Jabiru J450, Руководство конструктора, Страница: 24 / 343

Jabiru J450 Constructors Manual
Pre-Paint>Fuselage>Fit ventral fin and trim horn
Tuesday, April 6, 2010 24 of 343
Fit the ventral fin
Use a chalk line to mark the fore and aft centreline of the fuselage.
Lay the ventral fin on the rear of the fuselage and seat it so that it matches the curve of the
fuselage, then check that the fin is centred at the front and the rear and tape it in place. Drill
3/16” holes though each of the marked locations in the ventral fin mounting lip and through
the fuselage. Remove the ventral fin then enlarge the holes in the fuselage to 13/64” and use a
fluted wood drill bit (pictured right) to recess the hole so that the lip of the insert sits flush
with the surface and then tap each hole to a 1/4” UNC thread.
Use a screw and spacer (shown above right) as a tool to place
each insert. Before fitting the insert put a single drop of super-
glue onto the outside thread and then screw it into place.
Fit the trim horn
Sand away any remaining gel coat and roughness from around the trim horn mounting area.
The trim horn is slightly offset from the fuselage centreline so it will be necessary to sand the
foot of the trim horn so that it will sit completely upright when it is mounted. Sand the sides
of the trim horn at the same time so that the glass fibre cloth will bond correctly.
Mix up a small batch of 5-minute Araldite and
flock and coat the foot of the trim horn, then place
it on the marked line and use a length of tape to
hold it upright. Put masking tape over the threaded
inserts nearest to the trim horn to prevent flock
getting into the threads.
When the Araldite/flock mix has cured apply a small amount of resin and flock to make a
smooth radius at the foot of the trim horn and then apply 3 layers of AF303 glass fibre cloth to
each side of the trim horn. The bag labelled “Trim Horn” contains 2 sizes of glass fibre cloth:
the larger pieces (100 x 170) go on the side nearest the fuselage centreline. Leave to cure
overnight. The next day any excess cloth can be trimmed away with a sharp knife.
75 x 170
100 x 170