Carf-Models Composite-ARF Extra 300L Instruction Manual page 16

Composite-ARF Extra 300L (2.12m/84")
techsupport@composite-arf.com
the torque of a standard servo is not enough - it
is the play in the gears which could cause prob-
lems centering, and might result in high speed
flutter.
IMPORTANT -
Servo Output Discs:
We strongly recommend that you fit metal output
discs to all hi-power servos that will have the
phenolic servo arm extensions fitted to them,
and not the standard plastic discs - as shown
here. This is because the extreme torque of the
current digital hi-torque servos can, in some
cases, strip the splines from the plastic discs -
causing instant flutter ... and probable destruc-
tion of your plane.
The phenolic arms are tack glued to the metal
discs in the same way as described for the plas-
tic type, and then secured with a couple of small
(M2) bolts and nuts. Suitable metal output discs
are available from many companies, for exam-
ple the 'Hanger 9' type, part numbers:
#HAN3526 or 3520. (photo right)
This applies to the elevator, rudder and aileron
servos in this plane.
The elevator servos are installed in the fuselage,
due to the thin stab profile. Put some masking
tape on the fuselage and carefully mark and cut
out the 2 holes to the size for your servos. If
using a standard sized servo, like the
JR/Graupner 8511/8611, then the back of the
servo cutout holes should be 152mm (6") from
the back of the fuselage, and the bottom edge 5-
6mm above the lower chine (angled corner) of
the fuselage. This position gives clearance for
the rudder pull-pull cables, which pass just
above the servo case.
Use the 3mm milled plywood reinforcing plates
to mark the holes accurately and file to shape
with a Permagrit file or similar. Rough up the
inside of the fuselage carefully, and glue the ply
plates in place inside with 30 min epoxy and
micro-balloons mixture (see photo above).
NB: Screw the servos into place with the Ø 2.9
x 13mm screws provided in the kit - not the standard screws that come with the servos.
The slots are already partly milled in the elevators for the horns, but you will need mill them deep-
er - to about 13mm (1/2") depth so that the phenolic horn fits into the balsa block in the eleva-
tors right up to the small shoulders on the horn (see photo on page 21). It is important that both
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