tendencies while maneuvering. When a large amount of rudder
is applied to sustain knife-edge flight, most airplanes tend to
gently roll in the direction that the rudder is being held. Many
fliers will mix a small amount of opposite aileron with the
Normal Aerobatic ( Low / ) Rates 3-D ( High ) Rates
:n oitc elfe D :n oitc elfe D
Sample Travel & Expo Rules-of-Thumb
Dave Scott is a top full-scale aerobatics competitor, professional RC air show pilot, founder of the 1st U.S. R/C Flight School, and author of several RC flight training manuals. His books and articles feature accelerated training techniques that he developed while instructing more than
1,200 RC pilots during his school’s four- and five-day courses.
More information about Dave’s books and flight school can
be found at www.rcflightschool.com.
Linear = Predictable
Illustrations by the author
rudder to cancel out the rolling tendency during knife-edge.
If you’re thinking about using computerized mixing to
minimize certain unwanted tendencies, you need to first
understand that everything in aviation is a tradeoff. A mix that
a pilot puts in may help the maneuver for which it is intended,
but it may also turn out to be contrary to what’s needed during
another maneuver or cause a deviation somewhere else that
otherwise would not have existed. You must mix prudently.
The process of mixing typically unfolds when a pilot detects
some negative tendencies during certain maneuvers. He or
she then attempts to eliminate them with different mixes. As
more maneuvers are introduced, the pilot starts running into
situations where the deviation that he or she wants to remove
is actually caused by an earlier mix.
What follows are hours of experimenting to determine
which mixes stay, which need to be reduced, which need to be
removed or reversed, and when it is time to take the initiative
to correct yourself (Figure 8).
Unless you intend to only fly a few maneuvers, the most
efficient and effective use of programmable mixes is to mix no
more than 5% to 10% (15% maximum).
Limiting your mixes
to these percentages
will hopefully make
your flying easier
without having too
much impact on
other maneuvers or
causing you to
backtrack as your
Exhibit A: Holding
in left rudder
flight results in the
airplane also gently
rolling left. Mixing
a small amount of
right aileron with left
rudder cancels the
roll tendency during
Many unwanted tendencies are held in check at higher
speeds, and only show up when the airplane is flying slower.
mixes are only appropriate at certain airspeeds and throttle
settings. This partly explains why pilots who look to mixing
to take the place of developing better flying skills experience
little or no long-term improvement.
A person could spend a lifetime flipping switches and trying
to program complex mixing curves in an attempt to eliminate
unwanted tendencies, but at a certain point the returns for all
of that effort are negligible. At some point you will have to
settle for being close on your setup and focus on improving
your flying skills.
A person can travel across the country and observe fliers
involved in an endless cycle of dialing the corrections into
their radios that they could easily be making—only to have to
keep repeating the process each time conditions change, a new
maneuver grabs their interest, or a different airplane is flown.
Radio programming has become their hobby!
Often, it no longer even occurs to people that sometimes
the simplest and most effective thing that they could do to
improve their flying is learn how to make corrections. Mixes
can prove helpful, but nothing will have more impact on your
flying than your flying skills.
1st U.S. R/C Flight School
Wikipedia (Flight Dynamics for Fixed-Wing Aircraft)
AUGUST 2013 www.ModelAviation.com