CARF-Models Extra 330SC (3.1m)
www.carf-models.com
13
the factory during manufacture. Hinge the rudder to the
vertical stabilizer with the 4mm Ø brass tube supplied, in the
same way as the elevators. Check for smooth movement.
You can solder an M4 metal washer onto one end of the
tube, and then secure this with a small piece of clear tape for
flight.
The rudder is a big surface on the Extra. If you want to install
only two servos, we highly recommend to use JR DS8911 or
Futaba BLS152 or BLS172. Both servo types can be fitted in
our CNC milled rudder tray, so the choice is up to you. Make
up the rudder tray from the milled parts. Prepare all joints by
sanding, and assemble as shown, using thin CA to secure all
the tabs and slots. Cut 4 small pieces of plywood (30mm x
12mm) and epoxy onto the bottom of all the servo rails.
Finally reinforce all joints with epoxy and micro-balloons
mixture. Drill the 2mm Ø holes for the 2.9mmØ servo
mounting screws before gluing the assembly into the
fuselage - it’s much easier!
Prepare the inside surface of the fuselage carefully with
sanding and clean off with de-natured alcohol (or equiv.),
and glue the complete rudder tray assembly in place with
epoxy and microballoons mixture, with a nice fillet on all
joints.
Install the servos into the rudder tray using the 2.9mm Ø x
13mm screws supplied, with the servo output shafts towards
the tail of the plane. We recommend to use full metal servo
arms (SWB or Secraft).
With the R/C switched ‘ON’ place the rudder servo horns and
align so that they are at 90° to the rudder servo tray. Now
connect the horns together with the 45mm long M3 all-
thread, two ball-links or alternatively one aluminium clevise
(q.v. Stabs), M3 bolts and locknuts provided. Adjust them so
that there is no servo ‘buzzing’ at neutral or full throw.
It's absolutely important that the two servo arms are as
parallel as possible. Any divergence will cause tensions
increasing current draw unnecessarily.
You will need to cut 40mm long slots for
the cable exits.
Mark the slots on a piece of masking tape stuck to the
fuselage, and cut them out a bit too small to begin with,
using a very sharp knife, and then adjust with a small file - all
the time checking the alignment with the rudder cables. As
only small slots are needed, it's recommendable to cross the
cables. If your servo arm is smaller than the rudder control
horn, rudder will have a bit backlash at maximum throw.
Don't worry about that. At maximum throw there is always
force on the rudder during flight by which flutter is prevented.
Position of the rudder tray
when installing DA200
Position of the rudder tray
when installing DA170 on tuned
pipes
Some measure to start with
