The Bandicoot is a mid wing
sport, aerobatic model with a fully symmetrical
wing and is designed around a .35 to .40 size engine,
it requires a four channel radio and has a fixed
undercarriage. It was a breeze to build with a balsa/ply
construction and a foam core wing. The motor is
fully enclosed in a removable cowl which makes the
model look very streamline.
I used a HP 40 Gold Cup engine
which proved to be perfect for this model. The model
has been a pleasure to build and fly, and should
not cause any problem to anyone who has previously
built a aircraft with a box type fuselage.
CONSTRUCTION
I began by cutting as many parts
as I could into kit form, fuselage sides, fuselage
doublers, plywood formers, tailplane, elevator,
fin, rudder etc. I then taped the plans to my building
bench and covered them with plastic lunch wrap to
protect them. I laid the fuselage sides down and
glued the fuselage doublers to them making sure
I made opposite sides.
Once dry mark both fuselage sides to position all
formers as per plan. As I have a fuselage jig I
sat the two fuselage sides into the jig and positioned
F2, F3, F4, F5 and F6 making sure that the centre
line of all formers were straight. Allow to fully
dry before removing.
Then I glued the 9.5mm balsa triangle
to the formers on the top and bottom, then tac glue
the 6.5mm balsa to the top of the fuselage and trial
fit the tailplane and fin to check alignment. Once
satisfied glue properly.
Then fit wing to fuselage and drill wing locating
dowel holes and fit wing bolt to trailing edge.
Then glue the two bottom fuselage sides onto the
wing and add the 9.5mm triangle balsa to match with
the fuselage. Then fit the bottom sheeting, round
off all the corners then sand to section as per
plan.
Mount the engine to the fire wall with a piece
of 1.5mm balsa between the mount and the fire wall.
That way once the cowl has been made you can remove
the balsa and you will get a perfect match of the
spinner to the cowl. Tack glue F1 to the spinner
and mount the spinner to the engine. Note right
thrust.
Cut out 12mm balsa wedges that fit between F1 and
F2 shape and glue as you go. Once completed sand
and shape till satisfied. Remove spinner and with
the use of a razor saw carefully cut cowl from firewall.
I covered the cowl with a lightweight fibreglass
cloth and resin. Once dry hollow out the inside
of the cowl to make room for the carby, throttle
linkage, etc.
It seemed pointless to me having
the engine fully cowled with an ugly muffler hanging
of the side, so I went to Gee Bee Hobbies with my
problem and Gerry showed me a J'TEK in cowl muffler
which looked like it was made for it.
Then I cut the hole out of the
cowl to fit the muffler and needle valve. Glue three
hardwood blocks to F2 for the cowl screws.
Make rear canopy block from solid balsa, hollow
out and sand to section. Once satisfied sand the
whole fuselage.
WINGS
Cut two plywood templates, one
being the wing tip, the other one being the wing
root, check for accuracy. Mark the centre lines
through both templates. I cut two pieces of polystyrene
30cm x 61cm x 7cm. I then marked the centre line
of both pieces of polystyrene and pinned the templates
on each end, lining up the centre lines and having
both templates level with the trailing edge of
the foam.
I then cut out the cores to shape
with the help of another person to make it easier.
I glued four pieces of 1.5mm balsa together widthwise
and cut roughly to shape leaving about 5mm overlap.
I made four of them, then I glued them to the
foam cores using liquid nails and put some weights
on them until the glue had dried.
Once the glue has dried sand
off balsa overhang and glue leading and trailing
edge in place and then sand smooth.
I then glued the two wing halves
together using slow cure epoxy. Lift 1 wing tip
8mm to give 0 degrees dihedral. Once dry use cutoffs
from ailerons, glue in place to support torsion
rods, fibreglass centre section of wing with fibreglass
cloth.
Make wing tips out of three pieces of 6.5mm balsa
sheet laminated together. Glue to wing tip and sand
to section as per plan.
COVERING
The model was covered in iron
on covering. The black being Profilm and the blue
being Solarfilm. The fuselage was done in four
stages, the bottom was done first followed by
the two sides and then the top.
It is a fairly easy model to
cover and the wings were done in four pieces ie.
the two bottom sides of the wing were done first
and then the top.
I fitted all the radio gear to the model as per
plan and it balanced out perfectly without the use
of lead weight.
FLYING
On the day of the test flight the weather was excellent
with virtually no wind. I got to the field early
in the morning so there wouldn't be a crowd because
the first flight of a new model makes me nervous.
I did all the preliminary checks making sure that
all the controls were moving the right way, that
the batteries were charged and finally a range check.
All systems were go. It was time to fuel her up,
put the glowplug clip on and flick the prop. The
HP 40 started second flick so without any more hesitation
the model was lined up on the run way.
I applied full throttle and the
Bandicoot screamed up the run way for about twenty
feet. Then lifting into the air two clicks of
down and one click of right trim had the Bandicoot
flying level. Now it was time for the aerobatics,
rolls, loops, inverted flying and even knife edge
was easy and smooth. With the HP flat out vertical
performance was unbelievable. With plenty of height
it was time to see if the model had any bad habits.
The throttle was reduced to idle and the nose
pointed up slightly making the model stall but
it refused to drop a wingtip. After that the model
was brought around for a landing. The glide rate
of the Bandicoot was excellent and it flaired
out beautifully for a perfect landing.
All in all the Bandicoot is a excellent aircraft
and would be a good model for someone who wants
to start of in aerobatics like the sporty forty
event.
