Carf-Models Ultra Flash, Instruction Manual

Page: 29 / 44

retract unit, and insert one of the M4 x 16 allen bolts to
hold it in position. Then drill the other 3 holes, also insert-
ing a bolt to keep the correct alignment after each hole is
drilled. Remove the retract unit and open up all the holes
to Ø5.5mm for the M4 T-nuts. Using one M4 bolt and a
large washer, pull the spikes of each T-nut into the top sur-
face of the mounting rails
just a little , with a drop of 30
minute epoxy on each. Re-install the retract units and tight-
en all four M4 x 16 bolts tightly, which will make sure that
the T-nuts are perfectly aligned when the glue has cured.
With wheels retracted into the wheel-wells the bottom sur-
face of the wheel should be flush with the wing, or maxi-
mum 1mm inside it (see photos P18 and P19). This height
can be adjusted using the milled 1.5mm plywood packers
provided, glued to the retract mounting rails with CA.
Now set the alignment of the wheels using a large 90
degree set-square from the trailing edge of the wing, which
is exactly at 90° to the fuselage centreline. Set the main
wheels with a very little ‘toe-in’ (front edge of the wheel
angles inwards towards the centreline of the fuselage),
about 1 - 1.5mm only, for best ground handling. Mark
through the empty M5 set-screw hole in the oleo leg with a
felt pen, remove the oleo and grind the flat spot. Refit the
oleo legs to the retracts, check wheel alignment, and
repeat for the other set screw on each leg. When satisfied
tighten all the set-screws fully with a drop of Loctite on
them. Complete the final assembly of the wheels, brakes
and axles - securing the set screws with a little Loctite onto
the ‘flats’ ground on the wheel axles.
The supplied fibreglass leg-covers need trimming as
shown to fit into the wing - and cover the space between
the retract unit and the wheel-wells. Use a small pair of
scissors and a straight sanding block, checking several
times to get a good fit.
Note that there is a ‘left’ and ‘right’ fibreglass leg cover.
The front side of each cover is about 2mm higher than the
back side to allow for the wing profile.
You may also need to sand the inner edges of the moulded
flanges in the wing until the leg covers fit flush. The width
inside the wheel covers should be 24 - 25mm. When com-
plete drill a hole in them for routing the tubes from the
retracts, as shown above, Route the retract tubes through
the 10mm diameter holes in the wing spar just inboard of
the retract units, into the tank bay. Glue the leg-covers in
position with a little 5-minute epoxy, and then reinstall the
retract units and servo covers.
27
(above) Mark the slots on the
servo covers exactly in line with
the oleo legs, and mill as shown.
Make them at least 38mm long, so
that there is space for the brake
tube to enter the wing outboard
of the retract unit.
(above) Trim the moulded fibre-
glass leg-covers as shown to fit
into the flanges in the wing.
(below) Fibreglass leg covers
trimmed and trial installed in wing
for final adjustment. You can also
see the ply packers used to adjust
height of wheels in wheel-wells.