The undocumented feature that I missed at this
step was to first remove the black plastic film
from both sides of the plastic motor mounts.
Assembly of Boom Arms to Chassis
Plates ( 20 minutes)
Attach standoffs to the top chassis plate
which is identical to the bottom plate. Using
standard 4-40 hardware and nylon spacers,
attach the arms and feet to the chassis plates.
In my model, both red arms face forward —
important for flying and for properly orienting
the onboard flight computer.
Although not necessary, I also attached the
top plate, just to make certain everything fit
properly, as shown in Photos 8 and
the top plate when you're satisfied everything
fits as it should.
Layout of ESCs ( 30 minutes)
The quadcopter is a symmetrical beast, and
that symmetry should be reflected in the
alignment and positioning of the four ESCs. The
goal is to maintain the center of gravity and
balance point in the center of the structure. So,
treat each of the four triangles formed by the
aluminum arms and the bottom plate
I used tie wraps to experiment with
different ESC and wiring configurations, and
ended up with the ESCs tucked into each apex
of their respective triangular spaces, with the
ESC flat against the bottom plate (see Photo
10). Note shrink wrap is only loosely applied so
that the signal connections can be changed
later during setup.
Programming and Prep
of the ESCs ( 10 minutes)
Although this is supposed to be a rundown
of the physical build, this is an opportune time
to program the ESCs. We could wait until later
and spend an hour fiddling with the R/C
transmitter or use the Turnigy programming
card, available from Parallax (see Photo 11).
The card enables you to program ESCs with
parameters such as type of battery, cutoff
voltage, timing mode, startup mode, and
others that won't make sense until later. All you
have to do is set the LEDs on the card to match
the table in the HoverFly Open Board manual
for each of the four ESCs and you're done. It
just takes a few minutes per ESC, but it saves
an hour or more of fiddling. More than worth
Photo 5. Motor mount assemblies with motors attached to bases
and nylon spacers attached to tops.
Photo 6. Side view of motor, motor
mount, and aluminum tube.
Note attachment of leg in the lower left
corner of the photo.
PHOTO 7. Completed motor arm
assemblies. Red arms are for the front
of the craft.
SERVO 09.2012 47