In my last column, I explained how a pilot could change the response of an airplane to suit his or her particular
needs. This month, I will continue to
discuss how to obtain a proper setup for
In addition to the importance of
having an airplane react in a preferred
manner, it is equally important to
examine the various radio programming
and the linkage installation of the throttle
Many will agree that the radio
installation and functionality, as well
as the engine, are the heart and soul of
your model. I have helped many pilots
program their airplanes only to find that
some did not take the time to properly
program settings that pertain to the
I will discuss which servo should be
used for throttle control, the various
programming functions I adjust for
proper functionality of the servo (which
include sub trims, adjustable travel
volume, etc.), the need and use of two
idle positions in a given flight, and review
proper linkage installations.
The 35% Hangar 9 Extra 300 is a great choice for Aerobatics competition and a good all-around
airplane. This month, we will take a look at throttle linkage setup and various procedures
required to ensure a reliable idle.
The author prefers to use a 4-40 ball link on the
pushrod end that secures the carburetor, as well
as the servo arm.
You shouldn’t have to worry about an
inconsistent idle at any point during your
flight. After all, a dead-stick approach can
be the difference between first and last
place in a competition! Without further
delay, let’s begin!
A Potential Problem
Typically, any maneuver that requires
the throttle stick to be at idle can be
problematic if the throttle servo and
Because the Extra 300
needed a long pushrod, the
author opted to insert an all-threaded 4-40 pushrod from
Du-Bro into a carbon tube.
J-B Weld was applied to the
ends to secure the pushrod.
linkage are not properly set up. In the
2012 Basic schedule, maneuver six is
a stall turn, which is also known as a
Hammerhead; maneuver 10 is a one-and-a-half-turn positive spin. The engine could
potentially quit while performing either of
A pilot could have an idle that is set too
low. Once the airplane is rotating, either at
the top of the stall turn or during the spin,
the engine may stop. The servo linkage
may bind and result in an unpredictable
idle position, which can also cause the
engine to stop functioning. I have often
seen it happen to others!
Please use this column as a guide for
the throttle servo and the other linkages
that are located on your airframe. Many
of these principles are applicable to all
Throttle Servo Selection
When someone asks me what servos
I recommend for a competition-level
aircraft, which can be 50cc and larger,
I urge him or her to invest in a high-performance servo for all applications.
The airplanes we fly are often expensive.
Having a servo fail, even on the throttle,
can be fatal for an aircraft.
Many manufacturers produce high-
126 Model Aviation OC TOBER 2012 www.ModelAviation.com
Setting up the heart and soul of your model
by John Glezellis