48 SERVO 11.2016
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 tighten.
Preparing for the Test Flight
We are finally ready to fly our creation! Before your
takeoff, be sure that you have registered with the Federal
Aviation Administration (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
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
that using community soccer or football fields in the off
season with permission works well. Place the quad on a
level surface and plug in the battery. I ultimately secured
my battery with a strip of Velcro™on top of the deck to
make it easy to get to for testing, and secured the deck
down with some Velcro straps for good measure.
Getting in the Air
Once the quad is powered up, power-on the
transmitter and take several steps back from the vehicle.
Check that the trim settings are centered on the LCD
screen. With the throttle all the way down, move the yaw
stick all the way to the right. This will cause the LEDs on the
top of the flight controller to change their flashing pattern.
This indicates that the quad is armed. Gently advance the
throttle and make sure all the motors are spinning up. We
are now ready to take off!
Orient yourself with the quad, facing the same right
and left direction. You should be facing the rear green
motor mount. Slowly push the throttle up until the airframe
just begins to lift off the grass. If it is trying to drift in one
direction, you can counteract with small control inputs.
Continue to increase the throttle until you have successfully
cleared the ground. Making continuous small adjustments,
try to hover. This is a skill that will take some time to
develop, but is essential to being a good pilot.
You can try to go forward, backward, left, and right,
but only make very small movements on your first voyage.
Finally, gently reduce the throttle until the quad begins to
descend. Hopefully, you will make a gentle touchdown with
a minimum of side-to-side movement when you land (lateral
velocity in aerospace lingo). Disarm the quad by placing the
throttle at the bottom and holding the yaw stick to the left.
You just completed your first flight!
Learning to fly can be a difficult process, but patience
and persistence are the only way to succeed. There are a
plethora of videos online offering tips that are good to
watch during your lunch hour. I’ve also posted a video
showing the flight of the quad with no further
modifications made ( https://youtu.be/l YqCfuLYOS8).
Once you are comfortable with basic hovering and
flight, you can begin to learn how to use the yaw control,
and get a feel for flying in different orientations. Just be
sure to keep safety first and stay below the 400 foot
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.
OpenPilot and LibrePilot
When researching different flight controllers and
flight controller software before doing this build, I
found a lot of references and even hardware
stamped with the OpenPilot name. The OpenPilot
website was down, though, and the forums
inaccessible. I also saw references to LibrePilot that
had software which looked very similar and
supported the same hardware.
Turns out that in June 2015, there was a rift in
the OpenPilot community. Many of the core
developers made a fork of the project called
LibrePilot with the idea to be open to all
contributors and governed by a board of members
keeping a steady course for the project.
The LibrePilot website and documentation are
still a work in progress, but should be considered as
the source for all official information and downloads
of the software.