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Bandicoot

by Brian Johnson

Plan No.576

The Bandicoot in flight

Plan Detail:
Plan No. 576
Price: AU$28.60 (3xSheets) 
plus P&H (AU$2.00 within Australia).
Moulded Canopy & Nose Cone: AU$27.50 plus AU$6.00 postage.

Order Details:
Order On-Line

By Phone:
(03) 9333 5100
ByFax:
(03) 9333 5099
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By Mail:
Airborne Plans Service: 
PO Box 30 Tullamarine,
VIC, Australia, 3043

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. 

 

Finished Bandicoot Close Up

 

Finished main components

 

 

 

 

 

Finished Fuselage

 

 

 

 

 

 

 

 

 

 

 

 

Cowl and Motor fitted

 

 

 

 

 

 

 

 

 

 

ready to paint

 

 

 

The Bandicoot in flight

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