CARF-Models
KOBUZ-3
Instruction Manual
The CARF-Models KOBUZ-3 is the replica of one of the most famous aerobatic gliders,
built in the 60s and won numerous Glider Acro Competitions. But it is not only a “scale
replica”, it also has the pedigree of an ultra high performance glider as it could not be any
stronger, faster, more precise - and even in thermal conditions more e
ffi
cient.
The CARF-Models KOBUZ-3 is readily built. Only RC equipment (and a turbine or EDF)
must be installed in order to fly. However, a few design features are important to
understand and some advises are to be followed in order to build and fly this airplane
successfully.
1) The Wings
The CARF-Models Kobuz-3 wings are made from all carbon UD and bi-directional fibre. It
is total area vacuum sandwiched and has the control surfaces attached by “elastic
hinge”. The hinge is at the bottom of the wing, the slot at the top, and that slot has a
perfectly fitted lip installed to seal the gap. Control horns are on the top, and they do have
very specific angle and position to allow to use maximum Butterfly settings for landing,
since we have (due to performance and safety) omitted the spoilers/speedbrakes
commonly found in these gliders. The internal design consists of a multi layer main spar
and 2 rear spars for flaps and ailerons. The rectangular socket for the carbon wing joiner
is bedded in the main spar with lots of carbon. These wings are literally undestroyable in
the air and it has been tested! Servo mounts are installed and the hatches are pre-fitted.
The wing joiner is also a full carbon design with 3 foam cores. It is literally undestroyable
in the air, just like the wings.
The ailerons and flaps are set up to be used for a very powerful butterfly action during
landing. Therefore geometry of horns, linkages and servo arm positions are crucial. The
control horn positions are precisely set and glued to position and they are NOT identical
on aileron and flap. That’s on purpose. The following are most important details for
Servo
Installation:
-
Use servos which fit the side mounts well. All Servos for the Kobuz-3 are Standard Size
and should have a torque of 25 kg min
-
Always put a drop of silicone on the servo case before you finally mount it in the frame.
That silicone is easy to remove but still keeps the servo from ever so little sliding in the
mount, which could give annoying trim irregularities in flight.
-
Flap servo arm
LENGTH 18 mm, ANGLE 90 degree (vertical)
to the servo for FLAP
NEUTRAL position
-
Ail servo arm
LENGTH 14.5mm, ANGLE 30 degree backwards from vertical
for
AILERON NEUTRAL position (approx. perpendicular to the linkage)
