The complete wiring for the receiver, battery, and retracts with the
HobbyKing landing gear door sequencer are shown. The two servos
would be used to open and close the gear doors.
Devices such as this landing gear door sequencer from HobbyKing are
plugged in between the receiver, the door servos, and the retracts to
control the the gear door operation sequence.
The Great Planes
film was removed
so wing fillets,
landing gear doors
could be added.
The model was then
painted. The size of
the cowl makes it
difficult to install a
You can take an existing RC car transmitter and add a metal
structure to attach flying lines. Modeler Dave Platt took all of
the guts out of an RC car handle and made his own CL handle
using those parts. Some modelers hold the RC car handle
in their left hand and use the trigger to fly with a standard
stunt handle with their right hand. Another option is to use a
traditional RC transmitter clipped to a belt, with a standard
stunt handle for the elevator.
CL Scale is all about mechanical or flight options that are
performed during a competition flight. When researching your
favorite aircraft, you will figure out which flight options can be
Retractable landing gear has been around for many years, but
has recently gone through some major changes. Air-powered
systems required a valve, air tank, servo, and retracts. Mechanical
retracts involved a servo retracting the gear with a pushrod.
Electric retracts are now available and act like servos because
they have an electric-powered jackscrew built into the retract
unit and they plug directly into the receiver. Install the 2. 4
GHz receiver, plug in the electric retracts, and you are done.
A P- 51’s landing gear would need a servo for each gear
door, gear door sequencer, and the electric retracts. Although
setting up and installing this gear is still not easy, the number
of linkages that were required in the past has been greatly
The gear door sequencer is an electronic device that plugs
into the receiver and does all of the timing for the gear doors
and retracts. Some aircraft, such as the B- 17, don’t have gear
doors and only require a receiver and electric retracts.
Flaps are easy to add with a standard servo and pushrod.
I use the end-point adjustment on the RC transmitter to
control the flaps’ up and down position. Servos can control
other features such as the bomb bay
doors and bomb drop.
Take advantage of navigation, strobe,
and landing lights by installing a simple
wire harness and an electronic board
that plugs into the 2. 4 GHz receiver.
It is controlled by a switch on the
The LED lights are installed at the
wingtips and controlled when the
navigation lights are turned on and off. I
recently purchased one of these units, and the deluxe version
turns the navigation lights on and off by moving a toggle
switch on the transmitter.
Flight options that can be used include touch-and-go, taxi,
overshoot, and aerobatic maneuvers if the full-scale aircraft
was capable of aerobatics. Duplicate how the full-scale aircraft
was flown. This means a loop can only be flown if the full-scale
airplane was capable of performing it.
Powering the Model
Now let’s discuss how to power the model. There are
myriad choices of motors and engines available including two-stroke glow engines, four-stroke engines, electric motors, and
turbine jet engines. Turbine jet engines have been used in CL
Scale, but a builder would need to research this power system
before considering that option. An AMA turbine waiver is also
A two-stroke, glow-powered engine is easy to use except
for trying to hide the muffler. A four-stroke engine has a great
sound and works well.
Electric power has been getting more attention because LiPo
batteries and motors are widely available. The size of the LiPo
batteries can vary, so determine the battery size needed before
24 Model Aviation JUNE 2015 www.ModelAviation.com