From the Knox County Radio Control club, Knoxville TN
The Three Deadly Sins of RC Flying
by Jeff Procise
In the three years that I’ve belonged to the Knox County Radio Control club,
Knoxville, Tennessee, I’ve witnessed my share of crashes and even thrilled my
buddies with a few of my own. One thing that amazes me about this hobby is how
often we crash. On any given weekend, one or two members will probably lose a
airplane. What’s even more amazing is that the vast majority of these crashes
are entirely preventable.
Most crashes are caused by simple errors that we make before the airplane leaves
the ground. Eliminate these errors and you’ll have a far better chance of
bringing the model home in one piece. Here are the three most common mistakes
that lead to crashes and simple steps for avoiding them.
Wrong Model Number
Programmable radios make the sport more fun and arguably safer, too. One of the
primary benefits of a programmable radio is that it can store settings for
several models. With the click of a button, you can call up the settings for
your favorite model, complete with trim settings, end-point adjustments, servo
directions, dual rates, exponentials, and more.
But programmable radios have a dark side. If you fail to select the right model
number before takeoff, you may find yourself flying with reversed ailerons, a
reversed elevator, improper trims or throws, or other ailments. Rare is the
airplane that lands safely when the radio is set to the wrong model number.
The solution is twofold. One, remember to check the model number the moment you
switch on your transmitter and make sure it matches the airplane you’re about to
fly. Two, always check the movement of the control surfaces before flying. Even
if you forget to check the model number, you’ll almost always catch the error if
you check the control surfaces before every flight.
Having a radio set to the wrong model number is the most common cause of
reversed servos, but it’s not the only cause. Occasionally we simply forget to
program in the servo directions before flying a new airplane. Again—make it a
habit to check the control surfaces before every flight and you’ll head
disasters off before they happen. Before flying a new airplane for the first
time, get a second pair of eyes to go over it with you. If the ailerons are
reversed and you overlooked it once, you’ll probably miss it again.
Improperly Located Center of Gravity
There’s an old saying in this hobby that says “A nose-heavy airplane flies
poorly; a tail-heavy airplane flies once.” Most beginners fail to appreciate how
big a role balance plays in the performance of an airplane. Balance is important
in full-scale airplanes, but it’s even more important in RC aircraft, where an
inch or so can make the difference between a model that flies well and one
that’s unmanageable in the air.
Most construction manuals specify where the model’s center of gravity (CG)
should be located, and a model shouldn’t be considered complete until you’ve
ensured that the CG is at or near the recommended location. If necessary, you
can add a few ounces of lead to the nose or tail to achieve the recommended CG
Often adding lead isn’t necessary; you can achieve the desired CG by moving the
receiver battery backward or forward.
Be certain to check the airplane’s CG before flying it for the first time. I
usually mark the location of the manufacturer’s recommended CG with short pieces
of trim tape. That way I can check the CG even if I don’t remember precisely
where it’s supposed to be. Assuming your aircraft’s fuel tank is on or in front
of the CG, be sure to check the CG with the tank empty. Finally, if your
airplane has retracts that fold backward (like the F4U Corsair) check the CG
with the wheels up.
Deploying the gear prior to landing will move the CG forward, but it’s better to
be nose-heavy during landing than tail-heavy during flight.
Inadequately Charged Batteries
If you crave excitement, try flying your favorite airplane without charging the
receiver battery. To double the fun, don’t charge the transmitter, either. Then
you can take bets on which will fail first. Joking aside, charge those batteries
before flying, and check them at the field if you’re not sure whether they’re
charged.
Most transmitters have built-in voltage meters; I don’t fly if the voltage is
less than 10 volts—just to be safe. You can check receiver batteries with an
inexpensive voltmeter (which should be part of every flight box), or you can
install an onboard voltage indicator like the Hobbico VoltWatch. Remember—low
batteries lead to dead airplanes. This is one case where an ounce of prevention
is worth a pound of cure.
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