This shows some of the details you will need for Authentic Scale. The judges will
look at the cockpit, surface details, and colors.
The lines with the handle are used with the 2. 4
GHz controls, while the other set of lines has
the connector that is required for down-the-lines electronic controls.
A typical three-line bellcrank for throttle control
is installed on Joe Eiben’s P- 51. One pushrod
controls the elevator, while another goes to the
Joe Eiben installed a 2. 4 GHz receiver for the
flaps and retract servo on his P- 51 ARF that he
flies for general sport flying. The throttle is
controlled with a three-line bellcrank.
This shows the evolution of throttle control systems: a three-line handle and bellcrank, servo
driver, a Bill Young handle, a converted RC car 2. 4 GHz controller, and a standard 2. 4 GHz RC
Below: Dave Platt took the internal parts from
an RC car’s 2. 4 GHz system and put them into a
custom-made handle for CL Scale.
Photos by the author
Profile Scale is the same as Sport Scale, except the
fuselage and nacelles are 1-inch maximum thickness.
There is also Team Scale, which is similar to Sport
A new event for 2015 is Authentic Scale, which
demands extensive documentation. The model is
judged up close and surface detail is expected. This is
the only CL Scale event where the cockpit is judged
and the judges can walk around the model and look
at details up close.
When building a model for Authentic Scale, it is
best to look at the full-scale subject in person, take
the pictures, and document the color of the full-scale
Throttle Control Systems
There are many choices, so select the level that you
are comfortable with and have fun.
Regardless of which event you choose, throttle
control is expected in CL Scale competition. There are many
options for the throttle control system including the traditional
three-line handle and bellcrank, which has been in use for
more than 50 years. This is a mechanical system where the
handle and bellcrank are matched with three lines and only
control one function.
Electronic controls were developed in the 1970s using RC
technology to transmit the signal down the insulated flying
lines without a frequency. This popular method has been
referred to as “down-the-lines” electronic controls.
Before 2013, the CL Scale rules were specific: no radio
frequency was allowed in CL Scale, but down-the-lines
electronic controls could be used. This is why the variety of
systems that used insulated lines, such as the single-channel
Electronic CL handle, Clancy Arnold’s U/T system, and
converted radios, were developed.
23 Model Aviation JUNE 2015 www.ModelAviation.com