Drew was challenged
in the area of
It takes a while to
understand where to
use plywood and what
direction the balsa
grain should run.
The B- 25 Sunday Punch was designed in CAD.
Drew had the task of joining
the wing panels.
Photos by the author
In the end we compromised. We
dropped the retracts, flaps, and bomb
drop (at least for the first article) and we
made a blood pact that we would finish
building the Sunday Punch if it killed us.
When I was young, I took every shop
class that was offered, including lots
of drafting. As a result, when I started
working with CAD as an engineer years ago, it was easy to
grasp spatial relationships between components and views in
the drawings. However, I really struggled with how to teach
CAD to a kid who had no foundation.
Most kids today have an innate understanding of computers
and video graphics that their parents do not. We do okay when
we apply ourselves, but for most kids it is effortless. I was
shocked (yes, jealous) at how Drew instantly understood how
to lay out sketches on various airplanes and then span the gaps
between them. He told me that it was similar to the Minecraft
game that he plays online.
Additionally, CAD has come a long way. Drew missed the
DOS-based versions of CAD that I learned on. Today’s CAD is
much more intuitive, driven by descriptive icons that represent
common concepts such as Punch or Mirror. He picked these
up quickly as well. Before we knew it we had a B- 25 flying on
Where Drew was disadvantaged was in the area of materials
science. It takes a while to understand where to use plywood,
what direction the balsa grain should run, and similar issues.
I took on most of the conversion of the solid model into a
framework and ultimately a laser-cut file. This kept the project
alive and gave Drew time to solo his first RC airplane.
If you are interested in building this airplane, the plans and
kit are available from Manzano Laser Works (see “Sources”).
Construction on the Sunday Punch started with the tail
group. Our basic premise was that this design should retain
scale lines, but the emphasis was on quick building.
The stock plans didn’t include functional rudders, but we
provided a meaty center post for anyone interested in adding
this feature. The horizontal stabilizer is sturdy enough for a
light build but can be sheeted with 1/16-inch balsa for extra
strength if retracts or larger motors are used.
All of the outline parts for the tail are laser-cut and built
over the plans. The bracing is 1/8 x 3/32 balsa strip stock. When
cured, sand the tail group
parts to shape. Separate the
elevators and bevel their LEs
to allow 3/8 inch of deflection.
We used CA hinges and a
music wire joiner rod to
connect the elevators.
30 Model Aviation OCTOBER2013 www.ModelAviation.com