One of the neatest features of the Prometheus is these L-shaped pins
that allow for quick installation or removal of the wing struts.
The removable cockpit hatch provides access to the radio compartment
to bind the AR636, as well as install the lower wing bolts and aileron
is fishing the servo wires through to
the interior. I used a pair of surgical
hemostats. It’s important to keep a
little tension on these as you slide the
wing halves into place to ensure that
you don’t trap any wires between the
wing halves and the fuselage. Aside
from possibly damaging the servo
extensions, it will make it impossible
to fully seat the wing halves. With the
bottom wing halves in place, they are
retained by one Phillips-head screw on
With the aileron servos connected,
I installed the aileron pushrods in
the same sequence as the rudder and
elevator. After adjusting them to the
proper length, they were snapped into
place on the ball links. All of the control
surfaces appear to have a positive and
The top wing halves slip into place
and are retained by two more Phillips-head screws.
The strut installation is well thought
out. A pin slides through the strut
and the strut mounts on the wings
and when properly seated, rotates 90°
into a slot. You could remove all four
pins and pull the wing struts in just a
few seconds—usually one of the most
tedious chores in preparing or breaking
down a biplane at the field.
A servo in each bottom wing drives
both ailerons on that side. Pushrods
with ball links on both ends snap into
place after they are adjusted so that all
four ailerons are flush. I was pleased to
see that everything lined up perfectly
and there was no warping on any of the
The 50-size brushless motor is already
installed and wired up to the speed
controller, so all that is required up front
is to install the propeller and spinner.
The propeller nut should be sufficiently
tight to prevent it from coming loose
in flight. I went ahead and put the
propeller on a magnetic propeller
balancer, but it was so close to perfectly
balanced that I didn’t mess with it any
I applied hook-and-loop tape to the
E-flite battery, and then set the center
of gravity (CG) per the manual. The
airplane was a tad nose-heavy, so I
moved the battery as far back as I could.
The manual states that roughly an
hour is required for assembly, but
mine took approximately 21/2 hours to
put together. That included fixing the
landing gear fairing.
I put my Hangar 9 wattmeter between
the battery and the motor and did a
power system test. With the stock setup
and the 30C E-flite battery I was using,
it measured 42 amps and 960 watts
at full throttle with a freshly charged
6S battery. This put the power loading
at roughly 150 watts per pound; not
ballistic, but no slouch either.
The radio setup was accomplished
using the control and exponential throws
recommended in the manual. I also set
up throttle cut on a switch as I do with
all of my electric models. The only thing
left was the fun part: taking it to the field
and wringing it out!
I noticed that the Prometheus
garnered even more than the average
amount of attention that a new review
model usually gets on a weekend.
Several pilots even commented that
they were thinking about getting one,
but were waiting to see one in person. It
seemed the wait was over.
Despite being short coupled, the
Prometheus taxied well on our paved
taxiway and runway. As I do with all
tail-draggers, I hold up-elevator to keep
some down-pressure on the tail wheel.
I lined up on centerline, set the controls
for mid-rates, and did one last control
direction test. With everything moving
as it should, I released the elevator and
gently added power.
The Prometheus broke ground after
approximately 30 feet and accelerated
cleanly while climbing with authority.
Some right rudder is required as power
is applied, but as long as power is
advanced smoothly, the Prometheus
doesn’t do anything scary during takeoff.
A few clicks of right trim and a couple
of down-elevator inputs were required
to get the Prometheus flying level at
3/4 throttle. The wing incidences and
the motor thrustlines appear to be well
tested because the Prometheus doesn’t
climb or descend with power changes.
Checking the CG, I pulled the
Prometheus up in a 45° upline, rolled it
inverted, and let go of the elevator. The
Prometheus arced gracefully toward the
ground, meaning it was slightly nose-heavy. If you like a neutral CG, you
59 Model Aviation SEP TEMBER 2016