Foam removal method 2: blade and rotary tool.
Mark and cut the sides as before. Remove the
foam with a rotary tool. A Dremel 115 cutter
Foam removal method 3: soldering iron tip.
This works well for control linkage snakes.
Draw a guideline and trace the line with a hot
Sanding blocks and knives work well for
shaping a fuselage. Using 1.25-inch pine stock
makes the sanding blocks easier to grip. Be
sure to have plenty of spare blades on hand.
build. I rarely follow the directions
exactly. I like to personalize the build.
Building is my art.
“When I have a project on my table,
I spend hours just thinking about
the build and all [of] the different
possibilities, potential problems,
and solutions. This in itself gives me
“Before I start a kit, I can already
visualize the finished product. This, I
feel, is very, very important, so all [of]
the systems fit and work well together.
“Over the years, I have helped friends
set up ARFs that they bought, and I
usually end up irritated trying to get
the model to work to my satisfaction.
I’m going through this now, trying
to shoehorn an O.S. . 95 four-stroke
[engine] into a Sig Kadet Senior ARF for
a friend. If I would have built the model
myself, it would have been easier.
“It’s like the difference between
buying a new cookie-cutter car or
restoring your favorite classic. Which one
are you going to be more proud of?”
Thank you for the inspiration, Ken.
Now for some building tips.
My most recent build was a Magnum
Models Cobra Racer. I selected this
aircraft anticipating competent or
superior performance at some of our
scrubby little high-wind, low-lift inland
Slope Soaring sites. Almost any Slope
sailplane will fly well in great lift. Great
Slope sailplanes will even fly in crummy
The Cobra Racer’s parts layout
drawing shows an old-fashioned
large receiver, but with new, smaller,
The factory all-up weight specification
is 23 ounces ( 9. 2 ounces per square
foot of wing loading), but mine came in
at 21. 3 ounces ( 8. 5 ounces per square
foot). My Cobra Racer will take two
slugs of ballast at the center of gravity,
raising the weight to 25. 3 ounces and
29. 3 ounces, and increasing the wing
loading to 10. 1 and 11. 7 ounces per
square foot. It will float like a butterfly
and zip like a dart.
On its first slope day, my Cobra Racer
exceeded expectations. Oh, the joy of
building my own sailplanes from kits.
Foam Kit Building Tips
EPP foam kit building includes
removing foam from cavities to fit the
components and shaping the outside of
the fuselage. The classic method to make
a cavity for a battery pack, for example,
is to slice the sides of the cavity with
a long-blade hobby knife and pull out
chunks of foam with long-nose pliers. It’s
crude, but that’s all that we knew back
in the early days of EPP kits.
A more refined method is to slice
the sides of the cavity and remove the
unnecessary material with a rotary tool
cutting bit. This method is more precise,
especially at the bottom of the cavity,
but it creates foam dust that sticks to
clothing and everything else because of
Another method that is less precise
than a blade or a cylindrical cutting tool,
but free from foam grinding dust, is
using a soldering iron. It generates fumes,
so you need to pay more attention to
ventilation, but this method is well
suited to cutting the channels for
I use long-blade hobby knives with
113 Model Aviation DECEMBER 2016 www.ModelAviation.com