Carf-Models Ultra Lightning Instruction Manual page 16

when all holes and pins line up and fit nicely, apply a little
slow epoxy to each pin, push into the holes in the front of
the hatch, and then install the hatch and tape it down firmly
until the glue has cured. Additional glue/micro-balloons
mixture can be added to the ends of the pins that project
inside the plywood in the hatch afterwards, and any excess
carbon rod cut off.
When the front hatch fixing is completed you need to drill
the holes for the 4 bolts that secure the hatch. Because it
is difficult to drill accurately through the curved outside sur-
face of the hatch, turn it over and drill 4mm diameter from
the inside thru' the ply plates in the hatch and the fibre-
glass outer surface. Position the holes about 13mm from
the edge of the hatch, and make sure to drill vertically.
Tape the hatch firmly in exactly the correct position on the
fuselage and drill 4mm Ø back thru' the holes, from the
outside, to transfer the positions to the plywood plates in
the fuselage. Once again, make sure that you drill accu-
rately and vertically, as any misalignment of the holes will
distort the hatch when the bolts are tightened. For best
alignment we suggest you complete the back 2 fixing bolts
and T-nuts first, before the middle two.
Enlarge the holes in the fuselage plates only to 5.5 or 6mm
Ø for the T-nuts. Enlarge the holes in the outside surface
of the hatch to 7mm diameter, to fit the bolt heads. Fit the four M4 T-nuts under the fuselage
plates and use a spare M4 bolt and large washer to pull the spikes into the ply just a little. Add
30 minute epoxy to secure each T-nut. Before the glue has cured, refit the hatch and insert the
M4 x 25mm bolts into the T-nuts and tighten, checking for good alignment. Short lengths of
tubing stop the bolts coming out and getting 'lost', as per the wing bolts. You can also add a
couple of small location tabs in the side-rails of the hatch to correct any slight mis-alignment,
using the phenolic strip supplied, in the same manner as seen on the side-rails of the cockpit
canopy frame.
Depending on your turbine set-up and installation, and the ambient temperatures you fly in,
you can increase the cooling airflow thru' the fuselage and around the exhaust ducting by cut-
ting a couple of slots (approx. 35mm x 80mm long) in the bottom hatch. Radius the corners to
prevent any tearing of the composite skin. You should glue a fine mesh on the inside of the
hatch, covering the slots, to prevent stones and debris getting into the fuselage (photo P19).
Tail Skid
If you should accidentally over-rotate during take-off or landing, the tips of the stabiliser, and
the elevator horns, could touch the runway due to the stab's anhedral. This especially likely if
you use smaller wheels than the ones we supply in our optional landing gear set.
To prevent any possible damage on the prototypes we installed a small 'sacrificial' tailskid,
using a length of bicycle spoke that fitted tightly into a short length of brass tube epoxied into
the the back edge of the ventral fin. Of course this is just an optional item, and there are many
methods of ensuring that the stab tips are not damaged on the runway surface.
(above) Drill holes from the inside,
fit the hatch and re-drill from out-
side to transfer holes to the ply
plates in the fuselage.(below)
Rear hatch fixing bolt & T-nuts.
Also shows a Stab fixing plate and
T-nuts, factory installed.
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