Don Apostolico

This arTiclE should help those
aeromodelers who don’t know what they
don’t know by documenting the first 13 of
30 major reasons why our airplanes go in.
42 MODEL AVIATION
DEFENSIVE RC FLYING DEFENSIVE RC FLYING DEFENSIVE RC FLYING DEFENSIVE RC FLYING
8. Failure to Test: Would you take your family in your car on a
400-mile trip and not check the gas gauge before you leave? Of
course not. But modelers frequently take off with their aircraft
without first checking its electrical gas tank (battery).
If a car runs out of gas, you simply pull over. If an airplane’s
battery dies, it crashes.
Many aeromodelers take their power systems for granted, and
that’s a poor attitude. Batteries are the second-leading cause of
crashes, behind pilot error.
I know the discharge curve of my batteries. When I observe a
change in this curve from the norm, I make further checks and
perform the appropriate maintenance.
Recommendation: Load-test batteries before and after every
flight.
9. Regulator Usage: Would you plug your new $3,000, highdefinition,
DLP, 60-inch LCD-screen TV rated for 110.0 volts into a
220.0-volt socket and then wonder why it doesn’t work? Modelers
do the equivalent with radio gear by installing a 7.0-volt or higher
battery in a radio rated for 6.0, or fewer, volts.
Some popular servos are rated for only 4.8 volts, with most rated
for up to 6.0. If a modeler uses a 6.0-volt battery without a regulator,
servos and receivers might not work or work intermittently, because
they are being overdriven with too much voltage.
The term “6.0-volt battery” is misleading, because 6.0-volt Ni-
Cd and NiMH batteries charge to higher than 7.0 volts and Lithium
types exceed 8.0 volts. Servos rated for 4.8 volts only can’t take 6.0
volts, even if used with a regulator. Check your servo specifications
and set the regulator correctly.
A regulator is used to step down high voltage so that the
electronics can operate within the manufacturer’s specified range.
The regulator goes after the switch and plugs into the receiver.
Failure to place the regulator in the correct place will lead to a crash;
you can’t back-charge through most regulators because of the diode.
Recommendation: When using a 6.0-volt Ni-Cd, NiMH, or
Lithium battery, employ a regulator and correctly set the output
based on the lowest recommended voltage component on the model.
10. Poor Power-System Balance: Would you buy new tires and not
have them balanced? Improperly setting up propellers and spinners
is a common source of vibration. Many aeromodelers make this
mistake and fly with unbalanced propellers and spinners and
untracked propellers.
Propeller tracking is the process used to square the propeller hub
so that the blades are perpendicular to the crankshaft. Unbalanced
spinners or vibrating propellers induce vibration in the model,
placing stress on electrical components, hinges, and glue joints, and
the engine is often blamed for being a “shaker.”
This constant pounding of the airframe can eventually trigger
electrical component, structural, or hinge failure. Cause and effect of
the crash are often overlooked, with blame placed on the servo or
switch that failed.
Beware of used engines. A pilot who has operated an engine with
an unbalanced or untracked propeller and/or unbalanced spinner will
How are the needle settings? Have a look
at the spark plug now and then. When
needles are set too rich, the electrode is
black.
When the needles are set too lean, the
electrode is white. This is a sign of
overheating. Heat is the sworn enemy of
any RC system.
When needle valves are properly adjusted,
the electrode is tan. A pilot will also notice
the absence of exhaust residue or change
in color.