Gently puttering around in the sky, coming to grips with primary control functions is what the Wallaby is all about.
Herešs a simple, 3 channel R/C low wing sport/trainer model designed for small motors.
Readers of Airborne magazine will recall the WOMBAT featured in issue #153. The Wallaby is a low wing variant of the Wombat and both models share a similar general layout.
Building the Wallaby was a breeze using the traditional built up balsa and ply method of construction with nothing complicated along the way. A flat bottom wing section provides slow and safe flight handling for beginners. The model is quite robust and will handle those hard knocks encountered during early training.
BUILDING THE MODEL
Study the plan carefully, cut out all the parts into kit form ready for assembling. Protect the plan with plastic or grease proof lunch wrap. Use a FLAT building board and build squarely and accurately.
Because the model is only three channel the wing has about 7 degree of dihedral for inherent stability. I decided to build the outer wing panels first, then the centre section with dihedral brace. The wing sections were then joined together and completed with sheeting.
After all the wing components are cut to size pin the lower spar and trailing edge down over the plan. Glue the ribs onto the spar and trailing edge, then add the leading edge and top spar.
The top D-box sheeting is added, the wing tip components can then be assembled and glued also with the sheeting on top side of the tips only. Allow to dry, then lift off the building board.
Build the centre wing section similarly with the addition of the dihedral braces.
The outer wing panels can now be glued to the centre section, prop up the outer wings 85mm under each wing tip. Complete the sheeting over the centre section and inboard wing panels over W1 from spar to trailing edge. Allow to dry then lift off board.
The underside D-box sheeting and centre section sheeting can now be completed.
Add cap strips onto ribs, top and bottom.
Lightly sand the entire wing, then glue the ply trailing edge reinforcement over the centre section area, bottom side only.
These are all flat 6.5mm balsa surfaces built up over the plan.
Sand the edges round and bevel the leading edge of the elevator and rudder for control movement. Fix the elevator joiner into place and hinge the elevator onto the tailplane, rudder onto the fin.
Glue the ply reinforcement piece onto the elevator. Fit the control horns for the rudder and elevator.
Cut out the fuselage sides from 3mm balsa sheet. Then prepare a left and right side by gluing the fuselage doublers and wing seating on the inside faces of the fuselage sides. Add nose blocks N at the front.
Using a square, or better still a building jig, glue the fuselage sides onto formers F2, F3 and F4, then draw the end together and glue in all other formers.
F1 is slightly offset for thrust lines. Glue the top spine into place, check for correct alignment of fuselage over plan.
Glue the turtle deck sides on, followed by the top sheet. When dry round off corners. Similarly glue the top front fuselage blocks, then sand to shape. The cockpit floor is then glued to complete the top fuselage deck.
Glue the undercarriage blocks in place. Bend the undercarriage legs to shape and trial fit onto blocks.
Fit the engine onto a radial mount and bolt onto F1. Temporarily fit the tank in place. Trial fit fuel lines, throttle cable to engine, then glue the tank floor in place.
Install the rudder, elevator and throttle servos together with cables or pushrods. Pin the fin and tailplane onto the fuselage and check control movement of rudder and elevator and also the throttle cable. When satisfied complete the fuselage with bottom sheeting, cross grained for strength.
Fit the wing dowels through the holes, test fit the wing. Glue the wing dowls in permanently after covering.
Make up tail wheel assembly or use a commercially available unit. Sand the entire fuselage for a smooth finish.
COVERING AND RADIO INSTALLATION
I covered my Wallaby using Profilm. I like bright, gaudy colours which makes them easy to see in the sky.
I installed a brand new Thunder Tiger .25 purchased from Big Eds Hobbies in Bathurst NSW. The Hi Tec four channel radio gear was fitted with the right stick controlling the throttle and rudder and the left stick handling the elevator only.
All controls were checked and with the motor run in the Wallaby was all set to go.
FLYING THE MODEL
With ideal conditions early one Sunday morning in the Central Tablelands the Bathurst Model Aircraft Club President was chosen for the gruelling task of test flying.
He needn't have poured so much sweat as the Wallaby rolled off on its take off run dead straight with no rudder input required.
A couple of clicks of down trim after throttling back was all it needed for slow settled straight and level flying. Less than half throttle kept the Wallaby hopping along just nicely.
Well what can you say about a three channel trainer? A simple loop, stall turn and a sort of barrel roll is about all you can do for aerobatics. But gently pottering around for someone wanting to come to grips with basic R/C functions is what the Wallaby is primarily intended for, and it does it well.
The Wallaby is a simple, easy to build and fly model with no vices which will appeal to a beginner or novice sport flyer.
Wallaby plans are available from:
Airborne Plans Service
AU$25.30 plus AU$2.00 P&H1
Plan No. 630
Click here to order this plan
This page was last modified on the 21-May-02