the servo means that a higher travel percentage will have to
be programmed into the radio because of the small (fine)
amount that each step is actually moving the pushrod,
thereby increasing the “resolution” of a given control surface
movement, leading to smoother (finer) control.
Conversely, connecting the pushrod near the end of the
servo arm sacrifices resolution and results in a coarser (abrupt)
control surface movement for each incremental step that
the servo arm moves. Of course, 3-D pilots must sacrifice
resolution in order to achieve the large travels necessary to
perform extreme 3-D stunts. Airplanes set up for 3-D are
consequently harder to fly precisely and feel less “connected”
because of the large amounts of exponential they require.
Before attaching the pushrods, you’ll need to decide whether
the airplane will be used primarily for 3-D or precision flying
and, if you’re smart, determine the optimized setup for what
you do most often.
True Control Surface Neutral
One setup mistake that almost everybody makes is lining
up the inboard root or tip of a control surface at neutral while
failing to step back and look at the position of the entire
control surface. Most lightweight wood ailerons, rudders, and
elevators are inherently twisted for part or all of their length,
so you should never set neutral using only the end of the
control surface.
You must look at the entire length of the control surface
and identify any twists or bows, and then “average” the twist
to set the true neutral position (see Figure 2). To reduce the
potential for programming errors and to simplify things at the
flying field, as a rule, always try to mechanically set the control
surface neutrals, and then use the radio to fine-tune things
when the limits of the mechanical adjustments have been
reached during setup.
Dual Rates/Flight Modes
Although not mandatory for sport flying or precision
aerobatics, it’s nice to have the options afforded by dual rates/
flight modes. “High rates” are typically set up to achieve
maximum travels for extreme 3-D flying or when taxiing
in strong winds, whereas “low (normal) rates” are set up to
provide optimum travels for takeoff and landing, precision
patterns, and aerobatics.
It is wise to put all of the dual rates/flight modes on one
switch to make it simpler to switch back and forth. It might
sound ideal to use dual rates to set up different control
responses for different maneuvers, but those who attempt to
do so often end up taking longer to achieve proficiency. That
is because instead of mastering one airplane, these pilots are
learning to fly multiple airplanes depending on the position of
the dual rates switch!
It’s no different from driving; it proves much easier to master
one consistent setup and learn to change the size of your
control inputs depending on the situation than it is to try to
juggle different rates or deal with control that is not consistent.
In short, those who most quickly identify appropriate setup
changes and early comfort use dual rates principally to switch
between precision flying and 3-D or taxi mode, and seldom
between or during maneuvers.
Tip: Page through any RC magazine today and it’s clear that
the sport is heavily oriented toward 3-D flying. Consequently,
the emphasis on 3-D tends to bias manufacturers to
recommend low rates that are less than high rates, but are
still far too much for most pilots! Pilots aiming for precision
handling will therefore almost always find it immediately
necessary to reduce the manufacturer’s low-rate percentages to
be able to takeoff, maneuver, and land comfortably.
Confirming Equal Throws!
When setting up the control surface travels or after making
adjustments, it is critically important that you physically
measure the control surface deflections in all directions (see
Figure 3). For a variety of reasons, it is likely that you will
have to program different percentages to achieve the same
control surface travel in both directions. Pilots often neglect to
physically measure all of the control surface deflections in both
directions because they assume that things are equal based on
the “numbers” read off of the transmitter.
Many pilots end up unhappy with the way their airplanes
handle, or assume that having to make numerous and/or
large adjustments at the flying field is an indication of a faulty
design. The problem is often no more complicated than
one aileron deflecting more than the other, or one elevator
half deflecting more than the other, and except for that, the
airplanes are fine.
Conclusion
The sport is full of people whose bad habits and lack
of appreciation for the fundamentals prevent them from
becoming better fliers, and therefore have little choice but to
look to elaborate programming to try to improve their flying,
albeit unsuccessfully. It is my hope that you understand that
no amount of elaborate programming can fix a fundamentally
flawed setup. Only after addressing the control setup
fundamentals that are essential to achieving a good-flying
airplane can you begin to effectively take advantage of the
more advanced programming capabilities to achieve a great-flying airplane!
On that note, next month we’ll look at how to take
advantage of exponential and mixing controls. Good luck!
—Dave Scott
1usrcfs@gmail.com
SOURCES:
1st U.S. R/C Flight School
www.rcflightschool.com
“... UNDERSTAND THAT NO AMOUNT OF
ELABORATE PROGRAMMING CAN FIX
A FUNDAMENTALLY FLAWED SETUP.”
23 Model Aviation JULY 2017 www.ModelAviation.com sponsored by HOW-TO issue
