The author’s scratch-built Profile Scale B- 29 has electric power and 2. 4 GHz controls for the throttle. The
96-inch wingspan model weighs 13 pounds.
These Great Planes Combat
ARF models were converted to
CL Scale and use a Tactic 2. 4 GHz
radio for throttle control. The P- 40 has iron-on film covering and electric
power. The Spitfire (top) uses a traditional glow-fuel-powered engine.
electric retracts, and 2. 4 GHz radio control. Using 2. 4 GHz for
the throttle and other features was approved for CL Scale and
CL Navy Carrier in 2013. The elevator must be controlled by a
bellcrank and mechanical pushrod, but all other features can be
controlled by 2. 4 GHz.
Getting Started in CL Scale
When starting a scale model, choose an aircraft that has
a special meaning. The big question is what size of model
you want to build. Models are traditionally built without a
removable wing and generally have wingspans of 55 inches
or smaller. If the wing can be removed for transportation, the
model can be built larger and still fit in a car.
I like to keep my models’ weight between 3 and 15 pounds.
The weight limit for competition is 20 pounds. Models with
a 40-inch wingspan ( 3 to 4 pounds) will generally have small
wing areas and will be limited to throttle only. If you build a
model with a 55-inch wingspan ( 6 to 7 pounds), the wing area
can carry more hardware, such as retracts and flaps, without
If you are building a model with a 65-inch wingspan, it
can carry even more hardware and have plenty of room for
details. Models with a wingspan larger than 75 inches are more
difficult to assemble and transport to the flying field, but have
no problems carrying hardware to control the flaps, retracts,
and other features. Smaller models are easier to handle at the
field, but larger ones tend to fly better.
I like to build CL Scale models in the 55- to 70-inch range
for competition. Larger models penetrate the wind better
compared with smaller models.
If you have ever looked for a CL Scale kit and couldn’t
find one, it’s probably because there are few available today.
Because of this, pilots have been converting RC plans, kits,
and ARFs to CL models for many years. If it has wings, weighs
less than 20 pounds, and requires a 1. 25 cubic inch or smaller
engine, it can be flown in CL Scale competition. An ARF can
be flown in CL Fun Scale or Team Scale because neither event
has a Builder-of-the-Model rule. All other CL Scale events
require that the pilot build the model.
If the model will be flown for sport, it can be built from
an ARF, kit, or plans and the scale markings do not need to
be accurate. I use this type of model for practice and general
flying at club events.
In CL Scale competition, half of the score is based on the
static score. The judges compare the model to the modeler-provided scale documentation and determine how well the
aircraft matches the full-scale airplane. Scale documentation
contains the following: three-view drawings, color information,
markings, photographs, and general information about the
A key feature is the airplane’s outline. The three-view
drawing shows the correct
outline, and any deviation by
the scale model will result in
a lower static score.
In Sport Scale, the modeler
is allowed eight pages of
documentation, so it has
to be well organized and
not confusing to the judges.
The layout of the scale
documentation is critical in
getting a good score. Only
provide the information
the judges need to compare
the model to the full-size
Choose the three-view drawing you plan
to use before you build.
If the model is flown in
competition, select the event in which you want to fly to
determine how much scale documentation is needed and
how much detail is required on the model. Fun Scale has the
least amount of documentation and detail on the aircraft.
Sport Scale requires more documentation, but the cockpit is
22 Model Aviation JUNE 2015 www.ModelAviation.com