with the manual. The instructions call for an offset on the
aileron servo arms—instead of 90° to the servo, the arms are
slightly canted forward at neutral.
I could see the reason for mechanical aileron differential,
but because the pushrod came in at an angle—combined with
the fact that many glider-capable radios have a built-in mix
for aileron differential—I decided to install the servos with the
servo arm at 90°. This was a good decision and I’ll explain why.
There are pull strings installed in the wings to route the
24-inch aileron extensions through. Even with the strings, the
thin airfoil makes this an exercise in patience. The procedure
for installing the aileron pushrods in the manual didn’t work.
I had to bend them in an elongated Z-pattern to get them
installed and working without binding. It took me more than
21/2 hours to get the ailerons properly working.
Flap servo installation is similar to that used for the ailerons
with the exception that the flap servos have the control horn
on the top of the wing. This provides the best mechanical
advantage and prevents blowback of the flap surfaces. The
manual fails to mention extensions for the flap servos, but they
are correctly listed in the required parts section and pull strings
are provided. It took me two more hours to get the flaps
The Mystique’s flaps are set up to give approximately 25° of
throw. This isn’t much by sailplane standards, but the design
team told me that the intent was to keep the flaps out of the
grass during landings, which could strip or dislodge the flap
I prefer to have more flap travel than limiting throw in
the radio, so I made tunnels in the wing’s TE. If you decide
to go this route, make sure you pull the flaps back up before
touchdown. If you are new to full-house gliders, use them as
designed or limit the travel in your radio until you have more
When I felt that all of the control surfaces were properly
rigged, I used Z- 42 blue threadlocker on the jam nuts.
The final step was to attach the linkage covers to the wings
with Formula 560 canopy glue and blue painter’s tape. Cut
these to a rough shape and sand them to their final dimension.
Scissors made for RC cars work well for vacuum-formed
plastic parts such as these.
Installing the Spektrum A4020 servos into the fuselage and
rigging the rudder and elevator servos was straightforward. The
elevator is aligned with the outline molded into the fuselage.
The rudder should be centered when you’re done.
When I was finished with the pushrod installation, I noticed
flex in the long pushrod runs. A plywood former anchors
the pushrod guide tubes, but it’s far back and any moderate
pressure on the control surfaces was enough to get the rods to
flex inside of the fuselage.
I remedied this by using a powerful magnet to pull the
pushrod against the fuselage, and then applied epoxy mixed
with micro balloons to glue the guide tubes to the fuselage.
I used a wooden dowel to apply the epoxy so that the tubes
were anchored in the middle of the two formers. Horizon
Hobby has since resolved this by further supporting the
A small LED flashlight attached with double-sided tape
and pointing toward the tail made things easier to see while
working in the tail. With an aileron-equipped airplane, the
rudder pushrod flex might not be a big issue, but flex in the
elevator pushrod could result in problems controlling the
aircraft at higher speeds.
The top-mounted flap linkage gives maximum mechanical advantage to
prevent surface blowback during flight. The author slightly notched the
TE to get more flap travel.
Until this point, all of the assembly steps have been
common to whichever version you are building. If constructing
the Mystique as a glider, the nose cone and towhook are
provided in the kit. Simply install the nose cone, attach the
towhook, balance the model, and set up your radio.
You will have to add plenty of ballast because you must
replace the weight of the motor, ESC, and battery. The
instructions suggest filling the nose cone with lead shot mixed
with epoxy before installing it.
I’m powering my Mystique with an E-flite Power 25
brushless engine. The shaft needs to be reversed and the
instructions are provided. Instead of tapping the shaft through
with a hammer, I used a block of wood with a hole drilled into
it and my drill press to push it through, and made sure I was
pushing the shaft straight.
One of the nice things about using all E-flite components
is that you simply have to follow the color-coded wires for
everything to correctly work. Because I needed to reverse the
motor shaft for the Mystique, I also had to reverse the rotation
of the motor. To do this, I switched two of the wires from the
ESC to the motor. I have black to black, red to blue, and blue
to red. The motor now runs in the correct direction.
The default of the E-flite ESC is “no brake,” so you also need
to reprogram that option by following the setup instructions. I
used “medium brake” to keep the motor from windmilling the
propeller throughout the flight.
Take care when assembling the folding propeller. A tapered
portion must go against the motor and it’s possible to put
everything together backward. Don’t launch the spring clips
AUGUST 2013 www.ModelAviation.com