Torque rods are a simple way to create hidden aileron linkages. Here,
music wire is used to drill holes for the torque rod.
The torque rod is created by bonding a wire crank to each end of a
tube. Here, the aileron crank is ready to be epoxied into the tube.
Aileron Torque Tubes
Builders have options for how to control ailerons. One is
to mount a separate servo and short linkage near each of the
ailerons. Alternatively, a single servo hidden in the center of
the wing can control both of the ailerons.
When a single servo is used, the linkage can be a set of rods
that slides into a sheath. Commonly called Sullivan rods, these
linkages usually emerge from the wing near the aileron control
A third option is to build a pair of simple bellcranks, known
as torque rods. I’m a fan of torque rods because they are low
friction, easy to adjust, and hidden inside the wing and the
The torque rods in the M. 20 prototype were made from
1/16-inch steel music wire rod and 1/8-inch carbon-fiber tubing.
The wire was cut and bent to form two 90° angles. The
carbon-fiber tubing was cut to length with a razor saw.
Begin the installation by drilling holes through the ribs to
cradle the carbon-fiber rod. A length of music wire makes a
nice, long drill bit after clipping off its end to make it sharp.
Twist it through each of the ribs between the servo and the
aileron then open the holes with a small rat-tail file until the
carbon-fiber tube slips into place.
Next, roughen the ends of the wire cranks and then epoxy
them into the carbon-fiber tube. Roughening the wire is
critical to the strength of the epoxy bond. Each end of the
carbon-fiber tube gets one crank. The one at the aileron points
horizontally toward the tail, while the one at the servo stands
An arm made from aluminum tubing connects the torque
rod to the servo. Flatten one end of the tube with a pair of
pliers then drill a hole for the Z-bend of a control rod to slip
through. Epoxy this arm onto the vertical end of the torque
31 Model Aviation SEP TEMBER 2015 www.ModelAviation.com