MFW June 2013 - Page 13

Profile Elevator Profile Components Profile cutting carbon laminate Make the overall spar depths slightly undersized, as it is easier to fill the surface rather than be stuck with a protruding spar. A dihedral brace wing joiner is glued to one side spar, and a box created on the other side to receive the joiner through the fuselage. Profile Spar and joiner box Servo plates and horn hard plates (top and bottom) are glued in flush. The leading and trailing edges are lined with balsa, PVA glued on as are the balsa shaped wingtips which can be hollowed out to reduce weight. I use Red Devil, One Time light-weight filler to repair any surface imperfections in the wings and fuselage foam edges. Once this is hard and sanded, then the brown paper covering can be applied, using a medium weight 65 gram paper from The Warehouse Stationary or similar. To glue it on, use an Aliphatic PVA thinned with 40% water applied generously to the foam or balsa surface. It pays to add a bit of tint to the glue so you see where it is applied. The brown paper, dampened with water spray and cut oversize is then laid on and spread out with a credit card. Then trim to oversize so there is enough to fold around the edges and make radial cuts into the edge to allow for the curvature and overlapping of the folds. Profile Covering of fuz Profile Spitfire wing cores The rudder is cut out of the fuselage profile foam sheet, a hinge post fitted and the foam is sliced or sanded to a thin trailing edge. A rudder horn balsa hard point is glued in and both sides are sheeted with 1.5 mm balsa and well sanded. The stab/elevator is cut from a sheet of 3.4mm coreflute and the edges are covered with 12mm wide strips of graphic-vinyl stretched around the periphery. A 250/300mm long 2.50/3.00mm carbon rod is glued into one of the stabilizer flutes to stiffen the surface, and a panel of 2.5mm sq balsa strips are inserted into the elevator across the joining strip to act as a stiffener and a hard point for the elevator horn. The hinge is formed by making a cut through the bottom surface each side of the hinge line and removing the coreflute fin between the surfaces. Again a generous amount of glue is brushed onto the folding strips and they are folded around the edges of the fuz and the wings. Then the whole of the outside surface is brushed with the diluted PVA which is left for a few minutes and then screeded off with the credit card. It is important to cover the other side of the piece being worked on before the first side dries so as to avoid warping. There is a surprising amount of shrinkage with the drying brown pa \XY][ ]YYH۝Y ]H[HY\ݙ\HH\XH\ []Hܘ\[\[HXY[YHHY\XY[[[H[[܈H]\[\ [HZ\\[Hݙ\[[H^Y]]\وۈ\\ۘHHݙ\[\\][HK[\X\[H[Y] Lܚ]\\[[HX\܈Z\\]Y [\\X[ۜ[H[YYZ[]ۙH[YK[]\‚