or JR8511/8611 (or Futaba 9351/9152), as shown in the photos. In addition we strongly recom-
mend that you use metal servo output arms, such as the 1.5” SWB ‘Double-Loc’ arms that are
shown in the photos.
We provide cnc milled carbon/ply servo mounting plates in the kit, and the photos show the rec-
ommended position - however you can fit these plates further forward if you wish. Wherever you
chose to fit them, it is important that you stiffen the fuselage at this position by laminating at least
4 carbon rovings (supplied) to the fuselage at the front ends of these plates, with 24hr laminat-
ing epoxy scuff up the fuselage to ensure good adhesion, and glue the servo plates in with slow
epoxy and micro-balloon mix. We have also provided 2 triangular balsa/carbon reinforcing plates
that are glued to each end of the servo plates as shown in the photos.
The elevator servos are installed in cnc milled phenolic plates, which are screwed to carbon/ply
plates that are already installed in the fuselage. We have included 2 different types of phenolic
plates - one pair fits the JR8411/8511/8611 servos, and the other for Futaba 9152 servos.
Note that the servos are bolted to the phenolic plate
without
using the rubber grommets supplied
with the servos. Instead the grommets and brass eyelets are installed in the cutouts around the
edges of the phenolic plate, and these are screwed to the ply/carbon plates using the 2.9Ø x
13mm sheetmetal screws provided in the kit.
The elevator pushrods are made from the 8mm Ø carbon tubes supplied, with short lengths of
M3 threaded rod and 6mm wood dowel glued into each end. Photo P8 shows the construction
technique. Make sure that you rough up the inside of the carbon tubes carefully, and glue the
attachments in with thick CA. Believe us - they will never come out ! Note that the M3 all-thread
should only project out of the carbon tubes about 22mm each end.
M3 aluminium clevises connect the pushrods to the servo arms, and M3 ball links are bolted
between the pairs of elevator horns with M3 x 20mm bolts and locknuts. Use a little Loctite to be
sure! When you have set up the throws and neutral points for both elevators, fit short lengths of
brass tube over the M3 threaded rod, with M3 nuts, and use Loctite or CA to retain. This stiffens
up the M3 all-thread and makes sure that nothing can move in flight.
Mark and cut holes for pushrod to exit the fuselage, and adjust to fit with 2mm clearance all
around the pushrods at full throws. When satisfied, trim and glue on the 2 plastic moulded
pushrod exit covers supplied. (Photo P11).
Note:
Try to always leave the stab tube fixed in one stab, and never remove that one bolt, as it
is difficult to find the right position for the stab tube again if it is removed from both stabs!
Finally add the CNC milled plywood supports for the pushrods inside the fuselage. (see photo
P12)
Rudder
The rudder is hinged to the fin with a 4mm Ø tube which passes thru’ the phenolic hinge posts
that are already installed for you. Retain the tube in the same manner as the elevator tubes.
The phenolic rudder horns are already installed for you. Connection to the servos uses the large
diameter cable, crimping tubes, M3 nuts and M3 connectors supplied.
Rudder servo set-up
The 4 servo rudder set-up is identical to our 3.3m Yak 55SP, and has been proven over several
Composite-ARF Pitts S12
8