Carf-Models Ultra Flash, Instruction Manual

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er as shown above. Then glue these 2 parts into the milled
slots in the front engine bulkhead as shown, using epoxy.
These will have M3 T-nuts glued to them to secure the
upper bypass later.
Trim and fit the ‘upper’ bypass. The stepped flange at the
back goes over the
outside of the carbon bellmouth, and if
it is a tight fit you can sand the Ø140mm hole in bulkhead
F6 a little. File the small notches in the back corners of the
bypass to clear the bellmouth mounting angles, and also in
each side to clear the turbine mounting. You might need to
sand the front outside edges of the carbon bellmouth a lit-
tle for the bypass duct to fit nicely over it.
When satisfied with the fit and alignment, drill Ø3mm diam-
eter through the bypass into the centre of each of the 2
small plywood blocks that you glued into the front of F5
earlier. There are small dimples in the carbon bypass
moulding to guide you on the hole position. Remove the
upper bypass, and redrill the 2 holes in the plywood blocks
to Ø4.5mm. Fit an M3 T-nut to the back of each block, with
a small drop of 30 minute epoxy. Refit the bypass and
secure it with two M3 x 12mm allen bolts and washers, screwed tightly into the T-nuts before
the epoxy cures to ensure perfect alignment (photo P5).
The bypass cover has stepped flanges that fit over the outside of the upper bypass, and it also
fits over the outside of the carbon bellmouth in F6. Trim it as shown, checking the fit on the
upper part several times to get good alignment. Chamfer the back end of the cutouts that go
over the engine mounting bracket, so that it is easy to get on and off - in case you have to
change a glow-plug at the airfield. If you fit a 116mØ JetCat with kerosene starting, then you
will have to make a small hole for clearance around the starter plug. Make sure that it is orient-
ed as shown in the photos, right at one end of the mounting bracket slot - so that it clears the
wing ! If necessary you can even mill a small clearance hole ( Ø 25mm) in the upper wing sur-
face without any loss of strength.
The cover is secured to the upper bypass with a single wrap of double-sided velcro band at
the front, as shown. These photos show 3 ‘handmade’ ply-
wood hoops glued to the upper bypass to retain the Velcro,
but production kits have CNC milled parts that give more
gluing area (inset photo). Mark where the fuel, gas and
electrical services will enter the bypass duct first, to deter-
mine the correct position of the Velcro band. Sand the
surface of the bypass as needed and glue them in place
with 30 minute epoxy.
Included in the hardware pack are some small and large
plastic grommets to protect the tubes and wires that must
enter the bypass duct for the turbine, and we strongly rec-
ommend that you use these. Carbon composite is
extremely abrasive, and electrically conductive, and can
cut through your fuel line or RPM sensor cables in just a
couple of seconds - maybe even from the vibration during
transporting your plane. Drill suitable holes, oval shaped if
14
(above) Upper bypass trimmed for
P80/P120 installation.
(below) Bypass cover trimmed
ready for final installation.
(below) View of upper bypass,
showing plastic grommets for tube
and cable protection and hoops
to retain Velcro strap. Inset is CNC
milled hoop included in kits