12 SERVO 08.2016
direction! On the next screen, we can invert the
direction of any axis of control. In my case, I only
had to invert the pitch axis (Figure 7).
The next screen will ask you to double-check
that all controls are moving in the correct direction.
Once you verify this, the transmitter setup is
complete and we can set the arming sequence. I
decided to set mine to be “Yaw Right,” meaning
that with the throttle off, placing the right control
stick to its rightmost extent will arm the vehicle.
Placing it to the left will disarm the vehicle. A
30 second timeout will also disarm the vehicle
Installing the Propellers
Okay. It’s finally time to make the quad able to lift itself
by installing the propellers. I really want to stress here that
the fast spinning propellers of a model aircraft can be
extremely dangerous. Never place any part of your body
near the quad when it is powered and armed. Even when
running at low speed, it can be difficult to see the exact arc
swept out by the propeller and get too close.
It’s easy to remove the propellers and put a scrap of
masking tape on the motor shaft if any testing
or calibration is needed — it takes less time and
effort than dealing with an injury. There are
even labs that are studying multi-rotor injury. A
You Tube video of a moving propeller impacting
a piece of pork is a good reminder of the
danger ( https://youtu.be/QQoTQZcwZWE).
The propeller nuts that came with the
motors have a hole in the end that the shank of
a hex-key or small rod can be passed through to
provide some leverage to tighten the prop nut. I
hesitate to recommend using Loctite on these,
though, as it degrades plastics and our
propellers are plastic. You can find nuts with a
nylon insert to lock them at the hardware store,
but I have had no problems using the provided
propeller nuts and simply checking them after
every couple of flights (a good habit to form
The propellers are shipped with a set of
plastic propeller bushings that adapt the
propeller to the motor shaft size. Find the
appropriate bushing for your motors and remove them from
the set. Press-fit them into the propeller recess and work
the propellers onto the motor shafts (Figure 9). Be sure the
correct propellers go on the correct motors! Most brands
mark the rotation with an “R” and “L” somewhere on the
casting. Secure the propellers with the prop nuts and firmly
Preparing for the Test Flight
We are finally ready to fly our creation! Before your
takeoff, be sure that you have registered with the FAA (see
the May 2016 issue of SERVO for details) and put your
registration information on the quad. I used a label maker
to make a weather resistant label with my registration
number, as well as contact information (Figure 10). This is
beyond what is required, but probably increases the
chances of getting your quad back if it flies off.
Make sure you have fresh batteries in the transmitter
and fully charge the main quad battery. The charger I chose
(Turnigy Compact Charger E3) is not remarkably fast, but
does the job. Again, observe the best safety practices when
charging batteries by never leaving them unattended and
preferably in a battery safe (such as http://amzn.com/
When everything is ready, wait for a nice calm day with
no wind. Take your quad out into a wide open space with
no nearby people, structures, powerlines, etc. I’ve found
Figure 8. Setting up arming is a crucial step, as
you need to remember the arming sequence to
get the vehicle ready to fly. The timeout is also a
nice feature as it can prevent you from forgetting
that the vehicle is armed if you become
distracted. Always be sure the vehicle is disarmed
before approaching it to disconnect the battery.
Figure 9. Find the appropriate propeller bushing
and press it into the recess of the propeller.
Also note which propellers are marked for left
and right handed rotation.
Figure 10. Registering with the FAA and putting your
registration information on the quad is required before you
can legally fly outdoors. Adding additional contact
information is not required, but probably increases the
chances of the quad being returned should it fly away.