The upturned wingtips give the
Robin S a unique look in the air.
The red flag on the end of the towline allows you to see that
you have positive separation when you release the glider.
servo screws were substituted and all of the servo-mounting
screw threads were hardened in identical fashion.
The Blanik’s manual is a compilation of 122 photo steps, but
again, each nut and bolt has a picture so it’s not that daunting.
The radio installation consists of a Spektrum AR9020
receiver bound to my DX-18G2. Hitec servos were used—
HS-5245 metal gear mini servos on the controls and an
HS-5645 standard high-torque servo for the tow release.
Taildragger RC provided a heavy-duty charge switch, a
2,500 mAh A123 receiver battery, and all of the heavy-duty,
20-gauge servo extensions.
Construction begins by installing the hinges. The control
surfaces use point-style hinges and a drop of oil or petroleum
jelly used at the pivot point prevents accidently gluing them.
The hinge areas are all pocketed, resulting in a tight gap on
the control surfaces for maximum efficiency. Our hinges were
installed using 30-minute Z-Poxy adhesive.
Pull strings are provided in the wings for the servo
installation. In order to make installing and removing the
wings easy, I ordered a set of two servo wing harnesses from
Taildragger RC. These are available in several sizes and servo
configurations and make setup and teardown a snap.
The servos mount so the top protrudes from the bottom
of the wing. I had to shim the aileron servos slightly to keep
them from hitting the sheeting on the top of the wing, but the
flap servos fit fine. The wingtips are removable for storage and
transport. That is a nice touch.
As with the Robin S, the control horns were cut to shape,
scuffed on their gluing surfaces, and installed with 15-minute
Z-Poxy. The control rods are a combination of ball links and
metal clevises and all of the control linkages were slop free.
With the wings completed, it was time to work on the tail.
Each stabilizer has an internally mounted servo that is directly
connected to each elevator half.
The rudder uses a wire pull-pull linkage (see the crimping
tip in the Robin S’s construction
section). The stabilizers and rudder
are attached to the airframe with
screws so all of them can be
removed. I used mason line and a
small weight to fish the elevator
servo cables through the fuselage
because no pull strings ware
Sharp-eyed readers will note that
I omitted the tail wheel. Flying
from grass, I didn’t feel the airplane
would benefit from the tail wheel
and it would have required more
weight in the front. During flight
testing, I didn’t have any problems
landing or taking off without it.
After the wings and tail were
done, the only steps left were the
final radio installation and finishing
the cockpit area. Even with the
battery as far forward as practical,
2. 5 pounds of lead shot mixed
with epoxy was required in the
nose to achieve the recommended
CG. The tow-release mechanism
has a preinstalled guide tube for
the towline, so it was a simple
matter to mix the lead and epoxy
and set the fuselage on its nose for
a few hours.
A basic airplane program was
used in my DX18 radio and the flaps were assigned to a slider.
Radio setup was simple and I added 20% aileron differential
and a switchable mix to add 25% rudder to the ailerons (this
mix should be off during the actual tow).
The Blanik doesn’t feature spoilers or retracts so setting up
the radio only took a few minutes. The total build time was 6
to 8 hours.
Flying the Robin S
The Robin S can be either easy or difficult to transport
because of its wing design. The main landing gear remains on
70 Model Aviation SEP TEMBER 2015 www.ModelAviation.com