MFW June 2013 - Page 14

stage I add a 12mm wide strip of brown paper down the top surface aileron hinge line to strengthen the BP skin hinge. A patch above the aileron servo on the top surface, and as many BP panels as the desire for authenticity allows. The wing panels are now trial fitted and the roots marked on the fuselage and the balsa sheet cut out on both sides, a couple of millimetres oversize all round. The spar should locate through the fuselage and into the “spar box” in the other panel setting the correct dihedral. Using masking tape, mask a neat line around the root on the fuz side and also across the wing root out from the fuselage. A bit like the root panel fairing line. I now mix up a generous quantity of epoxy bog using ordinary epoxy and micro balloons which makes slow setting light weight and strong filler glue, of a thick creamy texture. Apply a good measure of this to the roots either side of the fuselage and also into the spar joiner box and then press the wings into place. A certain amount of bog will squeeze out and this plus any more needed can be shaped into a nice fillet between the wing and the fuselage using a round ended kitchen knife or other tool that suits your purpose. During all this, you need to regularly check the fuselage is perpendicular to the wing root and adjust as necessary, its incidence position will be held accurately by the balsa fuselage sides, so the cutouts need to be accurate, as once it all dries it becomes an immovable one piece object ! The painting is a matter of personal choice. My preference is to spray the whole aircraft with a generous coat of a one Step acrylic primer and then sand well just to about expose the BP. Profile Undercoated Then pay a visit to Resene and purchase the inexpensive acrylic test pots of the desired colour, thin it with methanol and paint away (brush or spray). They also have a great new range of metallic colours. Panel lines of your choice can be created from BP panels, panelling tape, or my preference is to use a rounded point 6B pencil, being careful not to tear through the surface. Extra detail can be added with graphics vinyl strips and litho plate double sided on, exhaust stacks, guns etc, the sky is the limit only constrained by your imagination. Decals and lettering add the final touch, again I like to keep the cost down, and create these myself from vinyl scraps sourced from a friendly sign writer. Flying has been a breeze from an underhand launch, with all the prototypes having flown away with little trim input. Control throws can be a personal preference, and for connection, I have used 2.56 rods with a Z-bend and a Sullivan gold clevis. For setup and comparative purposes, the relative specs are; Profile Brown Paper covered assembly Similarly, the elevator is masked and bogged into place all the time checking the alignment with the wings and fuselage. The ailerons are now marked out and remembering that the top surface is used as a skin hinge, the bottom surface brown paper is cut through, removing a strip and cutting out a vee of foam to allow the aileron to hinge down. Needless to say, care must be taken not to cut through the top surface. Relief is cut at each end allowing 1.5mm balsa end plates to be added. Now fold the aileron up onto the top surface and glue a strip of brown paper across the inside, covering the exposed foam and adding another thickness to the underside of the hinge line. Construction is now finished and trial fitting of the gear can take place and determination that the C of G placement is satisfactory. The models have proven quite forgiving, but the CofG can be adjusted by making a longer battery recess box, lining it with Velcro and moving the battery about as necessary. Different motors , gear and weight of materials will have an effect, so it’s not a bad practise to be able to move the battery to adjust the CofG rather than adding dreaded nose weight !