surfaces using tape or covering within
the hinge line. Sealing a control surface
could solve a trim-related flight
problem. Eliminate the possibility of
trim-related flight issues by sealing
all of the control surfaces during an
aircraft build before the model is
brought to the field.
Radio manufacturers typically refer
to the travel adjustment function as
either adjustable travel volume (ATV)
or end-point adjustment (EPA). This
is a function that allows the end user
to adjust the total travel of a servo in
both directions. Properly using this
capability is mandatory!
Many pilots tend to use extremely
large servo arms to obtain large
amounts of control surface deflection.
By doing so, they actually decrease the
percentages found within the ATV or
EPA function so a specific servo will
not bind and move the control surface
beyond its physical limitations. This
practice is not the proper way to go
about this function. A servo has the
best resolution, torque, and response
when these values are maximized.
Always begin by maximizing the
travel adjustment percentages for
all control surfaces, then adjusting
the distance of the linkage to the
fastening point on the servo arm so the
control surface will not move beyond
its physical limitation. The ultimate
goal is to move a given stick on the
transmitter to the full amount, having
the servo move freely until maximum
deflection is obtained.
If it cannot move to the full range of
motion and binds at the hinge line, do
not decrease the ATV or EPA. Instead,
start to move the clevis (or ball link)
inward on the servo arm. This will not
only result in a “bind-free” setup, but
also improved resolution and more
torque from the servo.
You have now learned about some
of the setup fundamentals that
are required for a properly tuned
competition airframe. Always dedicate
time both at the shop and at the field
to evaluate an aircraft.
Attend an aerobatics competition or
a judging seminar to learn more about
proper setup and flying techniques.
The knowledge you can learn from
attending both is endless.
Please visit the IMAC website to see
if a competition or seminar is close to
you! After all, no matter how many
years you have been involved in the
competition scene, there is always
something to learn from others. This is
what competition is all about!
Until next time, fly hard!
SWB Manufacturing, Inc.
119 Model Aviation JUNE 2015 www.ModelAviation.com