Section 15: Elevator Control System Installation - Model Tech Magic Formula 3D ARF Manual

STEP 2: INSTALLING THE CONTROL HORNS
IMPORTANT Before installing the control horns and pushrod assemblies, please refer to section 23 on page # 41 about
sealing the control surface hinge gaps. It is strongly recommended that you do this, and it's much easier to do it now than later.
PRO TIP
Before installing the control horn in the next procedure, drip several drops of thin C/A into the pilot holes and allow
the C/A to fully cure. The C/A will harden the surrounding balsa, making the mounting area stronger.
Install the control horn and backplate, using two M2 x 12mm machine screws, being careful not to overtighten them.
Using a pair of wire cutters, cut off the machine screws flush with the top of the control horn backplate.
Repeat the previous procedures to align and install the second control horn assembly onto the other elevator half.
STEP 3: INSTALLING THE PUSHROD ASSEMBLIES
IMPORTANT Both elevator pushrod assemblies are assembled and installed exactly the same. The only difference is that
the servo arm on the right side of the fuselage will point up and the servo arm on the left side of the fuselage will point down.
Because the elevator servos are mounted offset, there is no need to use a servo reverser. The two elevator servos can be
plugged together using a standard Y-harness and they will both move in the same direction.
Position one nylon control horn onto one elevator half. When
aligned properly, the centerline of the control horn should be 3/8" out
from the inside edge of the elevator half (at the hinge line) and the clevis
attachment holes should be lined up over the hinge line. The base of
the control horn should be parallel to the hinge line, too, so that the
control horn will line up with the pushrod wire.
When satisfied with the alignment, mark and drill 5/64" diameter
pilot holes through the elevator for the control horn mounting screws.
Using a modeling knife, cut away all but one arm from a "4-point"
servo horn.
Enlarge the hole in the servo arm that is 9/16" out from the center of
the servo arm, using a 5/64" diameter drill bit.
Install the 90º bend in one 6-3/8" long pushrod wire into the hole that
you enlarged, using the nylon snap keeper provided. When installing
the snap keeper, make sure it "snaps" firmly into place over the
pushrod wire.
The pushrod wire should be orientated on top of the servo arm,
as shown.
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