Set the Control Throws
The next thing that has to be done is to make sure the
controls move the correct amount.
The control throws are a measure of how far the flight controls
(ailerons, elevator and rudder) move. If the controls move too
much, the plane will respond too quickly and be difficult to
control. If the controls do not move enough, it may not be
possible to recover the plane from adverse situations or to flare
for landing. Due to the great effect the control throws have on
the way a model flies, the control throws must be checked and
corrected if necessary.
❏
1. Turn on the transmitter and receiver. Center all the trim
levers on the transmitter.
We’ll do the elevator first…
❏
2. View the elevator and stab from the end. The elevator
should be centered as shown in the sketch at the top. If the
elevator is not centered with the stab (as shown in the bottom
sketch), disconnect the clevis from the elevator control horn.
Holding the end of the pushrod with pliers, thread or unthread
the clevis as necessary until the elevator is centered when
reconnected to the pushrod.
❏
3. Place the end of a ruler on your workbench and hold it up
to the elevator. Move the elevator all the way up by moving the
control stick on the transmitter. Measure the distance the
elevator moves. As shown in the Control Throws Chart on the
next page, the elevator should move up 1/2" [13mm]. Measure
the distance the elevator moves down.
❏
4. If the elevator moves up 1/2" [13mm] and down 1/2" [13mm]
the elevator throw is correct (a variance of 1/16" [2mm] in either
direction is acceptable). If the elevator does not move up and
down 1/2" [13mm], move the pushrod to a different hole in the
control horn on the elevator. To get more throw, move the
pushrod to a hole closer to the elevator. To get less throw, move
the pushrod to a hole farther out. The throw can also be
changed by moving the pushrod to different holes in the servo
arm. Refer to the diagram below.
To get the controls to move farther (
increase the throw),
connect the pushrod to a hole farther in on the control horn,
or connect the pushrod to a hole farther out on the servo arm.
To get the controls to move less (
decrease the throw), connect
the pushrod the opposite as described above.
❏
5. Center the rudder and ailerons by adjusting the clevises
on the pushrods as necessary. Refer to the Control Throws
Chart for the correct measurements and check the throws. If
necessary, adjust the throws as previously described.
Note that pulling the elevator stick back moves the elevator
up (which, in flight, pushes the tail down, thus increasing the
angle of the wing thereby making the model climb). The best
way to keep this in mind is to think in terms of a pilot in an
airplane. He pulls the control stick back to “pull up” the nose
of the plane.
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