Carf-Models Ultra Flash Instruction Manual page 24

linkages are needed. This door also gives some speed-
braking effect during landing.
Trim the door to fit in the opening with about 1mm gap all
round. Leave the front edge of the retract opening as far
backwards as possible, as this improves the operating
angle. Normally the front edge of the opening should be
about 2mm behind the moulded-in line. Prepare the inside
of the fuselage for gluing the hinge by sanding with 80 grit,
and also the inside front surface of the door. Rough up one
side of the plastic hinge in the same way, and tack-glue it
inside the fuselage as shown, with 1 drop of thick CA.
Make sure that the hinge is level and exactly parallel to the
fuselage centreline. NB: Don't use any CA-Activator
('Kicker") as it can make the plastic hinge go brittle.
Trial fit the nosegear door to the hinge with one small drop
of thick CA, and check that it operates smoothly and stays
parallel and centred on the oleo leg in the gear up and
down positions. Using thin CA, glue 2 squares (25 x
25mm) of the 0.8mm thick plywood supplied onto a block
of the 10mm thick balsa strip to make a sandwich. Cut to
shape as shown, and sand a smooth radius on the back
corner. The block should be 25mm wide and 25mm high at
this time.
With the retract in the fully down position, tack glue this
block to the back of the nosegear door with one small drop
of CA, directly in front of the oleo, and only 2 - 3mm above
'knuckle' of the trailing link oleo mechanism (see photo
P13 and P14). Operate the retract by hand to check that
the door just clears the oleo knuckle during opening and
closing. At this point you the block will be too wide (25mm)
and although it clears the knuckle, the door will not lie flush
with the fuselage when the gear is retracted.
Remove the block from the door and sand the front face of
it, and check the fit again, until the door is about 1.5 - 2mm
(1/16" - 3/32") above the surface of the fuse-
lage in the 'closed' position. This last small
adjustment to the thickness is made by sanding
a small radius inside the back of the block with
a round file until the door lies completely flush.
This radius also keeps the door centralised on
the leg during gear operation.
When satisfied, glue the block to the door per-
manently with a 30 minute epoxy, and secure
the plastic hinge to the door and fuselage using
3 of the small (Ø2.2 x 10mm) sheetmetal
screws, tightened into pilot holes drilled at
1.6mm (1/16") diameter.
(above) Nosegear door hinge
glued and screwed in position.
(below) Nose door should have
1mm gap all round.
(above) Block is made from sand-
wich of 0.8mm plywood and
10mm balsa. Shape as shown.
(below) Adjust thickness of block
and depth of radius so that door
just clears oleo knuckle when
opening, and closes completely.
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