave Diels kits, please see the source
listing at the end of the column.
Seen at the annual Best Electrics of
Southwest Texas (BEST) fly-in was a
small, multimotor model by Thomas
Blakeney. He has been featured in this
column in the past for his innovation and
workmanship.
Thomas outdid himself at the 2005
event held north of Houston, Texas. His
accomplishment this time was a wonderful
rendition of the Republic X-12 Rainbow.
In Thomas’s eye, that is the most beautiful
full-scale airplane ever built.
At 1/72 scale, his model certainly does
justice to the prototype. It is carved from
blue foam and features four Mabuchi M20
electric motors. The energy source is a
two-cell, 250 mAh Li-Poly battery pack.
The motors are wired as two pair of series
connections in parallel, so each motor
only sees the equivalent voltage of one
cell.
The flying weight is roughly 4 ounces.
With a wingspan of 22 inches and all those
propellers spinning with full enthusiasm,
that little Rainbow looked great in the air.
Thomas is planning to build a larger
version of this attractive airplane in the
not-too-distant future. I hope he will send
me a picture when it is finished and flying.
As usual, nice work, Thomas.
Carl Hock and his converted FF Dumas
Brewster Buffalo were also at the BEST
fly-in. The model uses a standard GWS
IPS motor/drive. It is nice and light and
looks great with that skillfully applied
camouflage paint scheme.
The markings are those Finland used
when it employed the Buffalo as the
country’s primary fighter aircraft. Dumas
kits make excellent RC-conversion
subjects for small-field flying.
I have come to the end of this installment.
Please feel free to drop me a line via Email
or through the regular mail. My
address is 32238 Spinnaker Run, Magnolia
TX 77354.
I would like to see and share what you are
creating during this building season.