Main Gear Doors - Carf-Models Ultra Flash Instruction Manual

Main Gear doors:

Actually these are not really gear doors - just covers over
the main oleo legs (see photo above). Mark the servo cov-
ers as shown and mill 17mm wide 'U' shaped slots in each,
38mm long, for clearance of the oleo leg when the gear is
down.
Sand the milled parts to fit inside the fibreglass leg covers
in the wing, with about 1mm gap either side. Make up 4
more sandwich blocks (22mm wide and 25mm high) from
the 10mm balsa strip, with the 0.8mm plywood glued onto
both sides. Sand the rounded shape in each block as
shown in the photo (right), using a Dremel sanding drum
which exactly the correct diameter. Carefully drill a 3mm
diameter hole in each block for the brake tube. It's a good
idea to strengthen the soft balsa block in this are with thin
CA before drilling, as it stops the wood breaking out. Don't
make the holes too big - the supplied brake tubing should
be a tight fit in these holes so that the oleo leg pushes the
excess tube into the wing when the gear is extended,
rather than allowing it to bend and kink outside the wing
surface which could prevent proper gear operation.
Adjust the thickness of the 4 blocks by sanding, so that the
'doors' will lay flush with the bottom surface of the wing
when they are glued in place. Wipe any oil or grease off
the surface of the oleo legs with Acetone, or similar, and
tack glue 2 blocks to each leg with a drop of thick CA.
Sand the inside surface of the doors, and glue to the
blocks with a thick 30 minute epoxy and micro-balloons
mixture - to give you time for final adjustment before the
glue cures. Keep the end of the leg nearest to the retract
about 4 - 6mm away from the edge of the servo cover for
clearance during operation. Reinforce the CA joint between
the blocks and leg with 5 minute epoxy. Don't use a very
strong glue for this, or the doors could be damaged in a
bad landing. It is better that they come off the legs !
When the glue is hard, install the brake tubing though the
pre-drilled holes and connect to the nipples on the back of
the wheel brakes. Mill a small clearance hole, or slot, in
the upper end of each 'door' for access to the M5 set-
screws that secures the oleo legs to the connecting pins.
Route the brake tube through the hole in the plywood rib
outside the landing gear mount, and then through the oval
hole in the spar with the servo extension cables.
(above) The blocks to support the
gear doors are 10mm balsa strip
and 0.8mm ply sandwich. Shape
with a Dremel sanding drum.
(below) The blocks are glued to
oleo legs with CA.
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