Lynn Boss’ Top Flite Gold edition P- 47 has throttle, flaps,
retracts, and a bomb drop with down-the-line JR direct servo
electronic controls. The model is powered with a .90-size
One of the plans I have in my collection is from the Modern Hobbycraft Products line and is
dated 1946. These Control Line (CL)
Scale plans show a Bantam ignition engine
and a 28-inch wingspan model. The aircraft
was so small that there was barely enough
room for the engine and a small bellcrank.
By 1947, the glow engine had made its
appearance, making ignition engines
In 1961, RC proportional controls
were introduced, making reed systems
outmoded. Then engine manufacturers
figured out how to make the glow engine
with throttle control. By 1964, larger
engines were available, making it possible
to fly larger models. So you may ask, “What
does all of this have to do with CL Scale?”
CL Scale pilots began using these newer
throttled engines with a three-line handle
and bellcrank, but fitting an engine, fuel
tank, and a three-line bellcrank into a small
model proved to be difficult, so designers
started making larger models. Even in the
1960s, the technology was changing the
CL models that we fly today.
CL Scale is all about making a scale
model that flies like the full-scale aircraft.
Today’s typical models are limited to
throttle only, and most do not have
retractable landing gear or flaps.
What if you wanted to build a P- 51
Mustang that could retract its landing gear,
lower the flaps, and then maybe drop some
bombs? This required several mechanical
linkages and adding additional lines. What
if I told you that you could build that
model, install a simple two-line bellcrank,
and have full control of these features?
The question is how to make these
features work and what controls are at
the handle to make them work. For some,
electric would be the power system of
choice. This is often used in RC models.
This article will discuss how to build for
CL Scale by taking advantage of items that
weren’t designed for CL. You can build for
fun and never enter a competition, or build
a serious scale model with the intention of
entering a CL Scale competition.
The growth of items designed for other
events has dramatically changed CL Scale.
A variety of retractable landing gear, servos,
electronics, 2. 4 GHz transmitters, electric
power, four-stroke engines, sound modules,
navigation and landing lights, and other
items has made it possible to do things in
CL Scale that were never done before.
In the 1960s, CL Scale pilots took
advantage of new technology and are now
at another crossroad with electric power,
by Fred Cronenwett
21 Model Aviation JUNE 2015 www.ModelAviation.com