Carf-Models Ultra Lightning Instruction Manual page 20

Mill a 4 mm diameter hole in the back of the balsa spar
box for the front plastic tube, right up against the inside of
the wing sandwich. The hole is oversize to allow for some
adjustment. As the wing construction sandwich is a bit
thicker than the door thickness you must relieve the sand-
wich above the hole a little, and also in the position for the
back hinge tube, so that the doors close completely flush.
A flat Permagrit needle file, that can be bent and then
straightened afterwards, is excellent for this job (right).
Trial fit the door and check that it closes completely flush
with the wing surface. Tack glue the outer plastic tubes into
the holes with a a drop of slow CA, and set the door align-
ment with the moulded recess on the bottom wing surface
before it cures. Add some thickened epoxy and micro bal-
loons to secure the tubes properly, and a small block of
hard balsa or ply under the rear tube (photo right). Secure
the inner tubes and the phenolic hinge to the door properly
now also, again using a small fillet of epoxy and micro. The
'L' shape bend at the inner end of the hinge pins can be
secured to the door with a drop of 5 min. epoxy, so that
they can be removed for maintenance if required.
Bolt the short BVM door cylinder to the back side of the
front phenolic horn with a small nut and bolt. This cylinder
is only just short enough, and needs to be fitted accurately
in quite a small space. You will need to cut a small slot in
the wing root rib that the inner 'ear' of the door cyclinder
attachment sticks thru' (see photo P20 and above), and
you can also carefully mill a small indentation in the foam
sandwich to give an extra 1 or 2mm of depth here (see
photo above). Make up the fixing block for the door cyclin-
der with 3 small squares of 3mm plywood glued together
with CA (cut from the 12mm wide ply strip provided). Cut
or file a slot in the block for clearance of the air tube as
shown, and mark and drill the hole for the single securing
screw now - it is difficult to do when the block is glued in
the wing!
Attach 2 lengths of air tube to the door cyclinder, and
screw to the securing block. Prepare the area in the wing
for gluing the ply block in place. Trial fit in the wing, with
the 'ear' of the attachment thru' the slot in the root rib. Tack
in place with 1 drop of thin CA and check that the door
closes flush with the wing, and also that you have clear-
ance to your wheel when the door is fully open. Adjust if
necessary. When satisfied glue the block in place perma-
nently with epoxy and micro-balloons mix.
Outer Doors and Servo Covers:
Separate the outer door from the rest of the servo and LG
cover, and clean the edges as needed for a perfect fit. Drill
thru' the cover and the lip around the recessed opening in
(above) Indentation and slot for
door cylinder, and hole on back
of balsa spar box for plastic tube.
(below) Fit a hard balsa or ply
support under back hinge tube.
(above) Small block made from
3mm ply for the door cylinder.
20